MARSBUGS: The Electronic Astrobiology Newsletter Volume 6, Number 39, 29 November 1999. Editors: Dr. David J. Thomas, Biology and Chemistry Division, Lyon College, Batesville, AR 72503-2317, USA. Dthomas@lyon.edu or marsbugs@aol.com Dr. Julian A. Hiscox, School of Animal and Microbial Sciences, University of Reading, Reading, RG6 6AJ, United Kingdom. J.A.Hiscox@reading.ac.uk Marsbugs is published on a weekly to quarterly basis as warranted by the number of articles and announcements. Copyright of this compilation exists with the editors, except for specific articles, in which instance copyright exists with the author/authors. While we cannot copyright our mailing list, our readers would appreciate it if others would not send unsolicited e-mail using the Marsbugs mailing list. The editors do not condone "spamming" of our subscribers. Persons who have information that may be of interest to subscribers of Marsbugs should send that information to the editors. E-mail subscriptions are free, and may be obtained by contacting either of the editors. Article contributions are welcome, and should be submitted to either of the two editors. Contributions should include a short biographical statement about the author(s) along with the author(s)' correspondence address. Subscribers are advised to make appropriate inquiries before joining societies, ordering goods etc. Back issues and Adobe Acrobat PDF files suitable for printing may be obtained from the official Marsbugs web page at http://www.lyon.edu/webdata/users/dthomas/marsbugs/marsbugs.html . The purpose of this newsletter is to provide a channel of information for scientists, educators and other persons interested in exobiology and related fields. This newsletter is not intended to replace peer-reviewed journals, but to supplement them. We, the editors, envision Marsbugs as a medium in which people can informally present ideas for investigation, questions about exobiology, and announcements of upcoming events. Astrobiology is still a relatively young field, and new ideas may come out of the most unexpected places. Subjects may include, but are not limited to: exobiology and astrobiology (life on other planets), the search for extraterrestrial intelligence (SETI), ecopoeisis and terraformation, Earth from space, planetary biology, primordial evolution, space physiology, biological life support systems, and human habitation of space and other planets. ---------------------------------------------------------------- CONTENTS 1) MYSTERY OF THE MISSING ATMOSPHERE By Oliver Morton 2) MARS LANDING EVENTS AND MEDIA COVERAGE INFORMATION NASA note N99-60 3) MARS POLAR LANDER SCIENCE TO BEGIN DECEMBER 3 University of Arizona release 4) TERRA SPACECRAFT TO LEAD THE WAY NASA release 99-120 5) MARS POLAR LANDER COLOR SLIDE SET By Ron Baalke 6) PURPLE SALT AND TINY DROPS OF WATER IN METEORITES By G. Jeffrey Taylor 7) JPL MARS MICROMISSION CONTRACTOR SELECTED FOR NEGOTIATION JPL release 8) MARS POLAR LANDER, DEEP SPACE 2 SET FOR ARRIVAL JPL release 9) THREE DAYS ON GALILEO [TWICE] JPL releases 10) GALILEO MISSION STATUS JPL release 11) NEW MARS GLOBAL SURVEYOR IMAGE By Ron Baalke 12) STARDUST STATUS REPORT JPL release ---------------------------------------------------------------- MYSTERY OF THE MISSING ATMOSPHERE By Oliver Morton From New Scientist http://www.newscientist.com 20 November 1999 As atmospheres go, it has mostly gone. Admittedly, if you plough into the martian atmosphere at the speed of a meteorite, as the misguided Mars Climate Observer did in September, there is still enough there to tear you apart. But under most other circumstances, it is a poor excuse for an atmosphere. At the planet's surface, the pressure is a paltry 1 per cent of that on Earth. Why should Mars have so little atmosphere when Venus and Earth have so much? Though it might simply have been born that way, there are plenty of hints that the atmosphere was once much thicker--the evidence of water, for example. Today the martian surface is cold and exceedingly arid. But the surface bears unmistakable signs that liquid water once raged through flood channels and valleys, left shorelines in craters and may even have formed oceans in the Great Northern Basin. It's hard to be wet with an average temperature of about -53°C, so liquid water implies warmth. And warmth implies a thick insulating atmosphere, replete with warming greenhouse gases such as carbon dioxide. If the Martian atmosphere was once much thicker, where did all the gas go? Despite diligent searching, no one knows. But in the past year, NASA's Mars Global Surveyor--which itself used the atmosphere to brake and change orbit--has been collecting information that could answer that question. And its findings are not at all what its designers expected. In the 1980s, researchers developed a theory for why Mars was once warm and wet. First they calculated how much CO2 it would take to melt the martian ice and allow water to flow, and came up with a figure of between 5 and 10 bars (one bar is the pressure of about one Earth atmosphere). That's rather a lot for a planet with only a few millibars left today, so they had to explain where the CO2 might have disappeared to since. According to their picture, the atmosphere sowed the seeds of its own destruction. When liquid water is around, a CO2 atmosphere