- Email: [email protected]
6. News from space organizations
6.
NEWS FROM SPACE ORGANIZATIONS
6.1.
ARCTIC OZONE WORSENS
second influence on stratospheric ozone levels is the indirect impact of greenhouse gases on atmospheric temperatures as ozone destruction is quite sensitive to temperature increases in the atmosphere.
DEPLETION
Since upper atmospheric temperatures in the northern hemisphere during winter and spring are generally warmer than those in the southern hemisphere, ozone depletion over the Arctic has been much smaller than over the Antarctic during the 1980s and early 1990s. The Arctic stratosphere, however, has cooled gradually over the past few decades resulting in very large ozone depletion, especially during 1996-97.
[From NASA Press Release 98-58, 8 April 19981 In late 1997, the levels of ozone over the Arctic were less than in any previous year on record. A study using climate models suggested the increase in greenhouse gas emissions is one possible cause of the observed trends in Arctic ozone losses and that this may delay recovery of the ozone layer. The team conducting this study consisting of researchers from NASA‘s Goddard Institute for Space Studies (GISS) and Columbia University, New York, investigated the response of ozone to projected future emissions of greenhouse gases and ozone-depleting halogens over time, using the GISS climate model. This is the first time that the interaction between ozone chemistry and the gradual build-up of greenhouse gases has been studied in a climate model.
In the simulations performed by Shindell and his team, temperature and wind changes, induced by increasing greenhouse gases, clearly alter the dynamics of the atmosphere. According to this model, as the abundance of greenhouse gases gradually increases, the frequency of northern hemisphere sudden stratospheric warmings is reduced, leading to significantly colder temperatures in the lower stratosphere. If proven correct, this dynamic effect would add to the greenhouse cooling of the stratosphere.
“Build-up of greenhouse gases leads to global warming at the Earth‘s surface, but cools the stratosphere. Since ozone chemistry is very sensitive to temperature, this cooling results in more ozone depletion in the polar regions” said Dr Drew Shindell of Columbia University, the lead author of the study. NASA will continue research in this area to determine if these models are accurate.
“Results suggest that the combination of these two cooling effects causes dramatically increased ozone depletion so that the modelled ozone loss in the Arctic by the year 2020 is roughly double what it would be without greenhouse gas increases” said Dr David Rind of GISS, a co-author of the paper, published in Nature (9 April). Increasing greenhouse gases therefore may be at least partially responsible for the very large Arctic ozone losses in recent winters.
The ‘greenhouse effect’ is defined as the warming of climate that results when the atmosphere traps heat radiating from Earth toward space. Certain gases in the atmosphere, notably water vapour, carbon dioxide, nitrous oxides and chlorofluorocarbons, act like glass in a greenhouse, allowing sunlight to pass into the ‘greenhouse’ but blocking the Earth‘s heat from escaping into space.
Although the model predicts a general trend towards. increasing ozone depletion, the yearto-year variability is quite large, especially in the Arctic. For example, several years in the late 1990s and early 2000s show in the model very little Arctic ozone depletion, while others show record losses. In fact, the 1997-98 winter that has just occurred was characterized by significantly less ozone loss than had occurred in the preceding six winters. A factor that should be considered, however, is the consistency in model predictions, i.e., whether the same results can be reproduced by other models.
Distribution and concentration of stratospheric ozone are influenced in two ways by human-driven activity in addition to natural, seasonal variations. Of first importance is the direct impact of industrially-produced chlorofluorocarbons. Although ozone levels around the globe are expected to continue to decline over the next several years, NASA is now detecting decreasing growth rates of ozonedepleting compounds in the upper part of the atmo-sphere, indicating that international treaties to protect the ozone layer are working. The
According to this model, the severity and duration of the Antarctic ozone depletion may also increase due to greenhouse gas-induced 35
stratospheric cooling over the coming decades. However, ozone in the Antarctic is already so depleted that any additional losses may be relatively small.
years from now? Such exciting ideas for studying the Sun are on offer, it is hard to choose between them”. In addition to the Solar Orbiter, workshop participants looked at three other possible space missions:
The research was conducted by scientists at GISS, The Center for Climate Systems Research, Columbia University, and Science Systems and Applications Inc., New York. The GISS research is part of NASA’s Earth Science Enterprise, a long-term coordinated research effort to study the Earth as a global system.
6.2.
Stereo is a proposal to send several spacecraft to different positions in the solar system. By viewing the Sun from different directions, they could build up 3-D pictures (stereoscopic or tomographic). These would reveal clearly, for the first time, the complex contortions of gas and magnetic fields involved in solar eruptions. The consequences include solar flares and the mass ejections of gas which, arriving at the Earth, can cause satellite failures and power black-outs.
AN ORBITING SPACECRAFT TO SKIM THE SUN
[From RAS Press 19981
Notice
PN 98/15,
6 April
Solar physicists from the UK and other European countries are urging ESA to build a new spacecraft to orbit the Sun. The Solar Orbiter would circle much closer to the Sun than any previous spacecraft, approaching to within 20 million km of the Sun’s surface - 3 times closer than the innermost planet, Mercury. Following a special workshop sponsored by ESA and organized by Professor Eric Priest of the University of St Andrews, the scientists are suggesting that the Solar Orbiferproject should be part of a coordinated international approach to learn more about the Sun. It would follow up the success of Ulysses and SOHO, two spacecraft currently being used to study the Sun.
