Bibliography for the fourth quarter of 1969

ICARUS 13, 114-151 (1970)

Bibliography for the Fourth Quarter of 1969 Air _Force Cambridge Research Laboratory, Laurence G. Hanscom _Field, Bedford, Massachusetts 01730 Received March, 3, 1970

Presented in this section is a bibliography on lunar and planetary subjects furnished by the Air Force Cambridge Research Laboratory and supplied and edited by John W. Salisbury. The categories included are as follows: Astrobiology, Comets, Meteorite Craters and Cratering Effects, Moon-General, Moon-Atmosphere, Moon-Figure and Internal Structure, Moon-Surface l~catures, Moon-Surface Layer, Moon-Temperature, Origin of the Solar System, Planets-General, Planets-Asteroids, PlanetsJupiter, Planets-Mars, Planets-Mercury, Planets-Neptune, Planets-Venus, and Tektites.--ED. ASTROBIOLOGY LEIOHTOI% R. B., HoxowlTz, 1%I.H., MURRAY, B. C., SHARP, R. P., HERRIMAI% A. H., YoI~G, A. T., SMITH, B. A., DAVIES, M. E., and LEOVY, C. B., 1969. Mariner 6 and 7 television pictures: Preliminary analysis. Science, V. 166, p. 49-67. See Planets--Mars.

DELSEMME, A. H., and MILLER, D. C., 1969. A n ew model of the cometary, nucleus and coma. Bulletin of the American Astronomical Society,

V. 1, p. 339. Former arguments which have ruled out adsorption processes in the cometary nucleus are shown to have no ground. However a new argument, based on absolute values of desorption times, is developed. I t shows that, if desorption were the leading factor, the major gas production would appear between 14 and 9 a.u., which COMETS entirely contradicts the observations. However, COImTEN, H. C., BI~OWN, D. W., ALBERT, if Whipple's model is accepted, water is likely to D. B., and GENBEttO, R. W., 1969. Search for be abundant, and then gas clathrates will solar proximate comets. Bulletin of the American simulate in some respects an adsorption with a Astronomical Society, V. l, p. 338-339. During very large specific area of about 500 m2/g. The evaporation of the gas clathrates icy matrix is the total solar eclipse of 22 September, 1968, the going to be the leading factor in gas production, search for small, bright comets near the sun was and will therefore control the liberation of the continued. The initial a t t e m p t by Donn and Dossin in 1963 yielded one nonstellar image other molecules and radicals imprisoned in this whose origin might be cometary. An intensive icy matrix. I n particular, former objections against large concentrations of radicals disphotographic search conducted in 1966 indicated appear, as they could be trapped within the the possibility of ten nonstellar objects within clathrate structure in larger concentrations than ten solar radii. These preliminary findings were in any other crystal lattice. The only other presented at the AAS Williams B a y meeting in 1967. Since that time, confirmation of seven of serious argument against the direct ejection of some of the observed ra~licals comes from the the ten images has been reported by an indeobserved lifetimes in the inner coma, which have pendent observer. Most of t h e data from photobeen attributed to parent molecules, but the graphic and photoelectric observations made in identification of individual parent molecules has Siberia during the 1968 eclipse have been been unsuccessful so far. A model is developed reduced. There is good evidence for nine nonwhere the observed lifetimes are nothing else stellar images originating in the near-angular than lifetimes of ice grains in the evaporating vicinity of the sun. The observational results halo, releasing the radicals within an extended will be discussed, as well as the scanning, narrowband photometer which was designed source. Of course, the observed radicals still decay in the solar field. The pseudoadsorption especially for comet searches. Plans for the process leading to gas clathrates m a y also play March 1970 eclipse observation effort will be described along with a request for cooperative an important role in the building-up of intereffort from the astronomical community. (Ab- stellar grains. (Abstract of a paper presented at the August 1969 meeting of the American stract of a paper presented at the August 1969 meeting of the American Astronomical Society.) Astronomical Society.) 114

COM~.TS HAVNES, O. 1969. Capture of comets by Jupiter. Astrophysics andSpace Science, 9, p. 272282. The capture of comets in parabolic orbits by J u p i t er is investigated. The influence of the gravitational force of the Sun on the cometary orbit during the passage to J u p i te r ' s sphere of influence is taken into account. A comparison of the present results with previous calculations demonstrates the importance of the solar perturbations. I t is also shown t h a t captures of comets with parabolic orbits and repeated close passages to J u p i t e r cannot explain all of the observed cometary orbits found in the family of Jupiter. Jos s , P. C., H~mwi~, M., and MtmX,EMAN, D. O. 1969. Orientation-dependence of the evolution of long-period comet orbits. Bulletin

o/ the American Astronomical Society, V. l, p. 349-350. After a comet from the Oort cloud has been captured by planetary perturbations into a long-period orbit, stellar perturbations can no longer greatly change its heliocentric angular momentum. Consequently, the spatial orientation of the orbit is well defined from one perihelion passage to the next. However, over m a n y perihelion passages, the orbital orientation and perihelion distance slowly. Some orbits evolve in such a way t h a t the minimum possible distance of approach of the comet to J u p i t e r (Am) decreases with time, while for other orbits Am increases with time. For an orbit of the former type with Am ~< 1 a.u., the largest possible perturbation in ]1/a] increases with time, which enhances the probability t h a t such a comet will be injected into a hyperbolic orbit (1/a < 0) and lost from the long-period cloud. For given orbital inclination, the orbit with m a x i m u m A m (which tends to have lower probability for ejection from the cloud) is that for which the latitude of perihelion is m a x i m u m in absolute value. This is reflected in the observational statistics by a strong correlation between latitude of perihelion and inclination. In other words, the cloud of long-period comets is not isotropie. This anisotropy m a y have a bearing on the problem of the possible capture of long-period comets into short-period orbits. The quantitative theory is simplest for comets with small perihelion distances. Detailed numerical calculations have been carried out on 100 hypothetical orbits with perihelion distances of 0.1 a.u. and 190 orbits with somewhat larger initial perihelion distances. The results confirm the above conclusions and reproduce the observational statistics, provided the intrinsic lifetimes of the long-period comets are assumed to be on the order of a few thousand perihelion passages. (Abstract of a paper presented at the August

115

1969 meeting of the American Astronomical Society.) MARSDEN, B. G. 1969. On the relationship between comets and minor planets. Bulletin of the American Astronomical Society, V. 1, p. 353354. The studies on the nongravitational forces affecting the motions of comets lend support to the notion t h a t some of the minor planets m ay be defunct cometary nuclei. There is a tendency for the magnitude of these forces to decrease with time; while P/Arend-Rigaux and P/ N eu j m i n 1, two comets that appear to be physically very much like minor planets, are not noticeably affected by nongravitational forces at all. The Apollo and Amor planets can possibly be explained as the remnants of comets t h a t have experienced secular accelerations for a long time in the past. However, if P/Arend-Rigaux, P Neujmin 1 and probably Hidalgo are objects in the transition phase, there should exist now a number of minor planets with orbits indistinguishable from those of the comets of the J u p i t e r family. Although there are broad similarities between the orbits of the comets and of the minor planets there remains the important difference that the comets frequent]y have close encounters with Jupiter, whereas the minor planets (except for Hidalgo) do not, being involved if necessary in librations t h a t preclude the possibility of such encounters. Further results concerning the librations of individual minor planets are presented. The m a t t e r of librations is discussed as it pertains to comets. In spite of their passes near Jupiter, comets are sometimes temporarily involved in ]ibration for several libration periods. The two comets that have been the most successful at avoiding J u p i t er are P/Arend-Rigaux and P/ N eu j m i n 1. This latter object is of particular interest since it has a revolution period of 18 yr and is in fact librating about the 2:3 resonance with Jupiter. The situation is influenced by Saturn, however, and it was an encounter with this planet in the year 773 that set the comet into libration originally. (Abstract of a paper presented at the August 1969 meeting of the American Astronomical Society.) ROEMER, B. 1969. Comet notes. Publications of the Astronomical Society of the Pacific, V. 81, p. 907-910. Discoveries of two new comets, Kohoutek, 1969b and Fujikawa, 1969d are described. Recovery of P/Whipple, 1969e and P/Honda-Mukos-Paj dusakova, 1969eisreported. An unsuccessful search for P/Slaughter-Burnham, 1958 VI and successful observations of P / F a y e and P/Comas Sola, 1968g are mentioned. A restudy of past motion of P/Tempel-Swift by

116

AFCRL BIBLIOGRAPHY

Marsden suggests that it may, after all, be observable in December. SEKANn~A, Z. 1969. Dynamical and evolutionary aspects of gradual deactivation and disintegration of short-period comets. The Astronomical Journal, V. 74, p. 1223-1234. Massloss rates averaging O.1 to 1% of the total mass per revolution have been found for six shortperiod comets from the nongravitational terms in the equations of motion applied by Mardsen. The escaping m a t t e r is believed to be of the nature of a neutral gas and to be mostly invisible. The steep decrease in nongravitational activity noticed for some of the six comets is interpreted as a rapid-loss process of the comets' reservoirs of volatile materials. The comparison of the present values of the half-lives of the comets with the half-lives of their nongravitational activity strongly suggests that nowadays the relative deactivation rates characterizing the decrease in the activity of the comets are several orders of magnitude higher than the corresponding mass-loss rates. I n other words, the short-period comets apparently do not disintegrate to nothing. Particular attention is given to the secular variations in the nongravitational parameter K of P/Encke. Possible solutions are studied under restricted conditions for estimating secular variations in the revolution period of PfEncke due to the nongravitational mechanism over very long periods in the past. I t is concluded t h a t the mechanism is powerful enough to reduce strongly the comet's orbital energy during an interval of time of the order of 10,OO0 yr, and that a "core-mantle" model of the comet's nucleus, with a core of a porous solid skeleton filled by ices and enveloped by a very thick icy layer, m a y provide the best interpretation of the present results. I t is believed that after complete loss of its volatile materials, the deactivated core of the original nucleus of P / E n ek e will become a minor planet of the Apollo type. S E K A ~ A , Z. 1969. Dynamical aspects of gradual disactivation and disintegration of short-period comets. Bulletin of the American Astronomical Society, V. l, p. 361. Mass-loss rates of 0.1-1.0% of the total mass per revolution, on an average, have been found for six short-period comets from the nongravitational terms in the equations of motion applied by Marsden. The escaping m a t t e r is believed to be of neutral gas nature, mostly invisible, A steep decrease in the nongravitational activity is noticed for some of the six comets, interpreted as a rapid exhaustion process of the comets' reservoir of volatile materials. The comparison of the present values of the comets' half-lives

with the half-lives of their nongravitational activity strongly suggests t h a t nowadays the relative disactivation rates are several orders of magnitude higher than the corresponding massloss rates. In other words, the short-period comets apparently do not disintegrate into nothing. A particular interest is given to the secular variations in the nongravitational parameter Xof P/Encke. Possible solutions are studied under restricted conditions for estimating secular variations in the revolution period of P /En ck e due to the nongravitational mechanism over very long periods in the past. I t is concluded t h a t a "core-mantle" model of the comet's nucleus, with a core made of a porous solid skeleton filled by ices, and enveloped by a very thick icy layer m a y apparently interpret the present results most properly. I t is believed t h a t after a complete exhaustion of volatile materials, the disactivated core of the original nucleus o f P / En ck e will become a minor planet of the Apollo type. (Abstract of a paper presented at the August 1969 meeting of the American Astronomical Society.) VAN~YSEK, V. 1969. Determination of the lifetime of parent molecules in comets from the brightness outbursts. Publications of the Astronomieal Society of the Pacific, V. 81, p. 840-847. The possibility of using the brightness outbursts or flares in comets for determination of the lifetime of parent molecules is discussed. I t is shown that monochromatic measurements of the comets' flares carried out photoelectrically m ay be a very useful method for a determination of the upper limit of the lifetime of C1~ and C2 precursors. Vx~vYSV,K, V. 1969. Dissociation processes in comets. Bulletin of the American Astronomical Society, V. 1, p. 367. A method for determination of the lifetime of parents of the radicals in cometary atmospheres is discussed. The method which is based on intensity variation of the molecular emission lead to the estimation of upper limits of lifetimes for CN and C~ precursors about 144 sec. This results in an agreement with previously estimated lifetimes, however, incompatible with photodissociation hypothesis. Some possible processes of formation of radicals are discussed. I t is shown t h a t there is some link between the lifetime of parent molecules and the presence of dust particles. I t cannot be excluded t h a t yet unknown compounds, perhaps some type of unstable molecules with rather large geometrical and dissociation cross sections, are sources of the observed radicals in comets. (Abstract of a paper presented at the August 1969 meeting of the American Astronomical Society.) VSEKHSVAYATSKII,S. K. 1969. The m a x i m u m

METEORITE CRATERS AND CRATERING EFFECTS l e n g t h o f c o m e t tails a n d some c o n s i d e r a t i o n s o n t h e i r classification. Soviet Astronomy--A.J., V. 15, p. 343-351. T h e m a x i m u m l e n g t h s o f c o m e t t a i l s are c o m p a r e d w i t h t h e o r b i t a l p r o p e r t i e s and the absolute magnitudes of the comets. A r g u m e n t s are g i v e n for t h e o c c u r r e n c e o f t y p e I I d u s t tails in s h o r t - p e r i h e l i o n c o m e t s a n d t y p e I I m o l e c u l a r t a i l s i n b r i g h t c o m e t s . I t is e s t a b lished t h a t c o m p o u n d tails of differing n a t u r e c a n e x i s t aV v a r i o u s d i s t a n c e s f r o m t h e nucleus, a n d t h a t t w o p r i n c i p a l p a r e n t molecules m a y b e r e s p o n s i b l e for t y p e I gaseous p l a s m a tails. S o m e n e w c o m e t tail classifications a r e p r o p o s e d . METEORITE EFFECTS

CRATERS AND CRATERING

FUDALI, R . F. 1969. Coesite f r o m t h e R i c h a t D o m e , M a u r i t a n i a . A m i s i d e n t i f i e a t i o n . Science, V. 166, p. 228-230. T h e " s h a t t e r e d s a n d s t o n e " f r o m R i c h a t r e p o r t e d to c o n t a i n coesite is a t e c t o n i c breccia a n d p r o b a b l y r e p r e s e n t s a s h e a r zone d e v e l o p e d d u r i n g t h e s t r u c t u r a l d o m i n g . A n o p t i c a l a n d x - r a y e x a m i n a t i o n of concent r a t e s f r o m t h i s breccia d e m o n s t r a t e d t h a t t h e s u p p o s e d x - r a y reflections o f coesite a r e a c t u a l l y due to barite, introduced into the permeable c r u s h e d zone b y g r o u n d w a t e r . BANDERMANN, L. W., a n d SINGER, S. F. 1969. Interplanetary dust measurements near the e a r t h . Reviews of Geophysics, V. 7, p. 759-797. The impact of dust particles on space vehicles n e a r t h e e a r t h gives i m p o r t a n t i n f o r m a t i o n a b o u t i n t e r p l a n e t a r y d u s t . Satellite i m p a c t measurements have been made with two types o f d e t e c t o r s : acoustic a n d p e n e t r a t i o n d e t e c t o r s . These types of detectors correspond to moment u m a n d e n e r g y restrictions, respectively, o n t h e i m p a c t r a t e of d u s t . T h e e a r l y a c o u s t i c d a t a showed a greatly enhanced rate near the earth, w h i c h s u g g e s t e d t h a t t h e r e w a s a h i g h concentration near the earth ("dust belt"). Quite to the c o n t r a r y , f r o m t h e o r y n o sensible e n h a n c e m e n t in c o n c e n t r a t i o n cax~,be~de~dved b u t , i n s t e a d , a moderate enhancement in impact rate, depending o n t h e g e o c e n t r i c v e l o c i t y of the~ particles. T h e d u s t b e l t w o u l d t h e r e f o r e exist o n l y as a consequence of the measurement technique. H e r e t h e a u t h o r s r e v i e w t h e t h e o r y t h a t allows us t o c a l c u l a t e t h e following, for a g i v e n geocentric velocity of dust particles and a distribut i o n of velocities (all isotopic): (1) t h e c o n c e n t r a t i o n ; (2) t h e f l u x ; a n d (3) t h e i m p a c t r a t e (mom e n t u m - a n d e n e r g y - l i m i t e d ) a t v a r i o u s dist a n c e s f r o m t h e e a r t h a n d for v a r i o u s d e t e c t o r velocities so as t o b r a c k e t all possible experim e n t a l s i t u a t i o n s . W i t h t h e use o f t h e s e results, it is t h e n possible t o a n a l y z e a n d c o m p a r e

l 17

r e s u l t s f r o m different e x p e r i m e n t s . O f t h e e x p e r i m e n t a l d a t a reviewed, b o t h U.S. a n d R u s s i a n , o n l y c e r t a i n are selected for a m o r e d e t a i l e d analysis. T h e t h e o r y a c c o u n t s well for t h e o b s e r v e d p e n e t r a t i o n d a t a in s p a c e vehicles flown n e a r t h e e a r t h a n d t h e m o o n ; t h e y lead t o a zodiacal d u s t m o d e l similar t o v a n de H u l s t ' s model, h a v i n g a p a r t i c l e p o p u l a t i o n p r e d o m i n a n t l y in t h e m i c r o n a n d d e c a m i c r o n size r a n g e ( r a t h e r t h a n s u b m i e r o n ) , w i t h a flat ( r a t h e r t h a n steep) size d i s t r i b u t i o n , a n d w i t h geocentric velocities of 5 t o 15 k m / s e c . A t h e o r e t i c a l a n a l y s i s is also p r e s e n t e d for a n o n i s o t r o p i c v e l o c i t y d i s t r i b u t i o n . T h i s is o f p r a c t i c a l imp o r t a n c e for v e r y s m a l l particles, w h i c h , are p a r t l y s u p p o r t e d b y solar r a d i a t i o n p r e s s u r e a n d therefore develop a streaming velocity with r e s p e c t t o t h e e a r t h ; in a d d i t i o n , t h e e a r t h itself i n t r o d u c e s a n a s y m m e t r y , since its o r b i t a l v e l o c i t y v a r i e s t h r o u g h o u t t h e year. N u m e r i c a l r e s u l t s are g i v e n for p r e d i c t e d a s y m m e t r i e s in c o n c e n t r a t i o n , influx o f d u s t i n t o t h e a t m o s p h e r e , a n d in t h e satellite i m p a c t r a t e s . I m p a c t r a t e s f r o m s o m e satellites e x h i b i t e d s u c h a s y m m e t r i e s , a n d t h e s e cases s u p p o r t t h e h y p o t h e s i s t h a t t h e heliocentric dust orbits have small inclination a n d s m a l l e c c e n t r i c i t y . T h e s e r e s u l t s are inconclusive b e c a u s e t h e d a t a are s c a n t ; a s y s t e m atic a n a l y s i s of all a v a i l a b l e i m p a c t d a t a w i t h r e s p e c t to a s y m m e t r i e s is n e e d e d . BREd'r, R., a n d HmoxNS, G. T. 1969. Cliftonite : A p r o p o s e d origin, a n d its b e a r i n g o n t h e origin o f d i a m o n d s in m e t e o r i t e s . Geochimica et Cosmochimica Acts, V. 33, p. 1473-1484. Cliftenite, a p o l y c r y s t a l l i n e a g g r e g a t e of g r a p h i t e w i t h s p h e r u l i t i c s t r u c t u r e a n d c u b i c m o r p h o l o g y , is k n o w n i n 14 m e t e o r i t e s . Some w o r k e r s h a v e c o n s i d e r e d i t t o b e a p s e u d o m o r p h a f t e r diamonds, and have used the proposed diamond a n c e s t r y as e v i d e n c e o f a m e t e o r i t i c p a r e n t b o d y of a t least l u n a r d i m e n s i o n s . Careful e x a m i n a t i o n of m e t e o r i t i c s a m p l e s i n d i c a t e s t h a t e l i f t o n i t e forms by precipitation within kamacite. The a u t h o r s h a v e also d e m o n s t r a t e d t h a t g r a p h i t e w i t h cubic m o r p h o l o g y m a y be s y n t h e s i z e d in a F e - N i - C alloy a n n e a l e d in a v a c u u m . T h e a u t h o r s t h e r e f o r e s u g g e s t t h a t a h i g h p r e s s u r e origin is u n n e c e s s a r y for m e t e o r i t e s w h i c h c o n t a i n cliftonite, a n d t h a t t h e s e m e t e o r i t e s were f o r m e d a t low pressures. T h i s conclusion is in a g r e e m e n t w i t h o t h e r r e c e n t evidence. T h e a u t h o r s also s u g g e s t that recently discovered cubes and cuboo c t a h e d r a o f l o n s d a l e i t e in t h e C a n y o n D i a b l o m e t e o r i t e are p s e u d o m o r p h s a f t e r eliftonite, n o t d i a m o n d , as h a s p r e v i o u s l y b e e n suggested. B ~ c H , T. E., a n d FUCHS, L. H . 1969. A n e w m i n e r a l : B r e z i n a i t e , CrsS4, a n d t h e T u c s o n m e t e o r i t e . The American Mineralogist, V. 54, p.

118

AFCRL BIBLIOGRAPHY

1509-1518. Brezinaite, a new c h r o m i u m sulphide, occurs in t h e m e t a l m a t r i x a n d contiguous t o silicate inclusions in t h e Tuscon iron meteorite. T h e following average composition of brezinaite was d e t e r m i n e d b y t h e electron m i c r o p r o b e : Cr 48.3; F e 3.9; V 1.61; Ti 0.96; Mn 0.86; Ni 0.08; S 45.0, s u m 100.71 wt.~o. The unit cell is monoclinic w i t h a = 5.96 ± 0.01, b = 3.425 g0.005, a n d c = 11.27 g-0.015 /~; ~ = 91 ° 32", V = 229.97 A a. Calculated X - r a y density is 4.12 g / c m 8 (Z ~ 2). V e r y low iron c o n t e n t o f t h e silicates, presence of c h r o m i u m sulphide, significant a m o u n t s of silicon in t h e nickel-iron, a n d t h e chalcophile b e h a v i o r of v a n a d i u m indicate a v e r y h i g h degree of r e d u c t i o n in Tucson similar to e n s t a t i t e chondrites a n d e n s t a t i t e achondrites. BUSECK, P. R., a n d GOLDSTEII~, J . I. 1969. Olivine compositions a n d cooling rates of pallasitic meteorites. Geological Society of America BuUe~in, V. 80, p. 2141-2158. E l e c t r o n m i c r o p r o b e m e a s u r e m e n t s of olivine a n d m e t a l in a b o u t 85~o o f t h e k n o w n pallasites were made. T h e olivines are uuzoned, a n d coexisting crystals w i t h i n m o s t pallasites h a v e identical compositions. This indicates a high degree of i n t e r n a l equilibrium. R e l a t i v e to terrestrial olivines, pallasitic olivines are d e p l e t e d in Ni. T h e r m o c h e m i c a l calculations d e m o n s t r a t e t h a t t h e low N i c o n t e n t s of pallasitic olivines are consistent w i t h m e t a l - o l i v i n e e q u i l i b r i u m a t 1000°C or less. Cooling rate m e a s u r e m e n t s show t h a t t h e pallasites cooled m o r e slowly (0.5 ° to 2.0°C per million years) t h a n t h e bulk of t h e iron m e t e o r i t e s a n d t h a t t h e pallasites form' a h o m ogeneous cooling r a t e group. Application of a modified P r i o r ' s rule t o t h e pallasites suggests t h a t olivine a n d m e t a l equilibrated in t h e pres. ence of o t h e r silicates. T h e observed compositional distribution of olivine from pallasites is c o m p a t i b l e w i t h t h a t p r e d i c t e d f r o m a chondritic p a r e n t melt. The pallasites were p r o b a b l y derived f r o m deep w i t h i n t h e i r p a r e n t body, either at or n e a r t h e core. Most iron m e t e o r i t e s were either formed f r o m different p a r e n t bodies or c a m e f r o m isolated m e t a l pools within t h e silicate m a n t l e . COMERFORD, M. F. 1969. Meteorites: An X - r a y analysis of d e f o r m e d k a m a c i t e . Journal of Geophysical Research, V. 74, p. 6675-6678. A n X - r a y line-broadening analysis was carried out to s t u d y t h e degree and n a t u r e of lattice d a m a g e t h a t is present in t h e k a m a c i t e phase of iron meteorites. Single plates of k a m a c i t e were r e m o v e d from t h r e e octahedrites, and diffractionline profiles were m e a s u r e d on a s p e c t r o m e t e r for several orders of (110) and (200) reflections. W i t h identical X - r a y g e o m e t r y , corresponding

line-profile m e a s u r e m e n t s were m a d e of t h e (110) a n d (200) reflections f r o m an a n n e a l e d single crystal in order to correct for i n h e r e n t geometrical breadths. The contributions of t h e two principal factors affecting k a m a c i t e line b r e a d t h , i.e., particle size and elastic strain, h a v e been evaluated. T h e results are e x a m i n e d in t h e light of t h e probable state of t h e k a m a c i t e , as inferred f r o m metallographic observations. CooK, A. F., and FRAZ~LI~¢, F. A. 1969. Meteoroidal b o m b a r d m e n t of S a t u r n ' s rings.

B u l ~ i n el the American Astronom~l Society, V. 1, p. 338. A n e s t i m a t e of t h e rate of i m p a c t on S a t u r n ' s rings b y meteoroids can only be m a d e f r o m observations of meteoroids a t t h e E a r t h . W h i p p l e has shown t h a t meteoroids and particles of t h e zodiacal cloud n e a r t h e E a r t h p r o b a b l y originate p r e d o m i n a n t l y f r o m periodic C o m e t E n c k e a n d secondarily f r o m o t h e r short-period comets of J u p i t e r ' s family. H o w e v e r , a comp o n e n t of meteors and comets in n e a r l y parabolic orbits of r a n d o m orientation is also observed. W e h a v e e m p l o y e d a correction developed b y Lewin for observational selection to establish t h e d e n s i t y of this c a t e g o r y of meteoroids near t h e E a r t h . W e t h e n e x t r a p o l a t e this q u a n t i t y to its v a l u e n e a r Saturn. Our discussion of m e t e o r o i d a l i m p a c t s on S a t u r n ' s rings n a t u r a l l y proceeds in two stages. The first considers t h e v e l o c i t y distribution of i m p a c t i n g particles largely d e t e r m i n e d b y S a t u r n ' s g r a v i t a t i o n a l field. T h e second stage employs m a t h e m a t i c a l representations of e x p e r i m e n t s on h y p e r v e l o c i t y i m p a c t . W e find t h a t m o s t of t h e spall orbits to t h e n e x t node on t h e plane of the rings or b a c k to t h e node of origin and reimpinges on t h e ring. Some spall orbits into t h e a t m o s p h e r e of S a t u r n a n d still less leaves in escaping orbits. Cascading seconda r y spall does n o t p l a y an i m p o r t a n t role in t h e loss of m a t e r i a l either to t h e p l a n e t or in escaping orbits. I t is not clear w h e t h e r t h e rings are gaining or losing mass, b u t a n y change is v e r y slow. This result is in stark c o n t r a s t to t h a t r e p o r t e d b y B a n d e r m a n n a n d W o l s t e n c r o f t at t h e H a w a i i meeting, where an erosion of ~ 50 m of ring m a t e r i a l during t h e solar s y s t e m lifetime was proposed. (Abstract of a p a p e r presented a t t h e A u g u s t 1969 m e e t i n g o f t h e A m e r i c a n Astronomical Society.) COOK, A. F., a n d FRAXffKLIlff,F . A . 1969. The effect of m e t e o r o i d a l b o m b a r d m e n t on S a t u r n ' s

rings. Smithsonian Astrophysical Observatory Special Report 304, 31 pp. This s t u d y tries to establish w h e t h e r S a t u r n ' s rings are undergoing a loss or a gain of m a t e r i a l as a result of impacts w i t h i n t e r p l a n e t a r y particles. C o m e t a r y meteoroids p r o b a b l y d o m i n a t e o v e r interstellar d u s t at Saturn, and meteoroids f r o m comets like

METEORITE CRATERS AND CRATERING EFFECTS

P / C o m e t H a l l e y p r o b a b l y c o n s t i t u t e t h e b u l k of t h e i n t e r p l a n e t a r y d u s t n e a r S a t u r n . M o s t of t h e spalled fragments from the ring particles travel e i t h e r t o t h e o t h e r n o d e or b a c k t o t h e n o d e of origin a n d are r e c o v e r e d b y t h e rings. Some fragm e n t s are lost i n t o e s c a p i n g o r b i t s : r a t h e r m o r e e n t e r t h e p l a n e t ' s a t m o s p h e r e . T h e r e is s o m e d o u b t as t o w h e t h e r t h e r i n g s are slowly s e c r e t i n g or losing m a t t e r , a l t h o u g h o u r r e s u l t s s o m e w h a t f a v o r t h e l a t t e r . I f n e t erosion is t a k i n g place, its m a x i m u m a m o u n t in 4 × 109 y e a r s is a b o u t 3 g c m -~ or a d e p t h of 60 c m for a d e n s i t y o f t h e r i n g p a r t i c l e s n e a r t h e i r surfaces of 0.05 g e m a. E r o s i o n as v a p o r i z e d ice (steam) is p r o b a b l y q u i t e negligible. T h e r a t e of i m p i n g e m e n t o f s p e l l e d m a s s o n S a t u r n is a t m o s t s i m i l a r t o t h a t o f m e t e o r i t i c m a s s , a b o u t 10 k g sec -1. T h i s is m u c h t o o s m a l l t o h a v e a n y o b s e r v a b l e effect on the atmosphere. FUCHS, L. H . 1969. O c c u r r e n c e of c o r d i e r i t e and aluminous orthoenstatite in the Allende m e t e o r i t e . The American Mineralogist, V. 54, p. 1645-1653. T h e first m e t e o r i t i c o c c u r r e n c e o f cordierite, in a n o d u l e in t h e A l l e n d e T y p e I I I c a r b o n a c e o u s c h o n d r i t e , is r e p o r t e d . X - R a y p o w d e r p a t t e r n s i n d i c a t e t h a t its s t r u c t u r e is v e r y close t o t h a t o f h e x a g o n a l , or h i g h cordierite. A s s o c i a t e d m i n e r a l s are a l u m i n o u s o r t h o e n s t a t i t e , a n o r t h i t e , spinel, olivine, a n d sodalite. A discussion o f t h e m i n e r a l a s s e m b l a g e is p r e s e n t e d b u t it c a n n o t b e e s t a b l i s h e d w h e t h e r t h e i n c l u s i o n f o r m e d as a h i g h l y f r a c t i o n a t e d s y s t e m w i t h i n t h e m e t e o r i t e or as p a r t of a c h e m i c a l - p r e s s u r e e n v i r o n m e n t foreign t o t h a t i n d i c a t e d for t h e m e t e o r i t e . GI~DILIS, L. M., DXVARI, N. B., a n d REZNOVA, L. V. 1969. Solar r a d i a t i o n p r e s s u r e o n p a r t i c l e s o f i n t e r p l a n e t a r y d u s t . Sower Astronomy--A.J., V. 13, p. 114-119. T h e p r e s e n t article c o n t a i n s r e s u l t s o f a c a l c u l a t i o n of t h e f a c t o r s affecting t h e effectiveness w i t h w h i c h solar r a d i a t i o n p r e s s u r e a c t s o n s p h e r i c a l p a r t i c l e s of v a r i o u s s u b s t a n c e s a n d a c a l c u l a t i o n o f t h e force e x e r t e d b y solar radiation pressure on particles of interplanetary d u s t as a f u n c t i o n o f t h e i r r a d i u s a n d d e n s i t y . T h e p a r t i c l e p a r a m e t e r s a t w h i c h solar r a d i a t i o n p r e s s u r e exceeds t h e g r a v i t a t i o n a l a t t r a c t i o n o f t h e s u n are e v a l u a t e d . I t is c o n c l u d e d t h a t t h e m i c r o n a n d s u b m i c r o n c o m p o n e n t s of i n t e r p l a n e t a r y d u s t m u s t p r i m a r i l y consist o f comp a r a t i v e l y d e n s e (dielectric a n d a b s o r b i n g ) p a r t i c l e s o f a n a s t e r o i d a l origin. F o r p a r t i c l e d i m e n s i o n s of t h e o r d e r of several m i c r o n s or larger, as well as for v e r y s m a l l d i m e n s i o n s , i n t e r p l a n e t a r y s p a c e m u s t c o n t a i n less d e n s e p a r t i c l e s of c o m e t a r y origin in a d d i t i o n t o t h e a s t e r o i d a l particles. A b s o r b i n g p a r t i c l e s w i t h

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r a d i i less t h a n 0.1-0.5/~ c a n n o t b e p r e s e n t in tile interplanetary dust. HELLYE~, B. 1969. S t a t i s t i c s of m e t e o r i t e falls. Earth and Planetary Science Letters, V. 7, p. 148-150. D a t a f r o m a large n u m b e r of o b s e r v e d m e t e o r i t e falls h a v e b e e n i n v e s t i g a t e d . Correlations have been sought between the ratio of m u l t i p l e falls t o t o t a l falls a n d (a) t h e m a s s of t h e m e t e o r i t e , (b) t h e local t i m e o f fall a n d (c) t h e class of t h e m e t e o r i t e . I t w a s f o u n d t h a t t h e p r o b a b i l i t y of f r a g m e n t a t i o n is s t r o n g l y d e p e n d e n t o n t h e m a s s o f t h e b o d y . T h e r a t i o of m u l t i p l e falls is r e l a t i v e l y h i g h for c a r b o n a c e o u s e h o n d r i t e s a n d low for irons b u t seems i n d e p e n d e n t o f all o t h e r f a c t o r s considered. HOHENBERG, C. M. 1969. R a d i o i s o t o p e s a n d t h e h i s t o r y of n u c l e o s y n t h e s i s i n t h e g a l a x y . Science, V. 166, p. 212-215. See Origin of t h e Solar S y s t e m . HOH~,NBERG, C. M., a n d REYNOLDS, J . H . 1969. P r e s e r v a t i o n o f t h e i o d i n e - x e n o n r e c o r d in m e t e o r i t e s . Journal of Geophysical Research, V. 74, p. 6679-6683. I n i o d i n e - x e n o n d a t i n g o f the Abee enstatite chondrite by a technique that c o m b i n e s n e u t r o n a c t i v a t i o n a n d stepwise m a s s s p e c t r o m e t r i c a n a l y s i s of t h e x e n o n s u b s e q u e n t l y released b y h e a t i n g , one s a m p l e was p r e h e a t e d t o 1200°C in v a c u u m before t h e n e u t r o n i r r a d i a t i o n . A l t h o u g h m o s t of t h e x e n o n w a s expelled in t h e p r e h e a t i n g , t h e basic I - X e c o r r e l a t i o n w a s u n d i s t u r b e d e v e n in a r a n g e of t e m p e r a t u r e s w h e r e t h e r e h a d b e e n s u b s t a n t i a l loss o f radiogenic Xe129 d u e t o t h e p r e h e a t i n g . T h e r e s u l t suggests t h a t i o d i n e - x e n o n d a t i n g d e p e n d s for its v a l i d i t y n o t u p o n q u a n t i t a t i v e r e t e n t i o n b u t u p o n w h a t is effectively p r o p o r t i o n a t e iodinex e n o n r e t e n t i o n . One m o d e l w h i c h e x h i b i t s t h i s b e h a v i o r w o u l d h a v e t h e r e t e n t i v e l y s i t e d iodine a n d radiogenic X e 129 coexisting a t t r a p p i n g sites, w h i c h u n d e r g o t h e r m a l r u p t u r e as h e a t i n g proceeds. U n t i l t h e r m a l r u p t u r e , t h e s t r a p p i n g sites r e t a i n b o t h iodine a n d x e n o n q u a n t i t a t i v e l y . KEA¥, C. S. L., a n d ET,T,YETT, C. D. 1969. S o u t h e r n h e m i s p h e r e m e t e o r r a t e s . Memoirs of the Royal AstronomicalSociety, V. 72, p. 185-232. M e t e o r r a t e d a t a of h i g h q u a l i t y a r e p r e s e n t e d from a controlled-parameter radar survey of m e t e o r a c t i v i t y in t h e s o u t h e r n h e m i s p h e r e . T h e s u r v e y e x t e n d e d c o n t i n u o u s l y for 31 m o n t h s f r o m F e b r u a r y 1963 u n t i l A u g u s t 1965 inclusive. The data have been very thoroughly screened a n d t h e m e t e o r r a t e s p r e s e n t e d in t a b u l a r f o r m c o v e r a l m o s t 90°/0 of t h e s u r v e y period. T h e t a b l e s c o n t a i n a t o t a l of 2,304,333 m e t e o r s , a n a v e r a g e of 114 p e r h o u r . T h e a v e r a g e d i u r n a l v a r i a t i o n in m e t e o r a c t i v i t y is e x a c t l y s i m i l a r t o t h a t o b t a i n e d in a n earlier s u r v e y i n 1960-61 b u t some c h a n g e s are e v i d e n t in t h e a n n u a l v a r i a t i o n .