becomes unstable-- the gas dissolves, chemically weathers the silicate rocks on the planet's surface, and is ultimately locked up in the form of carbonates. The proof is beneath your feet. There was a time when CO2 dominated the Earth's atmosphere, which was probably a good deal thicker than it is today. Now, despite humanity's eager attempts to redress the matter, CO2 has dwindled to a trace of its former glory, making up less than a thousandth of the air we breathe. The reason is that over billions of years, chemical weathering has stored a great deal of CO2 as carbonates. According to Jim Kasting of Pennsylvania State University in University Park, who was one of the researchers who put together the warm, wet, early Mars theory--and one of the first to point out some of its flaws--if you released all the CO2 that is now locked up in the Earth's carbonate sediments you'd get about 60 atmospheres worth of the stuff. If chemical weathering can destroy greenhouses so easily, why did the Earth not freeze as Mars did? The answer, the researchers decided, was recycling. On Earth, some of the CO2 from carbonates is recycled through plate tectonics. When carbonate-rich sediments start their journey down into the mantle at a subduction zone, where one plate slides under another, they are heated up and release CO2 back into the atmosphere, where it can warm the planet. On cold little Mars, though, the recycling seems not to have been so good. Unlike Earth, Mars doesn't have enough internal heat to keep pushing lumps of its crust around, or to resurface itself with great big burps, as Venus may have done. There is little evidence that Mars's inner fires ever drove a system of plate tectonics, and while the planet may well have had some other ways of using its internal heat to recycle carbonates, they would have run out of oomph fairly early on as the planet's innards cooled down. CO2 recycling would have started to lag behind the production of new carbonates, and the atmosphere would have begun to shrink in earnest. So far so good. Now all the researchers needed to do was find some carbonates on the planet's surface to confirm their story. The best technology for doing the job from space is infrared spectroscopy, which picks up features in the infrared spectrum unique to specific minerals. This year, Mars Global Surveyor's spectrometer, the Thermal Emission Spectrometer (TES), completed its first thorough study of the planet, covering almost three- quarters of the surface. According to the scientist in charge of the instrument, Phil Christensen of Arizona State University, Tempe, it has found that carbonates make up less than 15 per cent of the surface--probably a lot less. "We're trying to be conservative with the 10 or 15 per cent--there's basically no discernible carbonate signature," says Christensen. "My guess is that the most profound discovery that TES will make and the most interesting paper we'll write is that there aren't carbonates on Mars, at the surface at least." If Christensen's suspicions are correct, then Mars researchers face some intriguing choices. They must either find another way to get rid of the atmosphere or make do with less atmosphere in the first place--or possibly do a bit of both. Take the other hiding places first. There is probably some CO2 frozen into the planet's soil, or hidden in dry-ice deposits underneath the water-ice exteriors of the polar caps (though other observations from Mars Global Surveyor are throwing some doubt on that second possibility). Reservoirs like these could account for ten times as much CO2 as is currently seen in the atmosphere. But since the current atmosphere is less than a hundredth of a bar, that isn't enough to explain the difference between past and present. Then there could be carbonates hidden below the surface. The 13 Martian meteorites found on Earth all contain faint traces of carbonate, and the oldest of them, ALH 84001, has veins of carbonate running through it. It's conceivable that you could lose a fair amount of CO2 in the martian underground. Again, though, it doesn't seem likely that you could get rid of a few bars of atmosphere without leaving any discernible carbonate sediments on the surface. So perhaps the atmosphere quit the planet altogether. There are two ways this could have happened: very big impacts and very small impacts. Asteroids and comets hitting a planet's surface can throw swathes of the atmosphere off at such high speeds that they escape the planet's gravity for good. In the very early days of the Solar System, when the planets had only just been assembled, there was plenty of rubble left over. During this period, known as the late heavy bombardment, Mars was hit by dozens of large chunks and hundreds of smaller ones, all of which could mark the passing of parts of the atmosphere. After asteroid impacts eroded the early martian atmosphere from the bottom up, a subtler process could have nibbled at it from the top down. The upper atmosphere of the planet is constantly being buffeted by the solar wind. In itself this wind is fairly harmless, since it is thin and made of very light particles, but it also carries a magnetic field. This can pick up ions from the upper atmosphere, accelerate them and then slam them back into their fellows. "You can have ions slammed into