Solar-Net is a rival scheme, aiming to inspect the stormy surface and atmosphere of the Sun in much sharper detail. A combination of three telescopes in an interferometer could achieve a clarity of vision 40 times better than that of the present instruments in space.The immense magnetic explosions responsible for heating the Sun’s atmosphere and for sparking solar flares occur in regions too small to be clearly resolved by available telescopes. Probe is a scheme to send a spacecraft into the Sun’s hot atmosphere, where it could sample its atoms directly and measure the magnetic fields. Probe would fly by the Sun at a distance of only 2 million kilometres from the surface. The Earth-Sun distance is 150 million kilometres. Remarkable heat shields would have to maintain the spacecraft at an operable temperature in sunshine 2500 times stronger than at the Earth.
The Sun is an important subject for research by ESA. As our nearest star, the Sun is of great significance for astronomy as a whole and provides the best opportunity for astronomers to study basic cosmical processes in great detail. In addition, it affects the Earth‘s environment and its ejecta can damage satellites and disrupt electricity supplies.
After a lively debate, the following consensus emerged. A coherent international programme of missions should be set up. Stereo and Probe are likely to be realized within NASA’s programme, but it was agreed that they would benefit ‘greatly by participation of European scientists with ESA endorsement. Solar-Net was recognized to be of high scientific interest and was considered suitable for a small demonstration mission. Solar Orbiter was recommended as the main ESA element in the programme. In contrast to Probe, which would fly right past the Sun in less than a day, Solar Orbiterwould remain above the same region of the Sun for several days and would continue to orbit the Sun many times. At a later stage, the aim would be to observe in detail, for the first time, the mysterious polar regions of the Sun.
A hundred of the world‘s leading solar physicists met at an ESA workshop, held at the lnstituto de Astrofisica de Canarias on the Spanish island of Tenerife at the end of March. They considered various solar space missions being planned by different groups of scientists around the world and concluded that the Solar Orbiter, provided by ESA in collaboration with other space agencies, would be a key part of a coherent international programme. “Space missions take many years to plan” said Professor Priest. “From time to time, we have to stand back and decide what key scientific questions we should try to answer in the future. In what direction should we head? What might be technologically feasible in 10 or 20
36
ent-day Mars, but it may give us an idea of what early Mars was like and how some of its surface features were formed” said Principal Investigator Dr Pascal Lee of NASA’s Ames Research Center, Moffett Field, Ca.
Additionally Solar Orbiter would be able to see the regions through which Probe was flying. Commenting on the choice of Solar Orbiter, Professor Priest said “What tipped the scales was the exciting new science, its key role in the overall international programme, and the broad backing of the world’s solar scientists. By selecting Solar Orbiter as the project for which we will all now be pressing, we can be certain that Europe will create a fitting successor to SO/-/O, which is already revolutionizing solar science”. As with any proposal like this, Solar Orbiter will have to go through ESA’s procedures for mission selection before it can be authorized. Assessments by expert committees and detailed studies of the science, engineering and costs are required. Any collaboration with other space agencies has to be negotiated. However, the support of the specialists in solar physics helps strengthen the case for Solar Orbiter as ESA’s next solar project, to be considered for possible launch between 2005 and 2010.
During the expedition, Dr Omead Amidi and other engineers from Carnegie Mellon University’s Robotics Institute, Pittsburgh, Pa, will conduct field tests of an experimental, robotic helicopter. “The mission provides a great opportunity to demonstrate the feasibility and the value of robotic aircraft for mapping and surveying applications” Amidi said. Carnegie Mellon’s small, 160-lb autonomous helicopter has vision-based stability and position control, as well as an onboard navigation computer, laser rangefinder and video system for site mapping. More information about the unpiloted helicopter may be found at the following website: http://www.ri.cmu.edu/project/chopper. In addition to the tests with the autonomous helicopter, experiments will be conducted with a ground-penetrating radar system, a field spectrometer, drilling equipment and a stereo camera.
Images to support this story can be found at the following internet location: http://www-solar.dcs.st-andrews.ac.ukl -eric/tenerife.html
6.3.
The radar system will be deployed in an attempt to map ground-ice and other subsurface conditions within and outside the crater’s 12-mile (20-kilometre) diameter. “The ability to find underground ice, both for human consumption and geologic studies, will be critical in the exploration of Mars”, said Dr Aaron Zent of Ames, Dr Lee’s postdoctoral research advisor.
FUTURE EXPLORATION TECHNOLOGIES TO BE TESTED IN ARCTIC CRATER
[From NASA Press Release 98-105, 19981
16 June
NASA scientists are to explore a barren Arctic meteorite impact crater in an attempt to learn more about Mars and its early history, while testing technologies useful for future robotic and human exploration of the planet. From 22 June to 26 July, a 20-member science team from NASA and several other research organisations were to explore the Haughton Impact Crater and its surroundings on Devon Island inside the Arctic Circle.
A field spectrometer will be used to determine the site’s reflective qualities and secure a better understanding of the crater’s compositional evolution. In another experiment, a portable drill will be used to obtain core samples from ten feet deep in the frozen ground. Core samples of sediments from a lake that once occupied the crater will provide information about local climate evolution. Since the use of liquid drilling lubricants might be precluded on Mars, none will be used in this test.
Scientists consider the site a potential Mars analogue because many of its geological features, such as the crater’s ice-rich terrains, its ancient lake sediments and nearby networks of small valleys, resemble those repot-ted at the surface of Mars. The site may shed light in particular on the early history of Mars, when the planet’s climate may have been wetter and warmer. “The cold, relatively dry, windy and unvegetated environment at the Haughton site is milder and wetter than pres-
A portable stereo camera system previously used by Carnegie Mellon’s Nomad rover during its unprecedented 133-mile wheeled trek through Chile’s Atacama Desert last summer will provide high-resolution images of the site, and produce images for a 360 degree photorealistic virtual reality project being developed by Ames’ Intelligent Mechanisms Group.
