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A proposal for a radio frequency interference-free dedicated lunar far side crater for high sensitivity radioastronomy: programmatic issues
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Acta Astronautica Vol. 46, No. 8, pp. 555±558, 2000 7 2000 Elsevier Science Ltd. All rights reserved Printed in Great Britain 0094-5765/00 $ - see front matter S0094-5765(00)00002-3
ACADEMY TRANSACTIONS NOTE A PROPOSAL FOR A RADIO FREQUENCY INTERFERENCE-FREE DEDICATED LUNAR FAR SIDE CRATER FOR HIGH SENSITIVITY RADIOASTRONOMY: PROGRAMMATIC ISSUES{ JEAN HEIDMANN{ Observatoire de Paris, 92195 Meudon, France (Received 9 November 1999) AbstractÐIn a previous paper I singled out a very speci®c farside lunar crater, Saha, as an excellent candidate for future high sensitivity radioastronomy, in particular for SETI. In order to initiate discussions on programmatic issues raised by this prospect for the coming decennies, I present here elements relative to transportations and communications with a main permanent base on the Moon. 7 2000 Elsevier Science Ltd. All rights reserved
1. INTRODUCTION
Within 20±30 years it will be impossible to conduct high sensitivity radioastronomy from locations in direct view of Earth because of: 1. the increase in near-Earth man-made radio frequency interference (RFI); and 2. the increase in the sensitivities of receiving equipment. In the case of SETI (Search for ExtraTerrestrial Intelligence), over 40 years since the ®rst search, the eciency of the search systems has doubled every eight months, a tremendous rate indeed, and now SETI is strongly implanted in numerous Institutes: Berkeley, Harvard and Ohio Universities, Istituto Argentino de Radioastronomia, Bologna Istituto di Radioastronomia and SETI Institute (in place of the failing NASA), without mentioning the support of the Planetary Society and projects at Parkes, Australia, Poona, India and Nanc° ay, France. Furthermore, it is not unreasonable to conjecture that within the next 20±30 years, humankind will be deeply involved in collecting information contained in signals emitted from quite a number of extraterrestrial civilizations. As soon as an arti®cial signal is unravelled (if ever), this will be immediate proof that extraterrestrial civilizations are plentiful in the cosmos and the drive to investigate them, in all of their varieties, will get stronger. {This note is an extract from paper ]IAF-94-Q.1.330, unpublished, given at the 45th IAF Congress in Jerusalem, 1994. {IAA Member (Basic Sciences)
In an Academy Transaction Note [1], from very simple and sensible criteria, I pointed out that SETI would need only one very speci®c clearly singled out crater: crater SAHA, a strong circular 100 km diameter ringed structure, in the equatorial Eastern region, just enough on the farside for protection, a little farther than Mare Smythii. 2. PROGRAMMATIC ISSUES
This proposal, considered as a current plan for the next decennies, implies speci®c and new programmatic issues and mission aspects in numerous domains, particularly: transportation, direct from space or from a main lunar base; telecommunications with a main lunar base, ground- or wave-based; mutual environmental protection, especially from RFI; infrastructure requirements, automated or mantended; long-term maintenance; international and interdisciplinary concerted technical planning.
3. LUNAR GROUND TRANSPORTATIONS
It is likely that a major general purpose base, human/robotic-tended, will be established, on the nearside, before any substantial high-sensitivity radioastronomical equipment is set on the farside of 555
556
J. Heidmann
the Moon. According to previous studies [2,3] such a main base would better be set in Mare Smythii for quite a number of reasons. Then the question of material communications between Saha and Mare Smythii is immediately raised. Even if some of the basic equipment may be landed directly inside Saha from space, mounting, refurbishment and maintenance would need lighter equipment transportation. 4. SAHA LUNAR ROUTE
Figure 1 shows a topographic map of the region involved up to Saha, kindly provided by Paul Spudis (NASA topographic map of the Moon; Eastern region-LOC-3, equatorial scale 1:2,750,000). From it a choice of a path minimizing lengths and slopes to be negotiated is indicated. Its vertical pro®le referred to the lunar geoid, is shown in Fig. 2. Starting from a point on the East edge of Mare Smythii ¯oor at ÿ4000 m altitude, it climbs 2000 m to a ®rst plateau South of Babcock and, passing North of Wyld, climbs again 4000 m up to a pass on the West edge of Saha rim, where it goes down on its ¯oor at ÿ1000 m altitude. The strongest large scale slopes are smaller than 5 degrees. The overall length from Mare Smythii East edge to Saha at point b (28S, 1028E) on the ¯oor is 340 km.