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AFCRL BIBLIOGRAPHY

T h e v a r i o u s f a c t o r s w h i c h influence t h e o b s e r v e d m e t e o r r a t e s are discussed. L~.~SKIY, L. K., MURIN, A. N., a n d APRUB, S. V. 1969. Diffusion of i n e r t gases f r o m s t o n e m e t e o r i t e s - - ( R a d i o g e n i c Argon). Geochemistry International, V. 5, p. 1081-1086. Diffusion p a r a m e t e r s for t h e l i b e r a t i o n of 40Ar h a v e b e e n determined by a dynamic annealing method. T h e m e a s u r e d a c t i v a t i o n energies are (in k c a l / g a t o m ) : b r o n z i t e c h o n d r i t e s , 27 a n d 45; h y p e r s t h e n e c h o n d r i t e s , 21 a n d 37; a c h o n d r i t e s ( a u b r i t e s ) ; 21 a n d 22. L i m i t a t i o n s o n t h e t e m p e r a t u r e r e g i m e of c h o n d r i t e s h a v e b e e n calcul a t e d f r o m t h e s e results. LEVSKIY, L. K., MURIN, A. N., a n d APRUB, S. V. 1969. N a t u r e of t h e p r i m o r d i a l gases in m e t e o r i t e s . Geochemistry International, V. 5, p. 1182. T h e k i n e t i c s of p r i m o r d i a l gas diffusion from the Staroye Pesyanoye achondrite has been i n v e s t i g a t e d a s s u m i n g t h a t t h e m o d e of gas release o n h e a t i n g is d e p e n d e n t o n t h e m o d e of i n t r o d u c t i o n . Diffusion p a r a m e t e r s for a r g o n h a v e b e e n m e a s u r e d in m o d e l e x p e r i m e n t s b y d r i v i n g a r g o n a t o m s w i t h different energies i n t o polycrystalline targets and by thermal argon s o r p t i o n o n q u a r t z . I n t h e l a t t e r case a n i n v e r s e d e p e n d e n c e b e t w e e n t h e a m o u n t of s o r b e d gas a n d t h e g r a i n d i a m e t e r w a s n o t e d . I t is possible t o e x p l a i n t h i s o b s e r v e d r e l a t i o n in t e r m s of t h e i n h o m o g e n e i t y of t h e r e l a t i v e l y large m e t e o r i t i c p a r t i c l e s a n d t h e p r e s e n c e of t r a c e s of m a t e r i a l r i c h in p r i m o r d i a l gases. W h i l e n o t r e j e c t i n g t h e solar w i n d i m p r e g n a t i o n h y p o t h e s i s , it is n o t e d t h a t t h e r m a l i m p r e g n a t i o n h a s m u c h justificat i o n . ~ a s i n c o r p o r a t i o n is n o t d u e t o p r e s s u r e of t h e i n e r t gases in t h e free a t m o s p h e r e ; m o r e p r o b a b l y gas i n c o r p o r a t i o n c a n b e e x p l a i n e d b y t h e p r e s e n c e of i n t e r n a l a t m o s p h e r e s in t h e a s t e r o i d a l b o d i e s in w h i c h t h e p r i m o r d i a l d u s t p a r t i c l e s were dispersed. ( A b s t r a c t Only.) MA~TI, K . 1969. S o l a r - t y p e x e n o n : A n e w isotopic c o m p o s i t i o n o f x e n o n in t h e P e s y a n o e m e t e o r i t e . Science, V. 166, p. 1263-1265. X e n o n in t h e P e s y a n o e m e t e o r i t e is a m i x t u r e of several c o m p o n e n t s . S o l a r - t y p e x e n o n is a n e w c o m p o n e n t deficient in t h e n e u t r o n - r i c h isotopes as compared to both trapped chondritic and terrestrial atmospheric xenon. ~-ASUDA, A. 1969. L a n t h a n i d e s in t h e silicate inclusion o f t h e W o o d b i n e m e t e o r i t e . Nature, V. 224, p. 164-165. Silicate inclusion m a t e r i a l w e i g h i n g 235 m g was a n a l y z e d for l a n t h a n i d e s , a n d t h e i r a b u n d a n c e s were d e t e r m i n e d b y t h e isotope d i l u t i o n t e c h n i q u e . T h e r e l a t i v e a b u n d a n c e s of l a n t h a n i d e s in t h e W o o d b i n e inclusion are different f r o m t h o s e in c h o n d r i t e s . T h e W o o d b i n e silicate m a t e r i a l is also c h a r a c t e r i s t i c in s h o w i n g a r e l a t i v e d e p l e t i o n of e u r o p i u m b y

a f a c t o r o f 1.63; t h e silicate p h a s e of m e s o s i d e r i t e does n o t s h o w a e u r o p i u m d e p l e t i o n . T h u s , t h e silicate m a t e r i a l in W o o d b i n e is different f r o m b o t h the~ m e s o s i d e r i t e silicate p h a s e a n d t h e ehondrite. MORGAN, J. W., REBAGEY, T. V., SHOWALTER, D. L., NADKARNI, R . A., G u _ ~ , D. E., M c K o w N , D. M., a n d EHMANN, W . D. 1969. A l l e n d e m e t e o r i t e : Some m a j o r a n d t r a c e element abundances by neutron activation analysis. Nature, V. 224, p. 789-790. S o m e specific c o m p a r i s o n s of t h e e l e m e n t a l a b u n d a n c e s r e p o r t e d for A l l e n d e a n d for M o k o i a are given. T h e s i m i l a r i t y of t h e s e t w o m e t e o r i t e s e x t e n d s t o t h e t r a c e e l e m e n t a b u n d a n c e s r e p o r t e d in t h e present investigation. NILSSON, C. S., WRIGHT, F. W., a n d WILSON, D. 1969. A t t e m p t s t o m e a s u r e m i c r o m e t e o r o i d flux o n t h e e G O 2 a n d e G O 4 satellites. Journal of Geophysical Research, V. 74, p. 5268-5276. T h e micrometeoroid experiments on the eGO 2 and e G O 4 satellites are described. T h e a i m o f t h e e G O 2 e x p e r i m e n t w a s to m e a s u r e t h e velocities, masses, a n d o r b i t s o f d u s t p a r t i c l e s in t h e e a r t h ' s d u s t cloud. No o r b i t s were d e t e r m i n e d , a n d i t is questionable whether any micrometeoroids of m a s s > 1 0 -12 g i m p a c t e d o n t h e sensors d u r i n g t h e 1300 h o u r s in w h i c h good d a t a were o b t a i n e d . T h e e G O 4 e x p e r i m e n t w a s m o d i f i e d in a n a t t e m p t t o m e a s u r e a flux o b v i o u s l y m u c h smaller t h a n p r e v i o u s l y a n t i c i p a t e d . N o m i c r o m e t e o r o i d s c a p a b l e of p e n e t r a t i n g 4000 A of A1 h a v e i m p a c t e d o n i o n i z a t i o n sensors of t o t a l effective a r e a 5 c m 2 s t e r d u r i n g 3000 h o u r e x p o s u r e : T h u s , t h e a u t h o r s find t h a t t h e flux of m i c r o m e t e o r o i d s > 1 0 -12 g in t h e n e i g h b o r h o o d o f t h e e a r t h is less t h a n 2 x 10 - s p a r t i e l e s / m 2 sec 2 ~ ster. OSTIC, R. G., EL-BADR¥, H . M., a n d KOHMAN, T. P. 1969. I s o t o p i c c o m p o s i t i o n of m e t e o r i t i c t h a l l i u m . Earth and Planetary Science Letters, V. 7, p. 72-76. T h a l l i u m c o n t e n t s h a v e b e e n d e t e r m i n e d as 2.5 ± 0.5 × 10 -e in I v i g t u t , G r e e n l a n d , g a l e n a ; 7 ± 2 × 10 -10 in P l a i n v i e w c h o n d r i t e ; 1.5 ± 0.3 × 10 -9 in C a n y o n D i a b l o t r o i l i t e a n d 2.5 ± 0.5 × 10 - i s in C a n y o n D i a b l o m e t a l . T h e 205T1/203T1 r a t i o is i d e n t i c a l w i t h i n a b o u t 0 . 6 % of t h a t of t e r r e s t r i a l t h a l l i u m r e a g e n t , t h u s y i e l d i n g n o i n d i c a t i o n of e x t i n c t n a t u r a l r a d i o a c t i v i t y of 2°sPb (half-life ~ 24 m.y.). U s i n g p u b l i s h e d lead c o n t e n t s o f t h e m e t e o r i t i c m a t e r i a l s , of p l o t o f 205T1/2°aT1 v e r s u s 204pb/20aT1 h a s b e e n m a d e of o u r r e s u l t s a n d t h o s e of A n d e r s a n d S t e v e n s . Cogenetic p h a s e s i n i t i a l l y i n c o r p o r a t i n g 205pb s h o u l d yield a s t r a i g h t - l i n e isochron. O n l y l i m i t i n g slopes c a n b e i n d i c a t e d for v a r i o u s g r o u p s of d a t a . The uncertainties of these data and the indicated

METEORITE

CRATERS

AND

v a r i a b i l i t y of t h e T1/Pb r a t i o in m e t e o r i t i c m a t e r i a l s suggest t h a t m o r e precise a n d e x t e n s i v e m e a s u r e m e n t s m a y r e v e a l r a d i o g e n i c 205T1. RAlqCITELLI, L. A., PERKINS, R . W., COOPER, J . A., K A Y , , J . H., a n d WOGMA~, 1~. A. 1969. R a d i o - i o d i d e c o m p o s i t i o n of t h e A l l e n d e m e t e o r ite f r o m n o n d e s t r u c t i v e g a m m a - r a y s p e c t r o m e t r i c analysis. ScOnce, V. 166, p. 1269-1272. T h e c o n c e n t r a t i o n s of b e r y l l i u m - 7 , sodium-22, aluminum-26, potassium-40, scandium-46, vanadium-48, chromium-51, manganese-54, cobalt57, cobalt-60, a n d t h o r i u m - 2 3 2 ( t h a l l i u m - 2 0 8 ) have been measured in the Allende meteorite by nondestructive gamma-ray spectrometry. The h i g h c o b a l t - 6 0 c o n t e n t o f t h e m e t e o r i t e is i n d i c a t i v e of a p r e a t m o s p h e r i c b o d y w i t h a m i n i m u m effective r a d i u s o f 50 c e n t i m e t e r s a n d a w e i g h t of 1650 k i l o g r a m s ; t h e a l u m i n u m - 2 6 a c t i v i t y i n d i c a t e s a m i n i m u m e x p o s u r e age of 3 million years. ROOSEN, R . G., a n d WOLFF, C. L. 1969. A r e t h e l i b r a t i o n clouds real? Nature, V. 224, p. 571. To d e m o n s t r a t e t h a t o b s e r v a b l e c o n c e n t r a t i o n s o f i n t e r p l a n e t a r y d u s t m i g h t exist, t h e a u t h o r s h a v e c o n s i d e r e d t h e r e s u l t s f r o m five A m e r i c a n a n d Soviet satellites w h i c h c a r r i e d d u s t c o u n t i n g e x p e r i m e n t s a n d w h i c h o b s e r v e d m a n y periods o f s u s t a i n e d increases in t h e c o u n t i n g r a t e . T h e fine s t r u c t u r e of t h e V a n g u a r d I I I e v e n t is a b o u t 104 s w i t h a n i m p a c t r a t e o f a b o u t 10 -5 p a r t i c l e s era-2 s-1. T h e b r i g h t n e s s o f s u c h a c l o u d is well above the visual threshold of detection. Such clouds near the Earth could explain the many r e p o r t e d f l u c t u a t i o n s in b r i g h t n e s s a n d s h a p e o f t h e zodiacal l i g h t a n d g e g e n s c h e i n , a n d f u r t h e r f r o m t h e E a r t h m i g h t a c c o u n t for t h e clouds r e p o r t e d b y K o r d y l e w s k i a n d o t h e r s . T h e r e are m a n y possible e x p l a n a t i o n s of curious p a t c h e s o f l i g h t seen in t h e n i g h t s k y ; h o w e v e r , E a r t h - M o o n l i b r a t i o n clouds are v e r y unlikely. SIMMONDS, P. G., BAUMAN, A. J., BOLLIN, E . M., GELPI, E., a n d ORO, J . 1969. T h e u n e x t r a c t a b l e organic f r a c t i o n of t h e P e u b l i t o d e AIlende m e t e o r i t e : E v i d e n c e for its i n d i g e n o u s n a t u r e . Proceedings of the National Academy of Sciences, V. 64, p. 1027-1034. T h e P u e b l i t o de A l l e n d e m e t e o r i t e c o n t a i n s o n l y 0.1-0.5 p p m of s o l v e n t - e x t r a c t a b l e c a r b o n , m o s t or all of w h i c h is d u e t o t e r r e s t r i a l c o n t a m i n a t i o n . D e t e r m i n a t i o n s of t h e t o t a l c a r b o n c o n t e n t gives v a l u e s f r o m 0.23 t o 0 . 3 5 % . T h e p r e s u m e d i n d i g e n o u s i n s o l u b l e c a r b o n is t h u s p r e s e n t in a r a t i o of 2300:1 r e l a t i v e t o c o n t a m i n a n t c a r b o n . A s a m p l e of t h e m e t e o r i t e was e x t r a c t e d w i t h a deuterated solvent containing benzene:methanol (4:1 w/w) t o r e m o v e c o n t a m i n a n t s a n d t h e n was s u b j e c t e d t o p y r o l y s i s - g a s c h r o m a t o g r a p h y m a s s s p e c t r o m e t r y t o i n v e s t i g a t e t h e n a t u r e of

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121

the remaining carbon. The pyrolysis products ( a b o u t 20 p p m ) c o n s i s t e d chiefly of a r o m a t i c a n d substituted aromatic hydrocarbons. The pyrolysis r e s u l t s were c o n f i r m e d b y o x i d a t i v e t h e r m a l a n a l y s i s w h i c h s h o w e d t h a t t h e b u l k of t h e c a r b o n present was a macromoleeular structure and not graphite. This suggests that an insoluble nong r a p h i t e c o n d e n s e d a r o m a t i c p o l y m e r is i n d i g e n ous t o t h e m e t e o r i t e . T h e origin a n d precise chemical structure of this material has not been d e t e r m i n e d , b u t it b e a r s a superficial r e s e m b l a n c e t o coal-like s t r u c t u r e s . TURNER, F. J . , a n d ULBRICH, M. 1969. Comp a r i s o n of l u n a r w i t h t e r r e s t r i a l a n d m e t e o r i t i c rocks. Proceedings of the National Academy of Sciences, V. 64, p. 1016-1020. T h i s n o t e e x a m i n e s c r i t i c a l l y r e c e n t a t t e m p t s t o i d e n t i f y or closely c o r r e l a t e l u n a r surface s a m p l e s - - o n t h e basis o f a l p h a - s c a t t e r i n g a n a l y s i s - - w i t h t e r r e s t r i a l ign e o u s r o c k s (basalts) or w i t h e u c r i t e m e t e o r i t e s . B a s a l t s s h o w c o n s i d e r a b l e v a r i e t y ; b u t all h a v e c h e m i c a l c h a r a c t e r i s t i c s i n h e r i t e d f r o m terrestrial mantle rock melted under a limited range of terrestrial pressure-temperature conditions. W h a t is c h a r a c t e r i s t i c is n o t so m u c h t h e c o n t e n t of a n y p a r t i c u l a r e l e m e n t or oxide, e.g., SiO2 47-52 percent, but rather a complete chemical p a t t e r n in w h i c h s u c h r a t i o s as F e / M g a n d C a / ( N a + K ) show c o n s i s t e n t r e l a t i o n s h i p s t o Si c o n t e n t . T h e s e are t h e c h e m i c a l c r i t e r i a t h a t m i g h t b e useful in c o m p a r i n g t e r r e s t r i a l b a s a l t w i t h e x t r a t e r r e s t r i a l rocks, B a s a l t s also h a v e distinctive mineralogical and textural characteristics; a n d i f a l u n a r or m e t e o r i t i c r o c k is t o b e identified as b a s a l t it m u s t possess t h e s e , too. T u r k e v i c h ' s a n a l y s i s o f a l p h a - s c a t t e r i n g d a t a for l u n a r s a m p l e s ( S u r v e y o r V) s h o w significant departure from basaltic composition. Very high (Ca + K ) / N a a s s o c i a t e d w i t h d i s t i n c t l y h i g h Fe/Mg. I n b a s a l t s r e l a t i v e l y h i g h (Ca + K ) / N a - in n o case a p p r o a c h i n g t h e r e p o r t e d l u n a r v a l u e s - - t e n d s t o b e a s s o c i a t e d w i t h F e / M g v a l u e s lower than average. The same "lunar" pattern of high (Ca + K ) / N a a n d F e / M g a p p e a r s in r e c o r d e d analyses of eucrite meteorites. In the lunar s a m p l e s , Ti is n o t a b l y h i g h e r t h a n in b a s a l t s , a n d e v e n m o r e so t h a n in eucrites. I f e u c r i t e s are o f l u n a r origin t h e i r T i v a l u e s are, so far, a real anomaly. WAI, C. M., a n d WASSON, J . T. 1969. Silicon c o n c e n t r a t i o n s in t h e m e t a l o f iron m e t e o r i t e s . Geochiraica et Cosmochimica Aeta, V. 33, p. 1 4 6 5 1471. E l e c t r o n m i c r o p r o b e d e t e r m i n a t i o n s of Si in t h e m e t a l of 19 iron m e t e o r i t e s , i n c l u d i n g r e p r e s e n t a t i v e s o f t h e n i n e c h e m i c a l groups, r e v e a l Si c o n c e n t r a t i o n s b e l o w o u r d e t e c t i o n l i m i t ( a b o u t 25 p p m ) in all b u t t w o cases. T h e t w o o b j e c t s are T u c s o n , a n i r o n o f a n o m a l o u s

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is restricted to the t w o - b o d y p r o b l e m and radial tides a n d " w e a k " tidal friction are considered. E q u a t i o n s are developed to a c c o u n t for t e m p o r a l changes of t h e m o m e n t of inertia of t h e p l a n e t caused b y changes in t h e s t r u c t u r e a n d size of its core. The eccentricity of the Moon's orbit at 10 E a r t h radii is n u m e r i c a l l y calculated; it d e p e n d s on two quantities, n and tim, accounting, respectively, for changes of core dimensions a n d for t h e r a t e of dissipation in t h e interior of t h e Moon. T h e Moon e n t e r e d t h e R o c h e limit for some years, b u t in all cases it did so only for e x t r e m e l y short t i m e s ; therefore a c o m p l e t e disruption could n o t h a v e occurred. The limits of t h e possible values of tim, a c c o u n t i n g for t h e rate of dissipation in t h e interior of t h e Moon, p e r m i t one to conclude t h a t t h e ratio of t h e relaxation times TMoon/~'Earth should h a v e been a b o u t 10 -1 to 10 -2. The v a l u e of "rMoonhas been r e s t r i c t e d to 0.5-10 sec. This small v a l u e is regarded as a hint of a r e l a t i v e l y " h o t " Moon a t t h e t i m e of its capture. T h e c a p t u r e of the Moon b y t h e E a r t h is investigated, supposing t h a t dissipation t a k e s place only in t h e b o d y of t h e Moon b y radial tides. I t is found t h a t a p l a n e t o i d w i t h a r e l a t i v e v e l o c i t y v ~ = 1 km/sec could revolve a r o u n d t h e Sun in an i n d e p e n d e n t orbit no longer t h a n 10 e years at most. A f t e r this t i m e it would collide w i t h t h e E a r t h or be c a p t u r e d . To clear this discrepancy, t h e d e v e l o p m e n t of masses being created in t h e asteroidal belt a t a n y t i m e is investigated. A g r e e m e n t w i t h t h e MOON---GENERAL d e r i v e d t i m e scale can be a c h i e v e d only if t h e FALLER, J., WINER, I., CARRION, W., JOHNSON, f o r m a t i o n of masses in such orbits t o o k place no earlier t h a n 0.5-1 × 109 years before t h e Moon T. S., SPADIN, P,, ROBINSON, L., WAMPLER, E. J., was captured. and WIEBER, D. 1969. Laser b e a m directed at t h e JONES, M. r . 1969. A q u a n t i t a t i v e e v a l u a t i o n l u n a r retro-reflector a r r a y : Observations of t h e of t h e u n i f o r m i t y of t h e light scattering properties first returns. Science, V. 166, p. 99-102. On of t h e lunar surface. The Moon, V. 1, p. 31-58. 1 A u g u s t b e t w e e n 10:15 and 12:50 U n i v e r s a l A catalogue was compiled in t h e a u t h o r ' s Time, w i t h t h e Lick O b s e r v a t o r y 120-inch previous p a p e r (Jones, Icarus, V. 10, No. 1, 1969) (304-cm) telescope and a laser operating at of t h e r e l a t i v e brightness of 199 l u n a r features as 6943 angstroms, r e t u r n signals from an optical observed at phase angles of 2~1, 17~5, 32~5, retro-reflector a r r a y placed on t h e m o o n b y the 46~2, 59~4, and 72~I before full Moon, in t h e Apollo 11 a s t r o n a u t s were successfully detected. w a v e l e n g t h i n t e r v a l 5500 to 7000 A. The present A f t e r t h e r e t u r n signal was first d e t e c t e d it p a p e r is concerned w i t h an i n t e r p r e t a t i o n o f this c o n t i n u e d to appear w i t h t h e e x p e c t e d t i m e delay d a t a in t e r m s of t h e u n i f o r m i t y of t h e p h o t o for t h e r e m a i n d e r of t h e night. The observed m e t r i c function of t h e lunar surface. I f due range is in excellent a g r e e m e n t w i t h t h e predicted ephemeris. T r a n s m i t t i n g b e t w e e n 7 and 8 account is t a k e n of the effect of second order scattering it is found t h a t all t h e s u r v e y points joules per pulse, t h e authors found t h a t each studied scatter light according to t h e s a m e r e t u r n signal a v e r a g e d m o r e t h a n one photop h o t o m e t r i c function i n d e p e n d e n t of the t y p e electron. This is in good a g r e e m e n t w i t h calculaof terrain on which t h e y are located. tions of t h e e x p e c t e d signal strength. M~RCUS, A. H. 1969. Speculations on mass loss GERSTENKORN, H. 1969. The earliest p a s t of b y m e t e o r o i d i m p a c t a n d f o r m a t i o n of t h e t h e E a r t h - M o o n system. Icarus, V. 11, p. 189planets. Icarus, V. 11, p, 76-87. The ratio be207. F u n d a m e n t a l e q u a t i o n s are derived for t h e t w e e n mass of a meteoroidal projectile and t h e secular changes of t h e elliptic orbit of a satellite mass of ejecta f r o m t h e i m p a c t of t h e projectile u n d e r t h e action of tidal friction. The discussion

composition containing highly reduced silicate inclusions, and Horse Creek, a m e t e o r i t e which is m o r e a p p r o p r i a t e l y classified w i t h t h e c n s t a t i t e chondrites t h a n w i t h t h e iron meteorites. W e conclude t h a t m o s t (probably m o r e t h a n 99~o) of t h e iron m e t e o r i t e s contain less t h a n 30 p p m Si in t h e metal, and t h a t meteoritic evidence for t h e presence of Si in t h e e a r t h ' s core is v e r y weak. Some details regarding t h e structures and composition of Tucson are given. WEINBERG, J . L., BEESON, D. E., and HUTCHISON, P. B. 1969. P h o t o m e t r y of lunar libration regions. Bulletin of the American Astronomical Society, V. 1, p. 368. Photoelectric, photographic, a n d visual observations h a v e been m a d e at t h e H a l e a k a l a O b s e r v a t o r y on 18 nights b e t w e e n March 1966 and J u l y 1968 of regions containing lunar libration points L4 and La. The a u t h o r s were unable, in these observations, t o ' detect t h e presence of a p h o t o m e t r i c enhancem e n t t h a t can be a t t r i b u t e d to lunar libration clouds. Differential techniques applied to the photoelectric observations allow t h e m to distinguish a n y e n h a n c e m e n t t h a t is a p p r o x i m a t e l y 0 . 5 % a b o v e t h e background. This m e t h o d is used to o b t a i n an u p p e r limit at 5080 /~ for brightness t h a t could be associated w i t h these clouds. (Abstract of a p a p e r presented at the A u g u s t 1969 m e e t i n g of t h e A m e r i c a n Astronomical Society.)