37
Laptop computer systems and mobile workstations, developed by Ames’ intelligent Mobile Technologies Team will be used for communications between team members in the field and for sending live images via a radio link. Team members will operate from a base camp on a terrace of the Haughton River within the crater’s perimeter and explore the site with All-Terrain Vehicles. Supplies will be brought in by Twin Otter airplane, while a helicopter will aid exploration of remote sites. As part of the expedition’s educational outreach programme, the following website will be updated regularly with new data and images as available: http://www.arctic-mars.org.
The scientific objectives of the Mars Microprobes include searching for the presence of water-ice in the soil and characterizing its thermal and physical properties. A small drill will bring a soil sample inside the probe, heat it, and look for the presence of water vapour using a tunable diode laser. An impact accelerometer will measure the rate at which the probes come to rest, giving an indication of the hardness of the soil and of any layers present. Temperature sensors will estimate how well the Martian soil conducts heat, a property sensitive to different soil properties such as grain size and water content. A sensor at the surface will measure atmospheric pressure in tandem with a sensor on the Mars Polar Lander.
The total cost of the project is $ 80 000. NASA is partially funding the project through a National Research Council grant. Additional support is provided by Ames Research Center; NASA’s Johnson Space Center, Houston, TX; the Geological Survey of Canada; the Polar Continental Shelf Project of Canada; the Nunavut Research Institute, Canada; the Robotics Institute of Carnegie Mellon University; NovAtel Communications, Calgary, Alberta, Canada; and the National Geographic Society.
6.4.
TECHNOLOGY VALIDATION MISSION TO INVESTIGATE SUBSURFACE OF MARS
[From NASA 19981
Press
Release
98-59,
The Mars Microprobes mission, also known as Deep Space-2 (DS-2), is scheduled to be the second launch in NASA’s New Millennium Program of technology validation flights, designed to enable advanced science missions in the 21st century.
8 April
Nine researchers have been selected to be the Science Team for the Mars Microprobes, a technology validation mission that will hitchhike a ride to the red planet aboard NASA’s Mars Polar Lander mission. Two identical probes will be carried as a secondary payload on the lander, due for launch in January 1999. Following an 1 lmonth cruise, the Microprobes will separate from the lander before it enters the Martian atmosphere, and then hit the ground at approximately 400 mph. During the impact, each microprobe will separate into two sections: the forebody and its instruments will penetrate up to 2 m below the surface, while the aftbody will remain near the surface to communicate with a radio relay on the Mars Global Surveyor orbiter while making meteorological measurements.
* *
Julio Magalhaes, NASA Ames Research Center Jeffrey Moersch, NASA Ames Research Center Paul Morgan, Northern Arizona University, Flagstaff James Murphy, NASA Ames Research Center Bruce Murray, California Institute of Technology, Pasadena Marsha Presley, Arizona State University, Phoenix Aaron Zent, NASA Ames Research Center
“I’m delighted with the selection of this excellent group of investigators. The Mars Microprobe will give us a glimpse of the subsurface of Mars, which in many ways is a window into the planet’s history” said Dr Suzanne Smrekar, the DS-2 project scientist at NASA’s Jet Propulsion Laboratory, Pasadena, Ca. “The region of Mars we will explore is similar to Earth’s polar regions in that it is believed to collect ice and dust over many millions of years. By studying the history of Mars and its climate, we are likely to better understand the more complex system on our own planet”. In addition to the miniaturized science instruments capable of surviving high velocity impact, technologies to be tested on DS-2 include a non-erosive, lightweight, single-stage atmospheric entry system (aeroshell); power microelectronics with mixed digital/analogue
The nine scientists selected are: David Catling, NASA Ames Research Center, Moffett Field, Ca Ralph Lorenz, University of Arizona, Tucson
38
advanced integrated circuits; an ultra-low temperature lithium battery; an advanced three-dimensional microcontroller; and flexible interconnects for system cabling. The combination of a single-stage entry vehicle with electronics and instrumentation that can survive very high impact loads will enable us to design a whole new class of very small, rugged spacecraft for the in-situ exploration of planets” explained Sarah Gavit, DS-2 project manager at JPL. ‘Slamming high-precision science instruments into the surface of Mars at 400 mph is very challenging, no doubt about it! But once this type of technology is demonstrated, we can envision future missions that could sample numerous regions on Mars or make network measurements of global weather and possible Marsquakes” said DS-2 progra,mme scientist Dr Michael Meyer of NASA Headquarters, Washington, DC. Further information on DS-2 is available the Internet at the following URL: http:Nnmp.jpl.nasa.gov/ds2/.
on
changed. In addition, several enhancements to the station’s assembly have been made, including an exterior warehouse for spare parts and a Brazilian-provided carrier for exterior station components that are launched aboard the Space Shuttle. The International Space Station partners set an April 1999 target launch date for the Russian Service Module. The first station crew (Commander Bill Shepherd, Soyuz Commander Yuri Gidzenko and Flight Engineer Sergei Krikalev) will be launched aboard a Russian Soyuz spacecraft in summer 1999 to begin a five-month inaugural stay. Launch of the US Laboratory module is set for October 1999. Launches of other laboratory modules, provided by Europe, Japan and Russia, will take place later in the assembly sequence. The Canadian-provided station robotic arm (or Space Station Remote Manipulator System) will be launched in December 1999. Scientific research aboard the station will commence early in the year 2000. The expansion from a three-person crew to a six-person capability is planned for November 2002. The final launch in the assembly sequence is set for January 2004, only one month later than in the previous assembly plan. Some issues in this assembly sequence remain under review and will be resolved at a Space Station Control Board meeting in September.