Such a path could have its surface layer regolith lightly bulldozed, providing a Lunar Road allowing a passage for lunar rovers. 5. TELECOMMUNICATIONS
The telecommunications should address the general protection of the Saha site against RFI, and for our purpose here, insure communications between the Saha base and the main base and with rovers along the Saha Lunar Road. The most aÁ la mode solution is, quite unfortunately, to use a relay radio satellite at the Lagrangean L2 point 64,000 km behind the Moon. This point is 108 above the horizon of Saha, whose RFI protection would then be devastated, though this site was chosen as close as possible to the Moon limb. Evidently, better solutions should be aimed at for a pro®table co-operation. Laser technology, cellular equipment, optic ®ber networks could provide solutions. The fact that Saha ¯oor is shielded from any lunar ground-based emissions by its wall is a strong help. It should also be noted that the very modest and restricted choice of a speci®c single crater for advanced radioastronomy has quite interesting con-
Fig. 1. Path of Lunar Road between Mare Smythii (MS) and crater Saha (S). B: Babcock; W: Wyld; . 1,2,3: mains relais; latitude, longitude and scale are indicated; altitudes in metres.
Lunar crater for radioastronomy
557
Fig. 2. Vertical pro®le of Saha Lunar Road in metres w.r.t. lunar geoid along the way in kilometres from point a (28N, 92 8 E) in Eastern Mare Smythii. MS: Mare Smythii; S: Saha; C1: ®rst climb; p: plateau; C2: second climb; P: pass; R: rim.
sequences for an harmonious co-operation with other explorations and exploitations of the Moon: radio telecommunications with satellites in lunar orbit would be acceptable for all orbits which lie entirely under the Saha horizon: e.g. lunar polar orbits whose planes are aimed at the Earth, and whole classes of others. As for communications along the Saha Lunar Road, they could be provided by a very small number of relays, either radio or laser, deposited on the way along the road: ]1 on a hill near the top of the ®rst climb, ]2 in view of the long stretch along the plateau and of the second climb and ]3 on an eminence near the pass on the Saha West rim. There is a possibility, as far as can be said from the provisional accuracy of the LOC map, for needing two more intermediate relays. The relays would allow telepresence and teleoperating of transportation robotic rovers between Mare Smythii and Saha. 6. CONCLUSIONS
The philosophy aimed at saving for the coming decennies a radio frequency interference-free site on the far side of the Moon led to the very speci®c choice of crater Saha [1]. In this paper we looked at a ®rst partial approach to the programmatic issues and mission aspects this choice would raise. It appears that the concept of a speci®c lunar route from Mare Smythii to Saha, via South of crater Babcock and North of crater Wyld, with bull-
dozed surface regolith, main telecommunications relays at a few strategic locations and 5 degrees maximum slopes, is an interesting perspective for transportation. This would insure material, human and data connections with future large scale high sensitivity radioastronomical paraphernalia lying on the ¯oor of Saha with a main base in Mare Smythii. This view would considerably ease the problems of mutual environmental protection between future explorations and exploitations of the Moon, particularly, and most importantly for radioastronomy, in the ®eld of radio frequency interferences. This view allows even radio telecommunication lunar satellites to be established in lunar orbits, provided that their orbits are entirely under the horizon of Saha (with the absolute exclusion of the far Lagrangean point L2 ). In addition, lunar-ground level networks could be established without a polluting eect inside the Saha rim. Though this study was initiated for SETI purpose, it is clear that other sensitive radio observations in radioastronomy at large, from decimetric to submillimetre wavelengths, might pro®t from Saha, provided an intracrater common protocol for no RFI generations inside Saha is set up.
REFERENCES
1. Heidmann, J., Saha crater: a candidate for a SETI lunar base. Acta Astronautica, 1994, 32, 471.
558
J. Heidmann
2. Spudis, P. D. and Hood, L. L. Geological and geophysical ®eld investigations from a lunar base at Mare Smythii. in The Second Conference on Lunar Bases and Space Activities of the 21st Century, NASA Conf. Pub. 3166. vol. 1, 1992. p. 163.
3. Morrison, D. A. and Homan, S. J., Lunar science strategy: exploring the Moon with humans and machines. In Missions, Technologies and Design of Planetary Mobile Vehicles, Centre National d'Etudes Spatiales 1992 Colloquium, 1993, p. 63.