MOON--GENERAL w h i c h escapes t h e t a r g e t p l a n e t is c o m p u t e d f r o m e x t r a p o l a t i o n s of a v a i l a b l e l a b o r a t o r y hypervelocity impact data. If primitive protoplanets have grown by accretion, the meteoroids a n d p l a n e t e s i m a l s t h e y a c c u m u l a t e d c o u l d n o t h a v e h a d i m p a c t s p e e d s m u c h in excess o f t h e p r o t o p l a n e t a r y e s c a p e speed. T h e similarities in sizes of t h e m a j o r satellites c a n b e e x p l a i n e d b y t h e p r e s e n c e o f a h i g h m a s s loss r a t i o for e s c a p e speeds b e t w e e n 2 a n d 4 kin/see. A t present, asteroids and lunar-sized objects are p r o b a b l y u n d e r g o i n g n e t erosion b y i m p a c t s . NEWTON, R . R . 1969. S e c u l a r a c c e l e r a t i o n s of t h e e a r t h a n d m o o n . Science, V. 166, p. 825-831. T h e a c c e l e r a t i o n of t h e e a r t h ' S spin, w h i c h is o b v i o u s l y i m p o r t a n t t o a s t r o n o m y , h a s also b e e n used extensively to provide information about i m p o r t a n t g e o p h y s i c a l processes. T h i s article d e a l s w i t h c o m p o n e n t s h a v i n g a t i m e scale of c e n t u r i e s or m o r e . T h e a v e r a g e a c c e l e r a t i o n o v e r a n i n t e r v a l of a t least s e v e r a l c e n t u r i e s is u s u a l l y called t h e secular a c c e l e r a t i o n . T h e m o o n also h a s a s e c u l a r a c c e l e r a t i o n , w h i c h is t h a t p a r t of the orbital acceleration coming from dissipative sources a n d n o t t h a t p a r t g i v e n b y t h e g r a v i t a t i o n a l t h e o r y of t h e solar s y s t e m . T h e n a t u r e o f the available data makes the study of the secular a c c e l e r a t i o n s of t h e e a r t h a n d m o o n i n s e p a r a b l e . D a t a f r o m p a l e o n t o l o g y , satellites, and ancient astronomy yield accelerations that geophysics cannot yet explain. The moon's s e c u l a r a c c e l e r a t i o n is n e g a t i v e a n d is d u e e n t i r e l y t o t i d a l friction, so f a r as we k n o w . T h e a m o u n t o f t i d a l f r i c t i o n t e n c e n t u r i e s ago was a b o u t t w i c e w h a t it is now. S p e c u l a t i o n is t h a t m u c h f r i c t i o n o r i g i n a t e s in t h e A n t a r c t i c ice shelves. T h e e a r t h ' s secular a c c e l e r a t i o n is n e g a t i v e , a v e r a g e d o v e r t h e p a s t 10 or 20 c e n t u r i e s , b u t it is p o s s i b l y p o s i t i v e p r e s e n t l y . T h u s , it is p r o b a b l y n o t governed by tidal friction within historic times. F r o m p a l e o n t o l o g i c a l d a t a it is s u g g e s t e d t h a t much of the nonfrictional component comes from i n t e r n a l processes t h a t c o n s e r v e a n g u l a r m o mentum. SCHWARTZ, K., SO~I~E~r, C. P., a n d COT,BU~, D. S. 1969. U n i p o l a r i n d u c t i o n i n t h e M o o n a n d a l u n a r l i m b s h o c k m e c h a n i s m . The Moon, V. l, p. 7-30. T h e u n i p o l a r i n d u c t i o n m e c h a n i s m is e m p l o y e d t o c a l c u l a t e electric field profiles i n t h e interior of a chemically homogeneous Moon possessing a s t e e p r a d i a l t h e r m a l g r a d i e n t c h a r a c t e r i s t i c of l o n g - t e r m r a d i o a c t i v e h e a t i n g . The thermal models used are those of Frieker, Reynolds, and Summers. From the magnetic field, t h e m a g n e t i c b a c k p r e s s u r e u p o n t h e s o l a r w i n d is f o u n d . T h e electric field profile is s h o w n t o d e p e n d o n l y u p o n t h e a c t i v a t i o n energy, E0, of t h e geological m a t e r i a l a n d t h e r a d i a l g r a d i e n t o f

123

t h e reciprocal t e m p e r a t u r e . T h e c u r r e n t is a d d i t i o n a l l y d e p e n d e n t u p o n t h e coefficient of t h e electrical c o n d u c t i v i t y f u n c t i o n b u t o n l y b y a scale f a c t o r . Since t h e M o o n is e x p e r i m e n t a l l y k n o w n t o c o r r e s p o n d t o t h e case o f w e a k i n t e r action with the solar wind, the magnetic back p r e s s u r e is c a l c u l a t e d w i t h o u t t h e n e e d for a n iterative procedure. The results indicate that a h o t M o o n c a n yield sufficient c u r r e n t flow so t h a t t h e m a g n e t i c b a c k p r e s s u r e is o b s e r v a b l e as a vestigial l i m b s h o c k w a v e u s i n g a n a c t i v a t i o n e n e r g y o f a b o u t ] eV t o g e t h e r w i t h a c o n d u c t i v i t y coefficient of a b o u t 10 a m h o s / m . S u c h m a t t e r is approximated by diabase-like composition, although the result that both the activation e n e r g y a n d coefficient e n t e r i n t o t h e c u r r e n t d e t e r m i n a t i o n does n o t rule o u t t h e p o s s i b i l i t y of a match with other similar substances. The c a l c u l a t i o n s are e n t i r e l y c o n s i s t e n t w i t h earlier r e s u l t s w h i c h i n d i c a t e d a m o d e l w h e r e t h e unip o l a r c u r r e n t d e n s i t y is d o m i n a t e d b y a h i g h i m p e d a n c e surface l a y e r a n d a s t r o n g s h o c k w a v e is i n h i b i t e d . I n a d d i t i o n t o t h e m a g n e t i c b a c k pressure, t h e i n t e g r a t i o n o f t h e c u r r e n t c o n t i n u i t y e q u a t i o n p e r m i t s c u r r e n t d e n s i t i e s a n d joule heating rates to be calculated, though the magnit u d e o f t h e l a t t e r for p r e s e n t solar w i n d condit i o n s is n o t t h e r m a l l y i m p o r t a n t . WISE, D. U. 1969. Origin of t h e m o o n f r o m t h e e a r t h : Some n e w m e c h a n i s m s a n d c o m p a r i s o n s . Journal of Geophysical Research, V. 74, p. 6 0 3 4 6045. Several m a j o r criticisms c o m m o n l y c l a i m e d t o i n v a l i d a t e t h e o r i e s of l u n a r origin b y fission f r o m t h e e a r t h are s h a r e d b y o t h e r l u n a r t h e o r i e s or are a n s w e r a b l e b y m e c h a n i s m s a s s o c i a t e d w i t h fission. A r g m n e n t s b a s e d o n t h e p r e s e n t r a t e o f r e t r e a t , w h i c h r e q u i r e t h e m o o n t o b e a newc o m e r t o t h e e a r t h a b o u t 1.8 b.y. ago, are in d i r e c t conflict w i t h t h e geologic r e c o r d ; M a c D o n a l d ' s c a l c u l a t i o n s of t h e a m o u n t of t i d a l energy to be dissipated by lunar capture would r e q u i r e , in m i d d l e P r e c a m b r i a n t i m e , surface t e m p e r a t u r e s of e a r t h a p p r o a c h i n g t h o s e of t h e sun. One i n t e r p r e t a t i o n of h i s m e t h o d o f m a n y m o o n c a p t u r e t o e x t e n d t h e t i m e scale fails b y a t least t w o orders o f m a g n i t u d e . T h e s i m p l e s t conclusion is t h a t s o m e t h i n g is w r o n g w i t h p r e s e n t r a t e - o f - r e t r e a t d e t e r m i n a t i o n s or p r o j e c t i o n s . Discrepancies of present angular momentum of the earth-moon system versus pre-moon values for e a r t h a r e a l m o s t as g r e a t for t h e r e t r o g r a d e c a p t u r e t h e o r y as for t h e fission t h e o r y . T h e a n g u l a r m o m e n t u m a t fission c a n b e h a l v e d f r o m earlier e s t i m a t e s b y u s i n g a g r a v i t y - s t r a t i f i e d ellipsoid plus C h a n d r a s e k h a r ' s c a l c u l a t i o n t h a t all J a c o b i a n ellipsoids a r e in u n s t a b l e r o t a t i o n . T h e e n t i r e r e m a i n i n g a n g u l a r m o m e n t u m disc r e p a n c y c a n b e a c c o u n t e d for b y escape of a n

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incandescent silicate a t m o s p h e r e volatilized b y t h e huge tidal frictions i m m e d i a t e l y following fission. B y t h e use of a reasonable set of assumptions, escape of 4 % of t h e mass of the e a r t h using ~ of t h e available tidal energy can account for t h e entire angular m o m e n t u m discrepancy. Goldreich's calculation of t h e history o f t h e lunar orbit, w i t h which he argues strongly against fission a n d against all o t h e r lunar theories as well, omits one significant possibility, t h a t e a r t h ' s e q u a t o r had been tilted a b o u t 10 ° to t h e ecliptic prior to t h e t i m e of fission. I f this is true, t h e inclination of e a r t h ' s e q u a t o r and of t h e lunar orbit to t h e ecliptic fit nicely into Goldreich's curves. I t is concluded t h a t there are fewer outs t a n d i n g criticisms of t h e hypothesis of lunar origin b y fission t h a n of o t h e r hypotheses. The average lunar density and t h e results of t h e S u r v e y o r chemical analyses lead us to argue t h a t fission f r o m t h e e a r t h triggered b y t h e e a r t h core f o r m a t i o n is t h e m o s t probable origin of t h e moon, considering t h e d a t a available now. MOON--ATMOSPHERE ELCO, R . A. 1969. I n t e r a c t i o n of the solar wind w i t h p l a n e t a r y atmospheres. Journal of Geophysical Research, V. 74, p. 5073-5082. See Planets--General. MOON--FIGURE AND INTERNAL STRUCTURE GERSTENKORN, H. 1969. T h e earliest p a s t of t h e E a r t h - M o o n system. Icarus, V. 11, p. 189-207. See M o o n - - G e n e r a l . GOTTLIEB, P., MLrLLER, P. M., and SJOOREN, W. L. 1969. Nonexistence of large mascons at Mare Margiuis and Mare Orientale. Science, V. 166, p. 1145-1147. The analysis of line-of-sight residual accelerations from L u n a r Orbiters 3 and 5 does not show any evidence for large mascons near t h e lunar limbs. A l t h o u g h unfavorable g e o m e t r y reduces t h e acceleration effect due to a n y mascon near t h e limb, simulations show t h a t large masses at Mare Orientale and Mare Marginis would produce substantial accelerations, in complete disagreement w i t h t h e actual Doppler t r a c k i n g d a t a obtained from a L u n a r Orbiter experiment. KA~rLA, W. M. 1969. T h e g r a v i t a t i o n a l field of t h e Moon. Science, V. 166, p. 1581-1588. This article concerns t h e distribution of mass in the moon, b o t h radial and lateral, t h e m e a s u r e m e n t o f t h e g r a v i t a t i o n a l field, and t h e resulting questions of mass transfer, mass support, and density irregularities. K n o w l e d g e of the m o o n ' s g r a v i t y is derived m a i n l y f r o m heliometric

m e a s u r e m e n t s of t h e m o o n ' s librations, photog r a m m e t r i c m e a s u r e m e n t s of t h e m o o n ' s shape, a n d Doppler t r a c k i n g of probes a n d lunar satellites. The a u t h o r discusses, first, t h e deterruination of p a r a m e t e r s - mass, radius, m o m e n t s of inertia, g r a v i t y anomalies, a n d topographic irregularities, and, second, t h e inferences d r a w n from these d e t e r m i n a t i o n s w i t h respect to t h e m o o n ' s origin, history, a n d structure. Several new clues h a v e been g e n e r a t e d in recent years, in particular b y t h e lunar satellite perturbations. T h e gross h o m o g e n e i t y of t h e m o o n seems well established. The m o o n is closer to equilibrium t h a n t h e earth, b u t far f r o m completely inactive. More m e a s u r e m e n t s are needed to explain t h e mascons, and to p r o v i d e the s a m e a c c u r a c y for d a t a related to t h e b a c k side of t h e m o o n as for d a t a related to t h e front side. MoGAI~R, A., L A ~ , G. V., and GAD'LT,D. E. 1969. Meteoroid impacts as sources of seismicity on t h e moon. Journal of Geophysical Research, V. 74, p. 5981-5994. I n c o n j u n c t i o n w i t h t h e Apollo lunar passive seismic experiment, a s t u d y was u n d e r t a k e n to d e t e r m i n e t h e efficiency of m e t e o r o i d i m p a c t s on t h e lunar surface as potential sources of seismic energy. This s t u d y is based on e x p e r i m e n t s p e r f o r m e d at A m e s Research Center to d e t e r m i n e t h e coupling b e t w e e n an i m p a c t i n g projectile and seismic waves. H i g h - v e l o c i t y guns at A m e s were used to fire projectiles into t a r g e t s in a v a c u u m chamber, Projectile velocities ranged from less t h a n 1 to more t h a n 7 k m / s e c ; projectile masses ranged from a b o u t 0.25 to 5 grams. Targets were of two t y p e s h a v i n g considerably different elastic properties. E x p e r i m e n t a l results indicate t h a t t h e seismic source function of an i m p a c t can be expressed as a function of the kinetic energy of t h e projectile. E x t r a p o l a t i n g our results up to the kinetic energies of meteoroids, it is possible to predict t h e n u m b e r of i m p a c t s t h a t will be d e t e c t e d b y t h e Apollo passive seismic e x p e r i m e n t during its nominal lifetime of one y e a r if assumptions are m a d e a b o u t t h e physical properties of the moon. F o r t h e m o s t optimistic set of assumptions, t h e i n s t r u m e n t will detect a b o u t 370 m e t e o r o i d i m p a c t s ; for t h e m o s t pessimistic, a b o u t 3 impacts. Most of these impacts will be within 10 to 20 k m f r o m t h e seismometers. T h e e x p e r i m e n t a l d a t a of this s t u d y can be used to e s t i m a t e t h e effectiveness of i m p a c t i n g spent spacecraft stages as artificial seismic sources. The results suggest t h a t surface w a v e s g e n e r a t e d b y t h e i m p a c t of the Saturn S - I V B stage of t h e Apollo booster would be d e t e c t e d at distances of from 41 to 681 k m from the seismometer, depending on t h e properties assumed for t h e l u n a r surface material.

MOON--SURFACE FEATURES NA~cE, R . L. 1969. G r a v i t y : F i r s t measurem e n t on t h e lunar surface. Science, V. 166, p. 384-385. The g r a v i t y a t t h e landing site of t h e first lunar-landing mission has been d e t e r m i n e d to be 162,821,680 milligals from d a t a telem e t e r e d to e a r t h b y t h e l u n a r module on t h e lunar surface. T h e g r a v i t y was m e a s u r e d w i t h a pulsed i n t e g r a t i n g pendulous accelerometer. These m e a s u r e m e n t s were used to c o m p u t e t h e g r a v i t y a n o m a l y a n d radius at t h e landing site. SCHUBERT, G., and SCHw~tTz, K. 1969. A t h e o r y for t h e i n t e r p r e t a t i o n of lunar surface m a g n e t o m e t e r data. The Moon. V. 1, p. 106-117. The solution to t h e p r o b l e m of t h e m o t i o n of t h e Moon relative to spatial irregularities in t h e i n t e r p l a n e t a r y m a g n e t i c field is found. The lunar electrical c o n d u c t i v i t y is modeled b y a twolayer c o n d u c t i v i t y profile. F o r t h e interaction of t h e Moon w i t h t h e c o r o t a t i n g sector structure of t h e i n t e r p l a n e t a r y m a g n e t i c field it is found t h a t the m a g n e t i c field in t h e lunar shell is t h e superposition of an oscillatory uniform field, a n oscillatory dipole field and an oscillatory field t h a t is toroidal a b o u t t h e axis of t h e m o t i o n a l electric field. W i t h various h m a r c o n d u c t i v i t y models and t h e t h e o r y of this paper, l u n a r surface m a g n e t o m e t e r d a t a can be q u a n t i t a t i v e l y i n t e r p r e t e d to yield i n f o r m a t i o n on t h e cond u c t i v i t y and c o n s e q u e n t l y t h e t e m p e r a t u r e of t h e lunar core. SCHUBERT, G., TUttCOTTE, D. L., and OXBURaH, E. R. 1969. S t a b i l i t y of p l a n e t a r y interiors. Geophysical Journal of the Royal Astronomical Society, V. 18, p. 441-460. See Planets--~Mars. SCHW)~tTZ, K., SONETT, C. P., and COLBUI~, D. S. 1969. U n l p o l a r induction in t h e Moon and a lunar limb shock mechanism. The Moon, V. 1, p. 7-30. See M o o n - - G e n e r a l . WOOD, J . A., MARWN, U. B., POWELL, B. N., and DICKEY, J . S., J m 1969. Mineralogy a n d p e t r o l o g y of t h e Apollo 11 lunar sample. Smith-

sonian Astrophysical Observatory Special Report 307, 99 pp. See M o o n - - S u r f a c e Layer. MOON--SURFACE FEATURES KANE, J., CARUCCI, G., TURNER, B., and McENT~.E, J . 1969. Mascons, m a r i a and sinuous r i l l e s - - A p o s t u l a t e d igneous origin. Nature, V. 224, p. 164. Mascons m a y be subsurface m a g m a c h a m b e r s or batholiths which would be denser t h a n t h e surrounding p r o t o l u n a r p a r t i c u l a t e m a t t e r f r o m which t h e y formed. Maria m a y be huge caldera-type collapse features filled w i t h e x t r u d e d l a v a or t e p h r a f r o m t h e u n d e r l y i n g m a g m a . Sinuous rilles, which often widen as t h e y r u n downhill and originate f r o m craterlets on

125

small cones are m a r e edges, m a y be channels formed b y t e p h r a flows which spread out before depositing their particles t h i n l y b e y o n d t h e ends or rilles. Sinuous rilles w i t h rows of craterlet along their floors m a y be ring-dike or graben depressions formed peripherally on caldera floors similar to those associated w i t h terrestrial caldera margins. KOPAL, Z. 1969. The earliest m a p s of the Moon. The Moon, V. 1, p. 59-66. The a i m of t h e present p a p e r is to give a brief account of t h e history o f lunar m a p p i n g in t h e pro-telescopic era, and t h a t i m m e d i a t e l y following t h e discovery o f t h e telescope. I t is pointed out t h a t t h e first (and also last ) e x t a n t m a p of the Moon based on nakedeye observations was p r e p a r e d some t i m e before 1603 b y William G i l b e r t - - d i s e o v e r e r of terrestrial m a g n e t i s m - - t h o u g h it was published only p o s t h u m o u s l y in 1651. Moreover, the recently u n e a r t h e d drawings of t h e Moon b y T h o m a s H a r r i o t t in E n g l a n d based on telescope observations between 1609 and 1610 are in no w a y inferior (if n o t otherwise) t h a n those published b y Galileo Galilei at t h e same time. As G. C. L a Galla's drawings of t h e Moon published in Venice in 1612 are in reality identical w i t h those of Galileo, t h e t h i r d i n d e p e n d e n t contribution to l u n a r m a p p i n g was m a d e b y P. Christoph Scheiner in G e r m a n y between 1611 a n d 1613; preceding those b y C. Malapert (1916) or Gassendi and Mellan more t h a n t w e n t y years later. MARCUS, A. H . 1969. Distribution of slopes on a cratered p l a n e t a r y surface: T h e o r y a n d pr~liminary.~pplieations. Journal of Geophysical Research, V. 74, p. 5253-5267. The distribution of slopes o v e r a n y finite span on a surface excav a t e d b y p r i m a r y i m p a c t craters is derived from a representation of t h e surface as a " m o v i n g a v e r a g e " of i m p a c t events. The c u m u l a n t s are always positive, and t h e y are large for t y p i c a l m a r e crater densities. I n some cases the dist r i b u t i o n can be a p p r o x i m a t e d b y a rapidly c o n v e r g e n t Gram-Charlier t y p e A series. The slope distribution has a m u c h higher p e a k near zero slope and also has m u c h h e a v i e r tails t h a n a Gaussian distribution w i t h t h e same variance. U n d e r some conditions t h e slopes h a v e app r o x i m a t e l y a s y m m e t r i c stable distribution law w i t h characteristic e x p o n e n t one unit smaller t h a n t h e crater d i a m e t e r p o p u l a t i o n index. Observations of slopes in Mare C o g n i t u m are in good a g r e e m e n t w i t h theory, if t h e v a l i d i t y of t h e photoelinometric d a t a and t h e m o d e l can be accepted. MILLS, A. A. 1969. Fluidization p h e n o m e n a a n d possible implications for t h e origin of l u n a r craters. -Nature, V. 224, p. 863-866. Craters

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resembling those of t h e Moon and Mars are p r o d u c e d on a fluidized bed. VAI~ DIGGELEN, J . 1969. A p h o t o m e t r i c i n v e s t i g a t i o n o f t h e lunar crater rays. The Moon. V. 1, p. 67-84. This investigation deals w i t h a c c u r a t e p h o t o m e t r i c d a t a concerning a n u m b e r o f r a y s of Tycho, Copernicus, Kepler, and Aristarchus. T h e y h a v e been derived f r o m plates t a k e n at t h e Yerkes O b s e r v a t o r y in a n i g h t of a t o t a l lunar eclipse near phase angle 0 °. B y comparing t h e n o r m a l albedo w i t h t h a t of t h e surroundings of t h e rays we found t h a t t h e y can be i n t e r p r e t e d as samples of telescopically unresolved b r i g h t patches. The fractional area k covered b y these patches varies along t h e r a y and shows t h a t t h e y are composed of a n u m b e r of separate r a y elements. The observed v a l u e of ]c is in accordance w i t h counts on a R a n g e r photograph. The distribution of t h e brightness along t h e r a y s has also been c o m p a r e d w i t h t h e mass distribution of t h e e j e c t s in t h e rays a r o u n d terrestrial explosion craters. The m e a n length of t h e lunar r a y s is in full accordance w i t h its e x t r a p o l a t e d terrestrial value. W e c a n n o t assume, however, t h a t t h e rays are regions covered w i t h a homogeneous layer of white powder, because t h e comparison w i t h t h e terrestrial explosion craters gives an u n p r o b a b l c v a l u e for t h e h e i g h t of t h e layer of t h e ejects. The same results follow n o w from t h e p h o t o m e t r i c properties of t h e rays. F r o m a comparison w i t h t h e difference in albedo at t h e S u r v e y o r ' s footprints follows t h e suggestion t h a t t h e lunar rays are composed of bright patches, where t h e surface m a t e r i a l c a m e into a state of lower porosity, while it has a higher porosity in t h e d a r k halos a r o u n d t h e craters. A suspected d a r k halo around T y c h o has p h o t o m e t r i c a l l y been m e a s u r e d a n d t h e results p r o v e t h a t it really exists. K e p l e r also shows a v e r y w e a k halo. MOON--SURFACE LAYER 1969. A s t r o n a u t a c t i v i t y on t h e lunar surface.

learus, V. l l , p. 260-267. P h o t o g r a p h s of astron a u t a c t i v i t y on t h e lunar surface, supplied b y t h e M a n n e d Spacecraft Centre, N a t i o n a l Aeronautics and Space A d m i n i s t r a t i o n , are reproduced. Apollo 11 A s t r o n a u t s Neil A. A r m strong, Michael Collins, a n d E d w i n E. Aldrin, Jr., were l a u n c h e d to the Moon b y a Saturn V launch vehicle at 9:32 a.m. E D T J u l y 16, 1969 from Complex 39A, Cape K e n n e d y , Florida. A r m s t r o n g and Aldrin landed on t h e Moon J u l y 20, 1969 and, after take-off f r o m t h e Moon J u l y 21, joined Collins in t h e C o m m a n d m o d u l e orbiting t h e Moon. The a s t r o n a u t s splashed down in t h e Pacific Ocean and r e c o v e r y was m a d e

b y t h e U.S.S. Hornet a t 12 : 50 p.m. E D T J u l y 24, 1969. B(~ItLER, F., EBERHARDT, P., GEISS, J . , MEISTER, J., and SIQ~E~, P. 1969. Apollo 11 solar wind composition e x p e r i m e n t : F i r s t results. Science, V. 166, p. 1502-1503. T h e helium-4 solar wind flux during t h e Apollo 11 lunar surface excursion was (6.3 ± 1.2)× l0 e a t o m s per square c e n t i m e t e r per second. T h e solar wind direction and e n e r g y are essentially not p e r t u r b e d b y t h e moon. E v i d e n c e for a l u n a r solar wind albedo was found. BURNS, A. A. 1969. Diffuse c o m p o n e n t of h i n a r r a d a r echoes. Journal of Geophysical Research, V. 74, p. 6553-6566. A simple m o d e l consisting of v o l u m e b a c k s c a t t e r i n g from within t h e l u n a r regolith can explain t h e observed diffuse comp o n e n t of lunar r a d a r echoes. A t a w a v e l e n g t h of 68 cm, a good m a t c h of t h e m o d e l w i t h t h e d a t a yields a value of 2.5-3 for t h e r e l a t i v e p e r m i t t i v i t y of t h e regolith in good a g r e e m e n t w i t h t h e quasi-specular b a c k s c a t t e r i n g estimates. T h e fit at 23 c m is poorer b u t yields a v a l u e slightly less t h a n 2. A t 3.8 era, t h e v a l u e is below 1.5, and b o t h t h a t v a l u e a n d t h e 23 c m v a l u e are in good a g r e e m e n t w i t h t h e r a d i o m e t r i c a l l y determ i n e d values at their respective wavelengths. These lower values a t short w a v e l e n g t h s are p r o b a b l y a result of t h e rapid d e n s i t y increase w i t h d e p t h just at t h e surface. A slope-dependent reflectivity can reconcile t h e values of r e l a t i v e p e r m i t t i v i t y o b t a i n e d radiometrically and f r o m t h e proposed diffuse b a c k s c a t t e r i n g m o d e l to those o b t a i n e d f r o m r a d a r cross-section measurements. There is some evidence t h a t t h e p e r m i t t i v i t y of t h e rocks forming t h e lunar highlands m a y be lower t h a n t h a t of t h e rocks u n d e r l y i n g t h e maria. CAMPBELL, M. J., and Um~ICHS, J . 1969. Electrical properties of rocks and their significance for lunar r a d a r observations. Journal of Geophysical Research, V. 74, p. 5867-5881. A w i d e v a r i e t y of terrestrial rocks has been i n v e s t i g a t e d to d e t e r m i n e the range of v a r i a t i o n of t h e highf r e q u e n c y electrical properties. B o t h solid rocks a n d powders of various t y p e s h a v e been m e a s u r e d at frequencies of 450 M H z and 35 G H z ; some m e a s u r e m e n t s h a v e been m a d e at e l e v a t e d t e m p e r a t u r e s . Solid materials show wide variations in p e r m i t t i v i t y and absorption length, b u t a p a r t f r o m a small t r e n d w i t h silica c o n t e n t it is not clear t h a t there is a n y p a t t e r n to t h e variations, and it is unlikely t h a t m e a s u r e m e n t s limited to these r a d a r frequencies will be useful for identification. W i t h p o w d e r e d rocks, on t h e o t h e r hand, t h e v a r i a t i o n f r o m rock t y p e to rock t y p e is m u c h smaller, b u t depends on t h e p o w d e r d e n s i t y in a quite predictable way.

MOON--SURFACE LAYER Consequently, radar information can be employed to make precise estimates of density and of density profiles even in the absence of information about composition. The long absorption lengths in powdered rocks indicate that radar reflections m ay occur at considerable depths in a regolith of the type found on the moon. CHOATE, R., BATTERSOI~,S. A., CHRISTENSEN, E. M., HUTTON, P~. E., JAI~FE, L. D., JONES, R. H., Ko, H. Y., SPENCER, R. L., and SPERLING, F. B. 1969. Lunar surface mechanical properties. Journal of Geophysical Research, V. 74, p. 61496174. Although the lunar surface at the Surveyor 7 highland landing site is somewhat rougher than the surface at previous mare landing sites, many of the physical properties of the soil at the sites are similar. The soil is primarily finegrained, compressible, and slightly cohesive; only 2.8o//o of the surface is covered by rocks larger than 5 cm in diameter. The average soil static bearing strength is 0.2 N/cm 2 at O.2-cm depth and 3.4 N/em 2 at 4-cm depth. CRUIKSHA~K, D. P. 1969. Ion-induced changes in simulated lunar rocks. Icarus, V. 11, p. 145154. To study the effects of the solar wind flux on the infrared refleetivity of rocks and minerals on the Moon, a laboratory apparatus was constructed for irradiation of rock samples with an ion flux having the same energy as the ambient solar wind, but with 107 to l0 s times the flux density. The infrared eolorimetrie profiles from 0.8 to 2.2 p were measured for several natural and irradiated samples. Irradiated rocks became generally "redder" in the total wavelength region considered (the albedo curve is steepened toward the red), and absorption bands attributed to Fe 3+ were transformed into Fe 2+ bands. The relationship of the visual darkening of the rocks on irradiation and the changes in iron absorption bands are discussed relative to the lunar surface. The problem of oil contamination in the ion system is discussed and it is concluded t h a t in the present experiment, the observed changes in rock samples result mostly from sputtering of sample materials and from reduction of th e oxidation state of metal atoms by the action of protons. CRUIXSHANK, D. P. 1969. Moon: Infrared studies of surface composition. Science, V. 166, p. 215-218. Infrared reflectance studies of small lunar regions reveal several absorption bands which m a t c h those of ferrous iron in laboratory spectra of olivines and orthopyroxenes. The craters Kepler and Aristarchus exhibit absorption bands suggestive of orthopyroxene, whereas the background ware material shows a band probably due to olivine. DUBOIS, J., and LI~K, F. 1969. Analyse 5

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Photom~trique De La P~nombre Pendant Les Eclipses De Lune. The Moon, V. 1, p. 85-105. Photometric analysis of the penumbra during 2 I eclipses between 1921 and 1968 based upon the homogeneous observational material reveals some anomalies which m a y be explained by the lunar luminescence excited by LrV-X solar radiations whose sources are located in the low corona and above the K-3 plages. The influence of the terrestrial upper atmosphere is detectable on the border of the umbra. (In French. ) GREER, R. T., and WEBER, J. N. 1969. Correlation of mineral luminescent phenomena and its selenological implications. Icarus, V. 11, p. 55-65. Quantitative optical fluorescence spectra and color pattern displays have application in the characterization of inorganic solids. The luminescence response for enstatite, a common rock-forming silicate mineral, has been investigated for bulk specimens, for powders, and for individual grains by studying the interrelationships of crystal host, activator, and impurity as they influence the wavelength and intensity of the emission colors. The effect on luminescent response of impurities, polymorph present, and conditions of formation of the solid can be precisely evaluated both on a point by point basis (1-micron diameter, when required) and by two-dimensional color raster patterns at different wavelengths for the specimen surface. High concentrations of iron and calcium tend to suppress optical fluorescence whereas manganese acts as an activator. The concentrations of both iron and calcium, however, are positively correlated with the concentrations of manganese, and the quenching effect of iron and calcium is in some cases sufficiently large to cancel the contribution of manganese to the visible emission spectrum. These observations are consistent with the influence of differences in crystal structure, host, activator concentration, impurity level, and history of the specimen. The observed correlations and contrasts provide a reasonable basis to expect useful information from studying the luminescent response and patterns that can be obtained from lunar specimens. HAGFORS, T., GREEN, J. L., and GUILLE~, A. 1969. Determination of the albedo of the moon at a wavelength of 6 m. The Astronomical Journal, V. 74, p. 1214-1219. A method is described whereby the refleetivity of the lunar surface m ay be determined by measuring the amount of cosmic noise being reflected. The method is applied to data obtained at the Jicamarca R a d a r Observatory. I t is determined t h a t the apparent dielectric constant of the lunar sur-

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face m a t e r i a l a t a w a v e l e n g t h of 6 m is 3.7 -4- 0.7. This i n d i c a t e s t h a t t h e w a v e l e n g t h d e p e n d e n c e of t h e r e f l e c t i v i t y is n o t q u i t e as s t r o n g as p r e v ious o b s e r v a t i o n a l r e s u l t s w o u l d t e n d t o indicate, a n d t h a t r e l a t i v e l y loosely p a c k e d surface s t r a t a m u s t e x i s t t o d e p t h s o f several m e t e r s . ROYLE, F. 1969. P l a n e t a r y f o r m a t i o n a n d l u n a r m a t e r i a l . Science, V. 166, p. 401. T h e inclications t h a t " i g n e o u s " l u n a r r o c k s are old, p e r h a p s as old as t h e m e t e o r i t e s , m a y lead to t h e suggestion that the moon experienced a period of i n t e n s e v o l c a n i c a c t i v i t y e a r l y in its h i s t o r y . T h e a u t h o r p o i n t s o u t h e r e t h a t t h e r e is n o n e e d for v o l c a n o e s t o h a v e o c c u r r e d in s i t u o n t h e m o o n . C o n s i d e r a t i o n s of a n g u l a r m o m e n t u m s h o w t h a t p l a n e t a r y m a t e r i a l p r o b a b l y separated from the sun when the radius of the latter w a s c o n s i d e r a b l y g r e a t e r t h a n its p r e s e n t value. P r i m i t i v e p l a n e t a r y m a t e r i a l c o u l d well h a v e b e e n c o n s i d e r a b l y h o t t e r t h a n w o u l d b e estim a t e d for m a t e r i a l a t c o r r e s p o n d i n g d i s t a n c e s f r o m t h e p r e s e n t d a y sun. D r i v e n o u t t o t h e t e r r e s t r i a l d i s t a n c e , it c o u l d h a v e experiermed t e m p e r a t u r e s , w h i c h are n o t m u c h different f r o m t h e t e m p e r a t u r e i n volcanoes. M e l t i n g a n d c h e m i c a l s e g r e g a t i o n c o u l d h a v e t a k e n place even in a short-lived hot phase. If the existence of such a hot phase can be established by the lunar s a m p l e s , f e a t u r e s of t e r r e s t r i a l , g e o c h e m i s t r y , w h i c h h a v e h i t h e r t o b e e n a t t r i b u t e d t o igcnous a c t i v i t i e s o n t h e e a r t h itself, m a y b e d i s c o v e r e d t o r e a l l y b e l o n g t o t h e initial p r i m i t i v e p h a s e of t h e solar s y s t e m . JAFFE, L. D., a n d STEINBACHER,R . H . 1969. S u r v e y o r 7 l u n a r mission. Journal of Geophysical Research, V. 74, p. 6702-6705. T h i s p a p e r is a b r i e f r e v i e w of t h e S u r v e y o r 7 mission, b e g i n n i n g w i t h its l a n d i n g o n t h e o u t e r r i m o f t h e c r a t e r T y c h o o n J a n u a r y 10, 1968. T h e r e s u l t s o b t a i n e d o n t h e m i s s i o n are r e p o r t e d elsewhere. JOHNSOn, T. V., a n d SODERBT.OM, L. A. 1969. R e l a t i v e r e f l e c t i v i t y (0.4 ~ t o 1.1 ~) of t h e l u n a r l a n d i n g site Apollo 7. Journal of Geophysical Research, V. 74, p. 6046-6048. R e s u l t s s h o w t h a t t h e r e f l e c t i v i t y of site Apollo 7 differs signif i c a n t l y f r o m t h a t o f Apollo 2. T h e f l a t n e s s of t h e Apollo 7 c u r v e i n d i c a t e s t h a t its r e f l e e t i v i t y is v e r y s i m i l a r t o t h a t of t h e s t a n d a r d area. I n c o m p a r i s o n w i t h t h e over-all v a r i a t i o n in r e f l e c t i v i t y a m o n g m a r e sites s t u d i e d b y McCord a n d J o h n s o n , t h e difference b e t w e e n t h e s e c u r v e s is r e l a t i v e l y large. F r o m t h e s e r e s u l t s a n d t h o s e of t h e p r e v i o u s Apollo site s t u d y ( M u r r a y et al.), we c o n c l u d e t h a t t h e differences b e t w e e n t h e r e f l e e t i v i t y c u r v e s of l a n d i n g sites Apollo 2 a n d Apollo 7 i n d i c a t e c o m p o s i t i o n a l a n d / o r m i n e r a l ogical differences, p r o b a b l y arising f r o m v a r i a t i o n s in v a l e n c e s t a t e or m i n o r c o n s t i t u e n t s .