The New Millennium Programme is managed by JPL for NASA’s Office of Space Science in Washington, DC.
6.5.
REVISED LAUNCH DATES FOR ;pEW& STATION COMPO-
Representatives of all nations involved in the International Space Station have agreed officially to target a November 1998 launch for the first station component and to revise launch target dates for the remainder of the 43-flight station assembly plan. In meetings of the Space Station Control Board and the Heads-of-Agency on 30 and 31 May at the Kennedy Space Center, all station partners agreed to target launch dates of 20 November 1998 for the Control Module (FGB) - now named Zarya (the Russian word for sunrise) and 3 December 1998 for Shuttle mission STS-88 with Unity (Node 1). Changes in construction schedule for the third station component, the Russian-provided Service Module, led the partners to reschedule the first assembly launches. The Service Module will house the first station occupants and the Data Management System to be provided by ESA.
NASA continues to develop an Interim Control Module (ICM) as a contingency against further delays in the Service Module and as a potential additional propellant capability for a more robust space station. A decision concerning the configuration of the ICM will be made later this year. During the Heads-of-Agency meeting, the Russian Space Agency (RSA) stated that the Russian government has made the International Space Station its number one civil space priority. RSA noted that progress on the Service Module continues to meet the target for a launch in April 1999. RSA is also working to deorbit Micas early as is safely possible, with the goal of developing the potential to deorbit by July 1999. The international partners expressed their concern at delays to the International Space Station programme to date and brought to the attention of RSA the critical need for the station programme schedule to be met for all participating nations. The agencies’ leaders also acknowledged the atmosphere of cooperation, the accomplishments and the
Although the new dates move the launch of the first station component, Zafya, from June to November, the target dates agreed upon for many major station milestones during the latter stages of the five-year assembly plan are little
39
successful achievements of the Shuttle-Mir Program (Phase 1) and looked forward to the smooth transition to Phases 2 and 3 of the International Space Station. In addition, they highlighted the ongoing International Space Station training currently under way for the first four station crews.
6.6
ment, in the design, development, operations and data analysis from this unique venture” said Dr Ghassem Asrar, NASA Associate Administrator for Earth Science. “It would allow scientists to track natural events such as hurricanes, large fires and volcano plumes. We expect further innovative applications to blossom as we let this singular view inspire the imaginations of all the citizens of planet Earth”.
EARTH-VIEWING SATELLITE WITH EDUCATIONAL FOCUS
Early plans envisage a 330-pound satellite linked to Earth through three simple, low-cost ground stations equally spaced around the globe to provide continuous downlink capability. One new image would be downlinked every few minutes. The satellite would be developed and launched within two years of a competitive selection process. College students would participate in the design and development of the spacecraft, and student teams would operate the ground stations. The total mission cost, including launch and operations, would not exceed $ 50 million.
[From NASA Press Release 98-46, 13 March 19981 In response to a concept proposed by Vice President Al Gore, NASA is developing plans for a small satellite which could provide continuous views of the Earth by the year 2000. In March 1998, NASA planned to issue educational, scientific and, possibly, commercial announcements of opportunity in the near future, following the Vice President’s call for NASA to design, build and launch the satellite by 2000,
6.7 “Vice President Gore has given us an exciting challenge” said NASA Administrator Daniel S. Goldin. “In the coming weeks, we plan to solicit ideas from the academic, environmental, scientific and commercial communities. We will synthesize these ideas and communicate with Congress as we go forward”. Goldin said NASA envisions ‘down-to-Earth’ applications: “This view of our planet can help us plan as fires ravage wilderness areas, and it may be able to save lives as we watch hurricanes and typhoons form and threaten coastlines across the grand sweep of ocean basins. Moreover, we think it is important to inspire young minds, provide new perspectives on the planet for our scientific community, and perhaps provide commercial applications as well. We’re going to pave the way for an Earth Channel”.
ARIANE 503 TEST FLIGHT
[From ESA 19981
Press
Release
21-98,
15 June
With the destruction by fire of the Wl communications satellite developed for Eutelsat, the W2 satellite, which was to have been carried as a commercial passenger on the last of the Ariane-5 qualification flights (Ariane 503) will instead be launched by an Ariane-4 vehicle. Ariane-5 is an ESA programme for which ESA delegated responsibilities to CNES. As the search for a new commercial passenger cannot be reconciled with the planning schedule leading to entry of Ariane-5 into operational service, the Ariane 503 payload will consist, in addition to the ARD (Atmospheric Reentry Demonstrator) - which has already been delivered to the Guiana Space Centre of a representative mock-up of the Eutelsat’s W2 satellite (Ariane 502 in 30 October 1997). Taking account of the time needed to develop, test and integrate the mock-up, the Ariane 503 launch is now scheduled for mid-October 1998.
The satellite concept would place a high definition television camera - paired with an eight-inch telescope - into an orbit at a unique vantage point a million miles from Earth where it could provide 24-hour views of the home planet. It would orbit at a point in space where the gravitational attraction of the Sun and the Earth essentially cancel one another out, allowing the satellite to constantly view a fully sunlit hemisphere.
With these two payloads, the Ariane 503 flight will complete the qualification of the Ariane-5 launcher; the launcher to be used for this flight will be the first production-series unit ordered by Arianespace from European industry.