the upper atmosphere at more than 400 kilometers per second," says Bruce Jakosky of the University of Colorado at Boulder. "It's like shooting pool. On the break shot you knock everything all to hell. You can knock stuff out of the atmosphere entirely." This process, called sputtering, is still thought to be eroding Mars's atmosphere today, though no one knows how quickly. How do these different processes fit together? The biggest factor was probably impacts. According to Kevin Zahnle of NASA's Ames Research Center in California, the evidence suggests that they stripped off a huge amount of the original atmosphere--more than 99 per cent of it, in fact. That figure, he says, comes from looking at the ratios of different isotopes of xenon in the atmosphere. The mixture of xenon isotopes in the martian atmosphere today contains a far higher proportion of xenon-129 than is found in the Earth's atmosphere, or in the Sun. Xenon-129 is produced by the decay of iodine-129. For xenon-129 to be so predominant, the original atmosphere--in which the mixture of xenon isotopes was presumably similar to that in the rest of the Solar System-- must have been more or less stripped off the planet before most of the radioactive iodine inside the planet had decayed. With hardly any other xenon around, the newly released gas would have quickly come to dominate the isotopic distribution, as it does today. But though Zahnle's calculations suggest that impact erosion was a scourge of biblical proportions, it did not succeed in flaying away the entire atmosphere. It's hard to say how thick that remnant atmosphere was, but it could have been a good bit thicker than it is today. Zahnle thinks some of the atmosphere may have sat out the bombardment trapped in the crust, emerging only when it was safe to do so. In a paper presented at the Fifth International Mars Conference in Pasadena, California, this summer--the first really big meeting to be saturated with the heady new findings of the Mars Global Surveyor--Kattathu Mathew and Kurt Marti from the University of California, San Diego, described a new analysis of the gases trapped in the meteorite ALH 84001. These ancient martian gases apparently correspond to the time when the rock first formed. They bear a xenon ratio quite like that seen today, and so presumably postdate the first great flaying. But the meteorite's nitrogen isotopes set it apart from the modern Martian atmosphere. Today's atmosphere is highly enriched with the heavy isotope of nitrogen. But Mathew's samples of ALH 84001 show no such enrichment. As it happens, sputtering is particularly good at removing light nitrogen. In the upper reaches of the atmosphere there is very little turbulence, and so a delicate isotopic layering takes place, with the lighter isotopes of each gas rising to the top. Since sputtering works from the top down, it is more likely to knock lighter isotopes out than the heavier ones. So the sample in ALH 84001 looks as though it comes from a time when sputtering had not yet begun--from a time when the upper atmosphere of Mars was protected against the depredations of the solar wind. And this is where another intriguing discovery from Mars Global Surveyor comes in. While the spacecraft was using the upper atmosphere of Mars to change its orbit, it flew quite low over the planet's southern highlands--low enough for its magnetometer to pick up unexpected signals from the crust. Since then it has become clear that, although Mars has no global magnetic field today, in its youth it had a very strong one, traces of which were imprinted on its crust. Again, Mars was too small to keep up such exertions for long. The internal energy that drove its magnetic dynamo must have run out fairly quickly, since it is only in the oldest crust that the magnetic field's signature has been seen. As long as the magnetic field was around, it would have shielded the planet from the depredations of the solar wind. So the post-bombardment atmosphere might have been able to stay reasonably thick--or at least thicker than it is today--for as long as the magnetic field held up. But was there enough to explain the water? It's hard to say. Nobody knows how fast the sputtering is happening today, or how strong the solar wind was in the early Solar System. While most estimates have put sputtering loss at a tenth of a bar or so over the planet's lifetime, Jakosky--who made some of those predictions--thinks it could conceivably have been ten times more. That still wouldn't add up to the pressure of between 5 and 10 bars that researchers originally thought they needed to explain a sustained, relatively wet period early on. But they may have overestimated the planet's requirements. The models that called for many bars of CO2 to explain the presence of liquid water did not take into account the formation of clouds. It turns out that, in principle, clouds of solid CO2 might have warmed Mars up quite nicely, even with an atmospheric pressure of only half a bar. In November 1997, Francois Forget of Pierre and Marie Curie University in Paris and Raymond Pierrehumbert of the University of Chicago calculated that large dry-ice crystals in such an atmosphere could be very good at scattering thermal radiation back towards the ground while letting incoming visible and ultraviolet light through (Science, 273:1273). A thin but cloudy atmosphere could have warmed Mars during the earliest phases of its history and then been sputtered away when the cooling core shut down the magnetic field. As the atmosphere thinned, the soil would have been able to absorb most of the relatively small amount of CO2, and carbonate production could have been minimal. The problem is that just because cooling clouds can be found in a model, doesn't mean they were ever there in real life. And Kasting points out that while some sorts of cloud may have warmed the surface, others might have cooled it--just as different clouds affect the temperature in different ways on Earth. Then there's the possibility that it was never really all that warm in the first place. Water can contrive to be liquid in some pretty cold places, at least fleetingly, and some think that a great many of the watermarks on Mars's surface may have formed in a few short, wet catastrophes. As Zahnle puts it, "I have seen evidence of liquid silicate lavas on the surface of the Earth: do I need to conclude that the global temperature was 1500 K? All I can fairly conclude is that the liquid was there, and that the liquid was hot." The river valleys might have formed through the action of groundwater heated by local volcanism or impacts. Or they might have formed under transient ice sheets that later sublimed away. Maybe warmth came in very brief spurts. That would explain why, despite the presence of valleys, there is little evidence of sustained erosion in many of the old craters, and some of them maintain an almost Moon-like sharpness. Victor Baker of the University of Tucson in Arizona believes that Mars has sometimes been very wet indeed thanks to gases from inside the planet forcing warm water from the depths of the crust out onto the surface. But these floods would have lasted only ten thousands years or so. Even a dozen such wet spells would add up to only a tiny fraction of Martian history, and leave the southern highlands untouched by erosion. It shouldn't really come as a surprise that you can't make sense of a whole planet with a few space missions. But the complexities and seeming contradictions of Mars's past are forcing the lesson home. The history of Mars may be more complex than the "warm-and-wet-then, cold-and-dry-now" model allowed. Mars's first billion years may have thrown up all sorts of perplexing puzzles, and to solve them researchers will propose theories that stretch, like Jakosky's ideas, from the planet's molten heart to the very edge of space. The thin Martian atmosphere may make a poor planetary blanket, but as a springboard for speculation it's second to none Oliver Morton is a science writer based in London New Scientist issue: 20th November 99 Source: Geo-Marine Letters (vol 18, p 285) Please mention New Scientist as the source of this story and, if publishing online, please carry a hyperlink to http://www.newscientist.com. ---------------------------------------------------------------- MARS LANDING EVENTS AND MEDIA COVERAGE INFORMATION NASA note N99-60 22 November 1999 NASA's Mars Polar Lander is due to set down under rocket power on layered, icy terrain near the south pole of Mars on December 3, with the first signal received on Earth that confirms the landing expected at 3:37 PM EST. The two Deep Space 2 microprobes that are piggybacking on the lander will impact the planet's surface at about this same time. NASA TV coverage of this event starts with a series of prelanding news briefings that begin on Tuesday, November 30, at 1 PM EST. Daily coverage, including periods of live commentary, will be provided through Friday, December 10, if early mission events proceed as planned. Daily mission status briefings generally will occur at this same time, with live coverage of mission operations primarily in the late-evening and early-morning hours. A detailed schedule of Mars mission briefings, periods of planned live commentary and related events will be posted and updated regularly on the following internet sites. http://www.jpl.nasa.gov/marsnews/ http://www.nasa.gov/ntv/breaking.html The NASA Jet Propulsion Laboratory (JPL) site also features links to the text press kit for the mission, digital image files and updated mission status reports. The schedule for reception of pictures and other data from the lander is highly dependent on the spacecraft's state following landing--particularly, how high a data rate the mission team can achieve using the lander's telecommunications system. For this reason, it is not possible to offer a firm schedule of when pictures and other data will be received and posted on the Internet. For general planning purposes, however, it is possible to note the earliest possible date for some items under an extremely best-case scenario. The first 45-minute communications session after landing may include a low-resolution black-and-white image. Later sessions during the evening of December 3 should include further imagery, possibly including some from the lander's descent camera. Data from the Deep Space 2 microprobes are expected to be received Friday evening, December 3, and could be reported as soon as the news briefing at 2:30 AM EST on December 4. The first sound from the surface of Mars via the lander's microphone could be released no earlier than