Acta Astronautica Vol. 46, No. 8, pp. 555±558, 2000 7 2000 Elsevier Science Ltd. All rights reserved Printed in Great Britain 0094-5765/00 $ - see front matter S0094-5765(00)00002-3
ACADEMY TRANSACTIONS NOTE A PROPOSAL FOR A RADIO FREQUENCY INTERFERENCE-FREE DEDICATED LUNAR FAR SIDE CRATER FOR HIGH SENSITIVITY RADIOASTRONOMY: PROGRAMMATIC ISSUES{ JEAN HEIDMANN{ Observatoire de Paris, 92195 Meudon, France (Received 9 November 1999) AbstractÐIn a previous paper I singled out a very speci®c farside lunar crater, Saha, as an excellent candidate for future high sensitivity radioastronomy, in particular for SETI. In order to initiate discussions on programmatic issues raised by this prospect for the coming decennies, I present here elements relative to transportations and communications with a main permanent base on the Moon. 7 2000 Elsevier Science Ltd. All rights reserved
1. INTRODUCTION
Within 20±30 years it will be impossible to conduct high sensitivity radioastronomy from locations in direct view of Earth because of: 1. the increase in near-Earth man-made radio frequency interference (RFI); and 2. the increase in the sensitivities of receiving equipment. In the case of SETI (Search for ExtraTerrestrial Intelligence), over 40 years since the ®rst search, the eciency of the search systems has doubled every eight months, a tremendous rate indeed, and now SETI is strongly implanted in numerous Institutes: Berkeley, Harvard and Ohio Universities, Istituto Argentino de Radioastronomia, Bologna Istituto di Radioastronomia and SETI Institute (in place of the failing NASA), without mentioning the support of the Planetary Society and projects at Parkes, Australia, Poona, India and Nanc° ay, France. Furthermore, it is not unreasonable to conjecture that within the next 20±30 years, humankind will be deeply involved in collecting information contained in signals emitted from quite a number of extraterrestrial civilizations. As soon as an arti®cial signal is unravelled (if ever), this will be immediate proof that extraterrestrial civilizations are plentiful in the cosmos and the drive to investigate them, in all of their varieties, will get stronger. {This note is an extract from paper ]IAF-94-Q.1.330, unpublished, given at the 45th IAF Congress in Jerusalem, 1994. {IAA Member (Basic Sciences)
In an Academy Transaction Note [1], from very simple and sensible criteria, I pointed out that SETI would need only one very speci®c clearly singled out crater: crater SAHA, a strong circular 100 km diameter ringed structure, in the equatorial Eastern region, just enough on the farside for protection, a little farther than Mare Smythii. 2. PROGRAMMATIC ISSUES
This proposal, considered as a current plan for the next decennies, implies speci®c and new programmatic issues and mission aspects in numerous domains, particularly: transportation, direct from space or from a main lunar base; telecommunications with a main lunar base, ground- or wave-based; mutual environmental protection, especially from RFI; infrastructure requirements, automated or mantended; long-term maintenance; international and interdisciplinary concerted technical planning.
3. LUNAR GROUND TRANSPORTATIONS
It is likely that a major general purpose base, human/robotic-tended, will be established, on the nearside, before any substantial high-sensitivity radioastronomical equipment is set on the farside of 555
556
J. Heidmann
the Moon. According to previous studies [2,3] such a main base would better be set in Mare Smythii for quite a number of reasons. Then the question of material communications between Saha and Mare Smythii is immediately raised. Even if some of the basic equipment may be landed directly inside Saha from space, mounting, refurbishment and maintenance would need lighter equipment transportation. 4. SAHA LUNAR ROUTE
Figure 1 shows a topographic map of the region involved up to Saha, kindly provided by Paul Spudis (NASA topographic map of the Moon; Eastern region-LOC-3, equatorial scale 1:2,750,000). From it a choice of a path minimizing lengths and slopes to be negotiated is indicated. Its vertical pro®le referred to the lunar geoid, is shown in Fig. 2. Starting from a point on the East edge of Mare Smythii ¯oor at ÿ4000 m altitude, it climbs 2000 m to a ®rst plateau South of Babcock and, passing North of Wyld, climbs again 4000 m up to a pass on the West edge of Saha rim, where it goes down on its ¯oor at ÿ1000 m altitude. The strongest large scale slopes are smaller than 5 degrees. The overall length from Mare Smythii East edge to Saha at point b (28S, 1028E) on the ¯oor is 340 km.