“We want to involve directly university students, teamed with industry and govern-
40
NEWS FROM SPACE ORGANIZATIONS
6.1.
ARCTIC OZONE WORSENS
second influence on stratospheric ozone levels is the indirect impact of greenhouse gases on atmospheric temperatures as ozone destruction is quite sensitive to temperature increases in the atmosphere.
DEPLETION
Since upper atmospheric temperatures in the northern hemisphere during winter and spring are generally warmer than those in the southern hemisphere, ozone depletion over the Arctic has been much smaller than over the Antarctic during the 1980s and early 1990s. The Arctic stratosphere, however, has cooled gradually over the past few decades resulting in very large ozone depletion, especially during 1996-97.
[From NASA Press Release 98-58, 8 April 19981 In late 1997, the levels of ozone over the Arctic were less than in any previous year on record. A study using climate models suggested the increase in greenhouse gas emissions is one possible cause of the observed trends in Arctic ozone losses and that this may delay recovery of the ozone layer. The team conducting this study consisting of researchers from NASA‘s Goddard Institute for Space Studies (GISS) and Columbia University, New York, investigated the response of ozone to projected future emissions of greenhouse gases and ozone-depleting halogens over time, using the GISS climate model. This is the first time that the interaction between ozone chemistry and the gradual build-up of greenhouse gases has been studied in a climate model.
In the simulations performed by Shindell and his team, temperature and wind changes, induced by increasing greenhouse gases, clearly alter the dynamics of the atmosphere. According to this model, as the abundance of greenhouse gases gradually increases, the frequency of northern hemisphere sudden stratospheric warmings is reduced, leading to significantly colder temperatures in the lower stratosphere. If proven correct, this dynamic effect would add to the greenhouse cooling of the stratosphere.
“Build-up of greenhouse gases leads to global warming at the Earth‘s surface, but cools the stratosphere. Since ozone chemistry is very sensitive to temperature, this cooling results in more ozone depletion in the polar regions” said Dr Drew Shindell of Columbia University, the lead author of the study. NASA will continue research in this area to determine if these models are accurate.
“Results suggest that the combination of these two cooling effects causes dramatically increased ozone depletion so that the modelled ozone loss in the Arctic by the year 2020 is roughly double what it would be without greenhouse gas increases” said Dr David Rind of GISS, a co-author of the paper, published in Nature (9 April). Increasing greenhouse gases therefore may be at least partially responsible for the very large Arctic ozone losses in recent winters.
The ‘greenhouse effect’ is defined as the warming of climate that results when the atmosphere traps heat radiating from Earth toward space. Certain gases in the atmosphere, notably water vapour, carbon dioxide, nitrous oxides and chlorofluorocarbons, act like glass in a greenhouse, allowing sunlight to pass into the ‘greenhouse’ but blocking the Earth‘s heat from escaping into space.
Although the model predicts a general trend towards. increasing ozone depletion, the yearto-year variability is quite large, especially in the Arctic. For example, several years in the late 1990s and early 2000s show in the model very little Arctic ozone depletion, while others show record losses. In fact, the 1997-98 winter that has just occurred was characterized by significantly less ozone loss than had occurred in the preceding six winters. A factor that should be considered, however, is the consistency in model predictions, i.e., whether the same results can be reproduced by other models.
Distribution and concentration of stratospheric ozone are influenced in two ways by human-driven activity in addition to natural, seasonal variations. Of first importance is the direct impact of industrially-produced chlorofluorocarbons. Although ozone levels around the globe are expected to continue to decline over the next several years, NASA is now detecting decreasing growth rates of ozonedepleting compounds in the upper part of the atmo-sphere, indicating that international treaties to protect the ozone layer are working. The
According to this model, the severity and duration of the Antarctic ozone depletion may also increase due to greenhouse gas-induced 35
stratospheric cooling over the coming decades. However, ozone in the Antarctic is already so depleted that any additional losses may be relatively small.
years from now? Such exciting ideas for studying the Sun are on offer, it is hard to choose between them”. In addition to the Solar Orbiter, workshop participants looked at three other possible space missions:
The research was conducted by scientists at GISS, The Center for Climate Systems Research, Columbia University, and Science Systems and Applications Inc., New York. The GISS research is part of NASA’s Earth Science Enterprise, a long-term coordinated research effort to study the Earth as a global system.
6.2.
Stereo is a proposal to send several spacecraft to different positions in the solar system. By viewing the Sun from different directions, they could build up 3-D pictures (stereoscopic or tomographic). These would reveal clearly, for the first time, the complex contortions of gas and magnetic fields involved in solar eruptions. The consequences include solar flares and the mass ejections of gas which, arriving at the Earth, can cause satellite failures and power black-outs.
AN ORBITING SPACECRAFT TO SKIM THE SUN
[From RAS Press 19981
Notice
PN 98/15,
6 April
Solar physicists from the UK and other European countries are urging ESA to build a new spacecraft to orbit the Sun. The Solar Orbiter would circle much closer to the Sun than any previous spacecraft, approaching to within 20 million km of the Sun’s surface - 3 times closer than the innermost planet, Mercury. Following a special workshop sponsored by ESA and organized by Professor Eric Priest of the University of St Andrews, the scientists are suggesting that the Solar Orbiferproject should be part of a coordinated international approach to learn more about the Sun. It would follow up the success of Ulysses and SOHO, two spacecraft currently being used to study the Sun.