J o ~ s , M. T. 1969. A q u a n t i t a t i v e e v a l u a t i o n of t h e u n i f o r m i t y o f t h e l i g h t s c a t t e r i n g p r o p e r ties o f t h e l u n a r surface. The Moon, V. 1, p. 31-58. See M o o n - - G e n e r a l . LI~BY, W . F. 1969. W h y is t h e M o o n g r a y ? Science, V. 166, p. 1437-1438. I f w a t e r ever w a s e m i t t e d f r o m t h e l u n a r surface, t h e r e s h o u l d h a v e b e e n a t e n d e n c y for t h e surface t o t u r n o r a n g e as a r e s u l t of t h e o x i d a t i o n of ferrous o x i d e in the rocks by photolytically liberated oxygen. T h e a u t h o r suggests t h a t t h e m o o n is g r a y a n d colorless b e c a u s e t h e solar w i n d b r i n g s in a t o m i c hydrogen, a most powerful reducing agent, to replace t h a t lost b y t h e p h o t o l y t i c d e c o m p o s i t i o n of w a t e r v a p o r . T h e color of t h e surface r o c k s o n t h e m o o n m a y i n d i c a t e t h e b a l a n c e of t h e t w o influences. I t seems likely t h a t l u n a r w a t e r as well as t h a t o n e a r t h e v o l v e d v e r y e a r l y ; t h e r e fore, t h e m o o n m a y h a v e s t a r t e d o u t as colored a n d i t m a y h a v e g r a d u a l l y b e e n r e d u c e d t o its p r e s e n t dull gray. T h e r e m a y b e b u r i e d o x i d i z e d r o c k c o n t a i n i n g ferric iron. T h e s a m e r e a s o n i n g c a n b e a p p l i e d t o Mars, w h i c h also h a s n o m a g n e t i c field a n d t h u s is p o t e n t i a l l y s u b j e c t t o solar w i n d c o n t a c t , t h o u g h t h e w i n d is deflected t o some e x t e n t b y t h e ionosphere. Mars w o u l d h a v e h a d t o p u t o u t e n o u g h w a t e r to c o v e r its surface t o a d e p t h of less t h a n ~ m t o h a v e r e t a i n e d its color. McGARR, A., LATHAM, G. V., a n d GAULT, D. E . 1969. M e t e o r o i d i m p a c t s as sources of s e i s m i c i t y o n t h e m o o n . Journal of Geophysical Research, V. 74, p. 5981-5994. See M o o n - - F i g u r e a n d Internal Structure. Mo~oz, V. I., DAVYDOV, V. D., a n d ZHEGUL~V, V. S. 1969. P h o t o m e t r i c a n d spectroscopic o b s e r v a t i o n s of p l a n e t s in t h e 8 - 1 4 ~ r a n g e . Soviet Astronomy~A.J., V. 13, p. 101-109. See Planets Venus. OLSE~, E . 1969. P y r o x e n e g a b b r o ( a n o r t h o s i t e association): Similarity to Surveyor V lunar analysis. Science, V. 166, p. 401-402. T h e d a t a f r o m t h e a l p h a - s e a t t e r i n g e x p e r i m e n t of Surv e y o r V i n Mare T r a n q u i l l i t a t i s r e s e m b l e d a t a f r o m a v e r a g e oceanic b a s a l t s w i t h , h o w e v e r , several m a j o r e x c e p t i o n s , p r i n c i p a l l y Ti. T u r k e v i c h et al. c o n c l u d e d t h a t n o c o m m o n e a r t h m a t e r i a l p r o v i d e d a m a t c h for t h e s e r e v i s e d l u n a r d a t a a n d t h a t p e r h a p s special g e o c h e m i c a l processes were r e q u i r e d t o p r o d u c e t h e l u n a r m a t e r i a l . T h e a u t h o r h a s f o u n d one s u c h special t e r r e s t r i a l r o c k t y p e , w h i c h does b e a r a s t r i k i n g r e s e m b l a n c e t o t h e s e refined d a t a : a g a b b r o or gabbroic anorthosite possibly associated with h i g h l y a n o r t h i t i c a n o r t h o s i t e masses. H e shows that pyroxene gabbro analyses from the Adirond a c k M o u n t a i n s are close to t h e S u r v e y o r d a t a , a n d in e v e n b e t t e r a g r e e m e n t w i t h r e s p e c t t o

MOON--SURFACELAYER t h e 1~a20 c o n t e n t assuming a more anorthiterich plagioclase. PATTERSON, J . H., FRAI~ZGROTE, E. J., TURKEVICH, A. L., ANDERSOI~, W. A., ECONOMOU, T. E., GRIFFIN, H. E., GROTCH, S. L., and SOWINSKI, K. P. 1969. A l p h a - s c a t t e r i n g e x p e r i m e n t on S u r v e y o r 7: Comparison w i t h Surveyors 5 and 6. Journal of Geophysical Research, V. 74, p. 6120-6148. The last three S u r v e y o r missions (5, 6 and 7) included an ~scattering e x p e r i m e n t t h a t o b t a i n e d e l e m e n t a l analyses of surface m a t e r i a l at three widely separated locations on t h e moon. On S u r v e y o r 7, three different samples were analyzed at a t e r r a site n e a r t h e crater Tycho. These samples are m u c h alike in composition b u t differ from t h e m a r e samples of Surveyors 5 and 6 in their lower c o n t e n t of " i r o n " (elements a p p r o x i m a t e l y of mass 56). The analyses at all three sites are similar to t h e compositions of some of t h e m o s t c o m m o n rocks found on the e a r t h ' s surface, such as basalts, b u t are quite different from t h e compositions of ultrabasic rocks and chondritic meteorites. The analyses at t h e three sites m a k e possible t h e prediction of t h e chemical and physical properties of l u n a r surface material. The difference between the analyses of t h e m a r e and t e r r a samples m a y c o n t r i b u t e to t h e difference in albedo of these two t y p e s of material and m a y also indicate geological separation of lunar materials of v a r y i n g density, as has h a p p e n e d on earth. PELLICORI, S. F. 1969. W a v e l e n g t h dependence of polarization. X I X . Comparison of t h e lunar surface with l a b o r a t o r y samples. The Astronomical Journal, V. 74, p. 1066-1072. Photoelectric p o l a r i m e t r y at several w a v e l e n g t h bands between 0.32 and 0.56 ~ of samples of " p u r e " m a r e and t e r r a and of lavas and chemicals are presented. The lunar particles are s o m e w h a t translucent, r a t h e r opaque. The w a v e l e n g t h dependence of t h e polarization of t h e moon, and b y comparison, of Mercury, Mars, and t h e asteroids is p r o d u c e d b y t h e decrease in translucency of t h e particles w i t h decreasing w a v e , length. The m a r i a show r e l a t i v e l y higher polarization at short w a v e l e n g t h s t h a n t h e terrae, suggesting either a greater absorption coefficient or larger particle sizes t h a n on t h e terrac. PHINNEY,R . A., O'KEEFE, g. A., ADAMS, J . B., GAtrLT, D. E., KUIPER, G. P., i~-ASURSKY, H., COLLINS, R. J., and SHOEMAKER, E. M. 1969. I m p l i c a t i o n s of t h e S u r v e y o r 7 results. Journal of Geophysical Research, V. 74, p. 6053-6080. The chemical and television d a t a from t h e S u r v e y o r 7 mission are discussed. The significance of the ~-scattering analysis is found to depend on

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w h e t h e r t h e flow unit underlying t h e spacecraft was laid down b y mass flow at t h e t i m e of t h e T y c h o - f o r m i n g impact. The chemical composition of t h e site is significantly lower in F e t h a n t h e composition of the previously analyzed m a r e sites; no other resolvable distinctions can be made. The higher albedo of t h e highlands is a t t r i b u t e d to t h e lower iron c o n t e n t in t h e silicate minerals. B y assigning t h e atomic composition to minerals c o m m o n in basaltic rocks, we e s t i m a t e t h e highland rock density to be 3.0 and t h e m a r e density to be 3.2. The densities m a y be incorporated into a discussion of recent information on the g r a v i t a t i o n a l field of t h e moon, yielding e s t i m a t e s of crustal thickness in t h e highlands a r o u n d 30 to 50 kin. A n u m b e r of television pictures of rocks a n d f r a g m e n t s are shown, and some suggestions are offered a b o u t the t y p e and origin o f these objects. T h e y compose a heterogeneous p o p u l a t i o n in which t h e brighter rocks seem to be more resistant to mechanical breakdown t h a n t h e d a r k rocks. The characteristics of t h e fine-grained c o m p o n e n t of t h e surface m a n t l e are found to be similar to those at earlier S u r v e y o r sites. The process o f eroding exposed rocks and covering t h e m w i t h a b l a n k e t of fine particles appears to be r e l a t i v e l y less a d v a n c e d t h a n at t h e sites previously studied. A bright line of light was seen on t h e western horizon after sunset, as was observed during S u r v e y o r 5 and 6; this r a t h e r puzzling p h e n o m e n o n is discussed again. R o s s , H . P., ADLER, J. E. M., and Htrsw, G. R. 1969. A statistical analysis of t h e reflectance of igneous rocks from 0.2 to 2.65 microns. Icarus, V. 11, p. 46-54. Reflectance spectra from 0.2 to 2.65 microns were o b t a i n e d for several igneous rocks and minerals. The reflectance of all the rock samples, w h e n crushed, increases w i t h decreasing particle size. A statistical analysis established t h e correlation between reflectance and t h e w a v e l e n g t h of energy, t h e generalized composition, and t h e particle size of t h e rock samples. Most of t h e absorption bands present in the spectra correspond to some form of w a t e r in the sample, or are c o m m o n to u n r e l a t e d rocks and minerals, and, therefore, are n o t diagnostic of composition. A correlation analysis between t h e generalized composition variable and t h e ratios of reflectance at two different w a v e l e n g t h s has indicated correlation coefficients as high as 0.88 and m a y p r o v e useful in selecting the more characterizing regions of t h e s p e c t r u m for r e m o t e sensing experiments. SCOTT, R. F., and ROBERTSON, F. I. 1969. Soil mechanics surface sampler. Journal of Geophysical Research, V. 74, p. 6175-6214. A lunar surface sampler essentially identical to t h a t

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o p e r a t e d f r o m S u r v e y o r 3 was m o u n t e d o n S u r v e y o r 7 a n d p e r f o r m e d flawlessly o n t h e m o o n throughout a range of operating temperatures from +180°F to -167°F. The motor current was sampled during lunar bearing and trenching tests, a n d t h e s e d a t a , t o g e t h e r w i t h preflight c a l i b r a t i o n s e n a b l e d u s t o c a l c u l a t e t h e forces i n v o l v e d i n t h e s e tests. A f t e r m i n i m a l l u n a r surface t e s t i n g , t h e surface s a m p l e r w a s emp l o y e d t o release t h e sensor h e a d of t h e ~s c a t t e r i n g i n s t r u m e n t , w h i c h h a d j a m m e d in its b a c k g r o u n d position. S u b s e q u e n t l y , t h e sensor h e a d was r e l o c a t e d t o a n a l y z e a r o c k a n d , still later, to a n a l y z e some s u b s u r f a c e l u n a r m a t e r i a l . T h e m e c h a n i c a l t e s t s of t h e surface in t h e v i c i n i t y o f T y c h o i n d i c a t e d t h a t t h e surface b e h a v e d in a m a n n e r t h a t was q u a n t i t a t i v e l y similar t o t h e b e h a v i o r of t h e m a t e r i a l close t o S u r v e y o r 3, b u t t h e surface n e a r T y c h o a p p e a r e d q u a l i t a t i v e l y t o b e m o r e d e f o r m a b l e a n d less b r i t t l e . A r o c k was w e i g h e d a n d f o u n d t o h a v e a d e n s i t y b e t w e e n 2.4 a n d 3.1 g / c m 3 ( e a r t h basis). A n o t h e r r o c k was b r o k e n b y a m o d e r a t e l y h a r d blow f r o m t h e s a m p l e r . T h e soil v a r i e d in d e p t h f r o m 1 t o a t least several i n c h e s o v e r u n d e r l y i n g r o c k fragm e n t s n e a r S u r v e y o r 7. L i t t l e a d h e s i o n o f l u n a r soil t o t h e m i r r o r surface of t h e ~ - s c a t t e r i n g e x p e r i m e n t sensor h e a d was o b s e r v e d o v e r a 2 4 - h o u r period. SHOEMAKER, E . M., BATSOI~, R . M., I~OLT, H . E., MoIt~Is, E . C., R E ~ I L S O ~ , J . J., a n d WHITAKER,E . A. 1969. O b s e r v a t i o n s of t h e l u n a r r e g o l i t h a n d t h e e a r t h f r o m t h e television c a m e r a o n S u r v e y o r 7. Journal of Geophysical Research, V. 74, p. 6081-6119. S u r v e y o r 7, t h e last spacec r a f t of t h e S u r v e y o r series, l a n d e d a b o u t 30 k m n o r t h of t h e r i m c r e s t o f T y c h o , one of t h e m o s t p r o m i n e n t a n d w e l l - k n o w n f e a t u r e s in t h e s o u t h e r n p a r t of t h e m o o n . A b o u t 21,000 p i c t u r e s were t r a n s m i t t e d d u r i n g t w o l u n a r d a y s o f o p e r a t i o n . A t t h e S u r v e y o r 7 site, t h e c u m u l a t i v e s i z e - f r e q u e n c y d i s t r i b u t i o n of c r a t e r s 13 c m t o 3 m e t e r s in d i a m e t e r follows closely t h e distribution of craters observed at the other S u r v e y o r sites in t h e l u n a r m a r i a . T h i s d i s t r i b u t i o n o f s m a l l c r a t e r s is b e l i e v e d t o b e a s t e a d y state distribution. The cumulative size-frequency d i s t r i b u t i o n of c r a t e r s 8 t o 118 m e t e r s i n dia m e t e r lies s i g n i f i c a n t l y b e l o w t h e s t e a d y - s t a t e d i s t r i b u t i o n , h o w e v e r , a n d h a s a s t e e p e r slope. T h e u p p e r l i m i t i n g c r a t e r d i a m e t e r for t h e s t e a d y - s t a t e d i s t r i b u t i o n a t t h e S u r v e y o r 7 site is a b o u t 3 m e t e r s . O n t h e b a s i s of t h e c r a t e r distribution, the predicted median thickness of t h e r e g o l i t h is 9 c m ; t h e t h i c k n e s s o f t h e r e g o l i t h based on the depths to coherent material e n c o u n t e r e d b y t h e surface s a m p l e r i n s t r u m e n t is 2.5 t o 15 cm. R o c k f r a g m e n t s n e a r S u r v e y o r 7

r a n g e f r o m less t h a n 1 m m t o s e v e r a l m e t e r s across. F r a g m e n t s coarser t h a n 1 m m in d i a m e t e r o c c u p y a b o u t 18°//o o f t h e s u r f a c e ; f r a g m e n t s coarser t h a n 10 c m in d i a m e t e r o c c u p y a b o u t 10~o o f t h e surface a n d a r e a n o r d e r o f m a g n i t u d e m o r e a b u n d a n t t h a n f r a g m e n t s o f s i m i l a r size a t t h e S u r v e y o r 6 l a n d i n g site in S i n u s Medii. T h e over-all p a r t i c l e size d i s t r i b u t i o n m u s t h a v e a t least t w o m o d e s , o n e i n t h e s u b m i l l i m e t e r r a n g e a n d one i n t h e r e s o l v a b l e r a n g e . T h e r o c k s a t t h e S u r v e y o r 7 l a n d i n g site e x h i b i t a far greater variety of textural and structural characteristics than the rocks observed at any m a r e site. Some are plain, b u t o t h e r f r a g m e n t s are s p o t t e d . Some f r a g m e n t s a p p e a r t o b e massive, but others exhibit well-developed l i n e a r s t r u c t u r e s o n t h e i r surfaces, w h i c h p r o b a b l y c o r r e s p o n d t o i n t e r n a l p l a n a r or l i n e a r s t r u c t u r e s . Most f r a g m e n t s a p p e a r t o b e relat i v e l y dense, b u t s o m e are clearly vesicular. Some rocks scattered about Surveyor 7 exhibit one or m o r e sets o f i n t e r s e c t i n g l i n e a r ridges a n d grooves o n t h e i r surfaces. T h e p r e s e n c e o f i n t e r s e c t i n g sets of s t r u c t u r e s suggests t h a t t h e fragments have been dynamically metamorp h o s e d . T h e c o m b i n e d e v i d e n c e of d y n a m i c m e t a m o r p h i s m a n d m e l t i n g , o b s e r v e d in a n u m b e r of f r a g m e n t s a t t h e S u r v e y o r 7 site, suggests these fragments have been shockm e t a m o r p h o s e d . T h e n o r m a l a l b e d o of t h e undisturbed fine-grained material near the s p a c e c r a f t is 13.4~o, w h e r e a s t h e r o c k f r a g m e n t s s c a t t e r e d o v e r t h e surface h a v e n o r m a l a l b e d o s r a n g i n g f r o m 14 t o 22~o. M a t e r i a l e j e c t e d b y t h e spacecraft footpads and excavated by the surface s a m p l e r h a s a n o r m a l a l b e d o o f 9.6~o. The polarimetric properties of the fine-grained m a t e r i a l n e a r S u r v e y o r 7 were f o u n d t o b e similar t o t h o s e o b s e r v e d w i t h t h e telescope for large p a r t s o f t h e l m l a r h i g h l a n d s . V a r i o u s r o c k surfaces, h o w e v e r , e x h i b i t e d m u c h different polarizing properties. SIMONEIT, B. R., BITRLINGAME, A. L., FLORY, D. A., a n d SMITH, I. D., 1969. Apollo l u n a r m o d u l e e n g i n e e x h a u s t p r o d u c t s . ScOnce, V. 166, p. 733-738. O r g a n i c c o m b u s t i o n p r o d u c t s genera t e d b y t h e l u n a r m o d u l e d e s c e n t engine, w h i c h b u r n s a 1 : 1 m i x t u r e of u n s y m m e t r i c a l d i m e t h y l h y d r a z i n e fuel a n d n i t r o g e n t e t r o x i d e oxidizer, h a v e b e e n a n a l y z e d . T h e m a j o r gaseous c o m b u s t i o n p r o d u c t s f o u n d were a m m o n i a , w a t e r , c a r b o n m o n o x i d e , n i t r o u s oxide, o x y g e n , c a r b o n dioxide, a n d n i t r i c oxide. T h e m i n o r p r o d u c t s were a c e t y l e n e , h y d r o g e n c y a n i d e , e t h y l e n e , formaldehyde, propadiene, ketene, cyanous acid, h y d r a z o i c acid, v a r i o u s m e t h y l a m i n e s , a c e t a l d e h y d e , m e t h y l n i t r i t e , formic acid, n i t r o u s acid, but.adiyne, n i t r i l o h y d r a z i n e s , n i t r o m e -

MOON--SURFACE LAYER thane, and nitrosohydrazines with other oxidized derivatives of unsymmetrical dimethylhydrazine and hydrazine. The ion intensities of the various species in all mass spectra were estimated as the following concentrations: the gases (NHa, H20, CO, NO, O2, CO2, and NO2), 87.7 percent; compounds of C, H, and O, 6.0% ; and compounds~ of C, H, and N (with traces of O), 5.8 °/o. TIKHONOVA, T. V., and TROITSKII, V. S. 1969. Effect of heat from within the moon on its radio emission for the case of lunar properties which v a r y with depth. Soviet Astromony--A.J., V. 13, p. 120-128. See Moon Temperature. Tu~, F. J., and ULBRICH,M. 1969. Comparison of lunar with terrestrial and meteoritic rocks. Proceedings of the National Academy of Sciences, V. 64, p. 1016-1020. See Meteors and Meteorites. ULRICHS, J., and CAMPBELL, M. J. 1969. Radiative heat transfer in the Lunar and Mereurian surfaces. Icarus, V. 11, p. 180-188. See Moon--Temperature. WALDBAUM, D. R. 1969. Lunar thermal anomalies: Magnetic phase transitions on the lunar surface? Science, V. 166, p. 531-532. See Moon--Temperature. WATTS, R. N., Jtt. 1969. First studies of lunar material. Sky and Telescope, V. 38, p. 312-314. A popular review of the team report (Science, V. 165, p. 1211-1227) of the major features of the first lunar samples. The article points out the glassy pits and spherules, the high content of titanium, zirconium yttrium, and chromium, and the low alkali metal content. WILDEY, R. L., and POHN, H. A. 1969. The normal albedo of the Apollo 11 landing site and intrinsic dispersion in the lunar heiligenschein. TheAstrophysivalJournal, V. 158, p. L129-L130. The normal albedo of the Apollo 11 landing site is 0.0995 from Apollo and Earth-based observations. The brightness surge between g = 1.5 ° and absolute full phase varies by at least 259% over the lunar surface. WOOD, J. A., MARW~, U. B., Pow~.I~, B. N., and DICKEY, J. S., JR. 1969. Mineralogy and petrology of the Apollo 11 lunar sample.

Smithsonian Astrophysical Observatory Special Report 307, 99 pp. The authors prepared and studied thin sections of 1676 rock fragments (diameter range 1 to 5 ram) from the Apollo 11 bulk sample. In almost all cases, the rocks are fine-grained enough for fragments of this size to constitute representative samples. They found the following proportions of rock types, evidently a mixture from m a n y sources: soil breceias, 52.4% ; basalts, 37.4% ; glasses, 5.1% ; anorthositie rocks, 3.6%; others (including less than

131

0.1% recognizable meteoritic debris), 1.5%. The basalts range in grain size from < 1 /z to > 300 /z and consist largely of pyroxene (~ 50 w~.°/o; titaniferous augite or sub-calcic augite plus pigeonite; ~ 30 mole % ferrosilite end member), plagioclase feldspar (~ 25%, An90-100 in most cases), and ilmenite (~ 20%). Some basalt specimens are surprisingly rich in K20 (0.7%). Their specific gravity is about 3.3 gm/em a. The glasses are impact-melted and range from deeply colored (brown, orangeyellow) to colorless; from clear and uniform to swirly, vesicular, and heterogeneous. The soil breccia is a consolidated mixture of mineral, rock, and glass fragments in a fine-grained, dark matrix (mostly glassy, but also mineral particles). Cementation is probably due to partial shock vitrification of an initially loose surface soil. Overall composition of the breccias is essentially the same as t h a t of the basalts, Only the 61 anorthosite fragments found were totally unexpected. These are light in color, low in density (~ 2.9 gm/cmS), and range from true anorthosites to anorthositic gabbros. They are much finergrained (10 to 100 /z) than terrestrial anorthosites, but apparently true cumulates. Their feldspar is slightly more ealeic than basaltic feldspar; the marie minerals are olivine (Fas0-50) and sub-calcic clinopyroxene. Ti content is low. The bulk composition of one such fragment, probably representative of most of them, matches the Surveyor V I I analysis ofejecta from the highlands crater Tycho. The authors believe the anorthosites are derived from the highlands. A lunar structural model is proposed in which a 25-kin anorthosite crust, produced by magnetic fractionation, floats on denser gabbro. Where early major impacts punched throug h the crust, basaltic lava welled up to equilibrium surface levels and solidified, forming the maria. An explanation for mascons is offered. Meteoritic debris and shock effects on the lunar surface are also discussed. Zr content of the lunar material is - 400 ppm. YOH, R. S., and VAN ALLEN, J. A. 1969. Alphaparticle emissivity of the Moon: An observed upper limit. Scivnce, V. 166, p. 370-372. Measurements made by the moon-orbiting spacecraft Explorer 35 during 1967-1968 show that it is unlikely that the alpha-particle emissivity of the moon is greater than 0.064 per square centimeter per second per steradian and exceedingly unlikely that it is greater than 0.128, these values being respectively O.1 and 0.2 of the provisional estimates made by Kraner e$ al., in 1966. This result implies that the abundance of uraninm-238 in the outer crust (approximately a few meters thick) of the moon is much less than

132

AFCRL BIBLIOGRAPHY

that typical of the earth's lithosphere, though it is c o n s i s t e n t w i t h t h e a b u n d a n c e of u r a n i u m - 2 3 8 i n t e r r e s t r i a l b a s a l t or in c h o n d r i t i c m e t e o r i t e s . MOON--TEMPERATURE GILVARRY, J . J . 1969. I n t e r n a l t e m p e r a t u r e of t h e Moon, Nature, V. 224, p. 968-970. T e m p e r a t u r e s p a s t a n d p r e s e n t arc i n f e r r e d f r o m the creep rate of lunar mascons and compared w i t h t h e r e s u l t s of o t h e r m e t h o d s . SCHUBERT, G., a n d SCHWARTZ, K . 1969. A t h e o r y for t h e i n t e r p r e t a t i o n o f l u n a r surface m a g n e t o m e t e r d a t a . The Moon, V. 1, p. 106-117. See M o o n - - F i g u r e a n d I n t e r n a l S t r u c t u r e . SCHWARTZ, K., SONETT, C. P., a n d COLBURI~, D. S. 1969. U n i p o l a r i n d u c t i o n in t h e M o o n a n d a l u n a r l i m b s h o c k m e c h a n i s m . The Moon, V. 1, p. 7-30. See M o o n - - G e n e r a l . TIKHONOVA, T. V., a n d TROITSKII, V. S. 1969. Effect o f h e a t f r o m w i t h i n t h e m o o n o n its r a d i o e m i s s i o n for t h e case of l u n a r p r o p e r t i e s w h i c h v a r y w i t h d e p t h . Soviet Astronomy--A.J., V. 18, p. 120-128. T h e c o n s t a n t c o m p o n e n t of t h e l u n a r r a d i o e m i s s i o n is discussed t h e o r e t i c a l l y for t h e case of h e a t flow o u t w a r d t h r o u g h a m o o n w i t h a p l a n e - l a y e r o u t e r s t r u c t u r e . Two m o d e l s are t r e a t e d : (1) T h e d e n s e l u n a r r o c k is c o v e r e d w i t h a p o r o u s l a y e r o f t h i c k n e s s a, w i t h i n w h i c h t h e d e n s i t y a n d t h e r m a l c o n d u c t i v i t y are c o n s t a n t . A t t h e lower b o u n d a r y o f t h i s p o r o u s layer, t h e thermal conductivity changes discontinuously b y a f a c t o r of 300-500 t i m e s its v a l u e for rock. (2) T h e d e n s i t y o f t h e p o r o u s l a y e r c h a n g e s l i n e a r l y f r o m P l a t t h e Surface o f p~ a t d e p t h a. The thermal conductivity changes linearly down t o a d e p t h of t h e o r d e r of a/3, a n d t h e n increases s h a r p l y b y a f a c t o r 300-500 t i m e s its v a l u e for rock. T h e d e p t h profile of t h e t e m p e r a t u r e is f o u n d i n b o t h cases as a f u n c t i o n of t h e t h e r m a l c o n d u c t i v i t y . I n b o t h cases t h e i n t e g r a t e d l u n a r r a d i a t i o n is f o u n d a n d c o m p a r e d w i t h t h e e x p e r i m e n t a l s p e c t r u m . E s t i m a t e s for t h e t h i c k ness a a n d t h e h e a t flow f r o m t h e l u n a r i n t e r i o r a r e f o u n d : for t h e first m o d e l a = 400 ± 100 cm, Os = 0.72 × 10 -6 ± 0.08 × 10 -6 c a l / c m 2 sec a n d for t h e s e c o n d model, a = 1000 ± 300 cm, Os = 0.94 × 10- 6 ± 0 . 1 6 × 1 0 - 6 c a l / c m 2 sec. T h e a c t u a l values are probably between these apparently l i m i t i n g values. IYLRICHS, J., a n d CAMPBELL, M. J . 1969. R a d i a t i v e h e a t t r a n s f e r in t h e L u n a r a n d M e r c u r i a n surfaces. Icarus, V. 11, p. 180-188. O b s e r v a tions of the Moon and Mercury have shown that a t e m p e r a t u r e - i n d e p e n d e n t c o n d u c t i v i t y is n o t adequate to explain the results; the available l a b o r a t o r y e x p e r i m e n t s o n h e a t flow in pDwdered solids lead t o t h e s a m e conclusion a n d p o i n t t o

t h e i m p o r t a n c e o f r a d i a t i v e ( p h o t o n ) processes o f heat transfer. In this paper the validity of the u s u a l a p p r o x i m a t e s o l u t i o n s t o a simple m o d e l o f h e a t t r a n s f e r is e x a m i n e d , i n c l u d i n g r a d i a t i v e transfer, in powders, by comparing them with an e x a c t n u m e r i c a l solution. I t is f o u n d t h a t t h e a p p r o x i m a t e s o l u t i o n s can, u n d e r some c i r c u m stances, a d e q u a t e l y d e s c r i b e t h e p l a n e t a r y o b s e r v a t i o n s p r o v i d e d c o g n i z a n c e is t a k e n o f t h e fact t h a t e m i s s i o n is a v o l u m e r a t h e r t h a n surface effect; n e g l e c t of v o l u m e e m i s s i o n m a y h a v e c a u s e d e r r o r s of as m u c h as 20°K in t h e i n t e r p r e t a t i o n of l u n a r eclipse o b s e r v a t i o n s . I t is also f o u n d t h a t t h e u s u a l a p p r o x i m a t e s o l u t i o n s c a n give v e r y m i s l e a d i n g r e s u l t s w h e n a p p l i e d t o those laboratory measurements of the thermal p r o p e r t i e s of p o w d e r s w h i c h i n v o l v e r a d i a t i o n f r o m o n e surface o f t h e p o w d e r . WALDBAUM, D. R . 1969. L u n a r t h e r m a l anomalies: Magnetic phase transitions on the l u n a r surface? Science, V. 166, p. 531-532. A possible e x p l a n a t i o n for t h e a n o m a l o u s b e h a v i o r of t e m p e r a t u r e - t i m e cooling d a t a for surface m a t e r i a l o f t h e l u n a r c r a t e r s T y c h o , Copernicus, a n d A r i s t a r e h u s c a n b e f o u n d in t h e t h e r m a l p r o p e r t i e s of t h e m i n e r a l s o f t h e l u n a r surface. Some o f t h e s e c r y s t a l l i n e p h a s e s u n d e r g o m a g netic phase transitions at temperatures ranging f r o m 56°K ( t i t a n o m a g n e t i t e ) t o 1033°K (metallic iron). I n cooling a p a r a m a g n e t i c m i n e r a l , a t h e r m a l a r r e s t m a y b e e n c o u n t e r e d d u e t o a large increase in h e a t c a p a c i t y i n t h e v i c i n i t y of t h e spin-ordering transition. If the thermal arrests are d u e o n l y t o m a g n e t i c ordering, t h e p r o l o n g e d a n o m a l i e s s u g g e s t t h a t o r d e r i n g is n o t c o m p l e t e l y a c h i e v e d before d a w n , I n some m i n e r a l s , it m a y go s o o n e r t o c o m p l e t i o n c a u s i n g t h e cooling c u r v e t o d r o p off s h a r p l y . T h u s , d e t a i l e d t e m p e r a t u r e - t i m e c u r v e s are likely t o yield n e w information on varying composition of the lunar surface, b u t it is p r e m a t u r e t o c o r r e l a t e t h e a v a i l a b l e d a t a w i t h a specific m i n e r a l a s s e m b l a g e . L a r g e d i s c o n t i n u i t i e s in t h e r m a l e x p a n s i o n , w h i c h are also a s s o c i a t e d w i t h some o r d e r i n g transitions (magnetite, quartz), would provide a n effective m e c h a n i s m for f r a c t u r e a n d erosion of t h e l u n a r surface. ORIGIN

OF THE

SOLAR

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HOHENBERG, C. M. 1969. R a d i o i s o t o p e s a n d t h e h i s t o r y o f n u c l e o s y n t h e s i s in t h e g a l a x y . Science, V. 166, p. 212-215. N e a r l y all of t h e h e a v i e r e l e m e n t s seem t o h a v e b e e n a s s e m b l e d b y successive n e u t r o n c a p t u r e s o c c u r r i n g in t w o d i s t i n c t processes: t h e s (slow) process refers t o n e u t r o n c a p t u r e a t a r a t e w h i c h is slow c o m p a r e d t o t h e i n t e r v e n i n g b e t a - d e c a y ; t h e r (rapid)