Saturday, December 4, under a best-case scenario. A movie built up from pictures from the lander's descent imager may be released no earlier than early in the week of December 6-10. A 360-degree color panorama from the camera on the lander's deck may be released in approximately this same time frame. Under a best-case scenario, the lander's robot arm could perform its first dig no earlier than late Tuesday evening, December 7. The first dig will probably occupy two evenings, with analysis of the soil sample performed on the second evening. All of these events and data releases, however, could move later into the mission due to telecommunications factors or other conditions. There is minimal direct overlap between key mission events on Mars Polar Lander and the STS-103 Space Shuttle mission to service the Hubble Space Telescope, under the current schedules for the two missions. Live coverage of some Mars Polar Lander robot arm activities likely will be broadcast on a separate satellite transponder, to be noted on the schedules posted at the above internet sites. ---------------------------------------------------------------- MARS POLAR LANDER SCIENCE TO BEGIN DECEMBER 3 University of Arizona release 22 November 1999 Days from now, scientists will witness their experiments complete an 11-month, 137-million-mile space trip to Mars. On Friday, December 3, NASA's Mars Polar Lander is to make a first- ever landing near a pole of the Red Planet, the south pole. Landing begins the first martian day of the 3-month mission, or "sol 0." The spacecraft carries a science payload package called MVACS, or the Mars Volatiles and Climate Surveyor. MVACS is to search for water and other gases that once filled a thick martian atmosphere. Scientists have convincing evidence that sometime in Mars' geological past, liquid water catastrophically flooded the planet. But today, the martian atmosphere is so thin that if temperatures were to reach above freezing, water would instantly boil away. What caused the climate to drastically change, and what happened to the atmospheric gases, the water and carbon dioxide--the "volatiles"? Past atmospheric gases may be locked as ice, salt and other compounds in the soil. MVACS scientists will dig for the answers. Their research tools were designed and built at the University of Arizona by Lunar and Planetary Laboratory (LPL) researchers, students and international colleagues. Soon after landing, a UA-built multi-spectral, stereoscopic camera called Surface Stereo Imager (SSI) will begin its photographic survey of the landing site. Peter H. Smith of LPL heads the group who built SSI. This camera is identical to the Pathfinder camera that landed on Mars on July 4, 1997 and took more than 16,500 images for what is widely regarded as one of the most successful and publicly popular missions in NASA history. Smith is sure to be a participant in some of the first news briefings from the NASA Jet Propulsion Laboratory (JPL) in Pasadena, which is managing the mission. According to current plans, which are subject to change, payload commanders will flex a six-foot, six-inch robotic digging arm on sol 4 or sol 5 (December 7 or 8). A sol, or day on Mars, is 24 hours and 37 minutes. Smith, his team and colleagues at Germany's Max Planck Institute for Aeronomy designed and built RAC, or the Robotic Arm Camera, on the wrist of the robotic arm. It will take close-up views of the icy martian terrain. This camera is able to resolve an image of a single human hair from a distance of half an inch. Researchers will see detail in good-sized chunks of gravel down to fine grains of sand. RAC will inspect trench walls as the robotic arm digs. Lamps mounted on this camera shine in red, blue and green from several directions. Without the colored lights, the scientists would see only black-and-white images. With them, they will see color as well as structure of the soil. While the 1997 Mars Pathfinder camera cost $5 million, SSI and RAC together were built for $2.7 million. They and the JPL- built robotic arm are integral to TEGA, the Thermal and Evolved Gas Analyzer investigation headed by William V. Boynton. Boynton, UA professor of planetary sciences, originally conceived the idea for the TEGA 16 years ago, while thinking about ways to measure ices in a comet. It features the tiniest out-of-this world ovens that ever cooked alien soil. On sol 5 (December 8) or after, the robotic arm will begin scooping samples of frozen dirt into TEGA so scientists can learn how much water and carbon dioxide are locked in the layered polar terrain. TEGA will use electric current to heat soil samples collected by the robotic arm scoop. The instrument has eight analyzers, each holding two ceramic ovens, each about the size of a piece of macaroni. One oven in each analyzer remains empty, the other will hold a thousandth of an ounce (about 30 milligrams) of Mars soil. The ovens heat at a controlled rate of a few degrees per minute up to 1,000 degrees Celsius. The ovens leak heat; they are not perfectly insulated. By measuring heat loss in the empty oven and subtracting that amount from the heat in the filled oven, researchers will know exactly how much energy the soil samples absorb. A carrier gas wafts gases released during heating into a chamber that uses lasers to analyze amounts of water and