Solar-Net is a rival scheme, aiming to inspect the stormy surface and atmosphere of the Sun in much sharper detail. A combination of three telescopes in an interferometer could achieve a clarity of vision 40 times better than that of the present instruments in space.The immense magnetic explosions responsible for heating the Sun’s atmosphere and for sparking solar flares occur in regions too small to be clearly resolved by available telescopes. Probe is a scheme to send a spacecraft into the Sun’s hot atmosphere, where it could sample its atoms directly and measure the magnetic fields. Probe would fly by the Sun at a distance of only 2 million kilometres from the surface. The Earth-Sun distance is 150 million kilometres. Remarkable heat shields would have to maintain the spacecraft at an operable temperature in sunshine 2500 times stronger than at the Earth.
The Sun is an important subject for research by ESA. As our nearest star, the Sun is of great significance for astronomy as a whole and provides the best opportunity for astronomers to study basic cosmical processes in great detail. In addition, it affects the Earth‘s environment and its ejecta can damage satellites and disrupt electricity supplies.
After a lively debate, the following consensus emerged. A coherent international programme of missions should be set up. Stereo and Probe are likely to be realized within NASA’s programme, but it was agreed that they would benefit ‘greatly by participation of European scientists with ESA endorsement. Solar-Net was recognized to be of high scientific interest and was considered suitable for a small demonstration mission. Solar Orbiter was recommended as the main ESA element in the programme. In contrast to Probe, which would fly right past the Sun in less than a day, Solar Orbiterwould remain above the same region of the Sun for several days and would continue to orbit the Sun many times. At a later stage, the aim would be to observe in detail, for the first time, the mysterious polar regions of the Sun.
A hundred of the world‘s leading solar physicists met at an ESA workshop, held at the lnstituto de Astrofisica de Canarias on the Spanish island of Tenerife at the end of March. They considered various solar space missions being planned by different groups of scientists around the world and concluded that the Solar Orbiter, provided by ESA in collaboration with other space agencies, would be a key part of a coherent international programme. “Space missions take many years to plan” said Professor Priest. “From time to time, we have to stand back and decide what key scientific questions we should try to answer in the future. In what direction should we head? What might be technologically feasible in 10 or 20
36
ent-day Mars, but it may give us an idea of what early Mars was like and how some of its surface features were formed” said Principal Investigator Dr Pascal Lee of NASA’s Ames Research Center, Moffett Field, Ca.
Additionally Solar Orbiter would be able to see the regions through which Probe was flying. Commenting on the choice of Solar Orbiter, Professor Priest said “What tipped the scales was the exciting new science, its key role in the overall international programme, and the broad backing of the world’s solar scientists. By selecting Solar Orbiter as the project for which we will all now be pressing, we can be certain that Europe will create a fitting successor to SO/-/O, which is already revolutionizing solar science”. As with any proposal like this, Solar Orbiter will have to go through ESA’s procedures for mission selection before it can be authorized. Assessments by expert committees and detailed studies of the science, engineering and costs are required. Any collaboration with other space agencies has to be negotiated. However, the support of the specialists in solar physics helps strengthen the case for Solar Orbiter as ESA’s next solar project, to be considered for possible launch between 2005 and 2010.
During the expedition, Dr Omead Amidi and other engineers from Carnegie Mellon University’s Robotics Institute, Pittsburgh, Pa, will conduct field tests of an experimental, robotic helicopter. “The mission provides a great opportunity to demonstrate the feasibility and the value of robotic aircraft for mapping and surveying applications” Amidi said. Carnegie Mellon’s small, 160-lb autonomous helicopter has vision-based stability and position control, as well as an onboard navigation computer, laser rangefinder and video system for site mapping. More information about the unpiloted helicopter may be found at the following website: http://www.ri.cmu.edu/project/chopper. In addition to the tests with the autonomous helicopter, experiments will be conducted with a ground-penetrating radar system, a field spectrometer, drilling equipment and a stereo camera.
Images to support this story can be found at the following internet location: http://www-solar.dcs.st-andrews.ac.ukl -eric/tenerife.html
6.3.
The radar system will be deployed in an attempt to map ground-ice and other subsurface conditions within and outside the crater’s 12-mile (20-kilometre) diameter. “The ability to find underground ice, both for human consumption and geologic studies, will be critical in the exploration of Mars”, said Dr Aaron Zent of Ames, Dr Lee’s postdoctoral research advisor.
FUTURE EXPLORATION TECHNOLOGIES TO BE TESTED IN ARCTIC CRATER
[From NASA Press Release 98-105, 19981
16 June
NASA scientists are to explore a barren Arctic meteorite impact crater in an attempt to learn more about Mars and its early history, while testing technologies useful for future robotic and human exploration of the planet. From 22 June to 26 July, a 20-member science team from NASA and several other research organisations were to explore the Haughton Impact Crater and its surroundings on Devon Island inside the Arctic Circle.
A field spectrometer will be used to determine the site’s reflective qualities and secure a better understanding of the crater’s compositional evolution. In another experiment, a portable drill will be used to obtain core samples from ten feet deep in the frozen ground. Core samples of sediments from a lake that once occupied the crater will provide information about local climate evolution. Since the use of liquid drilling lubricants might be precluded on Mars, none will be used in this test.
Scientists consider the site a potential Mars analogue because many of its geological features, such as the crater’s ice-rich terrains, its ancient lake sediments and nearby networks of small valleys, resemble those repot-ted at the surface of Mars. The site may shed light in particular on the early history of Mars, when the planet’s climate may have been wetter and warmer. “The cold, relatively dry, windy and unvegetated environment at the Haughton site is milder and wetter than pres-
A portable stereo camera system previously used by Carnegie Mellon’s Nomad rover during its unprecedented 133-mile wheeled trek through Chile’s Atacama Desert last summer will provide high-resolution images of the site, and produce images for a 360 degree photorealistic virtual reality project being developed by Ames’ Intelligent Mechanisms Group.