O R I G I N O1~ T H E S O L A R S Y S T E M

process refers to neutron capture at a rate which is rapid compared to the beta process. I t is becoming increasingly apparent that simple models for galactic r-process nucleosynthesis are inadequate. Modern astronomical observations, which indicate that the bulk of r-process synthesis m ay have occurred early in the life of the galaxy, cannot be ignored. Recent data on the fissiogonic xenon in whitlockite from the St. Severin meteorite also place stringent conditions on permissible models for element synthesis. I t appears t h a t neither sudden nor continuous models for element formation are consistent with isotopic data now available. The author proposes a more complex model for the synthesis of solar system material in which the r-process is allowed to occur in three distinct modes: a " p r o m p t " synthesis early in the history of the galaxy, a "continuous" synthesis whereby r-process products are continuously added to the galactic mix, and a "last-minute" synthesis which enriches the solar nebula with r-process material shortly before the formation of the solar system. Calculations based on the present abundances of uranium-235, uranium238, and thorium-232 and the measured abundances of iodine-129 and plutonium-244 present when meteorites began to retain xenon indicate t h a t the galactic age is between 8.0 and 8.8 billion years, with the initial " p r o m p t " synthesis accounting for 81 to 89 percent of the total r-process material ever produced, the "lastm i n u t e " synthesis contributing between 11 and 13 percent, and 0 to 8 percent occurring in the continuous mode. The time interval between the isolation of the solar nebula from galactic r-process and the onset of xenon retention in meteorites lies between 176 and 179 million years. HOYLE, F. 1969. Planetary formation and lunar material.Science, V. 166, p. 40 I. See M o o n - Surface Layer. KUIPER, G. P., and SILL, G. T. 1969. Identification of the Venus cloud layers. Bulletin of the American Astronomical Society, V. 1, p. 351. See Planets Venus. LE~BY, C. C., JR. 1969. The genesis of the solar system. Bulletin of the American Astronomical Society, V. 1, p. 352. I t is suggested t h a t noncentral, motional-gravitational fields (of a type found in modern gravitational theory) m a y have played a role in the genesis of the solar system. I f such "gravinetic" fields exist, their time-varying components should be capable of transferring angular m o m e n t u m between spinning and orbiting masses. Though much weaker than Newtonian gravitational fields, their integrated effects m a y have appreciably influenced the orbital configurations of the planets and their

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satellite systems. Hence, at the time of the formation of the solar system, the distribution of angular m o m e n t u m between the planets and the sun could have been quite different t h a n it is today. I n particular, the present total angular m o m e n t u m of the solar system could have been primitive to the sun and a small, dark, rapidly rotating companion (DC) whose spontaneous rotational breakup could have resulted in the present planets and their satellites. For a DC mass and mean density within the ranges of 0.0027-0.0270 g, and 0.25-1.5 g/cm a, and for a DC orbit (e ~< 0.4) lying wholly within 1.6 a.u. of the sun, its calculated (equatorial) rotational instability velocity is approximately equal to its orbital velocity. Thus, at breakup, parts of the DC would possess negligible total velocities (relative to the sun) and would fall into the sun; other parts would possess escape velocities; remaining portions of such low density surface material would execute energetic orbits (0.7 < e < 0.95) about the sun. Dense core components would execute orbits clustered about the original DC orbit. To provide the present total angular momentum, it must be assumed t h a t the sun initially rotated (uniformly) with a period of 1.1 to 1.4 d and that solar spin angular m o m e n t u m was gradually transferred to the planets (via gravinetic induction fields), thereby rounding and aligning planetary orbits and resulting in a differentially rotating sun. (Abstract of a paper presented at the August 1969 meeting of the American Astronomical Society.) M~RCuS, A. H., 1969. Speculations on mass loss by meteoroid impact and formation of the planets. Icarus, V. 11, p. 76-87. See M o o n - General. ZAROMB, S. 1969. A relativistic collision model of the origin of the solar system. Bulletin of the American Astronomical Society, V. 1, p. 371. Relativistic encounters between galactic nuclei and dense aggregates of cold Earth-like bodies were proposed to explain the occurrence of quasars and "exploding" galaxies (Zaromb, 1968, Astron. J., V. 73, p. $41). Such an event could also have given rise to the solar system as follows. A solid object of 10a0±2 g hitting a star off center at relativistic speed would be fragmented into: (a) deeply penetrating bodies triggering accelerated nuclear burning and a supernova explosion, (b) bodies passing through the peripheral regions and escaping the star's gravitational field, (c) intermediate fragments piercing through the star but decelerating sui~iciently to be bound by its gravitational field, yielding planets and asteroids orbiting in about the same plane and direction and also spinning in about the same direction. Moreover,

134

AFCRL BIBLIOGRAPHY

the m o m e n t u m imparted by the relativistic object and by the rocket action of the off-center explosion could suffice to eject the star from the galactic nucleus. During the brief traversal through the star, the outer shells of the planetary bodies would have become highly radioactive. This would explain the presence of radioisotopes mainly in the crusts rather than in the cores of the planets. Other observations, such as the correlation of Ga and Ge contents in the iron meteorites, the increase in hydrogen content and spin m o m e n t u m with orbiting distance, or the rapid temperature variations reealsed by some meteorites, are also consistent with this picture. The planetary fragments would at first have irregular structures. Approach toward isostasy through plastic flow would have been accelerated by tidal friction in the Earth-moon system. However, Venus m a y still conceal considerable asymmetry beneath its deep atmosphere. (Abstract of a paper presented at the August 1969 meeting of the American Astronomical Society,) PLANETS--GENERAL

ASHWORTH, D. G. 1969. Convection in planetary interiors---The effects of rotation. Astrophysics and Space Science, V. 5, p. 289-299. The conservation equations of mass, energy and m o m e n t u m are applied to the problem of thermal and nonthermal convective motions inside a homogeneous, compressible fluid sphere of uniform viscosity which is rotating with a constant angular velocity about the z-axis. The resulting equations are manipulated into a form which should be suitable for solution. BACKUS,G. E. 1969. Critique o f " T h e Resonant Structure of the Solar System" by A. M. Molchanov. Icarus, V. 11, p. 88-92. A. M. Molchanov's eight resonance relations among the orbital frequencies of the nine planets in the solar system are satisfied not exactly but with a relative error of 4.5 × 10-4. I t is shown t h a t with such a large error, those relations can be the result of chance. Such relations could be expected among any nine numbers chosen at random. Bv~x~., J. A. 1969. Evaporation from rotating planets. Monthly 2Votiees of the Royal Astronomical Society, V. 145, p. 487-492. Evaporation rates from a rapidly rotating planet are considerably augmented over those from a stationary planet. Simply regarding the rotation as diminishing the surface gravity m a y greatly underestimate the Vaporation rate. Evaporating material carries off an angular m o m e n t u m per unit mass larger than t h a t of the remaining material.

DICKINSON, R. F. 1969. The steady circulation of a nonrotating, viscous, heat-conducting atmosphere. Journal of the Atmospheric Scicnves, V. 26, p. 1199-1215. The problem of smallamplitude, steady motions and temperature perturbations in a stratified, ideal gas atmosphere with viscosity and heat conduction is investigated. Horizontally varying sources of heat, mass and m o m e n t u m force these motions. The model assumes two-dimensionality and no rotation. The solutions illustrate the coupling between motions and the temparature field in a stratified fluid with exponential increase in the vertical of the coefficients of kinematic viscosity and thermometric conductivity. Horizontal variation of temperature sets up pressure forces which drive horizontal winds. By continuity the divergence of these winds gives rise to vertical motions which alter the temperature fields. The solutions oscillate with height. Sources at relatively low levels can produce at high levels ~emperatures and circulations inverse to the directly driven temperature and wind oscillations. The mathematical analysis reduces to the solution of a sixth-order ordinary differential equation of the hypergeometric type. Power series solutions are obtained in the pressure variable. These are used to satisfy boundary conditions at the zero pressure boundary. Another fundamental set of solutions is constructed in the form of integral representations in order to satisfy a boundedness condition at large pressure. The two solution bases are matched by an expansion of the integrals in power series. The solutions are used to construct a Green's function for the inhomogeneous problem. A numerical example assuming a heat source at zero pressure is discussed. Tabulated values and asymptotic approximations are used to provide a detailed numerical description of the solutions, their derivatives, and the Green's function coefficients. ELco, R. A. 1969. Interaction of the solar wind with planetary atmospheres. Journal of Geophysical Research, V. 74, p. 5073-5082. Neither Venus nor the moon have a significant dipole magnetic field, and their atmospheres are exposed to the solar wind and the interplanetary magnetic field. As the solar wind ions penetrate the atmosphere, photo and charge-exchange ionization reactions alter the density and velocity of the ion stream. A collisionless reacting hydromagnetic model is used to describe the flow of atmospheric and solar wind ions normal to the interplanetary magnetic field. Because of the ionization reactions, the mass flow increases along the ion stream lines, and the usual adiabatic invariant, P_J_/nB, is not constant. The

PLANETS----GENERAL supersonic solutions obtained show that E/B d e c r e a s e s w i t h p e n e t r a t i o n o f t h e solar w i n d i n t o a n a t m o s p h e r e . A critical p e n e t r a t i o n o p t i c a l d e p t h , v,, a t w h i c h a h y d r o m a g n e t i c s h o c k forms, is d e t e r m i n e d as a f u n c t i o n o f t h e ion generation rate in the ionosphere and the ratio o f t h e p h o t o n flux t o t h e solar w i n d flux. Rec o m b i n a t i o n is t a k e n i n t o a c c o u n t a n d u s e d t o establish a minimum optical depth at which a h y d r o m a g n e t i c s h o c k c a n b e m a i n t a i n e d ir~ a n i s o t h e r m a l a t m o s p h e r e . I n t h e case of V e n u s (CO2 a t m o s p h e r e ) , t h e h y d r o m a g n e t i c s h o c k f o r m s for 10 - 9 < v s < 2 × 10 -4 , i.e., a b o v e t h e u s u a l C h a p m a n layer. T h e e x a c t v a l u e of v8 is s t r o n g l y d e p e n d e n t o n t h e v a l u e o f t h e scale h e i g h t w h i c h is used. F o r t h e m o o n , t h e l u n a r a t m o s p h e r i c o p t i c a l d e p t h is less t h a n t h a t r e q u i r e d for t h e f o r m a t i o n of a h y d r o m a g n e t i c shock.

GII~GERICH,O. 1969. K e p l e r a n d t h e r e s o n a n t s t r u c t u r e o f t h e solar s y s t e m . I c a r u s , V. 11, p. 111-113. M o l c h a n o v ' s o r d e r i n g t h e solar s y s t e m b y a t a b l e o f r e s o n a n c e r e l a t i o n s recalls a n earlier a t t e m p t b y J o h a n n e s K e p l e r (1571-1630). HANSEN, J . E . 1969. A b s o r p t i o n - l i n e f o r m a t i o n in a s c a t t e r i n g p l a n e t a r y a t m o s p h e r e : A t e s t of V a n d e H u l s t ' s s i m i l a r i t y r e l a t i o n s . The Astrophysical Journal, V. 158, p. 337-349. V a n d e Hulst's similarity relations, which reduce the p r o b l e m o f a n i s o t r o p i c s c a t t e r i n g in a h o m o g e n e o u s a t m o s p h e r e t o o n e o f isotropic s c a t t e r i n g b y scaling t h e o p t i c a l t h i c k n e s s a n d t h e singles c a t t e r i n g albedo, are t e s t e d for line f o r m a t i o n i n clouds a n d hazes. T h e r e l a t i o n s are s h o w n t o give good a p p r o x i m a t i o n s for a useful r a n g e o f s c a t t e r i n g angles w h e n ]c (the first c h a r a c t e r i s t i c e x p o n e n t o c c u r r i n g i n t h e s o l u t i o n of t h e t r a n s f e r e q u a t i o n i n u n b o u n d e d m e d i a ) is t h e basis for t h e scaling r e l a t i o n s . T h e r e s u l t s i n d i c a t e t h a t t h e d e n s i t y of c l o u d p a r t i c l e s o n V e n u s is a b o u t 6 times greater than the value suggested by the synthetic-spectra calculations of Belton, Hunt e n , a n d G o o d y for i s o t r o p i c s c a t t e r i n g , if it is assumed only that the cloud particles are at l e a s t ~ 1/~ in r a d i u s . T h i s implies t h a t t h e d e n s i t y of c l o u d p a r t i c l e s o n V e n u s is c o m p a r a b l e w i t h t h a t o f cirrus clouds o n E a r t h , a c o n c l u s i o n i n a g r e e m e n t w i t h a r e c e n t c o n c l u s i o n of P o t t e r . H~NON, M. 1969. A c o m m e n t o n " T h e R e s o n a n t S t r u c t u r e o f t h e Solar S y s t e m , " b y A. M. M o l c h a n o v . Icarus, V. 11, p. 93-94. T h e e i g h t i n t e g r a l r e l a t i o n s w h i c h A. M. M o l c h a n o v derived to relate the frequencies of the nine p l a n e t s c a n b e fully a c c o u n t e d for b y c h a n c e effects, a n d t h e r e f o r e do n o t n e c e s s a r i l y possess a n y p h y s i c a l significance. INGERSOLL, A. P. 1969. T h e r u n a w a y green6

135

h o u s e : A h i s t o r y o f w a t e r o n V e n u s . Journal of the Astmospheric Sciences, V. 26, p. 1191-1198. See P l a n e t s - - V e n u s . McCREA, W . H . 1969. D e n s i t i e s of t h e t e r r e s t r i a l p l a n e t s . Nature, V. 224, p. 28-29. R e c e n t d e t e r m i n a t i o n s of t h e m a s s e s a n d r a d i i o f t h e p l a n e t s m a y b e i n t e r p r e t e d as s h o w i n g t h a t t h e systems Earth-Moon-Mars and Mercury-Venus c o u l d h a v e r e s u l t e d f r o m t h e b r e a k - u p of t w o u n s t a b l e p l a n e t a r y b o d i e s of i d e n t i c a l c h e m i c a l c o m p o s i t i o n . T h e r e b y v a r i o u s f e a t u r e s of p l a n e t ary evolution would be elucidated. MOFFETT, R . J . 1969. H e a t i n g o f a p l a n e t a r y t h e r m o s p h e r e : Effects o f n o n - l i n e a r flow conductance terms and of convective terms. Planetary and Space Science, V. 17, p. 1850-1851. B a t e s a n d Moffett h a v e u s e d t h e m o d e l o f Cummack to investigate the diurnal variations o f p l a n e t a r y t h e r m o s p h e r e s . I t is n o w p o i n t e d o u t t h a t i n t h e special case w h e n t h e r a t i o v o f t h e a n g u l a r v e l o c i t y of t h e a t m o s p h e r e t o t h a t o f t h e p l a n e t is u n i t y , t h e i r c a l c u l a t i o n s t a k e full a c c o u n t o f t h e n o n l i n e a r t e r m WB ~T/az i n t h e h e a t e q u a t i o n , w h e r e T is t e m p e r a t u r e , z is a l t i t u d e a n d WB, called t h e b a r o m e t r i c v e l o c i t y is t h e v e r t i c a l v e l o c i t y o f t h e a t m o s p h e r e a r i s i n g d i r e c t l y f r o m its t h e r m a l e x p a n s i o n or c o n t r a c t i o n . T h e n o n l i n e a r t e r m s ( h e r e a f t e r called flow conductance terms) ignored by Bates and Moffett are, for e x a m p l e , t h o s e of t h e f o r m WD ~T/~z, w h e r e WD is t h e v e r t i c a l v e l o c i t y t h a t is a d d i t i o n a l t o t h e b a r o m e t r i c v e l o c i t y WB. I f t h e r e is s u c h a v e l o c i t y WD t h e n a c c o u n t m u s t also b e t a k e n of t h e c o n v e c t i v e t e r m WDg/c~, w h e r e g is t h e g r a v i t a t i o n a l a c c e l e r a t i o n a n d c~ is t h e specific h e a t p e r m o l e c u l e a t c o n s t a n t pressure. T h i s s e p a r a t i o n of t h e t o t a l v e r t i c a l air v e l o c i t y i n t o t h e p a r t s WB a n d WD follows t h e t r e a t m e n t of D i c k i n s o n a n d Geisler a n d R i s h b e t h et al., w h o t a k e WD (the d i v e r g e n c e v e l o c i t y ) as b e i n g n e c e s s a r y t o b a l a n c e t h e divergence or convergence produced by their c a l c u l a t e d large-scale h o r i z o n t a l w i n d s y s t e m s . F o r a t e m p e r a t u r e g r a d i e n t t h a t is p o s i t i v e u p w a r d s , t h e flow c o n d u c t a n c e t e r m in t h e h e a t e q u a t i o n a c t s as a h e a t s i n k or h e a t s o u r c e according to whether the vertical wind blows u p w a r d s or d o w n w a r d . T h e s a m e c o n c l u s i o n is r e a c h e d a b o u t t h e c o n v e c t i v e t e r m WDg/C~ a n d t h u s t h e flow c o n d u c t a n c e a n d c o n v e c t i v e effects o f WD are a d d i t i v e . MOLCHANOV, A. M. 1969. R e s o n a n c e s i n comp l e x s y s t e m s : A r e p l y t o critiques, lcarus, V. U , p. 95-103. T h e conclusions r e a c h e d b y Backus and H~non, that resonance relations in t h e solar s y s t e m of t h e s o r t p r o p o s e d b y Molc h a n o v are a r e s u l t o f c h a n c e , are b a s e d o n a v e r y crude statistical model. A more accurate model

136

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g i v e s a v a l u e P ~ 10 -10 for t h e p r o b a b i l i t y o f c h a n c e f o r m a t i o n of s y s t e m s s i m i l a r t o t h e solar system. MOLCHANOV, A. M. 1969. T h e r e a l i t y o f r e s o n a n c e s in t h e solar s y s t e m . Icarus, V. 11, p. 104-110. T h e o b j e c t of t h i s p a p e r is t o a t t e m p t a q u a n t i t a t i v e e v a l u a t i o n of t h e p r o b a b i l i t y of a g i v e n r e s o n a n t s t r u c t u r e . I t is s h o w n t h a t t h e formation of a "good" resonant structure by c h a n c e is n o t v e r y likely, a n d t h a t t h e r a n d o m p r o b a b i l i t y of t h e r e s o n a n t s t r u c t u r e o f t h e s o l a r s y s t e m is less t h a n 10 -10 . NEFF, J. S. 1969. P h o t o e l e c t r i c s p e c t r o p h o t o m e r r y of t h e m a j o r p l a n e t s . Bulletin of the Ameri~n Astronomical Society, V. l , p. 355-356. A p r o g r a m o f s p e c t r o p h o t o m e t r y of t h e m a j o r p l a n e t s is b e i n g c a r r i e d o u t w i t h t h e a u t o m a t i c photoelectric spectrophotometer of the University of Iowa Observatory. These observations are being made to investigate the temporal and s p a t i a l v a r i a t i o n s of t h e m a j o r p l a n e t s a n d t o d e t e r m i n e t h e i r g e o m e t r i c albedoes. T h e o b s e r v a t i o n s r e p o r t e d h e r e are of t h e whole disk of t h e p l a n e t a n d i n c l u d e t h e 2 ~ 3 2 0 0 - 5 4 0 0 - A region of t h e s p e c t r u m . E x c e p t for J u p i t e r , all t h e obs e r v a t i o n s were m a d e w i t h 32-A b a n d p a s s . J u p i t e r r e q u i r e d a large e n t r a n c e slit in o r d e r t o i n c l u d e all of t h e p l a n e t a r y i m a g e so t h a t t h e b a n d p a s s u s e d for his o b s e r v a t i o n s w a s 90 A. O b s e r v a t i o n s were m a d e of t h e s u n w i t h t h e s a m e a p p a r a t u s a n d b a n d p a s s e s as t h e s u n b y p l a c i n g a series of s k y baffles a n d diffusers in f r o n t o f t h e telescope. T h e i n t e g r a t e d l i g h t f r o m t h e s u n w a s r e d u c e d b y a f a c t o r of _ 109 w h i c h is w i t h i n t h e r a n g e of s e n s i t i v i t y o f t h e d e t e c t o r u s e d for s~ellar a n d p l a n e t a r y o b s e r v a t i o n s . P r e l i m i n a r y o b s e r v a t i o n s of t h e s u n h a v e b e e n r e d u c e d a n d are used to determine the wavelength dependence o f t h e a l b e d o e s of t h e m a j o r p l a n e t s . ( A b s t r a c t o f a p a p e r p r e s e n t e d a t t h e A u g u s t 1969 m e e t i n g o f t h e A m e r i c a n A s t r o n o m i c a l Society. ) R o s s , H . P., ADLER, J . E . M., a n d HUNT, G. R . 1969. A s t a t i s t i c a l a n a l y s i s of t h e reflectance of i~meous r o c k s f r o m 0.2 t o 2.65 m i c r o n s . Icarus, V. 11, p. 46-54. R e f l e c t a n c e s p e c t r a f r o m 0.2 to 2.65 m i c r o n s were o b t a i n e d for several igneous r o c k s a n d m i n e r a l s . T h e reflectance of all t h e r o c k samples, w h e n c r u s h e d , increases w i t h d e c r e a s i n g p a r t i c l e size. A s t a t i s t i c a l a n a l y s i s e s t a b l i s h e d t h e c o r r e l a t i o n b e t w e e n reflectance a n d t h e w a v e l e n g t h of energy, t h e g e n e r a l i z e d c o m p o s i t i o n , a n d t h e p a r t i c l e size of t h e r o c k samples. Most of t h e a b s o r p t i o n b a n d s p r e s e n t i n t h e s p e c t r a c o r r e s p o n d t o some f o r m o f w a t e r i n t h e sample, or are c o m m o n t o u n r e l a t e d r o c k s a n d m i n e r a l s , a n d , t h e r e f o r e , are n o t d i a g n o s t i c of composition. A correlation analysis between the generalized composition variable and the

r a t i o s o f reflectance a t t w o different w a v e l e n g t h s h a s i n d i c a t e d c o r r e l a t i o n coefficients as h i g h as 0.88 a n d m a y p r o v e useful in selecting t h e m o r e c h a r a c t e r i z i n g regions of t h e s p e c t r u m for r e m o t e sensing e x p e r i m e n t s . SOBOLEV, V. V. 1969. Surface a l b e d o a n d i l l u m i n a n c e of a p l a n e t w i t h a n a t m o s p h e r e . Soviet Astronomy--A.J., V. 13, p. 330-337. T h e s c a t t e r i n g of l i g h t is c o n s i d e r e d i n a p l a n e t a r y a t m o s p h e r e w i t h a n o p t i c a l t h i c k n e s s T0, a s c a t t e r i n g i n d i c a t r i x X ( y ) , a n d a parbicle a l b e d o ~, w i t h a l l o w a n c e for t h e reflection of l i g h t b y a p l a n e t a r y surface of a l b e d o a. S u n l i g h t is considered t o s t r i k e t h e a t m o s p h e r e a t a n a n g l e cos -1 (~, To) o f t h e p l a n e t a n d t h e surface i l l u m i n a n c e , V(~, To)Eo for a ~ 0 are e x p r e s s e d in t e r m s of t h e a l b e d o A(~, To) a n d i l l u m i n a n c e V(~, To)E0 for a = 0 . Moreover, a s y m p t o t i c e x p r e s s i o n s are o b t a i n e d for t h e q u a n t i t i e s A (~, To) a n d V (~, To) for T 0 ~ 1; t h e s e s i m p l i f y further under the additional assumption that 1 - A ~ 1. All t h e s e e q u a t i o n s h o l d for a n arbitrary scattering indicatrix. The spherical a l b e d o A*(T0) of t h e p l a n e t is t a b u l a t e d as a f u n c t i o n of a, A, a n d To. T h e t a b u l a t e d v a l u e s a n d t h e o b s e r v e d a l b e d o o f V e n u s yield a lower l i m i t for t h e optical t h i c k n e s s of its a t m o s p h e r e , To > 12 for a = 0.2 a n d a n u p p e r l i m i t for t h e p r o p o r t i o n of t r u e a b s o r p t i o n 1 - )1 < 0.0036 if a is n o t t o o large. UESUGI, A., a n d IRVINE, W . M. 1969. A r a p i d m e t h o d for c o m p u t a t i o n of a b s o r p t i o n s p e c t r a i n a p l a n e t a r y a t m o s p h e r e . Bulletin of the American Astronomical Society, V. 1. p. 366. T h e c o m p u t a t i o n o f a b s o r p t i o n s p e c t r a in a m u l t i p l y s c a t t e r i n g a t m o s p h e r e (such as a p l a n e t a r y a t m o s p h e r e in t h e visible or n e a r i n f r a r e d ) r e q u i r e d t h e s o l u t i o n of t h e e q u a t i o n o f r a d i a t i v e t r a n s f e r a t a large n u m b e r of f r e q u e n c y p o i n t s . I t is s h o w n t h a t t h i s p r o b l e m m a y b e conveniently handled by obtaining the l~eumann s o l u t i o n t o t h e t r a n s f e r e q u a t i o n for c o n s e r v a t i v e s c a t t e r i n g a n d t h e n o b t a i n i n g t h e s o l u t i o n for arbitrary single-scattering albedo through a s i m p l e s u m m a t i o n . T h e m e t h o d is feasible b e c a u s e t h e t e r m s of t h e N e u m a n n series a s s u m e a n a s y m p t o t i c f o r m for large orders of s c a t t e r i n g . U s e of t h i s a s y m p t o t i c f o r m d r a s t ically r e d u c e s t h e a m o u n t of c o m p u t a t i o n required. T h e m e t h o d m a y b e a p p l i e d for a r b i t r a r y p h a s e f u n c t i o n . S a m p l e r e s u l t s for t h e reflect i o n f u n c t i o n of t h e layer, t h e m e a n n u m b e r of s c a t t e r i n g s in t h e a t m o s p h e r e , t h e s h a p e of a n a b s o r p t i o n line, a n d t h e e q u i v a l e n t w i d t h of a L o r e n t z - b r o a d e n e d line are p r e s e n t e d . ( A b s t r a c t o f a p a p e r p r e s e n t e d a t t h e A u g u s t 1969 m e e t i n g of t h e A m e r i c a n A s t r o n o m i c a l Society.) YOUNG, A. T. 1969. H i g h - r e s o h i t i o n p h o t o -

PLA~TETS--JUPITER m e r r y of a t h i n p l a n e t a r y atmosphere. Icarus, V. 11, p. 1-23. See P l a n e t s - - M a r s .

PLANETS--ASTEROIDS ARNOLD, J . R. 1969. Asteroid families and " j e t s t r e a m s " . The Astronomical Journal, V. 74, p. 1235-1242. T h e asteroid families of H i r a y a m a and Brouwer h a v e been reexamined. The original families 1-9 are confirmed, while m o s t of t h e later families are e x t e n s i v e l y revised (and renumbered). E l e v e n e n t i r e l y n e w families are reported. T h e je~ s t r e a m F l o r a A described b y Alfvdn is confirmed and extended, and several n e w streams are added. The search for regularities a n d resonances in t h e m e a n f a m i l y elements has been unsuccessful. The origin of families b y eollisional b r e a k u p appears best to account for t h e data. HERGLOTZ, H. K., a n d McCARTER, J. W. 1969. O b s e r v e d position of m i n o r p l a n e t s : A t a m i (1139), H o l m i a (378), B a v a r i a (301), and 1931 TT1 (]624). The Astronomical Journal, V. 74, p. 1052. F o u r m i n o r planets were p h o t o g r a p h e d w h e n n e a r their opposition during t h e m o n t h s N o v e m b e r 1967 t h r o u g h April 1968. Positions were d e t e r m i n e d r e l a t i v e to coordinates of identified stars from t h e SAO Star Catalog, w i t h a precision of one second of arc or better. MARCUS, A. H . 1969. Speculations on mass loss b y m e t e o r o i d i m p a c t a n d f o r m a t i o n of t h e planets. Icarus, V. 11, p. 76-87. See M o o n - General. M-~RSDEN, B. G. 1969. On t h e relationship b e t w e e n comets and m i n o r planets. Bulletin of the American Astronomical Society, V. 1, p. 353354. See Comets.

PLANETS--JUPITER EFAI~OV, V. A., KISLYAKOV, A. G., MOISEEV, I. O., and NAUMOV, A. I. 1969. R a d i o emission of Venus and J u p i t e r at 2.25 and 8 ram. Soviet Astronomy--A.J., V. 13, p. 110-113. See Planets --Venus. GARY, B., a n d GULKm, S. 1969. N e w circularpolarization m e a s u r e m e n t s of J u p i t e r ' s decim e t e r radiation. The Astrophysical Journal, V. 158, p. L193-L195. Circular-polarization measu r e m e n t s of J u p i t e r at a w a v e l e n g t h of 13 em were m a d e during 1969 April and May w i t h t h e 210-foot radio telescope at Goldstone, California. A n u p p e r limit to t h e net degree of circular polarization in t h e i n t e g r a t e d emission is 1 per c e n t o v e r a limited longitude-range. GARY, B., GULKIS, S., KLEIN, M., a n d

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MEREDITH, B., 1969. J u p i t e r circular polarizaBulletin of the American Astronomical Society, V. 1, p. 344. J u p i t e r was tion m e a s u r e m e n t s .

observed at 13-cm w a v e l e n g t h w i t h t h e 210-ft a n t e n n a at Goldstone, California. A feed h o r n delivering orthogonal polarizations to two lownoise masers was used to simultaneously observe left- and r i g h t - h a n d e d flux. The observations span a limited range of J o v i a n S y s t e m I I I (1957.0) longitudes (10-100 ° and 160-250°). A n u p p e r limit of 1.0% circular polarization can be given for these longitudes. This contrasts w i t h an earlier d e t e r m i n a t i o n deduced from interferom e t e r fringephase d a t a which suggested t h e presence of 2 . 0 % circular polarization at our w a v e l e n g t h and within our longitude coverage. A plot of t o t a l flux vs J o v i a n longitude has been used to obtain a m a g n e t o s p h e r e r o t a t i o n period of 9:55:29.72 ± 0.11. The t o t a l flux d a t a define a b e a m i n g curve which has n o r t h - s o u t h s y m m e t r y a b o u t t h e m a g n e t i c equator. A m o d e l is proposed, i n v o l v i n g t h e shadowing of a p r e v i o u s l y rcp o r t e d brightness a n o m a l y in t h e magnetosphere, which is able to account for t h e a s y m m e t r i c b e a m i n g m e a s u r e d in 1964 at Parkes, b u t which c a n n o t simultaneously account for t h e symm e t r i c b e a m i n g of t h e present observations. (Abstract of a p a p e r presented at t h e A u g u s t 1969 m e e t i n g of t h e A m e r i c a n A s t r o n o m i c a l Society. ) GREE)r, T. C., and SHERRrLL, W. M. 1969. Iorelated polarization characteristics of t h e J o v i a n d e c a m e t e r emission. The Astrophysical Journal V. 158, p. 351-363. Measurements of t h e polarization of t h e d e c a m e t e r radiation f r o m J u p i t e r at 15-24 M H z were m a d e during t h e 1966-1967 a p p a r i t i o n and c o m b i n e d w i t h d a t a f r o m t h e 1963-1964 apparitions for analysis. Polarization d a t a analyzed in t e r m s of Io d e p a r t u r e angle from superior geocentric c o n j u n c t i o n showed axial-ratio profiles consistent w i t h t h e D u l k m o d e l of t h e J o v i a n source and also w i t h p r e v i o u s l y observed polarization characteristics r e p o r t e d as a function of S y s t e m I I I longitude. Comparison of the Southwest R e s e a r c h I n s t i t u t e (SwRI) d a t a w i t h cyclotron-model predictions and t h e r e c e n t l y r e p o r t e d d a t a f r o m Florida State U n i v e r s i t y shows t h e S w R I burst distribution a b o v e 16 MHz to be m o r e circular t h a n t h a t r e p o r t e d b y B a r r o w or p r e d i c t e d b y t h e c y c l o t r o n model. The inclusion in t h e analyses at S w R I of an intensity-selection effect favoring m o r e intense bursts t h a n those a n a l y z e d at Florida Stake U n i v e r s i t y is the simplest suggestion to explain t h e difference in results. O t h e r c y c l o t r o n - m o d e l predictions, however, i n v o l v i n g t h e u n i f o r m i t y of e m i t t e d polarization are in good a g r e e m e n t with the SwRI data.