carbon dioxide. The $4.4 million TEGA project is rare in university history because it was designed from scratch, assembled and tested entirely at the UA, without a space industry firm as major contractor. In three years, university engineers and scientists took TEGA from concept to blueprint to flight-ready science instrument with near-microscopic, delicate parts able to survive the force of 70Gs at launch (force 70 times that of Earth's gravity.) "We all gave three and a half years of our lives to the three year project," said senior LPL engineer Mike Williams. Smith and Boynton say their teams faced formidable technical challenges, stringent budget cost-caps and nail-biting deadlines. Soon after January 3 Mars Polar Lander launch, project staff accelerated into a hectic schedule of instrument systems testing and team training. Months prior landing, MVACS team members held round-the-clock operational readiness tests at the UCLA Science and Technology Research Building. This building also will be their science operations center during the mission. David Paige of the University of California Los Angeles is principal investigator for MVACS. The planetary scientists know space exploration is risky business. But to hear them talk, the risk is no match for possible rewards. "Today is the Renaissance for planetary science, just as the age of da Vinci and Titian was a Renaissance for art a few hundred years ago," Smith said. "Many questions (in planetary science) are being answered for the first time now, and we are lucky enough to be alive during this time. For me, it's tremendously exciting." Boynton said, "For me, the most exciting (new discovery) is that Mars was very, very wet in the past, because everything we know about life says that water is an essential part of it. If Mars was always as dry as it appears now to be, then it's not very likely life could have ever gotten started. But if there really were oceans on Mars at one time, that's exciting. If life didn't get started there, we'd really have to wonder why not." "There are not many places in the country where students have the opportunity to participate in exciting space missions like this one," Boynton said. "The students who have worked with us have learned an awful lot. And I think as far as NASA is concerned--as far as the country is concerned, for that matter-- educating students is probably the most important part of the space program. They will be the people we rely on for the next generation of technology that's going to keep our economy going." The UA camera team will post new images from Mars at the Mars Atmospheric and Geologic Imaging web site at http://imp.lpl.arizona.edu/mvacs The TEGA team will post their data at the TEGA web page at http://grs8.lpl.arizona.edu/tega/ and at the Boynton Group web site at http://nemesis.lpl.arizona.edu/ For more information on Mars Polar Lander, click on the JPL Mars Polar Lander web page at http://mars.jpl.nasa.gov/msp98/ or Exploring Mars at http://www.exploringmars.org/missions/mpl/. ---------------------------------------------------------------- TERRA SPACECRAFT TO LEAD THE WAY NASA release 99-120 23 November 1999 NASA will launch and deploy the "flagship" to the Earth Observing System series of satellites, part of a precedent setting program designed to provide daily information on the health of the planet. The Terra spacecraft, formerly known as "EOS AM-1," is scheduled for launch December 16, 1999. Terra begins a new generation of Earth science--one that studies the Earth's land, oceans, air, ice and life as a total global system. Terra will carry a complement of five synergistic state-of-the-art instruments. Researchers now recognize that the Earth--land, oceans, life, and atmosphere--operates as a system--one part impacting the other. EOS will help us to understand how the complex coupled Earth system of air, land, water and life is linked. A series of 10 spacecraft, known as the first EOS series, are scheduled for launch into the next decade. "After years of anxious anticipation we're extremely excited about this mission," said Dr. Ghassem Asrar, associate administrator, NASA's Earth Science Enterprise. "The Terra mission has nearly unlimited potential to improve scientific understanding of global climate change." The EOS series spacecraft are the cornerstone of NASA's Earth Science Enterprise, a long-term coordinated research effort to study the Earth as a global system and the effects of natural and human-induced changes on the global environment. Terra will use this unique perspective from space to observe the Earth's continents, oceans, and atmosphere with measurement accuracy and capability never before flown. This approach enables scientists to study the interactions among these three components of the Earth system, which determine the cycling of water and nutrients on Earth. "Terra will simultaneously study clouds, water vapor, aerosol particles, trace gases, terrestrial and oceanic properties, the interaction between them and their effect on atmospheric radiation and climate," said Dr. Yoram Kaufman, Terra project scientist from Goddard Space Flight Center, Greenbelt, Md. "Moreover, Terra will observe changes in Earth's radiation budget (a measurement of all the inputs and outputs of the Earth's radiative energy), together with