Such a path could have its surface layer regolith lightly bulldozed, providing a Lunar Road allowing a passage for lunar rovers. 5. TELECOMMUNICATIONS
The telecommunications should address the general protection of the Saha site against RFI, and for our purpose here, insure communications between the Saha base and the main base and with rovers along the Saha Lunar Road. The most aÁ la mode solution is, quite unfortunately, to use a relay radio satellite at the Lagrangean L2 point 64,000 km behind the Moon. This point is 108 above the horizon of Saha, whose RFI protection would then be devastated, though this site was chosen as close as possible to the Moon limb. Evidently, better solutions should be aimed at for a pro®table co-operation. Laser technology, cellular equipment, optic ®ber networks could provide solutions. The fact that Saha ¯oor is shielded from any lunar ground-based emissions by its wall is a strong help. It should also be noted that the very modest and restricted choice of a speci®c single crater for advanced radioastronomy has quite interesting con-
Fig. 1. Path of Lunar Road between Mare Smythii (MS) and crater Saha (S). B: Babcock; W: Wyld; . 1,2,3: mains relais; latitude, longitude and scale are indicated; altitudes in metres.
Lunar crater for radioastronomy
557
Fig. 2. Vertical pro®le of Saha Lunar Road in metres w.r.t. lunar geoid along the way in kilometres from point a (28N, 92 8 E) in Eastern Mare Smythii. MS: Mare Smythii; S: Saha; C1: ®rst climb; p: plateau; C2: second climb; P: pass; R: rim.
sequences for an harmonious co-operation with other explorations and exploitations of the Moon: radio telecommunications with satellites in lunar orbit would be acceptable for all orbits which lie entirely under the Saha horizon: e.g. lunar polar orbits whose planes are aimed at the Earth, and whole classes of others. As for communications along the Saha Lunar Road, they could be provided by a very small number of relays, either radio or laser, deposited on the way along the road: ]1 on a hill near the top of the ®rst climb, ]2 in view of the long stretch along the plateau and of the second climb and ]3 on an eminence near the pass on the Saha West rim. There is a possibility, as far as can be said from the provisional accuracy of the LOC map, for needing two more intermediate relays. The relays would allow telepresence and teleoperating of transportation robotic rovers between Mare Smythii and Saha. 6. CONCLUSIONS
The philosophy aimed at saving for the coming decennies a radio frequency interference-free site on the far side of the Moon led to the very speci®c choice of crater Saha [1]. In this paper we looked at a ®rst partial approach to the programmatic issues and mission aspects this choice would raise. It appears that the concept of a speci®c lunar route from Mare Smythii to Saha, via South of crater Babcock and North of crater Wyld, with bull-
dozed surface regolith, main telecommunications relays at a few strategic locations and 5 degrees maximum slopes, is an interesting perspective for transportation. This would insure material, human and data connections with future large scale high sensitivity radioastronomical paraphernalia lying on the ¯oor of Saha with a main base in Mare Smythii. This view would considerably ease the problems of mutual environmental protection between future explorations and exploitations of the Moon, particularly, and most importantly for radioastronomy, in the ®eld of radio frequency interferences. This view allows even radio telecommunication lunar satellites to be established in lunar orbits, provided that their orbits are entirely under the horizon of Saha (with the absolute exclusion of the far Lagrangean point L2 ). In addition, lunar-ground level networks could be established without a polluting eect inside the Saha rim. Though this study was initiated for SETI purpose, it is clear that other sensitive radio observations in radioastronomy at large, from decimetric to submillimetre wavelengths, might pro®t from Saha, provided an intracrater common protocol for no RFI generations inside Saha is set up.
REFERENCES
1. Heidmann, J., Saha crater: a candidate for a SETI lunar base. Acta Astronautica, 1994, 32, 471.
558
J. Heidmann
2. Spudis, P. D. and Hood, L. L. Geological and geophysical ®eld investigations from a lunar base at Mare Smythii. in The Second Conference on Lunar Bases and Space Activities of the 21st Century, NASA Conf. Pub. 3166. vol. 1, 1992. p. 163.
3. Morrison, D. A. and Homan, S. J., Lunar science strategy: exploring the Moon with humans and machines. In Missions, Technologies and Design of Planetary Mobile Vehicles, Centre National d'Etudes Spatiales 1992 Colloquium, 1993, p. 63.