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Laptop computer systems and mobile workstations, developed by Ames’ intelligent Mobile Technologies Team will be used for communications between team members in the field and for sending live images via a radio link. Team members will operate from a base camp on a terrace of the Haughton River within the crater’s perimeter and explore the site with All-Terrain Vehicles. Supplies will be brought in by Twin Otter airplane, while a helicopter will aid exploration of remote sites. As part of the expedition’s educational outreach programme, the following website will be updated regularly with new data and images as available: http://www.arctic-mars.org.
The scientific objectives of the Mars Microprobes include searching for the presence of water-ice in the soil and characterizing its thermal and physical properties. A small drill will bring a soil sample inside the probe, heat it, and look for the presence of water vapour using a tunable diode laser. An impact accelerometer will measure the rate at which the probes come to rest, giving an indication of the hardness of the soil and of any layers present. Temperature sensors will estimate how well the Martian soil conducts heat, a property sensitive to different soil properties such as grain size and water content. A sensor at the surface will measure atmospheric pressure in tandem with a sensor on the Mars Polar Lander.
The total cost of the project is $ 80 000. NASA is partially funding the project through a National Research Council grant. Additional support is provided by Ames Research Center; NASA’s Johnson Space Center, Houston, TX; the Geological Survey of Canada; the Polar Continental Shelf Project of Canada; the Nunavut Research Institute, Canada; the Robotics Institute of Carnegie Mellon University; NovAtel Communications, Calgary, Alberta, Canada; and the National Geographic Society.
6.4.
TECHNOLOGY VALIDATION MISSION TO INVESTIGATE SUBSURFACE OF MARS
[From NASA 19981
Press
Release
98-59,
The Mars Microprobes mission, also known as Deep Space-2 (DS-2), is scheduled to be the second launch in NASA’s New Millennium Program of technology validation flights, designed to enable advanced science missions in the 21st century.
8 April
Nine researchers have been selected to be the Science Team for the Mars Microprobes, a technology validation mission that will hitchhike a ride to the red planet aboard NASA’s Mars Polar Lander mission. Two identical probes will be carried as a secondary payload on the lander, due for launch in January 1999. Following an 1 lmonth cruise, the Microprobes will separate from the lander before it enters the Martian atmosphere, and then hit the ground at approximately 400 mph. During the impact, each microprobe will separate into two sections: the forebody and its instruments will penetrate up to 2 m below the surface, while the aftbody will remain near the surface to communicate with a radio relay on the Mars Global Surveyor orbiter while making meteorological measurements.
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Julio Magalhaes, NASA Ames Research Center Jeffrey Moersch, NASA Ames Research Center Paul Morgan, Northern Arizona University, Flagstaff James Murphy, NASA Ames Research Center Bruce Murray, California Institute of Technology, Pasadena Marsha Presley, Arizona State University, Phoenix Aaron Zent, NASA Ames Research Center
“I’m delighted with the selection of this excellent group of investigators. The Mars Microprobe will give us a glimpse of the subsurface of Mars, which in many ways is a window into the planet’s history” said Dr Suzanne Smrekar, the DS-2 project scientist at NASA’s Jet Propulsion Laboratory, Pasadena, Ca. “The region of Mars we will explore is similar to Earth’s polar regions in that it is believed to collect ice and dust over many millions of years. By studying the history of Mars and its climate, we are likely to better understand the more complex system on our own planet”. In addition to the miniaturized science instruments capable of surviving high velocity impact, technologies to be tested on DS-2 include a non-erosive, lightweight, single-stage atmospheric entry system (aeroshell); power microelectronics with mixed digital/analogue
The nine scientists selected are: David Catling, NASA Ames Research Center, Moffett Field, Ca Ralph Lorenz, University of Arizona, Tucson
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advanced integrated circuits; an ultra-low temperature lithium battery; an advanced three-dimensional microcontroller; and flexible interconnects for system cabling. The combination of a single-stage entry vehicle with electronics and instrumentation that can survive very high impact loads will enable us to design a whole new class of very small, rugged spacecraft for the in-situ exploration of planets” explained Sarah Gavit, DS-2 project manager at JPL. ‘Slamming high-precision science instruments into the surface of Mars at 400 mph is very challenging, no doubt about it! But once this type of technology is demonstrated, we can envision future missions that could sample numerous regions on Mars or make network measurements of global weather and possible Marsquakes” said DS-2 progra,mme scientist Dr Michael Meyer of NASA Headquarters, Washington, DC. Further information on DS-2 is available the Internet at the following URL: http:Nnmp.jpl.nasa.gov/ds2/.
on
changed. In addition, several enhancements to the station’s assembly have been made, including an exterior warehouse for spare parts and a Brazilian-provided carrier for exterior station components that are launched aboard the Space Shuttle. The International Space Station partners set an April 1999 target launch date for the Russian Service Module. The first station crew (Commander Bill Shepherd, Soyuz Commander Yuri Gidzenko and Flight Engineer Sergei Krikalev) will be launched aboard a Russian Soyuz spacecraft in summer 1999 to begin a five-month inaugural stay. Launch of the US Laboratory module is set for October 1999. Launches of other laboratory modules, provided by Europe, Japan and Russia, will take place later in the assembly sequence. The Canadian-provided station robotic arm (or Space Station Remote Manipulator System) will be launched in December 1999. Scientific research aboard the station will commence early in the year 2000. The expansion from a three-person crew to a six-person capability is planned for November 2002. The final launch in the assembly sequence is set for January 2004, only one month later than in the previous assembly plan. Some issues in this assembly sequence remain under review and will be resolved at a Space Station Control Board meeting in September.