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HAYNES, O. 1969. T h e c a p t u r e o f c o m e t s b y J u p i t e r . Astrophysics and Space Science, V. 5, p. 272-282. See Comets. HESS, S. L. 1969. V o r t i c i t y , R o s s b y n u m b e r , and geostrophy in the atmosphere of Jupiter. Icarus, V. U , p. 218-219. R e c e n t o b s e r v a t i o n s of s p o t s m o v i n g a r o u n d t h e G r e a t R e d Spot a r e used to calculate circulation, vortieity and a R o s s b y n u m b e r a t t h i s scale of a t m o s p h e r i c motions. The results arc quite comparable to v a l u e s w h i c h a r e a p p l i c a b l e t o large-scale atmospheric systems on Earth and indicate that g e o s t r o p h y is a f a c t o r i n J o v i a n a t m o s p h e r i c circulation. F I ~ , A , A. D. 1969. D e t e r m i n a t i o n o f t h e m a s s of J u p i t e r f r o m a s t u d y o f t h e m o t i o n of 57 M n e m o s y n e . Bulletin of the American Astronomical Society, V. 1, p. 342. M n e m o s y n e is one of t h e m i n o r p l a n e t s w h i c h Hill s u g g e s t e d w a s p a r t i c u l a r l y s u i t a b l e for use in d e t e r m i n i n g a m o r e a c c u r a t e m a s s o f J u p i t e r . A n a n a l y s i s of 1310 o b s e r v a t i o n s o v e r t h e p e r i o d 1859-1968 w a s m a d e , in w h i c h 84~o o f t h e o b s e r v a t i o n s were r e d u c e d t o t h e s y s t e m o f t h e F K 4 . I t was f o u n d that photographic and visual observations p r o d u c e r e s i d u a l s which, for u n k n o w n reasons, are s y s t e m a t i c a l l y b i a s e d w i t h r e s p e c t t o e a c h o t h e r . O r b i t c o m p u t a t i o n s were m a d e u s i n g a n n - b o d y i n t e g r a t i o n t o m o d e l t h e solar s y s t e m . T h e c o r r e c t i o n t o t h e reciprocal m a s s of J u p i t e r was i n c l u d e d as a n u n k n o w n in a l e a s t - s q u a r e s o r b i t c o r r e c t i o n scheme. T h e s o l u t i o n w a s s e n s i t i v e t o t h e a p p l i c a t i o n of t h e F K 4 corr e c t i o n s t o t h e o b s e r v a t i o n s . T h e d e r i v e d reciprocal m a s s is 1047.367 ± 0.004 m.e. f r o m 986 o b s e r v a t i o n s o n t h e F K 4 s y s t e m , a n d 1047.356 ± 0.004 m.e. f r o m all o b s e r v a t i o n s . ( A b s t r a c t o f a p a p e r p r e s e n t e d a t t h e A u g u s t 1969 m e e t i n g o f t h e A m e r i c a n A s t r o n o m i c a l Society.) FRA~Z, O. G., MILLIS, R . L., a n d PETTAUER, T. V. 1969. A s e a r c h for a n a n o m a l o u s b r i g h t e n i n g of Io a f t e r eclipse. Bulletin of the American Astronomical Society, V. 1, p. 344. A s e a r c h for t h e t e m p o r a r y b r i g h t e n i n g a f t e r eclipse of t h e J o v i a n satellite Io, p r e v i o u s l y r e p o r t e d b y B i n d e r a n d C r u i k s h a n k (1964, Icarus, V. 3, p. 299), h a s b e e n m a d e w i t h a n a r e a - s c a n n i n g p h o t o m e t e r . O b s e r v a t i o n s o f t h r e e eclipse r e a p p e a r a n c e s h a v e failed t o s h o w a n y e v i d e n c e of t h i s effect. ( A b s t r a c t o f a p a p e r p r e s e n t e d a t t h e A u g u s t 1969 m e e t i n g of t h e A m e r i c a n A s t r o n o m i c a l Society.) KAST~ER, S. O. 1969. Satellite s h a d o w s o n J u p i t e r as p r o b e s of its u p p e r a t m o s p h e r e . Icarus, V. l l , p. 208-211. T h e p h o t o m e t r i c profiles of t h e s h a d o w s c a s t o n J u p i t e r b y its large s a t e l l i t e s are d e t e r m i n e d to s o m e e x t e n t b y t h e

physical properties of the Jovian upper atmosp h e r e . Profiles of I o ' s s h a d o w are c o n s t r u c t e d o n t h e a s s u m p t i o n of e x p o n e n t i a l l y d e c r e a s i n g m e a n free p a t h a n d different p a t h l e n g t h s . Variations from the incident intensity distribut i o n occur, w h i c h m a y b e useful in t h e a t m o s p h e r i c analysis. MARGOLIS, J . S., a n d F o x , K . 1969. S t u d i e s of m e t h a n e a b s o r p t i o n i n t h e J o v i a n a t m o s p h e r e - - I I . A b u n d a n c e f r o m t h e 3va b a n d . The Astrophysical Journal, V. 158, p. 1183-1188. ~Iq4 (~ = air m a s s , N4 = a b u n d a n c e ) for m e t h a n e in t h e J o v i a n a t m o s p h e r e h a s b e e n d e d u c e d f r e m W a l k e r a n d H a y e s ' s e q u i v a l e n t w i d t h s o f lines in t h e R - b r a n c h of t h e 3v3 b a n d a t 1.1 ~. L a b o r a t o r y c u r v e s of g r o w t h were used to o b t a i n t h e line i n t e n s i t y for e a c h J - m a n i f o l d . S a t u r a t i o n effects were f o u n d t o b e i m p o r t a n t , a n d ~N4 was d e t e r m i n e d t o b e b e t w e e n 86 a n d 185 m - a t m , d e p e n d i n g o n t h e v a l u e u s e d for t h e line h a l f - w i d t h . MOROZ, V. I., DAVYDOV, V. D., a n d ZHEGULEV, V. S. 1969. P h o t o m e t r i c a n d spectroscopic o b s e r v a t i o n s of p l a n e t s in t h e S-14 /~ r a n g e . Soviet Astronomy--A.J., V. 13, p. 101-109. See Planets Venus. NEFF, J . S. 1969. P h o t o e l e c t r i c spectrop h o t o m e t r y of t h e m a j o r p l a n e t s . Bulletin of the American Astxonomical Society, V. 1, p. 355-356. See P l a n e t s - - G e n e r a l . OLSSON, C. N., SMITH, A. G., REGISTER, H . I., a n d MAY, J . 1969. C o m m e n c e m e n t t i m e s a n d d u r a t i o n s of J u p i t e r ' s r a d i o noise s t o r m s . Icarus, V. 11, p. 212-217. A n a l y s i s of 10 y e a r s of observations confirms Duncan's conclusion that t h e c o m m e n c e m e n t t i m e s of J u p i t e r ' s decam e t r i c noise s t o r m s define a c o n s t a n t p l a n e t a r y r o t a t i o n period, t h e v a l u e for w h i c h in t h e p r e s e n t i n v e s t i g a t i o n is 9 h 55 m 29s37. H o w e v e r , t h e s t u d y i n d i c a t e s t h a t t h e a p p a r e n t 12-year oscillation i n t h e l o n g i t u d e s of t h e c e n t e r s o f t h e c o n v e n t i o n a l sources does n o t r e s u l t f r o m a simple v a r i a t i o n in s t o r m l e n g t h . RIIHIMAA, J. J., D~-L~:, G. A., a n d WA~tWICK, J . W . 1969. M o r p h o l o g y of t h e fine s t r u c t u r e in t h e d y n a m i c s p e c t r a of J u p i t e r ' s d e c a m e t r i e r a d i a t i o n . The Astrophysical Journal, V. 158, p. 1243-1245. D y n a m i c s p e c t r a of t h e d e c a m e t r i c e m i s s i o n o f J u p i t e r were r e c o r d e d d u r ~ g 1963-1968 w i t h t h e t i m e a n d f r e q u e n c y r e s o l u t i o n close t o 0.1 sec a n d 50 k H z , respectively. T h e h i g h - r e s o l u t i o n s p e c t r a are classified i n t o t h r e e c o m p o n e n t s : t h e r a d i a t i o n envelope, t h e subs t r u c t u r e w i t h i n t h e envelope, a n d t h e superi m p o s e d m o d u l a t i o n lanes. T h e r e are t w o t y p e s o f s u b s t r u c t u r e . One looks like a c o n t i n u u m e m i s s i o n w i t h t h e t i m e r e s o l u t i o n used, a n d t h e

PLANETS--MARS o t h e r is c o m p o s e d o f s h o r t - d u r a t i o n pulses in a r a p i d succession. T h e m o d u l a t i o n lanes a p p e a r as f a i r l y r e g u l a r , ridgelike, r e p e a t e d m a x i m a a n d m i n i m a of i n t e n s i t y . T h e l a n e s are t i l t e d in t h e t i m e - f r e q u e n c y p l a n e , a n d are s l i g h t l y c u r v e d . I t is s u g g e s t e d t h a t t h e e n v e l o p e d u r a t i o n s b e t w e e n 1 a n d 10 sec a r e m a i n l y d u e t o t h e s c i n t i l l a t i o n effects i n t h e solar w i n d . I t is also m o s t likely t h a t t h e s u b s t r u c t u r e is a basic p r o p e r t y o f r a d i a t i o n w h i c h is i n h e r e n t l y conn e c t e d t o t h e source. SEAQUIST,E . R . 1969. Circular p o l a r i z a t i o n o f J u p i t e r a t 9.26 cm. Nature, V. 224, p. 1011-1012. T h e m e a s u r e d degree of c i r c u l a r p o l a r i z a t i o n is ÷0.08±0.09 percent. The longitude of the north magnetic pole--inferred from the longitude o f t h e c e n t r a l m e r i d i a n w h e n t h e left c i r c u l a r p o l a r i z a t i o n is m a x i m u m is 204.°4. ± 12"9. SMOLUCHOWSKI,R . 1969. M o t i o n o f t h e R e d S p o t o f J u p i t e r . Bulletin of the American Astronomical Society, V. 1, p. 363. H i d e ' s t h e o r y (Mem. Roy. Soc. Liege, V. 7, p. 481, 1963) o f t h e m o t i o n of J u p i t e r ' s r e d s p o t r e q u i r e s a h u g e a p e r i o d i c m o t i o n o f t h e w h o l e solid surface of t h e planet and an exchange of angular momentum w i t h a core. I t is p r o p o s e d i n s t e a d t h a t t h e m o t i o n m a y b e t h e r e s u l t of cellular c o n v e c t i o n d r i v e n b y a r a d i a l t h e r m a l g r a d i e n t , in t h e surface region, s u s t a i n e d b y t h e e n o r m o u s h e a t g e n e r a t e d i n t h e p l a n e t ' s i n t e r i o r . T h i s w o u l d a c c o u n t for a n a l m o s t c o n s t a n t e a s t w a r d or w e s t w a r d v e l o c i t y . T h e r e c e n t l y p r o p o s e d m o d e l (Nature, V. 215, p. 691, 1967) suggests t h a t o n J u p i t e r , besides a liquid m e t a l l i c h y d r o g e n - h e l i u m core (which m a y b e t h e source o f t h e h u g e m a g n e t i c field o f t h e p l a n e t ) a n d a m e t a l l i c m a n t l e , t h e r e is a solid m o l e c u l a r h y d r o g e n - h e l i u m m a n t l e below a supercritical atmosphere. An estimate o f t h e d i f f u s i o n - c o n t r o l l e d viscous c r e e p in t h e u p p e r solid m a n t l e leads t o a d r i f t o f t h e o r d e r o f 10 -5 c m sec -1 w h i c h is m u c h t o o slow as c o m p a r e d w i t h t h e o b s e r v e d v e l o c i t y o f 102 c m s e c - L I n o r d e r to e s t i m a t e t h e c o n v e c t i v e m o t i o n in t h e lower a t m o s p h e r e viscosity, t h e r m a l conductivity and thermal expansion have been e v a l u a t e d u s i n g r e c e n t t h e o r i e s of d e n s e liquids. T h e p r o b l e m of c o n v e c t i o n i n a r o t a t i n g s p h e r i c a l l i q u i d shell h a s b e e n s o l v e d b y D u r n e y (1968, J. Atmos. Sei., V. 25, p. 372), b u t o n l y for r a t h e r h i g h d i s s i p a t i v e t e r m s a n d low a n g u l a r velocities. T h u s o n e is forced t o use v a r i o u s e x t r a p o l a t i o n s a n d t h e r e s u l t s are n o t conclusive. N e v e r t h e l e s s , w i t h i n a f a c t o r o f 102 r i g h t velocities c a n b e o b t a i n e d . T h i s does n o t a n s w e r t h e q u e s t i o n c o n c e r n i n g t h e n a t u r e o f t h e r e d s p o t itself. (Abstract of a paper presented at the August 1969 m e e t i n g o f t h e A m e r i c a n A s t r o n o m i c a l Society.)

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Sky and Telescope, V. 38, p. 232-234. T h e m i s s i o n is d e s c r i b e d a n d p r e l i m i n a r y r e s u l t s are reported. 1969. F i r s t p i c t u r e s f r o m M a r i n e r s V I a n d V I I . Icarus, V. 11, p. 225-259. T h e M a r i n e r V I a n d V I I p h o t o g r a p h s o f Mars w h i c h were released in m i d - A u g u s t b y N A S A ' s Office o f P u b l i c I n f o r m a t i o n are p r e s e n t e d here. T h e y are r e p r e s e n t a t i v e of t h e c o n t e n t of t h e full p i c t u r e s e q u e n c e . A c c o m p a n y i n g t h e p i c t u r e s are t h e c a p t i o n s as r e l e a s e d b y N A S A . Dr. R . B. L e i g h t o n h e a d s t h e Television E x p e r i m e n t T e a m . 1969. M a r s p i c t u r e s f r o m M a r i n e r s 6 a n d 7. Sky and Telescope, V. 38, p. 212-221. A selection of p h o t o g r a p h s t a k e n b y t h e M a r i n e r s p a c e c r a f t are p r e s e n t e d w i t h n o t e s . B,~ABASHOV, N. P. 1969. T h e m a g n i t u d e o f Mars and the brightness distribution over the disk. Soviet Astronomy--A.J., V. 18, p. 338-342. T h e i n t e g r a t e d m a g n i t u d e of M a r s is s h o w n t o experience substantial fluctuations because of processes o c c u r r i n g a t t h e surface a n d i n t h e a t m o s p h e r e . T h u s , unless special v i s u a l o b s e r v a t i o n s are m a d e o n e c a n n o t use t h e i n t e g r a t e d magnitude to derive parameters characterizing t h e M a r t i a n surface a n d a t m o s p h e r e . BELTON, M. J . S., a n d HVNTEN, D. M. 1969. S p e c t r o g r a p h i c d e t e c t i o n of t o p o g r a p h i c f e a t u r e s o n Mars. Science, V. 166, p. 225-227. O b s e r v a t i o n s of t h e M a r t i a n c a r b o n dioxide b a n d a t 1.05 microns made with a three-channel multislit s p e c t r o p h o t o m e t e r i n d i c a t e gross h e i g h t v a r i a t i o n s in t h e ' v i c i n i t y of S y r t i s Maj or a n d s u r r o u n d ing d e s e r t regions. S y r t i s M a j o r a p p e a r s t o b e very high with essentially no detectable carbon dioxide a b o v e it. T h e d a t a a p p e a r t o c o n f i r m local t r e n d s a n d , in m a g n i t u d e a t least, t h e large v a r i a t i o n s of h e i g h t f o u n d in earlier r a d a r observations. A one-to-one correlation of height w i t h a l b e d o is n o t e v i d e n t i n t h e results. E l e v a t e d a r e a s are f o u n d in b o t h d e s e r t a n d d a r k regions. I n several regions d a r k a r e a s are a s s o c i a t e d w i t h r e l a t i v e l y s t e e p slopes. BINDER, A. B. 1969. T o p o g r a p h y a n d surface f e a t u r e s of Mars. Icarus, V. l l , p. 24-35. Topographic data obtained by radar ranging along t h e +21:5 parallel o f Mars h a v e b e e n c o r r e l a t e d w i t h surface detail. T h e d a t a s h o w t h a t t h e h i g h a r e a s a r e deserts, t h e c a n a l s o c c u r in b r o a d a n d f r e q u e n t l y deep valleys, a n d t h e m a r i a o c c u r in low a r e a s or o n slopes. T h e d a t a c o n f i r m t h e c o n c e p t t h a t f r o s t is d e p o s i t e d p r e d o m i n a t e l y i n the high areas and add support to the concept t h a t t h e d a r k a r e a s are biological i n n a t u r e . BOYCE, P. B. 1969. A r e a s c a n n i n g of M a r s

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d u r i n g 1969. Bulletin of the American Astronomical Society, V. 1, p. 336. A d u a l - c h a n n e l a r e a - s c a n n i n g p h o t o m e t e r d e s i g n e d for m a k i n g p l a n e t a r y o b s e r v a t i o n s h a s b e e n b u i l t a t Lowell Observatory. It was used in conjunction with the 24-inch, J 1 7 5 Lowell-Tololo reflector a t t h e Cerro Tololo I n t e r - A m e r i c a n O b s e r v a t o r y d u r i n g t h e m o n t h s o f M a y a n d J u n e 1969 t o o b t a i n o b s e r v a t i o n s of M a r t i a n clouds. E m p l o y i n g a dichroic m i r r o r a n d t w o p h o t o m n l t i p l i e r s , t h e area scanner produces two simultaneous intens i t y profiles o f t h e p l a n e t a r y d i s k ; one a t a fixed w a v e l e n g t h of 6000 /~, a n d t h e o t h e r a t a n y o f e i g h t w a v e l e n g t h s b e t w e e n 3300 a n d 5200 A. The spatial resolution of the scans was limited by t h e d i a m e t e r of ~he a p e r t u r e e m p l o y e d , g e n e r a l l y 1.2 see o f are or 1/16 o f t h e disk. Several different t y p e s o f clouds were o b s e r v e d o n Mars, all i n c r e a s i n g in b r i g h t n e s s w i t h d e c r e a s i n g w a v e l e n g t h s r e l a t i v e t o t h e M a r t i a n disk. P r e l i m i n a r y r e d u c t i o n s i n d i c a t e a g e n e r a l l y fiat a l b e d o f r o m 3400 t o 5000 A. I n e a r l y J u n e , t h e s o u t h p o l a r hood was the most conspicuous cloud observed, b e i n g visible as far t o t h e r e d as 5200 A, as well as h a v i n g t h e h i g h e s t a l b e d o in t h e blue. A p a r t f r o m t h e c l o u d y areas, t h e s c a n s in t h e far u l t r a v i o l e t were r e l a t i v e l y flat a n d featureless, w h i c h is c o n s i s t e n t w i t h t h e e x i s t e n c e of a n a t m o s p h e r e g e n e r a l l y o p a q u e t o blue a n d u l t r a v i o l e t light. S o m e d a r k f e a t u r e s s u c h as M a r e C i m m c r i u m were visible a t 4000 A, while o t h e r s s u c h as T r i v i u m C h a r o n t i s d i s a p p e a r e d a t 4600 A. I n n o case d i d a d a r k a r e a a t 6000 A b e c o m e b r i g h t e r than the surrounding areas at shorter wavel e n g t h s . S c a n s in e a r l y J u l y s h o w e d t h e n o r t h p o l a r h o o d t o v a r y in b r i g h t n e s s w i t h t i m e scale o f h a l f a d a y . A t its b r i g h t e s t , t h e a l b e d o d i d n o t differ f r o m t h a t o f t h e s o u t h p o l a r hood. ( A b s t r a c t of a p a p e r p r e s e n t e d a t t h e A u g u s t 1969 m e e t i n g o f t h e A m e r i c a n A s t r o n o m i c a l Society.) CHXPMA~, C. 1%., POnLACK, J . B., a n d SAGAN, C. 1969. A n a n a l y s i s of t h e M a r i n e r - 4 c r a t c r i n g statistics. The Astronomical Journal, V. 74, p. 1039-1051. A c a t a l o g u e of c r a t e r s a n d c r a t e r - l i k e o b j e c t s h a s b e e n p r e p a r e d f r o m several sets of contrast-enhanced high-quality positive transp a r e n c i e s of t h e M a r i n e r - 4 p h o t o g r a p h y . Craters were identified a n d c o u n t e d b y t h e s a m e proc e d u r e s u s e d i n t h e c o m p i l a t i o n of l u n a r c r a t e r c a t a l o g u e s ; p a r t i c u l a r a t t e n t i o n was g i v e n t o c r a t e r class a n d q u a l i t y . C o u n t s of c r a t e r s w i t h d i a m e t e r s D < 20 k m b e g i n t o s h o w t h e effects o f i n c o m p l e t e n e s s . S u b s t a n t i a l erosion a n d o b l i t e r a t i o n o f all b u t t h e l a r g e s t c r a t e r s h a s o c c u r r e d d u r i n g t h e h i s t o r y of Mars. T h e e p o c h s o f c r a t e r f o r m a t i o n a n d c r a t e r erosion a p p e a r t o be closely t i e d t o g e t h e r in t i m e . A s t a t i s t i c a l

c u r v e - f i t t i n g p r o g r a m for t h e o b s e r v e d c r a t e r d i a m e t e r - f r e q u e n c y r e l a t i o n s a n d a differential n u m b e r - d e n s i t y d i s t r i b u t i o n l a w o f A D -B g i v e B = 2.5 4- 0.2 for D > 2 0 k m , or B = 3.0 :h 0.2 for D > 30 k m . T h e p o p u l a t i o n o f i m p a c t i n g o b j e c t s a s s u m e d r e s p o n s i b l e for t h e s e c r a t e r s is t a k e n a s h a v i n g a differential n u m b e r d e n s i t y v a r y i n g as X - ~ , w h e r e X is t h e d i a m e t e r of t h e i m p a c t i n g object. T h e n u m b e r o f " l i v e " c o m e t s a n d A p o l l o o b j e c t s crossing t h e o r b i t o f M a r s is insufficient b y m o r e t h a n 2 orders o f m a g n i t u d e t o e x p l a i n t h e o b s e r v e d n u m b e r d e n s i t y o f c r a t e r s o n Mars. F o r a s t e r o i d a l o b j e c t s w i t h f~ = 2 or 3, t h e predicted and observed number densities cannot b e b r o u g h b i n t o a g r e e m e n t u n l e s s we a s s u m e a n e a r l y e p o c h o f v e r y h i g h c r a t e r i n g o n Mars. F o r = 4 or 5, a g r e e m e n t b e t w e e n t h e p r e d i c t e d a n d observed number densities can be secured with a nearly uniform rate of asteroidal bombardm e n t . F o r all r e a s o n a b l e v a l u e s o f f{, i m p a c t d a m a g e c o n t r i b u t e s t o c r a t e r erosion a n d obliteration, and asteroidal bombardment if c a p a b l e of a c c o u n t i n g q u a n t i t a t i v e l y for t h e o b s e r v e d v a l u e s o f b o t h A a n d B, p a r t i c u l a r l y is t h e zone o f o b l i t e r a t i o n a r o u n d M a r t i a n c r a t e r s is larger t h a n t h a t for l u n a r c r a t e r s . F o r n e a r saturation bombardment, the existing observat i o n s a r e o f v e r y little use i n d e t e r m i n i n g t h e v a l u e o f f~, or in d i s t i n g u i s h i n g b e t w e e n s a t u r a t i o n b o m b a r d m e n t a n d o t h e r erosion m e c h a n isms. T h e d u s t p r o d u c e d b y i m p a c t d u r i n g t h e h i s t o r y of M a r s is e s t i m a t e d t o h a v e d e p t h s b e t w e e n 0.1 a n d s e v e r a l kin. F o r ~ < 3, t h e m e a n ages o f M a r t i a n c r a t e r s a r e f o u n d t o b e a p p r o x i m a t e l y e q u a l t o t h e age o f t h e p l a n e t . H o w e v e r , for f{ significantly l a r g e r t h a n 3, different c r a t e r s will h a v e d i f f e r e n t m e a n ages, r a n g i n g d o w n t o ~< 107 y r for c r a t e r s s m a l l e r t h a n 20 k m . T h u s , t h e a b s e n c e of s u c h signs of r u n n i n g w a t e r as r i v e r v a l l e y s i n t h e M a r i n e r - 4 p h o t o g r a p h y is q u i t e i r r e l e v a n t t o t h e q u e s t i o n of t h e e x i s t e n c e of b o d i e s of w a t e r in e a r l y M a r t i a n h i s t o r y . CLOUTIER, P. A., MCELROY, H . B., a n d MICHEL, F. C. 1969. M o d i f i c a t i o n o f t h e M a r t i a n Joness p h e r e b y t h e solar w i n d . Journal of Geophysical Research, V. 74, p. 6215-6228. A d y n a m i c a l m o d e l is d e v e l o p e d for i n t e r a c t i o n of solar w i n d w i t h M a r t i a n i o n o s p h e r e . I t is a s s u m e d t h a t M a r s h a s a negligible m a g n e t i c m o m e n t , a n d a radiative equilibrium model, characterized by an e x o s p h e r i c t e m p e r a t u r e of 490°K, is a d o p t e d for the neutral atmosphere. The ionospheric s t r u c t u r e is d e t e r m i n e d b y i n t e g r a t i o n o f M a x w e l l ' s e q u a t i o n s for a 3 - c o m p o n e n t fluid, in c o m b i n a t i o n w i t h t h e e q u a t i o n s for c o n s e r v a t i o n of m a s s , m o m e n t u m , a n d energy. I t is d e m o n s t r a t e d t h a t a s t a n d i n g b o w s h o c k w a v e is r e q u i r e d b y t h e i n t e r a c t i o n of solar w i n d w i t h t h e

PLANETS--MARS ionosphere. Profiles of various flow parameters, as well as electric and magnetic field profiles, are calculated, and the problem of how to extrapolate present results, which are strictly applicable only at the subsolar point, to other locations on the planet is discussed. The computed ionospheric structure is compared with the ionospheric profile observed by Mariner 4 and is found to agree satisfactorily. I n particular, the dynamic model predicts a constant scale height of 29 km over an extensive altitude regime, in excellent agreement with the observed value. The dynamic scale height is smaller by a factor of 2 than the value computed under assumptions of photochemical equilibrium, a consequence of the pressure exerted on the ionosphere by the solar wind plasma. DAVIS, B. W. 1969. Some speculations on adsorption and desorption of COs in Martian bright areas. Icarus, V. 11, p. 155-158. Conjectures are made on t h e importance of COs adsorption in Martian bright areas. Reasonable assumptions relative to temperature, the partial pressure of COs, and the adsorptive properties of Martian dust permit computation of 4.4 × I0 -6 moles/cc of bulk as a conservative estimate for the amount desorbcd per unit bulk volume due to solar warming of bright area dust. The latter value is shown to be significant when compared with the tenuous Martian atmosphere. Possible relevance of a COs adsorption-desorption cycle to a hypothetical Martian organism is discussed. ]~GAN, W. G., FOREMAN, K. M., and MEAD, J. 1969. The significance of Mie scattering in the Martian atmosphere. Bulletin of the American Astronomical Society, V. 1, p: 340. A recent analysis of Martian polarimctry indicates t h a t accuracies of better than 0.1% can be achieved, and t h a t polarization data show internal and external consistency (Pollack and Silgan 1969, Space Sci. Rev., V. 9, p. 243). Mars polarization observations of the light "desert" regions in the visual spectral range (Dollfus, 1966, C.R. Acad. ScL Paris, V. 262, Ser. B, p. 519) exhibit a small (i.e., on the order of -0.1 to - 0 . 2 % ) but real difference, p 0 _ P0, t h a t becomes increasingly negative with viewing angle O (planctocentric longitude). Precision data on the closest limonite (Venango County, Pa.) simulation model (Egan, 1969, lcarus, V. 19, No. 2) have been compared with this Mars observational data and have been found similarly to exhibit a A P0 that is equal in magnitude but opposite in sign. Since Rayleigh scattering can only produce positive polarization, it is useful to investigate a Mie scattering aerosol distribution which could produce sufficient negative polarization to reconcile t h i s incompatibility between the planetary and

141

laboratory data. New and accurate data of the complex index of refraction, recently measured for an appropriate limonite (Egan and Becker, 1969, Appl. Opt., V. 8, p. 720) and bulk solid CO2 (Egan and Spagnolo, 1969, AppL Opt., to be published) in the wavelength range 0.35-1.0 ft have been employed in a Mie scattering computer program. The results indicate that under Mie scattering restrictions submicron size limonire aerosols are unsatisfactory to generate a negative polarization component; however, solid COs (and ice) aerosol spheres, with dominant particle radii in the range 0.28-0.35/~, could make the planetary and laboratory observations compatible. This size range is different from terrestrial aerosol experience. The physical existence of the deduced narrow-size distribution of solid COs or ice is difficult to justify at this time. (Abstract of a paper presented at the August 1969 meeting of the American Astronomical Society.) H~.~R, K. C., and PIMENTEL, G. C. 1969. Infrared absorptions near three microns recorded over the polar cap of Mars. Science, V. 166, p. 496-499. During the Mariner 7 flyby of Mars, the infrared spectrometer recorded distinct, sharp absorptions near 3020 and 3300 reciprocal centimeters between 61°S and 80°S, at the edge of the southern polar cap, with m a x i m u m optical density near 68°S and 341°E. These bands, which m at ch in frequency the v3 bands of methane and ammonia, can be associated with previously unreported spectral features of solid carbon dioxide exceeding 1 millimeter in thiekness. Possible reasons for the geographic loealization are discussed. KLIORE, A., FJELDBO, G., SEIDEL, B. L., and RASOOT,, S. I. 1969. Mariners 6 and 7: Radio occultation measurements of the atmosphere of Mars. Science, V. 166, p. 1393-1397. Radio occultation measurements with Mariners 6 and 7 provided refractivity data in the atmosphere of Mars at four points above its surface. )"or an atmosphere consisting predominantly of carbon dioxide, surface pressures between 6 and 7 millibars are obtained at three of the points of measurement, and 3.8 at the fourth, indicating an elevation of 5 to 6 kilometers. The temperature profile measured by Mariner 6 near the equator in the daytime indicates temperatures in the stratosphere about 100°K warmer than those predicted by theory. The measurements of Mariner 6 taken at 79°N at the beginning of polar night indicate t h a t conditions are favorable for the condensation of carbon dioxide at almost all altitudes. Mariner 7 measurements taken at 58°S in daytime and 38°1~ at night also show t h a t carbon dioxide condensation is ]3ossiblc at alti-

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AFCRL BIBLIOGRAPHY

tudes above about 25 kilometers. Measurements of the electron density in the ionosphere show t h a t the upper atmosphere is substantially warmer than it was in 1965, possibly because of increased solar activity and closer proximity to the sun. LEIGHTOI~T,R. B., HOROWITZ, N. H., MURRAY, B. C., SHARP, R. P., HERRIMAN, A. H., YounG, A. T., S~rrH, B. A., DAVIES, M. E., and LEOVY, C. B. 1969. Mariner 6 and 7 television.pictures: Preliminary analysis. Science, V. 166, p. 49-67. Following two similar articles about the Mariner 6 and 7 television pictures, respectively, t h i s article draws together the preliminary results from the two spacecraft. The authors provide information about the mission, the television system design and data return, and discuss the camera operation and picture appearance. The more important among the observed atmospheric and surface features are : no blue-absorbing haze is found; aerosol-scattering layers are present in the atmosphere; diurnal brightening in the " W-c l o u d " area is seen repeatedly; darkening of the polar cap in a band near the limb is observed; three different types of terrain are found: cratered, chaotic, and featureless; two distinct populations of craters are present; no tectonic and topographic forms similar to terrestrial forms are observed; evidences of both atmosphere-surface effects and topographic effects are seen on the south polar cap ; variable atmospheric and atmosphere-surface effects are found at high northern latitudes. Several classical features have been successfully identified with specific topographic forms, mostly craters or crater remnants. The findings are inconclusive on the question of life on Mars, but they support earlier evidence of scarcity of water. These results are still tentative, subject to considerable expansion and possible modification. LEerY, C., and MINTZ, Y. 1969. Numerical simulation of the atmospheric circulation and climate of Mars. Journal of the Atmospheric Sciences, V. 26, p. 1167-1190. The MintzArakawa two-level model for planetary atmospheres has been adapted to simulate the atmospheric circulation and climate of Mars. The model uses the primitive equations of atmospheric motion, with heating and cooling by solar and infrared radiative transfer and by turbulent convection. Carbon dioxide is the principal atmospheric constituent and is allowed to condense on the planet's surface, releasing latent heat where the surface cools to the CO2 frost point. Two numerical experiments are made; one simulates orbital conditions at the southern summer (northern winter) solstice of Mars, and

the other orbital conditions at the southern autumnal equinox. The results of the solstice experiment show strong zonal mean west winds in the middle and high latitudes of the winter hemisphere produced by the net eastward Coriolis torque t h a t accompanies the poleward mass transfer toward the condensing CO2 polar ice cap, wave cyclones in the winter hemisphere, a strong thermally-direct mean meridional circulation across the equator, with a strong east wind m a x i m u m near the equator, and weak east winds over most of the summer hemisphere. The results of the equinox experiment are more like conditions in the earth's atmosphere. In both hemispheres there are zonal mean west winds in the middle latitudes with wave cyclones in the middle and higher latitudes and east winds in the tropics. In both experiments there are large diurnal tidal components of the circulation. LIBBY, W. F. 1969. W h y is the Moon gray? Science, V. 166, p. 1437-1438. See M o o n - Surface Layer. MArcus, A. H. 1969. Distribution of slopes on a cratered planetary surface: Theory and preliminary applications. Journal of Geophysical Research, V. 74, p. 5253-5267. See M o o n - Surface Features. McELRoy, M. B., and HU~rrEN, D. M. 1969. Molecular hydrogen in the atmosphere of Mars. Journal of Geophysical Re, catch, V. 74, p. 58075809. Attention is directed to the destruction of H2 by reaction with CO2 + in the Martian ionosphere. I t is shown t h a t nearly all the H2 flowing into the ionosphere is converted into H and escapes in the latter form. MILLS, A. A. 1969. Fluidization phenomena and possible implications for the origin of lunar craters..Nature, V . 224, p. 863-866. See M o o n - Surface Features. MOROZ, V. I., DAVYDOV,V. D., and ZH~.GUL~V, V. S. 1969. Photometric and spectroscopic observations of planets in the 8-14 /~ range. Soviet Astronomy--A.J., V. 13, p. 101-109. See Planets--Venus. MORRISON, D., SAGAS, C., and POLLACK, J. B. 1969. Martian temperatures and thermal propcrties. Icarus, V. 11, p. 36-45. Previously unreduced 8-13 p m radiometry of Mars performed in 1954 by Sinton and Strong have been used to obtain the distribution of temperature over the Martian surface. The temperatures are consistent with predictions obtained from solution of the one-dimensional equation of heat conduction with a thermal inertia of about 0.005 cal cm -9 see-l/2 deg -1. This value is also suggested by the mean microwave brightness temperature of about 200°K. At the Martian atmospheric pressure, this inertia would result

Pr,A~ETS---MARS f r o m a v e r a g e p a r t i c l e sizes o f a b o u t 100 ~ m . T h e t h e r m a l i n e r t i a o f t h e d a r k e s t a r e a s is l a r g e r t h a n t h a t of t h e b r i g h t areas, as w o u l d b e e x p e c t e d i f t h e a t m o s p h e r i c p r e s s u r e is h i g h e r or t h e m e a n p a r t i c l e size is l a r g e r i n t h e d a r k areas. The observed latitudinal temperature gradient a p p e a r s t o b e c o n s i s t e n t w i t h t e m p e r a t u r e s of a p p r o x i m a t e l y 145°K a t 60 ° w i n t e r l a t i t u d e s a n d t h e r e f o r e w i t h a p o l a r c a p c o m p o s e d , a t least in p a r t , o f CO2. A t all l a t i t u d e s t h e m i n i m u m t e m p e r a t u r e falls b e l o w 190°K; u n d e r t h e s e c i r c u m s t a n c e s , a significant f r a c t i o n o f t h e a t m o s p h e r i c w a t e r v a p o r will c o n d e n s e a t n i g h t . c o n t r i b u t i n g t o t h e " d a w n h a z e . " A n a n a l y s i s of the microwave spectrum of Mars suggests that t h e loss t a n g e n t of t h e s u b s u r f a c e m a t e r i a l is less t h a n 0.03. MURPHY, R . E . 1969. P h o t o m e t r y of M a r s n e a r t h e t i m e of o p p o s i t i o n . Bulletin of the American Astronomical Society, V. 1, p. 355. T h e M a r t i a n o p p o s i t i o n effect r e p o r t e d b y O ' L e a r y a n d b y K o v a l i n 1967 is c o n f i r m e d b y a n u v b y study carried out at the Manna Kea Observatory during the 1969 opposition. The opposition effect is f o u n d t o b e s t r o n g e r in t h e blue a n d v i o l e t regions t h a n it is i n t h e yellow, s u g g e s t i n g t h a t it is a t m o s p h e r i c i n origin. A t a p h a s e a n g l e of 2 °, M a r s is f o u n d t o b e i n excess of 0.10 m a g b r i g h t e r i n t h e v i o l e t t h a n t h e l i n e a r p h a s e law w o u l d imply. (Abstract of a paper presented at the A u g u s t 1969 m e e t i n g o f t h e A m e r i c a n A s t r o n o m i c a l Society.) NEUGEBAUER, G., M ~ C H , G., CHASE, S. C.,

JR., HATZENBELER, H., MINER, E., and SCItOFIELD, D. 1969. M a r i n e r 1969: P r e l i m i n a r y r e s u l t s of t h e i n f r a r e d r a d i o m e t e r e x p e r i m e n t .