measurements of changes in land/ocean surface and interaction with the atmosphere through exchanges of energy, carbon, and water. Clearly comprehending these interactive processes is essential to understanding global climate change," he said. A polar-orbiting spacecraft, Terra is scheduled for launch aboard an Atlas-Centaur IIAS expendable launch vehicle from Vandenberg Air Force Base, CA. The 25-minute launch window opens at 1:33 PM EST (10:33 AM PST). Separation of the spacecraft from its launch vehicle will occur about 14 minutes after launch. Once in its final orbital position, the satellite will orbit the Earth at an altitude of approximately 438 miles (705 kilometers) with a Sun-synchronous 98-degree inclination and descend across the equator at 10:30 AM. Because Terra emphasizes observations of terrestrial surface features, its orbit is designed to cross the equator at this time when cloud cover, which obscures the land surface, is at its daily minimum. The orbit will be adjusted so that it covers the complete Earth every 16 days. This orbit will be maintained with periodic adjustments during the six-year life of the mission. The spacecraft was built by Lockheed Martin Missiles and Space in Valley Forge, PA. The five instruments onboard Terra include the Clouds and the Earth's Radiant Energy System (CERES), the Multi-angle Imaging SpectroRadiometer (MISR), the Moderate- Resolution Imaging Spectroradiometer (MODIS), the Measurements of Pollution in The Troposphere (MOPITT), and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument. The CERES instruments, provided by NASA's Langley Research Center, Hampton, VA, and built by TRW, Redondo Beach, CA, perform measurements of the Earth's "radiation budget," the process that maintains a balance between the energy that reaches the Earth from the sun, and the energy that goes from Earth back out to space. The critical components that affect the Earth's energy balance are the planet's surface, atmosphere, aerosols, and clouds. MISR, built and provided by NASA's Jet Propulsion Laboratory, Pasadena, CA, will measure the variation of surface and cloud properties, and particles in the atmosphere, with cameras pointed in nine simultaneous different viewing directions. MISR will monitor monthly, seasonal, and long-term interactions between sunlight and these components of Earth's environment. Over a seven-minute period, points on the Earth within a 224 mile (360 kilometer) wide swath will be observed successively at all nine angles. The Moderate-Resolution Imaging Spectroradiometer (MODIS), provided by Goddard, and built by the Raytheon (formerly Hughes) Santa Barbara Remote Sensing, Santa Barbara, CA, will measure the atmosphere, land and ocean processes, (including surface temperature of both the land and ocean), ocean color, global vegetation, cloud characteristics, temperature and moisture profiles, and snow cover. MODIS will view the entire surface (land, oceans, clouds, aerosols, etc.) of the Earth every 1-2 days at a "moderate resolution" of one-quarter to one kilometer. The Measurements Of Pollution In The Troposphere (MOPITT) instrument, provided by the Canadian Space Agency and built by COM DEV International of Cambridge, Ontario, will map carbon monoxide and methane concentrations at altitudes between 10 miles and the ground. MOPITT is an infrared gas correlation radiometer and will produce maps over the entire globe every 4- 16 days. From these measurements the sources, motions and sinks of these gases can be determined. The ASTER instrument, provided by Japan's Ministry of International Trade and Industry and built by NEC, Mitsubishi Electronics Company and Fujitsu, Ltd., will measure cloud properties, vegetation index, surface mineralogy, soil properties, surface temperature, and surface topography for selected regions of the Earth. Hundreds of scientists from the U.S. and abroad are prepared to take full advantage of Terra observations to address key scientific issues and their environmental policy impacts. Every 1 to 2 days Terra instruments will collect data over the entire Earth's surface, making measurements across a wide spectrum ranging from visible to infrared light. This research ideally will help scientists develop computer models of atmospheric, oceanic, and terrestrial dynamics and subsequently gain a better understanding of these complex systems and how they interact. With this information, scientists will improve their ability to predict significant changes in Earth's environment before they occur. Terra will collect and archive an unprecedented quantity of high-quality multi-spectral data each day. The data will, for the first time, provide a high- resolution multi-faceted view of both seasonal and interannual changes in the terrestrial environment. The Terra Project Office, located at Goddard, manages Terra development for NASA's Office of Earth Science in Washington, DC. Goddard is responsible for the development of the satellite and the development and operation of the ground operations system. Spacecraft operations will be performed at a Mission Operations Center at Goddard. Terra is part of a global research program known as NASA's Earth Science Enterprise, a long-term program that is studying changes in Earth's global environment. NASA recognizes that the knowledge and data derived