The New Millennium Programme is managed by JPL for NASA’s Office of Space Science in Washington, DC.
6.5.
REVISED LAUNCH DATES FOR ;pEW& STATION COMPO-
Representatives of all nations involved in the International Space Station have agreed officially to target a November 1998 launch for the first station component and to revise launch target dates for the remainder of the 43-flight station assembly plan. In meetings of the Space Station Control Board and the Heads-of-Agency on 30 and 31 May at the Kennedy Space Center, all station partners agreed to target launch dates of 20 November 1998 for the Control Module (FGB) - now named Zarya (the Russian word for sunrise) and 3 December 1998 for Shuttle mission STS-88 with Unity (Node 1). Changes in construction schedule for the third station component, the Russian-provided Service Module, led the partners to reschedule the first assembly launches. The Service Module will house the first station occupants and the Data Management System to be provided by ESA.
NASA continues to develop an Interim Control Module (ICM) as a contingency against further delays in the Service Module and as a potential additional propellant capability for a more robust space station. A decision concerning the configuration of the ICM will be made later this year. During the Heads-of-Agency meeting, the Russian Space Agency (RSA) stated that the Russian government has made the International Space Station its number one civil space priority. RSA noted that progress on the Service Module continues to meet the target for a launch in April 1999. RSA is also working to deorbit Micas early as is safely possible, with the goal of developing the potential to deorbit by July 1999. The international partners expressed their concern at delays to the International Space Station programme to date and brought to the attention of RSA the critical need for the station programme schedule to be met for all participating nations. The agencies’ leaders also acknowledged the atmosphere of cooperation, the accomplishments and the
Although the new dates move the launch of the first station component, Zafya, from June to November, the target dates agreed upon for many major station milestones during the latter stages of the five-year assembly plan are little
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successful achievements of the Shuttle-Mir Program (Phase 1) and looked forward to the smooth transition to Phases 2 and 3 of the International Space Station. In addition, they highlighted the ongoing International Space Station training currently under way for the first four station crews.
6.6
ment, in the design, development, operations and data analysis from this unique venture” said Dr Ghassem Asrar, NASA Associate Administrator for Earth Science. “It would allow scientists to track natural events such as hurricanes, large fires and volcano plumes. We expect further innovative applications to blossom as we let this singular view inspire the imaginations of all the citizens of planet Earth”.
EARTH-VIEWING SATELLITE WITH EDUCATIONAL FOCUS
Early plans envisage a 330-pound satellite linked to Earth through three simple, low-cost ground stations equally spaced around the globe to provide continuous downlink capability. One new image would be downlinked every few minutes. The satellite would be developed and launched within two years of a competitive selection process. College students would participate in the design and development of the spacecraft, and student teams would operate the ground stations. The total mission cost, including launch and operations, would not exceed $ 50 million.
[From NASA Press Release 98-46, 13 March 19981 In response to a concept proposed by Vice President Al Gore, NASA is developing plans for a small satellite which could provide continuous views of the Earth by the year 2000. In March 1998, NASA planned to issue educational, scientific and, possibly, commercial announcements of opportunity in the near future, following the Vice President’s call for NASA to design, build and launch the satellite by 2000,
6.7 “Vice President Gore has given us an exciting challenge” said NASA Administrator Daniel S. Goldin. “In the coming weeks, we plan to solicit ideas from the academic, environmental, scientific and commercial communities. We will synthesize these ideas and communicate with Congress as we go forward”. Goldin said NASA envisions ‘down-to-Earth’ applications: “This view of our planet can help us plan as fires ravage wilderness areas, and it may be able to save lives as we watch hurricanes and typhoons form and threaten coastlines across the grand sweep of ocean basins. Moreover, we think it is important to inspire young minds, provide new perspectives on the planet for our scientific community, and perhaps provide commercial applications as well. We’re going to pave the way for an Earth Channel”.
ARIANE 503 TEST FLIGHT
[From ESA 19981
Press
Release
21-98,
15 June
With the destruction by fire of the Wl communications satellite developed for Eutelsat, the W2 satellite, which was to have been carried as a commercial passenger on the last of the Ariane-5 qualification flights (Ariane 503) will instead be launched by an Ariane-4 vehicle. Ariane-5 is an ESA programme for which ESA delegated responsibilities to CNES. As the search for a new commercial passenger cannot be reconciled with the planning schedule leading to entry of Ariane-5 into operational service, the Ariane 503 payload will consist, in addition to the ARD (Atmospheric Reentry Demonstrator) - which has already been delivered to the Guiana Space Centre of a representative mock-up of the Eutelsat’s W2 satellite (Ariane 502 in 30 October 1997). Taking account of the time needed to develop, test and integrate the mock-up, the Ariane 503 launch is now scheduled for mid-October 1998.
The satellite concept would place a high definition television camera - paired with an eight-inch telescope - into an orbit at a unique vantage point a million miles from Earth where it could provide 24-hour views of the home planet. It would orbit at a point in space where the gravitational attraction of the Sun and the Earth essentially cancel one another out, allowing the satellite to constantly view a fully sunlit hemisphere.
With these two payloads, the Ariane 503 flight will complete the qualification of the Ariane-5 launcher; the launcher to be used for this flight will be the first production-series unit ordered by Arianespace from European industry.
“We want to involve directly university students, teamed with industry and govern-
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