Science, V. 166, p. 98-99. T h e t h e r m a l e n e r g y e m i t t e d b y Mars was m e a s u r e d i n t h e 8- t o 12a n d 18- t o 2 5 - m i c r o m e t e r b a n d s . T h e m i n i m u m t e m p e r a t u r e d e r i v e d for t h e s o u t h e r n p o l a r c a p is 150°K, a n i n d i c a t i o n t h a t t h e c a p is f o r m e d b y f r o z e n c a r b o n dioxide. N o significant t e m p e r a t u r e f l u c t u a t i o n s were d e t e c t e d w i t h a 100k i l o m e t e r scale. NULL, G. W . 1969. A s o l u t i o n for t h e m a s s a n d d y n a m i c a l o b l a t e n e s s of Mars u s i n g M a r i n e r - I V D o p p l e r d a t a . Bulletin of the American Astronomical Society, V. l , p. 356. T h e M a r i n e r - I V s p a c e c r a f t p a s s e d Mars o n 15 J u l y 1965 a t a b o u t 9800 k m for t h e surface. C o h e r e n t S - b a n d Doppler data taken during the flyby by the N A S A - J P L D e e p Space S t a t i o n s h a d a n equiva l e n t r a n g e - r a t e a c c u r a c y o f 1.0 m m / s e c , c o u n t e d o v e r 1 m i n . A n initial s o l u t i o n for t h e i n v e r s e m a s s (m -1) o f 3098600 ± 600 u s i n g d a t a f r o m 10-20 J u l y 1965 (Null 1967, Astron. J., V. 73, p. 1292) w a s g i v e n a large s t a n d a r d e r r o r t o a c c o u n t for insufficient c o m p u t e r precision

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a n d M a r s e p h e m e r i s errors. E p h e m e r i s e r r o r s h a v e since ~b e e n r e d u c e d b y c o m b i n i n g M a r s radar data with other planetary radar and o p t i c a l d a t a a n d a 16-decimal d i g i t p r o g r a m is n o w u s e d for s p a c e c r a f t work. R e p r o c e s s i n g t h e 10-20 J u l y d a t a u s i n g a n a p r i o r i d a t a s t a n d a r d e r r o r of 3 m m / s e c for 1-min s a m p l e s g a v e t h e following r e s u l t s for m -1 a n d t h e o b l a t e n e s s (J2) o f M a r s : m -1 = 3098708 ± 9 , J 2 = (1.87 ± 0.07) × 10 -3. A n e q u a t o r i a l r a d i u s of M a r s (RM) o f 3394 k m was used. T h e f o r m a l errors include t h e effect of a 10-7-rad e r r o r in e a c h E c k e r t - B r o u w e r Set I I I e l e m e n t o f Mars. T h i s is t h e c u r r e n t m a j o r e r r o r source for m -1. O t h e r s o l u t i o n p a r a m e t e r s include initial spacecraft coordinates and tracking s t a t i o n locations. Small n o n g r a v i t a t i o n a l forces a n d h i g h e r h a r m o n i c s a t e x p e c t e d levels h a v e o n l y a m i n o r effect. W i l k i n s (Mantles of the Earth and Terrestrial Planets, p. 77, 1967) u s i n g a long arc o f M a r t i a n satellite d a t a h a d t h e results: m -1 = 3096000 ± 6000, J 2 = (1.97 ± 0.006) × 10 -a, for RM = 3394 k m . T h u s M a r i n e r IV provides an independent confirmation of the s t r o n g e r satellite J 2 solution. I f J 2 is fixed a t t h e a b o v e value, t h e M a r i n e r I V m -1 s o l u t i o n c h a n g e s negligibly. I t is a n t i c i p a t e d t h a t t h e real errors, as disclosed b y c o m p a r i s o n w i t h f u t u r e M a r s probes, will n o t e x c e e d t h r e e t i m e s t h e f o r m a l e r r o r s q u o t e d . ( A b s t r a c t of a p a p e r p r e s e n t e d a t t h e A u g u s t 1969 m e e t i n g of t h e A m e r i c a n A s t r o n o m i c a l Society.) N~-LL, G. W., a n d LIESKE, J . H . 1969. A s t r o n o m i c a l c o n s t a n t s f r o m o b s e r v a t i o n s of t h e i n n e r p l a n e t s a n d I c a r u s . Bulletin of the American Astronomical Society, V. l , p. 356-357. R a d a r o b s e r v a t i o n s o f M e r c u r y , V e n u s , a n d Mars f r o m 1964-68, t o g e t h e r w i t h m e r i d i a n circle o b s e r v a t i o n s of t h e s u n a n d four i n n e r p l a n e t s f r o m 1911-67, h a v e b e e n c o m b i n e d w i t h o b s e r v a t i o n s o f I c a r u s f r o m 1949-68 a n d a n a l y z e d t o d e t e r m i n e corrections to the orbits of the inner planets and I c a r u s , t o e s t i m a t e t h e v a l u e s of t h e g e n e r a l r e l a t i v i t y m u l t i p l i e r ~, t h e solar o b l a t e n e s s , t h e mass of Mercury, and other astronomical c o n s t a n t s . A s n o t e d in a p r e v i o u s p a p e r (Astron. J . , V. 74, p. 297, 1969) we were u n a b l e t o o b t a i n c o n s i s t e n t e s t i m a t e s of t h e r e l a t i v i t y p a r a m e t e r b u t f o u n d t h a t its v a l u e s t r o n g l y d e p e n d e d u p o n t h e E a r t h e p h e m e r i s . O u r s o l u t i o n for t h e m a s s of M e r c u r y f r o m I c a r u s d a t a i n t h a t p a p e r w a s m -1 = 5,934,000 ± 65,000. T h r o u g h c o n v e r s a t i o n s w i t h I. S h a p i r o we d i s c o v e r e d t h a t o u r error estimate resulted from a covariance matrix in which the Earth's mean motion was h e l d fixed; if one allows t h e m e a n m o t i o n o f t h e Earth to enter into the error determination, then o u r p r e v i o u s r e s u l t w o u l d b e m -1 = 5,935,000 ± 520,000. T h e I c a r u s d a t a were c o m b i n e d w i t h

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r a d a r a n d o p t i c a l o b s e r v a t i o n s of t h e i n n e r planets in the hope that the combination of data t y p e s w o u l d allow t h e s e p a r a t i o n o f r e l a t i v i s t i c a n d o b l a t e n e s s effects. I n t h e p r e s e n t effort o v e r 27,000 m e r i d i a n circle o b s e r v a t i o n s a n d 493 p u b l i s h e d r a d a r o b s e r v a t i o n s of t h e i n n e r p l a n e t s collected a n d e d i t e d b y I). O ' H a n d l e y t o g e t h e r w i t h 308 p h o t o g r a p h i c o b s e r v a t i o n s of I c a r u s were e m p l o y e d . T h e p l a n e t a r y d a t a c o m p l e t e l y dominate the information contained in the I c a r u s d a t a a n d we still are u n a b l e t o s e p a r a t e t h e effects of solar o b l a t e n e s s f r o m t h o s e o f t h e g e n e r a l r e l a t i v i t y p a r a m e t e r . I f one a s s u m e s zero solar o b l a t e n e s s , t h e n t h e d a t a c o n f i r m E i n s t e i n ' s g e n e r a l r e l a t i v i t y t o w i t h i n 2~/o. I f one a s s u m e s t h a t E i n s t e i n ' s g e n e r a l r e l a t i v i t y is v a l i d a n d e s t i m a t e s t h e solar o b l a t e n e s s , t h e r e s u l t (/,]2/< 10 -5 w i t h a f o r m a l e r r o r o f 0.7 x 10 -5 ) is five t i m e s smaller t h a n t h e solar o b l a t e ness o b s e r v e d b y D i c k e a n d G o l d e n b e r g (1967, Phys. Rev. Letters, V. 18, p. 313). F r o m t h e p u b l i s h e d d a t a we were u n a b l e t o o b t a i n significant information concerning the relativistic p r o p a g a t i o n effect (Shapiro, 1964, Phys. Rev. Letters, V. 13, p. 789; M u h l e m a n a n d Reichley, 1964, J P L Space Programs Summary 37-29, V. 4, p. 239). T h e e s t i m a t e of t h e m a s s of M e r c u r y does n o t s e e m t o b e s e n s i t i v e t o t h e inclusion or exclusion o f e s t i m a t e s for J 2 a n d A, b u t it is s e n s i t i v e t o w h e t h e r or n o t r a d a r a n d o p t i c a l d a t a are c o m b i n e d . ( A b s t r a c t of a p a p e r p r e s e n t e d a t t h e A u g u s t 1969 m e e t i n g of t h e A m e r i c a n A s t r o n o m i c a l Society.) PLUMMER, W . T., a n d CA~SO~, R . K . 1969. M a r s : I s t h e surface colored b y c a r b o n s u b o x i d e . Science, V. 166, p. 1141-1142. T h e reflection s p e c t r u m o f M a r s c a n b e well m a t c h e d f r o m 0.2 t h r o u g h 1.6 m i c r o n s ( a n d f a r t h e r ) b y p o l y m e r s o f c a r b o n s u b o x i d e , reflection s p e c t r a for w h i c h have now been measured. The authors propose t h a t t h e r e d d i s h color of Mars m i g h t b e a t tributed to carbon suboxidc, not the commonly c o n s i d e r e d l i m o n i t e or o t h e r i r o n - b e a r i n g m i n erals. SCHUBERT, G., TURCOTTE, D. L., a n d OXBURGH, E . •. 1969. S t a b i l i t y o f p l a n e t a r y interiors. Geophysical Journal of the Royal Astronomical Society, V. 18, p. 441-460. M a n y accept thermal convection within the mantle of t h e E a r t h as t h e d r i v i n g m e c h a n i s m for contin e n t a l drift. I t is also o f c o n s i d e r a b l e i n t e r e s t t o d e t e r m i n e w h e t h e r t h e r m a l c o n v e c t i o n is occ u r r i n g w i t h i n V e n u s , Mars, a n d t h e Moon. I n this paper a systematic treatment of the s t a b i l i t y of p l a n e t a r y i n t e r i o r s is given. T h e t h e r m a l s t a b i l i t y p r o b l e m for a l a y e r o f fluid h e a t e d f r o m b e l o w is solved w h e n t h e v i s c o s i t y o f t h e fluid increases e x p o n e n t i a l l y w i t h d e p t h .

F o r a semi-infinite fluid w i t h e x p o n e n t i a l l y i n c r e a s i n g v i s c o s i t y t h e critical R a y l e i g h n u m b e r b a s e d o n t h e s u r f a c e v i s c o s i t y a n d t h e scale l e n g t h o f t h e v i s c o s i t y i n c r e a s e is f o u n d t o b e 30 for a fixed surface b o u n d a r y c o n d i t i o n a n d 23 for a free surface b o u n d a r y c o n d i t i o n . T h i s s t a b i l i t y a n a l y s i s is also e x t e n d e d t o i n c l u d e v o l u m e h e a t release. T h e t h e r m a l s t a b i l i t y o f t h e i n t e r i o r s o f t h e E a r t h , V e n u s , Mars a n d t h e M o o n is e x a m i n e d . U s i n g t e m p e r a t u r e - d e p t h profiles i n t h e l i t e r a t u r e a n d a t h e o r e t i c a l e x p r e s s i o n for t h e v i s c o s i t y of a c r y s t a l l i n e solid b a s e d o n diffusion creep, v i s c o s i t y d e p t h profiles for p l a n e t a r y i n t e r i o r s are o b t a i n e d . B e c a u s e of t h e s t r o n g p r e s s u r e effect t h e v i s c o s i t y w i t h i n t h e E a r t h a n d V e n u s increases g r e a t l y f r o m a n e a r surface m i n i m u m . F o r M a r s t h e i n c r e a s e is less pronounced and within the interior of the Moon t h e v i s c o s i t y is n e a r l y c o n s t a n t . F o r all t h e cases considered the planetary interiors are found to b e t h e r m a l l y u n s t a b l e . B e c a u s e of t h e d e p e n d ence o f v i s c o s i t y o n d e p t h t h e i n t e r i o r s o f t h e M o o n a n d M a r s a r e f o u n d t o b e c o n s i d e r a b l y less s t a b l e t h a n V e n u s a n d t h e E a r t h . I t is c o n c l u d e d t h a t t h e r m a l c o n v e c t i o n is o c c u r r i n g w i t h i n t h e p l a n e t a r y b o d i e s considered. WELLS, R . A. 1969. M a r t i a n t o p o g r a p h y : Large-scale v a r i a t i o n s . Science, V. 166, p. 8 6 2 865. T h e v a r i a t i o n in c a r b o n d i o x i d e a b u n d a n c e s d e t e c t e d in t h e 1.05-micron b a n d o v e r s m a l l d i s c r e t e a r e a s o n Mars i n d i c a t e s t h a t largerscale t o p o g r a p h i c a l differences are p r e s e n t t h a n h a d p r e v i o u s l y b e e n believed. S p e c t r o s c o p i c m a p p i n g of t h e surface also i n d i c a t e s n o a p parent correlation between albedo and height; t h e r e s u l t s are i n good a g r e e m e n t w i t h t o p o graphical data derived from the range-gated r a d a r s c a n a l o n g +21°N. H i g h a n d low a r e a s a r e f o u n d in b o t h t h e m a j o r e q u a t o r i a l m a r i a a n d the bright deserts in the northern hemisphere. WILKINS, G. A. 1969. M o t i o n of P h o b o s . N a t u r e , V. 224, p. 789. A n y secular a c c e l e r a t i o n o f P h o b o s is m u c h less t h a n t h a t g i v e n b y Sharpless, b u t , u n f o r t u n a t e l y , a v a l u e t h a t c o u l d b e u s e d m e a n i n g f u l l y in e s t i m a t i n g t h e r e l e v a n t p h y s i c a l p r o p e r t i e s o f P h o b o s a n d Mars c a n n o t b e specified a t p r e s e n t . YOUNG, A. T. 1969. H i g h - r e s o l u t i o n p h o t o m e t r y o f a t h i n p l a n e t a r y a t m o s p h e r e . Icarus, V. 11, p. 1-23. H i g h - r e s o h i t i o n p h o t o m e t r y n e a r t h e l i m b of a p l a n e t c a n b e i n v e r t e d t o yield t h e scale h e i g h t a n d o p t i c a l d e p t h o f t h e a t m o s p h e r e i f t h e s c a t t e r i n g p h a s e f u n c t i o n is k n o w n . T h e m e t h o d is a p p l i e d t o M a r i n e r I V o b s e r v a t i o n s of Mars, a s s u m i n g a R a y l e i g h p h a s e f u n c t i o n . A f t e r m a k i n g a large c o r r e c t i o n for s c a t t e r e d light, we find h0 ~ 10 k m a n d ~ ~ 0.03 a t ~ = 0.6 p. T h e r e is some e v i d e n c e for a d u s t y l a y e r w i t h i n

PT.ANETS--YENUS a few k i l o m e t e r s of t h e g r o u n d . B e t t e r spacecraft data are needed to determine the optical p r o p e r t i e s of t h e M a r t i a n a t m o s p h e r e . PLANETS---MERCURY KLEIN, M. J . , a n d MOP.RISeN, D. 1969. T h e m i c r o w a v e s p e c t r u m of M e r c u r y . Bulletin of the American Astronomical Society, V. 1, p. 350. M e r c u r y ' s disk t e m p e r a t u r e h a s b e e n m e a s u r e d a t 6-cm w a v e l e n g t h u s i n g t h e 43-m a n t e n n a a t the National Radio Astronomy Observatory. T h e p h a s e - i n v a r i a n t c o m p o n e n t of t h e t e m p e r a t u r e is 380 ± 20°K, w h e r e t h e m e a n e r r o r i n c l u d e s a 5~/o u n c e r t a i n t y in t h e a b s o l u t e flux scale. T h i s m e a s u r e m e n t p r o v i d e s f u r t h e r evid e n c e t h a t t h e t i m e - a v e r a g e d disk t e m p e r a t u r e o f M e r c u r y i n c r e a s e s b y 25~o f r o m s h o r t millim e t e r w a v e l e n g t h s t o 6 era. T h i s d e p a r t u r e f r o m a t h e r m a l s p e c t r u m is p r o b a b l y d u e t o a n increase o f t h e m e a n t e m p e r a t u r e w i t h d e p t h n e a r t h e surface of t h e p l a n e t . I t is s h o w n t h a t t h i s a v e r a g e temperature gradient could be maintained by a s u b s u r f a c e " g r e e n h o u s e effect" i f r a d i a t i v e h e a t c o n d u c t i o n , w h i c h is s t r o n g l y t e m p e r a t u r e d e p e n d e n t , s u p p o r t s a large f r a c t i o n o f t h e d i u r n a l flow o f h e a t i n M e r c u r y ' s epilith. N o a t t e m p t was m a d e t o s p a c e o u r o b s e r v a t i o n s i n order to measure variation of temperature with p h a s e angle. H o w e v e r , t h e t e m p e r a t u r e s we o b t a i n e d are c o n s i s t e n t w i t h a m o d e l i n w h i c h t h e r a t i o of t h e electrical t o t h e r m a l s k i n d e p t h s is n e a r u n i t y a t l - e r a w a v e l e n g t h . ( A b s t r a c t of a p a p e r p r e s e n t e d a t t h e A u g u s t 1969 m e e t i n g of t h e A m e r i c a n A s t r o n o m i c a l Society.) NULL, G. W., a n d LIESKE, J . H . 1969. A s t r o n o m i c a l c o n s t a n t s f r o m o b s e r v a t i o n s of t h e i n n e r p l a n e t s a n d I c a r u s . Bulletin of the American Astronomical Society, V. 1, p. 356-357. See Planets--Mars. U ~ I C H S , J . , a n d C ~ P B E n L , M. J . 1969. R a d i a t i v e h e a t t r a n s f e r in t h e L u n a r a n d M e r c u r i a n surfaces. Icarus, V. 11, p. 180-188. See M o o n T e m p e r a t u r e . PLANETS--~EPTUNE BIXBY, J . E., a n d VAN FLANDERN,T. C. 1969. T h e d i a m e t e r o f N e p t u n e . The Astronomical Journal, V. 74, p. 1220-1222. F o u r t e e n m e r i d i a n circle o b s e r v a t i o n s m a d e before a n d a f t e r t h e o c c u l t a t i o n o f ZC 2232 b y N e p t u n e o n 7 April 1968 a n d o b s e r v a t i o n s o f t h e o c c u l t a t i o n f r o m Japan, New Zealand, and Australia have been u s e d to d e t e r m i n e c o r r e c t i o n s t o t h e e p h e m e r i s of the relative positions of the star and Neptune, o f ÷.6260 =~ 0:001 in r i g h t a s c e n s i o n a n d --0.~46 ± 0 : 0 7 in d e c l i n a t i o n , a n d a n e w s e m i d i a m e t e r o f N e p t u n e o f 33.~9 ± 1.~8 a t u n i t d i s t a n c e .

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SPINRAD, H . 1969. L a c k of a n o t i c e a b l e m e t h a n e a t m o s p h e r e o n T r i t o n . Publications of the Astronomical Society of the Pacific, V. 81, p. 8 9 5 - 8 9 6 . W i t h t h e 120-inch reflector a n d Wampler scanner the writer measured the ratio o f I(~6100)/I(~6200) w i t h a A ) t = 9 0 A o n :May 22 (U.T.) 1969. T h e v i s u a l m a g n i t u d e o f T r i t o n w a s 13.6; t h e satellite was t h e n n e a r a n elongation from Neptune. For objects with s t r o n g CH4 ( m a j o r p l a n e t s a n d T i t a n ) t h e i n t e n s i t y ratio, o n t h e i n s t r u m e n t a l s y s t e m , is r a t h e r larger t h a n u n i t y (r = 1.87 for N e p t u n e ) while it e q u a l s 1.014 for G d w a r f s a n d callisto ( J I V ) w i t h n o CH4. T h e T r i t o n CH4 ratio, carefully c o r r e c t e d for s c a t t e r e d light f r o m N e p t u n e , was 1.015 ± 0.01; t h i s m e a n s t h e satellite h a s e s s e n t i a l l y zero CH4 a t is t h e ~ 6190 b a n d . PLANETS--SATURN CooK, A. F., a n d F ~ ' ~ K L ~ , F . A. 1969. M e t e o r o i d a l b o m b a r d m e n t o f S a t u r n ' s rings.

Bulletin of the American Astronomical Society, V. 1, p. 338. See M e t e o r s a n d Meteorites. CooK, A. F., a n d F R A ~ J ~ , F. A. 1969. T h e effect o f m e t e o r o i d a l b o m b a r d m e n t o n S a t u r n ' s

rings. Smitheonian Astrophysical Observatory Special Report 304, 31 p p . See M e t e o r s a n d Meteorites. NEFF, J . S. 1969. P h o t o e l e c t r i c s p e c t r o p h o t o m e t r y of t h e m a j o r p l a n e t s . Bulletin of the American Astronomical Society, V. 1, p. 355-356. See P l a n e t s - - G e n e r a l . PLANETS~VENUS BI~OWN, R . R . 1969. Solar cosmic r a y effects in t h e lower i o n o s p h e r e of V e n u s . Planetary and Space Science, V. 17, p. 1923-1926. T h e s i m i l a r i t y of a t o m i c p a r a m e t e r s for t h e CO2 a t m o s p h e r e of V e n u s a n d t h a t of t h e E a r t h is u s e d t o c a l c u l a t e the ionization and optical emission rate in the u p p e r a t m o s p h e r e of V e n u s r e s u l t i n g f r o m a m a j o r solar cosmic r a y e v e n t . T h e p o s s i b i l i t y o f as m u c h as 10 p e r c e n t o f N~ in t h e a t m o s p h e r i c c o m p o s i t i o n o f V e n u s does n o t c h a n g e t h e s e effects a p p r e c i a b l y . EBERSTEIN, I. J., KH~-~E, B. N., a n d P O L I C E , J . B. 1969. I n f r a r e d t r a n s m i s s i o n p r o p e r t i e s o f CO, HC1, a n d SO2 a n d t h e i r significance for t h e g r e e n h o u s e effect o n V e n u s . Icarus, V. 11, p. 159-170. L o w r e s o l u t i o n (20 e m -1) t r a n s m i s s i o n m e a s u r e m e n t s were o b t a i n e d for s t r o n g i n f r a r e d a b s o r p t i o n f e a t u r e s o f CO, HC1, a n d SO2. E x p e r i m e n t s were p e r f o r m e d a t r o o m t e m p e r a t u r e w i t h a P e r k i n - E l m e r 621 g r a t i n g s p e c t r e p h o t o m e t e r a n d a 10 c m p a t h l e n g t h cell h a v i n g CsI windows. Some 4 m e t e r CO s t u d i e s were also m a d e . T h e a b s o r b e r s were p l a c e d i n a c a r r i e r gas

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o f n i t r o g e n or c a r b o n dioxide, a n d t h e p a r t i a l p r e s s u r e s o f a b s o r b e r a n d d i l u e n t , respectively, were v a r i e d . T h e l o g a r i t h m o f t h e a b s o r b a n c e was r e p r e s e n t e d as h a v i n g a p o w e r law d e p e n d e n c e o n a b s o r b e r a m o u n t a n d t o t a l pressure, w h e r e typically each variable varied over a larger r a n g e t h a n a n o r d e r o f m a g n i t u d e . T h e CO s p e c t r u m was s y n t h e s i z e d t h e o r e t i c a l l y a n d c o m p a r e d w i t h t h e p o w e r law r e p r e s e n t a t i o n t o explore the latter's range of validity. Finally, it was c o n c l u d e d t h a t n o n e of t h e a b o v e gases are significant for t h e s t r o n g g r e e n h o u s e effect o n V e n u s , e i t h e r b e c a u s e t h e y a r e n o t p r e s e n t in sufficient a m o u n t s , or b e c a u s e t h e y p r o d u c e o p a c i t y in s p e c t r a l regions w h e r e c a r b o n dioxide is a l r e a d y q u i t e o p a q u e . EFANOV, V. A., KISLYAKOV, A. G., MOISEEV, I. G., a n d NAUMOY, A. I. 1969. R a d i o e m i s s i o n of V e n u s a n d J u p i t e r a t 2.25 a n d 8 r a m . Soviet A stronomy--A.J., V. 13, p. 110-113. R e s u l t s are p r e s e n t e d of o b s e r v a t i o n s of t h e r a d i o e m i s s i o n of V e n u s a n d J u p i t e r a t 2.25 a n d 8 m m m a d e o n a 22 m r a d i o telescope d u r i n g S e p t e m b e r - O c t o b e r 1968. T h e b r i g h t n e s s t e m p e r a t u r e of V e n u s , d e t e r m i n e d b y c o m p a r i s o n w i t h t h e i n t e n s i t y of r a d i o e m i s s i o n f r o m J u p i t e r is Tv - 235 4- 4 0 ° K a t 2.25 m m a n d Tv = 375 ± 60°K a t 8 m m . T h e brightness temperatures of Venus and Jupiter a t 2.25 m m , d e t e r m i n e d b y t h e m e t h o d of c o m p a r i s o n w i t h t h e S u n ' s t e m p e r a t u r e (for t h e a c c e p t e d v a l u e Ts = 5600°K), is Tv = 290 ± 90°K a n d T~ = 180 ± 60°K. A n o p t i c a l t h i c k n e s s o f t h e c l o u d c o v e r of V e n u s ~,~ 2.33 h a s b e e n e s t i m a t e d as a lower limit. ELCO, R. A. 1969. I n t e r a c t i o n of t h e solar w i n d w i t h p l a n e t a r y a t m o s p h e r e s . Journal of Geophysical Research, V. 74, p. 5073-5082. See Planets--General. GLUSHNEVA, I. N. 1969. A n e w d e t e r m i n a t i o n of the wavelength dependence of Venus' albedo in t h e u l t r a v i o l e t region. Soviet Astronomy--A.J., V. 13, p. 162-165. A n e w d e t e r m i n a t i o n is m a d e of the wavelength dependence of Venus' albedo i n t h e u l t r a v i o l e t region 4 8 0 0 - 3 2 0 0 /~. T h e r e s u l t s o b t a i n e d w i t h a 125 c m reflector are in good a g r e e m e n t w i t h t h e findings of o b s e r v a t i o n s m a d e in 1963. I n t h e r a n g e 3800-3200 A V e n u s ' a l b e d 0 is f o u n d t o decline s o m e w h a t m o r e s t e e p l y t o w a r d s h o r t e r w a v e l e n g t h s t h a n for t h e 1963 observations. GRAY, L. D., SCHORN, R . A., a n d BARKER, E. 1969. H i g h dispersion spectroscopic o b s e r v a t i o n o f V e n u s . I V : T h e w e a k c a r b o n dioxide b a n d a t 7883 A. Applied Optics, V. 8, p. 2087-2093. T h e a v e r a g e r o t a t i o n a l t e m p e r a t u r e of t h e C y t h e r e a n a t m o s p h e r e a b o v e t h e c l o u d t o p s was f o u n d t o b e Trot = 244 ° ± 10°K b a s e d o n t w e l v e p l a t e s of t h e 7883-/~ CO2 b a n d . I f t h e t e m p e r a t u r e s f o u n d

f r o m t h e 7820-A b a n d o n t h e s a m e p l a t o a r e averaged with the temperatures found from the 7883-• b a n d , we o b t a i n a t e m p e r a t u r e o f Trot = 2 4 5 ° ± 6°K. T h e o b s e r v a t i o n s of V e n u s were m a d e b e t w e e n April a n d D e c e m b e r o f 1967. L a b o r a t o r y m e a s u r e m e n t s of t h e 7883-A b a n d are lacking, b u t we i n f e r t h a t t h e b a n d is h a l f as s t r o n g as t h e 7820-A b a n d . HANSEI'T, J. E. 1969. A b s o r p t i o n - l i n e f o r m a tion in a scattering planetary atmosphere: A t e s t of V a n de H u l s t ' s s i m i l a r i t y relations. The Astrophysical Journal, V. 158, p. 337-349. See Planets--General. II~GERSOLL, A. P. 1969. T h e r u n a w a y greenh o u s e : A h i s t o r y of w a t e r o n V e n u s . Journal of the Atmospheric Sciences. V. 26, p. 1191-1198. R a d i a t i v e - c o n v e c t i v e e q u i l i b r i u m m o d e l s of p l a n e t a r y a t m o s p h e r e s are discussed for t h e case w h e n t h e i n f r a r e d o p a c i t y is d u e t o a v a p o r i n e q u i l i b r i u m w i t h its l i q u i d or solid phase. F o r a g r e y gas, or for a g a s w h i c h a b s o r b s a t all i n f r a r e d w a v e l e n g t h s , e q u i l i b r i u m is i m p o s s i b l e w h e n t h e solar c o n s t a n t exceeds a critical value. E q u i l i b r i u m t h e r e f o r e r e q u i r e s t h a t t h e condensed phase evaporates into the atmosphere. Moist a d i a b a t i c a n d p s e u d o a d i a b a t i c a t m o s p h e r e s i n w h i c h t h e c o n d e n s i n g v a p o r is a m a j o r a t m o s p h e r i c c o n s t i t u e n t are considered. T h i s s i t u a t i o n w o u l d a p p l y if t h e solar c o n s t a n t w e r e supercritical with respect to an abundant s u b s t a n c e s u c h as w a t e r . I t is s h o w n t h e cond e n s i n g gas w o u l d b e a m a j o r c o n s t i t u e n t a t all levels i n s u c h a n a t m o s p h e r e . P h o t o d i s s o c i a t i o n of w a t e r in t h e p r i m o r d i a l V e n u s a t m o s p h e r e is discussed in t h i s c o n t e x t . KNUDSE)r, W. C., a n d ANDERSON, A. D. 1969. E s t i m a t e of radiogenic H e 4 a n d A r 40 c o n c e n t r a t i o n in t h e C y t h e r e a n a t m o s p h e r e . Journal of Geophysical Research, V. 74, p. 5629-5632. M i x i n g r a t i o s o f 2 × 10 -4 a n d 1 × 10 -a for H e 4 a n d Ara0, respectively, in a 100~o CO2 M a r i n e r 5 m o d e l o f t h e C y t h e r e a n lower a t m o s p h e r e are d e r i v e d b y a s s u m i n g t h a t t h e H e 4 a n d A r 40 are s e c o n d a r y in origin a n d r e s u l t e n t i r e l y f r o m r a d i o a c t i v e disintegration with subsequent outgassing from t h e p l a n e t . P r o d u c t i o n r a t e s o n V e n u s are ass u m e d e q u a l t o t h o s e for t h e e a r t h . T h e r m a l escape o f H e 4 is s h o w n t o b e negligible, a n d o t h e r loss m e c h a n i s m s are a s s u m e d u n i m p o r t a n t . C o n c e n t r a t i o n o f t h e s e gases i n t h e u p p e r a t m o s p h e r e of V e n u s are c a l c u l a t e d f r o m t h e m i x i n g r a t i o s a n d a t u r b o p a u s e a t 6180 k m r a d i u s . T h e H e a c o n c e n t r a t i o n in t h e u p p e r a t m o s p h e r e is a f a c t o r of 1O larger t h a n t h e m i n i m u m v a l u e e s t i m a t e d b y M c E l r o y a n d S t r o b e l to a c c o u n t for t h e o b s e r v e d n i g h t t i m e i o n o s p h e r e a n d is a b o u t a f a c t o r of 4 larger t h a n t h a t s u g g e s t e d b y Whitton to explain the observed daytime

PLANETS--VENUS i o n o s p h e r e . T h i s degree of a g r e e m e n t a m o n g three s e p a r a t e a p p r o a c h e s s t r e n g t h e n s t h e p o s s i b i l i t y t h a t H e 4 is a d o m i n a n t c o n s t i t u e n t in t h e u p p e r a t m o s p h e r e o f V e n u s a n d also implies t h a t loss o f H e 4 o n V e n u s b y p l a s m a e x p a n s i o n is u n i m p o r t a n t . H e 4 will b e t h e d o m i n a n t c o n s t i t u e n t o u t t o a r a d i u s of a b o u t 7600 k m if H2 is p r e s e n t a t t h e u p p e r l i m i t suggested by McElroy and Hunten and out to a r a d i u s of a b o u t 8700 k m if H2 is negligible. KUIPER, G. P., a n d SILL, G. T. 1969. I d e n t i fication of t h e V e n u s c l o u d layers. Bulletin o] the American Astronomical Society, V. l , p. 351. O b s e r v a t i o n s e s t a b l i s h t h e e x i s t e n c e of t w o wells e p a r a t e d c l o u d layers o n V e n u s : (a) a p a t c h y layer o b s e r v e d in p h o t o g r a p h s t a k e n a t ~ < 4200 A, a p p a r e n t l y c o n s i s t i n g of b r i g h t veils o f t e n t h o u s a n d s of k m in size, w h i c h a t t i m e s e x h i b i t r e t r o g r a d e m o t i o n s u p t o 100 m/see, c o m p o s e d of p a r t i c l e s a b o u t 0.1 /z i n d i a m e t e r ; a n d (b) a yellowish, o p t i c a l l y i m p e n e t r a b l e l a y e r e x h i b i t ing gross h o r i z o n t a l s t r u c t u r e o n l y rarely, b u t h a v i n g a v a r i a b l e u p p e r b o u n d a r y s i t u a t e d well within the troposphere. New diameter measures of t h e p l a n e t , c o u p l e d w i t h r e c e n t d a t a o n t h e a t m o s p h e r i c t e m p e r a t u r e profile, i n d i c a t e t h a t t h e u v l a y e r occurs i n t h e u p p e r s t r a t o s p h e r e , near the mesopause; and confirm that the b o u n d a r y of t h e t h i c k yellow h a z e l a y e r is j u s t below t h e t r o p o p a u s e , w i t h i n t h e t r o p o s p h e r e . W i t h t h e k n o w n m i x i n g r a t i o H 2 0 / C O 2 for t h e upper Venus troposphere, the possibility of w a t e r or ice clouds in t h e visible layers c a n b e d e a l t w i t h definitively. A c o m p i l a t i o n of p u b lished p h o t o m e t r i c d a t a f r o m 0 . 2 - 4 . 0 / z a n d n e w spectrophotometrie data, compared to new laboratory measures, show that the chief c o n s t i t u e n t of t h e yellow h a z e l a y e r is incomp l e t e l y h y d r a t e d FeC12, n _~ 1.55; t h r e e a b s o r p t i o n b a n d s o b s e r v e d o n V e n u s are a t t r i b u t e d t o F e 2+ (d-d) a n d one e a c h t o F e - H 2 0 , Fe-C1, a n d O-H. T h e v a p o r p r e s s u r e of H 2 0 in t h e u p p e r t r o p o s p h e r e of V e n u s , d e r i v e d f r o m t h e N A S A CV-990 r e s u l t s in C o m m . L P L , No. 100, is f o u n d to be essentially equal to the equilibrium d i s s o c i a t i o n p r e s s u r e of t h e V e n u s c l o u d p a r t i c l e s a n d is so i n t e r p r e t e d . T h e H 2 0 m e a s u r e m e n t s b y V e n e r a 4-6 for t h e d e e p e r layers are discussed b u t f o u n d t o b e i n c o m p a t i b l e w i t h welle s t a b l i s h e d results. T h e u p p e r u v h a z e l a y e r is t h e r e u p o n r e - e x a m i n e d a n d identified as NH4CI(s). T h e v i o l e t - b l u e h a z e c a n b e s i m u l a t e d in t h e l a b o r a t o r y b y a d d i n g HCl(g) t o N H s ( g ) in v e r y low c o n c e n t r a t i o n s . I t is c o n c l u d e d t h a t Venus has a halide meteorology, compared to a water meteorology on Earth, and an ammonia m e t e o r o l o g y in J u p i t e r a n d S a t u r n . T h e n e a r a b s e n c e of w a t e r o n V e n u s m u s t b e a basic

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planetary property, apparently resulting from a protoplanet temperature being substantially h i g h e r t h a n t h a t of p r o t o E a r t h , w h i c h c a u s e d H 2 0 t o b e in t h e v a p o r p h a s e a n d lost w i t h t h e i n e r t gases. T h i s m u s t h a v e b e e n c a u s e d b y V e n u s f o r m i n g l a t e r i n t h e solar d e v e l o p m e n t as well as closer t o t h e sun. ( A b s t r a c t o f a p a p e r p r e s e n t e d a t t h e A u g u s t 1969 m e e t i n g of t h e A m e r i c a n A s t r o n o m i c a l Society.) MOROZ, V. I., DAVYDOV, V. D., a n d ZH~.GULAV, V. S. 1969. P h o t o m e t r i c a n d s p e c t r o s c o p i c o b s e r v a t i o n s of p l a n e t s i n t h e 8 - 1 4 ~ r a n g e . Soviet Astronomy--A.J., V. 13, p. 101-109. Brightness temperatures of Venus, Mars and J u p i t e r in t h e 8 - 1 4 ~ r a n g e were m e a s u r e d in J u n e 1967 w i t h a 120 c m reflector. Some m e a s u r e m e n t s were m a d e w i t h a n a r r o w - b a n d filter c e n t e r e d a t 11/~. S p e c t r a of Mars, V e n u s a n d t h e m o o n in t h e 8 - 1 4 ~ r a n g e were also s e c u r e d w i t h a p r i s m s p e c t r o m e t e r . T h e color t e m p e r a t u r e of Mars, 280 4-20°K, is c o n s i d e r a b l y h i g h e r t h a n t h e m e a n b r i g h t n e s s t e m p e r a t u r e 225 + 1 2 3°K. F o r V e n u s a n d t h e m o o n t h e s e t e m p e r a t u r e s coincide t o w i t h i n t h e errors. A " h o t " 10.4 Aa b a n d of CO2 was o b s e r v e d in t h e s p e c t r u m of Mars. A c o m p a r i s o n of t h e m e a s u r e d i n t e n s i t y of this band with theoretical intensities computed for v a r i o u s m o d e l s shows t h a t t h e m e a n p r e s s u r e of t h e surface is a t least 10 m b , a n d t h e m e a n t e m p e r a t u r e of t h e a t m o s p h e r e is a t least 250°K. MUELLER, 1%. F. 1969. Effect of t e m p e r a t u r e o n t h e s t r e n g t h a n d c o m p o s i t i o n of t h e u p p e r l i t h o s p h e r e of V e n u s . Nature, V. 224, p. 354-356. T h e i m p o r t a n c e of t h e h i g h t e m p e r a t u r e o n t h e e v o l u t i o n of t h e u p p e r l i t h o s p h e r e of V e n u s is considered. I n p a r t i c u l a r t h e effect o n m a g n e t i c d i f f e r e n t i a t i o n , isostatic a d j u s t m e n t s a n d surface relief is discussed. NULL, G. W., a n d LIESKE, J . R . 1966. A s t r o n o m i c a l c o n s t a n t s f r o m o b s e r v a t i o n s of t h e i n n e r p l a n e t s a n d I c a r u s . Bulletin of the American Astronomical Society, V. l , p. 356-357. See Planets~Mars. OHRING, G. 1969. H i g h surface t e m p e r a t u r e o n V e n u s : E v a l u a t i o n of t h e g r e e n h o u s e e x p l a n a t i o n . Icarus, V. 11, p. 171-179. C a l c u l a t i o n s of t h e m e a n surface t e m p e r a t u r e of V e n u s a r e performed with a simple nongray radiation b a l a n c e model. T h e m o d e l is b a s e d u p o n a b a l a n c e of n e t i n c o m i n g solar r a d i a t i o n a n d e m e r g i n g t h e r m a l r a d i a t i o n a t t h e t o p of t h e a t m o s p h e r e . To c a l c u l a t e t h e e m e r g i n g t h e r m a l r a d i a t i o n , it is a s s u m e d t h a t t h e s h a p e of t h e v e r t i c a l t e m p e r a t u r e profile is similar t o t h a t o b s e r v e d b y M a r i n e r 5 a n d V e n e r a 4 - - t h a t is, a c o n s t a n t lapse r a t e o f 9°C/kin f r o m t h e surface t o a p r e s s u r e level o f a few t e n t h s of a n a t m o s phere, above which the temperature remains

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~FCRL BIBLIOGRAPHY

constant. Given the atmospheric composition depends to some extent on the temperature in and surface pressure, the surface temperature the photochemical region. The exospherie can be determined from the balance requirement temperature derived from the heat conduction at the top of the atmosphere. Calculations are equation is found to be 90,000°K using a photoperformed for a low surface pressure (20 arm) ionization heating efficiency of 0.30. This very and high surface pressure (65 arm) model. For high temperature, which is characteristic of a pure carbon dioxide atmosphere, the results atomic hydrogen when it is abundant, would indicate t h a t mean surface temperatures of cause all constituents in the thermosphere and 500 ° to 550°K can be maintained in the 20-arm exosphere to be rapidly lost. I t is concluded from model, and 600 ° to 650°K in the 65-arm model, if the results of this study t h a t if water vapor were water vapor mixing ratios are of the order of c o m p l e t e l y outgassed into the atmosphere, a large part of the CO2 content (as well as other 10-8. SCHUBERt, G., TURCO~I'E, D. L., and OX- gases) would be lost, requiring much more BURGH, R. E. 1969. Stability of planetary initial CO2. The results indicate that outgassing did not proceed as assumed but occurred at a interiors. Geophysical Journal of the Royal Astronomical Society, V. 18, p. 441-460. See slow rate with the accumulation of CO~ and the possible loss of water vapor as suggested by Planets--Mars. SINCLAIR, A. C. E., BASART, J. P., BUHL, D., Rasool. (Abstract of a paper presented at the GALE, W. A., and LIWSHITZ,M. 1969. The surface August 1969 meeting of the American Astrotemperature distribution on Venus. Bulletin of nomical Society.) WHrrTEI~, R. C. 1969. Thermal structure of the American Astronomical Socicty, V. 1, p. 362. The microwave brightness of Venus at l l - c m the ionosphere of Venus. Journal of Geophysical wavelength was observed during the spring of Research, V. 74, p. 5623-5628. There are two 1959 with the three-element N R A O interfere- possible heat sources for the sunlit ionosphere meter at Groenleft, W. Va., in order to determine of Venus, photoionization of the neutral species, mainly CO2, and influx from the solar wind. I t the surface temperature distribution on the planet. Choice of particular interferometer is shown that the electron temperature should be substantially higher (at least ~ 500°K) than the baselines allowed attention to be directed at differences in brightness from a uniform dis- temperature of the neutral atmosphere at tribution. Results for the polar cooling, the altitudes above 250 km but that the ion temdiurnal temperature variation, and the atmosperature probably does not greatly exceed t h a t pheric temperature and pressure profiles are of the neutral species. The significance of the presented. (Abstract of a paper presented at the solar wind as a heat source is also discussed. August 1969 meeting of the American AstroYounG, L. G. 1969. Interpretation of highresolution spectra of Venus--1. The 2v3 band nomical Society.) of 13C160180 at 2.21 microns. Icarus, V, 11, p. SMITH, L. L., and GROSS, S. H. 1969. The evolution of water vapor in the atmosphere of 66-75. The high-resolution spectra of Venus, Venus. Bulletin of the American Astronomical obtained by Janine and Pierre Connes in the Society, V. l, p. 363. The composition of the Venus region of 2 microns have been used to obtain a curve of growth for the 2vs band of the lsC160180 atmosphere is revealed to be deficient in water vapor by about 10 -4 compared with the total isotope of carbon dioxide. Several methods of data reduction are compared; the rotational amount on the Earth, if it is assumed that both temperature found from this band, using the planets evolved similarly, and that all of the water outgassed from the Venus surface went curve of growth, is 245 ° ± 3°K (standard deviation). Values for the effective pressure for into the atmosphere. What happened to this water vapor is an important problem in our line formation and the absorber amount above understanding of the evolution of the planets. A the clouds are also derived, but are dependent on steady-state model atmosphere is constructed the strengths of the lines. assuming an initial distribution of H 2 0 in TEKTITES hydrostatic equilibrium. Photodissociation by BARNES, V. E. 1969. Progress of tektite studies solar ultraviolet produces the constituents Ha, in China. Transactions off the American GeoH, O~, O, and OH, which recombine with each other until a steady state is reached at each level physical Union, V. 50, p. 704-708. A field study by Lee Da-ming of tektites on Leichow Peninsula of the lower atmosphere. The upper atmosphere and Hainan Island, published in 1963 in Scientia is in diffusive equilibrium with each constituent Geologica Sinica, is the first contribution from distributed according to its mass. I n the upper atmosphere, atomic hydrogen dominates, al- China on the tektite problem. This paper gives though the level of the crossover with H~ data additional to that of Lacroix on the occur-

TEKTITES

re nts and chemistry of tektites in China; the discussion of the stratigraphic occurrence of Chinese tektites is also of particular interest, as it helps to establish the age of Southeast Asian tektites. C~.~VrOLAHZI, F. J. 1969. Maximum tektite size as limited by thermal stress and aerodynamic loads. Journal of GeophyM/cal Research, V. 74, p. 6723-6736. An experimental investigation has been conducted on the thermal stresses induced in tektites cooled by radiation in space. The stresses were measured with conventional photoelastic techniques and correlated with computed temperature differences. The results show t h a t the internal tensile stresses increase with size until fracturing occurs. The largest tektite sphere t h a t could survive the stresses from both radiation cooling and atmosphere entry is limited by thermal stress and is estimated to be of the order of 1 kg. The largest cylinder is restricted by a combination of a thermal stress limit on diameter and an aerodynamic load limit on length, and is estimated to be of the order of 100 kg. Because the tektites break up in the atmosphere, these limits represent the approximate m a x i m u m size t h a t could be expected to impact the ground at one spot. CHAPMAN, D. R., and SHEIBER, L. C. 1969. Chemical investigation of Australasian tektites. Journal of Geophysical Research, V. 74, p. 67376776. Five hundred and t h i r t y Australasian tektites from 205 localities have been chemically analyzed. Specimens were selected for analysis mainly from measurements of the specific gravity of about 47,000 individual tektites. A variety of chemical types was revealed (e.g., HMg, HCa, H N a / K . LCaHAI, and HCu, B) several of which are new. The H N a / K australites are found to be so much like I v o r y Coast tektites in certain respects as to suggest the possibility of a related chemical genesis. The HMg group, extending from 64% to 78% SiO2, is overlapped and smoothly continued down to 48% SiO2 by the "bottle-green" microtektites. Numerous chemical trends in this group, and also in the HCa group, are the same as those characteristic of fractional crystallization in a cooling magma. All groups show relatively restricted fields of chemical variation and numerous common chemical eongruencies, and all are concluded to be of igneous origin. New experiments have been conducted on the chemical trends produced in tektite glass vaporized in a vacuum. These trends, and those determined earlier for vapor fractionation in an oxidizing atmosphere, are shown to be incompatible with the main tektite trends. I t is concluded t h a t tektite chemistry closely reflects that of the preimpact parent rock.

149

Since tektites are chemically unlike earth igneous rocks, it is inferred t h a t they are of extraterrestrial igneous origin. Some of t h e major differences between tetkites and earth igneous rocks are explained on the basis of magmatic evolution from lower pressures than are possible in the earth's interior. FLEISCHER, R. L., PRICE, P. B., and WOODS, R. T. 1969. A second tektite fall in Australia. Earth and Planetary Science Letters, V. 7, p. 5152. A chemical subgroup of tektites found in Australia (Chapman's "high sodium" tektites) have fission, track ages of approximately 4 m.y. and hence are part of a distinct tektite fall, one t h a t preceded the formation of the well known Australasian strewn field 0.7 m.y. ago. FRIEDMAN, I., and PA~KE~, C. J. 1969. Libyan desert glass: Its viscosity and some comments on its origin. Journal of Geophysical Research, V. 74, p. 6777-6779. The viscosity of Libyan desert glass has been determined over the temperature range 975°C to 1090°C. I t s viscosity of 10 TM poises at 1000°C and 101° at 1250°C is approximately 2 orders of magnitude less than that of fused silica, but it is 3½ orders of magnitude greater t h a n t h a t of moldavites and 6~ orders of magnitude greater than t h a t of obsidian. The viscosity has been used to calculate the time-temperature relation necessary to "fine" the Libyan desert glass and to remove the larger gas bubbles. For the six samples studied, it would take 47 days at 1600°C to remove the bubbles larger than 0.2 m m diameter, the largest diameter found in our samples. The time needed to remove the larger bubbles would be 0.5 day at 1800°C and 2 min at at 2OO0°C. GA~LT, D. E., and WEDEKIHD, J . A. 1969. The destruction of tetkites by micrometeoroid impact. Journal of Geophysical Research, V. 74, p. 6780-6794. Damage to tektites caused by collisions with micrometeoroids has been studied by firing small projectiles at high speed against glass spheres. In terms of the projectile kinetic energy per unit mass of the spheres, less than 10 s ergs/g produces a crater on the surface of the sphere. Increasing the energy per gram eauscs progressively larger craters and large spallation zones centered about the antipodal point of the impact. A kinetic energy input of approximately 107 ergs/g completely ruptures the sphere into small fragments; this rupture e n e r g y can he delivered either by a single impac~i or by multiple impacts having an equivalent total energy input. These results, combined with estimates for the flux of micrometeoroids at 1 AU, indicate t h a t the mean survival time before the complete destruction of tektites in

150

AFCl~L BIBLIOGRAPHY

circular heliocentric orbits is of the order o f 108 a n d 104 years for, respectively, objects 1 to 10 c m in diameter. P a r t i a l f r a g m e n t a t i o n a n d loss of physical i d e n t i t y as t e k t i t e s would occur in m u c h shorter periods of time. Thus, a n y t e k t i t e s ejected f r o m t h e m o o n t h a t initially miss t h e e a r t h a n d pass on into i n t e r p l a n e t a r y space do n o t provide a source of recognizable t e k t i t e bodies which the e a r t h could subsequently sweep up o v e r e x t e n d e d t i m e periods. MORQ~-~, J . W. 1969. U r a n i u m and t h o r i u m in tektites. Earth and Planetary ~cienee Letters, V. 7, p. 53-63. N e u t r o n a c t i v a t i o n analysis for u r a n i u m and t h o r i u m are r e p o r t e d for two australites, a j a v a i t e , a bediasite and a moldavite. A critical s u r v e y is m a d e of published u r a n i u m a n d t h o r i u m abundances in tektites, a n d superior analyses selected. U r a n i u m and t h o r i u m a b u n d a n c e s in t h e t e k t i t e groups are c o m p a r e d w i t h terrestrial s e d i m e n t a r y and acid igneous rocks. Granophyres m a t c h t e k t i t e s most closely in t h e a b u n d a n c e of these two elements, b u t c a l m o t be considered probable p a r e n t m a t e r i a l for a terrestrial t e k t i t e origin because of their limited distribution. A n extraterrestrial origin is also considered and a relationship in u r a n i u m and t h o r i u m a b u n d a n c e is observed b e t w e e n some achondrites and t h e tektites. O'KEEFE, J . A. 1969. The m i c r o t e k t i t e d a t a : I m p l i c a t i o n s for t h e hypothesis of t h e lunar origin o f tektites. Journal of Geophysical Research, V. 74, p. 6795-6804. The distribution of m i c r o t e k t i t e s provides m o r e definite boundaries for t h e Australasian strewn field. I t is found t h a t this field does n o t encompass t h e earth. I t encompasses so m u c h of t h e earth, however, t h a t , if it is t h e result of terrestrial impact, the initial velocity m u s t h a v e been m o r e t h a n 6 kin/see for m u c h of t h e m a t e r i a l and almost none could h a v e reached 7 kin/see. No trace is found of a c c o m p a n y i n g u n m e l t e d soil particles. T h e m i c r o t e k t i t e s p r o b a b l y cannot be ablation droplets f r o m larger t e k t i t e s because there are too m a n y and t h e y do n o t resemble australite flange m a t e r i a l ; t h e bottle-green m i e r o t e k t i t e s cannot be explained b y processes of volatilizat i o n ; a n d there is evidence t h a t , in fact, t h e Muong N o n g t e k t i t e s are t h e result of t h e welding of microtektites. I t follows t h a t the microt e k t i t e s m u s t come directly f r o m t h e moon, as p o s t u l a t e d b y C h a p m a n , if t h e y are extraterrestrial at all ; t h e p a r e n t - b o d y hypothesis will n o t work. P r e s u m a b l y t e k t i t e s which miss the e a r t h on t h e first encounter are destroyed b y the R a d z i e v s k y - P a d d a c k effect (rotational bursting induced b y a s y m m e t r i c radiation pressure). The chemical constitution is n o t decisively different from t h a t indicated b y t h e analyses of T u r k e v i c h

e x c e p t in c a l c i u m ; this can perhaps be explained. Microtektites m a y represent t h e u n w e l d e d c o m p o n e n t of a lunar ash flow, of which t h e Muong N o n g t e k t i t e s are t h e welded c o m p o n e n t . OSTERTAG, W., ERICKSON, A. A., a n d WILLIAMS, J . P. 1969. Magnetic susceptibility of some synthetic a n d n a t u r a l tektites. Journal of Geophy~eal Research, V. 74, p. 6805-6810. The m a g n e t i c susceptibility of a n u m b e r of synthetic australite- and philippinite-like tektites has been m e a s u r e d b e t w e e n 77 ° a n d 560°K. The specimens were p r e p a r e d u n d e r various m e l t i n g conditions to s t u d y t h e effect of atmosphere, m e l t i n g t e m p e r a t u r e , m e l t i n g time, and b a t c h composition on t h e l~e+8/Fe +9' ratio of t h e glasses. D a t a indicate t h a t crucible m e l t s p r e p a r e d f r o m Fe2Oa or m a g n e t i t e - c o n t a i n i n g m i x t u r e s at N 1700 ° and 1800°C in air atmosphere, as well as electric-arc m e l t s at ~ 2200°C, exhibit m a g n e t i c m o m e n t s close to those of some natural australasian tektites. V a c u u m melts and m e l t s m a d e u n d e r n i t r o g e n h e a t e d at ~ 1600°C produce glasses of similar oxidation state. Melting t e m p e r a t u r e s m u s t exceed 1450°C to a v o i d f o r m a t i o n of s u p e r p a r a m a g n e t i c precipitations in t h e glass. Results are discussed in t e r m s of possible modes of origin for tektites. I t is suggested t h a t t h e t h e r m a l history of tektites f r o m extraterrestrial sources m a y be s i m u l a t e d b y a v a c u u m melt, and t e k t i t e s of terrestrial origin can be simulated b y crucible a n d arc m e l t s in air. PINSON, W. H., JR., and GRISWOLD, T. B. 1969. The relationship of nickel and c h r o m i u m in t e k t i t e s : N e w d a t a on t h e I v o r y Coast tektites. Journal of Geophysical Research, V. "/4, p. 6811-6815. On t h e basis of published analyses, a correlation between Ni and Cr h a d been suspected in tektites. H o w e v e r , t h e n u m b e r of analyses was sufficient only to suggest a trend. To test t h e possibility o f correlation w i t h i n t h e I v o r y Coast tektites, 18 specimens were analyzed b y a t o m i c absorption a n d X - r a y emission techniques. Ni contents range f r o m 79 to 199 p p m and Cr from 213 to 270. The correlation coefficient is 0.0046, which is too small to be significant. A l t h o u g h there are few published d a t a on high Ni-high Cr t e k t i t e s from o t h e r areas, a plot of all t h e available analyses indicates a correlation, high Cr being i n v a r i a b l y accompanied b y high Ni. The analyses of Chao on bediasites and Taylor on australites show t h a t for t e k t i t e s h a v i n g less t h a n 100 p p m Cr a positive correlation exists. I n t h e a u t h o r s ' opinion this reflects t h e original correlation of these elements in t h e p a r e n t rock. Tektites, such as t h e I v o r y Coast and southern indochinites and possibly billitonites and Borneo tektites,

TEKTITES

151

experimental errors there was a one-to-one which contain anomalously high (> 100 ppm) but only slightly variant Cr, show both high correspondence between the calculated ferrous and highly variant Ni contents. High Cr con- iron and the measured total iron, showing a e e n t r ~ i o n s probably are produced by selective strong similarity to tektite glass. The bottlevolatization of the parent material, as suggested green microtektites showed properties similar b y the work of L. S. Walter. The impacting to the normal variety before leaching. Although the leaching process did not affect the bulk iron meteorite, whether iron or stony, does not contain enough Cr to account for high Cr content of the normal microtektite glass, it was possible to remove all iron from the bottle-green contents by contamination b u t is undoubtedly the source of the sometimes high and highly glass. I n this respect the bottle-green microvariable Ni contents. I f the concentration of Cr tektites are quite different from normal microis high, it is relatively invariant, and there is tektites or tektites. The solubility suggests t h a t simultaneous gross Ni contamination resulting the bottle-green specimens m a y have partially reacted with the sea water, thus altering their in both high and variable Ni contents. REST, R., 1969. Sculpturing of moldavites original magnetic properties. TAYLOR, H. P., JR., and EPSTEIN, S. 1969. and the problem of micromoldavites. Journal of GeophyM~al Research, V. "/4, p. 6816-6824. Correlations between O1s/O16 ratios and chemical Nininger and Huss stated in 1967 that the compositions of tektites. Journal of Geophysical sculpturing of the surfaces of two very rare Research, V. 74, p. 6834-6844. The limits of oxyindochinites from South Vietnam occurred in gen isotope variation in tektites have been deterthe atmosphere and was not due to etching by mined by analyzing 33 tektites that cover the widest possible spectrum of chemical composisoil agencies. However, very important a n d tions. O TMvalues were obtained for 7 australites convincing features observed in moldavites and reported in this paper support the opinion t h a t (8.9 to 11.0), 4 javaites (9.4 to 01.0), 3 indochinmoldavite sculpturing is due to chemical ires (9.3 to 10.6), 5 philippinites (9.8 to 10.6), corrosion in soils and gravels. I t is concluded 8 moldavites (10.7 to 11.8), and 6 I v o r y Coast t h a t when moldavites fell on the earth's surface tektites (13.0 to 13.6), as well as 2 samples of they were already cool solid bodies. Many of the Darwin glass (14.4 to 14.9). Various tektite falling moldavites, however, were fragmented groupings based on chemical composition and landing. All of them, emplaced in the soil, were geographic occurrence all show a systematic increase in O is with decreasing SiO~ content, strongly corroded. Pure (hyaline) and translucent glassy drops, a few tenths of a millimeter similar to that previously found for the bediain diameter, have been separated by washing sites. These systematic correlations must arise the material encountered by an 80-m-deep bore either by (1) vapor fractionation of tektite through Pannonian sediments in southern material during impact melting of (2) mixing of Moravia. These glassy drops m a y have been a SiO~-rich igneous component and a low-SiO2 produced as slag spherules from steam engines; component formed at a much lower temperature; they m a y have been in the volcanic dust from perhaps the mixing occurred during Weathering Slovakian rhyolites; or t h e y m a y be microat the earth's surface or during hydrothermal moldavites. To solve this problem, a more alteration of silicie igneous rocks either on the earth or the moon. detailed investigation would be necessary. SE~FTLE, F. E., THORPE, fiX.N., and SULLrVxN, VXRSH~EVA, A. K., and COOPER, A. R. 1969. S. 1969. Magnetic properties of microtektites. Inhomogeneities and iron diffusion in a Thailand Journal of Geophysical Research, V. 74, p. 6825- tektite. Journal of Geophysical Research, V. '/4, 6833. The magnetic susceptibility, magnetizap. 6845-6852. Sections of a Thailand tektite were tion, and Curie constants have been measured examined under an electron microprobe for for 17 normal and 11 bottle-green mierotektites composition fluctuations. A comparison is made found in deep-sea sediment cores. Unlike tekwith similar data from laboratory-synthesized tites, all the normal mierotektite specimens tektites of nearly duplicate compositions. To have a significant intensity of magnetization. estimate the kinetics of the diffusive mixing of This is ascribed to a ferromagnetic iron oxide local composition fluctuations, effective binary film on the surface of the mierotektites which can diffusion coefficients of iron were measured at be removed by acid leaching. The bulk iron withvarious temperatures above 115O°C. These data in the glass was assumed to be primarily in the are employed in a calculation of the homogenizaferrous state, as it is in tektites, and the ferrous tion times of a hypothetical tektite source with iron content was calculated from the Curie a periodic variation of iron. This in turn is used constant and compared with the total iron to suggest limits for the thermal history of determined with the electron probe. Within tektite glasses.