from Terra have significant practical value to society, and plans to foster increased access to, and use of, the information to make better, more informed decisions related to National needs which affect every American--health and safety, economic wellbeing, and qualify of life in our communities. A goal of the Earth Science Enterprise is to expand knowledge of the Earth System, from the unique vantage point of space. Earth Science Enterprise data, which will be distributed to researchers worldwide at the cost of reproduction, is essential to people making informed decisions about their environment. ---------------------------------------------------------------- MARS POLAR LANDER COLOR SLIDE SET By Ron Baalke 23 November 1999 A set of twenty color slides is now available on the Mars Polar Lander web site at http://mars.jpl.nasa.gov/msp98/slides/mplslides.html The slides are available as high-resolution images, which can be downloaded and printed out on your printer. Also, 35mm color slides can be ordered through Finley-Holiday Films for $8.95. Finley-Holiday Films can be reached at (562) 945-3325 and ask for product "JPL37". There is also a toll free 800 number to order the slide set: (800) 345-6707. ---------------------------------------------------------------- PURPLE SALT AND TINY DROPS OF WATER IN METEORITES By G. Jeffrey Taylor 24 November 1999 Some meteorites, especially those called carbonaceous chondrites, have been greatly affected by reaction with water on the asteroids in which they formed. These reactions, which took place during the first 10 million years of the Solar System's history, formed assorted water-bearing minerals, but nobody has found any of the water that caused the alteration. Nobody, that is, until now. Michael Zolensky and team of scientists from the Johnson Space Center in Houston and Virginia Tech (Blacksburg, Virginia) discovered strikingly purple sodium chloride (table salt) crystals in two meteorites. The salt contains tiny droplets of salt water (with some other elements dissolved in it). The salt is as old as the Solar System, so the water trapped inside the salt is also ancient. It might give us clues to the nature of the water that so pervasively altered carbonaceous chondrites and formed oceans on Europa and perhaps other icy satellites. However, how the salt got into the two meteorites and how it trapped the water remains a mystery--at least for now. Get the full story at http://www.soest.hawaii.edu/PSRdiscoveries/Nov99/PurpleSalt.html ---------------------------------------------------------------- JPL MARS MICROMISSION CONTRACTOR SELECTED FOR NEGOTIATION JPL release 24 November 1999 NASA's Jet Propulsion Laboratory has selected Ball Aerospace & Technologies Corp., Boulder, CO, for negotiations as the spacecraft contractor on the Mars Micromission--the first in a series of small, low-cost piggyback missions to send science probes, instruments and communication relay satellites to the red planet. The contract will be negotiated over the next two months and is contingent on funding approval by NASA for the Mars Micromission Project. This decision is expected by February 2000. The Mars Micromission Project is planning to launch a series of a small 220-kilogram (485-pound) low-cost spacecraft to Mars as piggyback payloads on the French Ariane 5 rocket when it launches commercial communication satellites into an Earth-based geosynchronous transfer orbit. From Earth orbit, the Mars Micromission spacecraft will use on-board propulsion and an innovative trajectory involving Lunar and Earth flybys to send the spacecraft on the proper trajectory to Mars. The launch services will be provided through the NASA partnership with the French space agency, Centre National D'Etudes Spatiales (CNES), at no cost to NASA. Launch of the first Mars Micromission spacecraft is planned for spring of 2003 from the Ariane launch facilities in Kourou, French Guiana. The design of the Mars Micromission spacecraft is based on a common spacecraft bus concept, which can be configured to deliver one or more science probes to the Martian atmosphere or carry extra propellant for orbit insertion into Mars orbit. The 2003 Mars Micromission would be a communication/navigation orbiter, the first of a constellation of Mars-orbiting satellites that would make up the Mars Network. The Mars Network is intended to dramatically increase the data returned to Earth from future landed or orbiting Mars missions by providing efficient relay communications, while also providing navigation capabilities like those of the Global Positioning Satellite system. "The combination of the common spacecraft design and the piggyback launch is essential to achieve the Mars Micromission Project goals of frequent low-cost access to Mars," said David Lehman, the JPL project manager for the Mars Micromission. "We plan to be able to launch at least two Mars Micromission spacecraft during every Mars opportunity, about every two years. About half of these spacecraft are expected to carry out focused science investigations selected through competition, while the other half will be used to build up the Mars Network of communication relay and navigation satellites." The Mars Micromission Project is managed by JPL for NASA's Office of Space Science, Washington, D.C., as part of the ongoing Mars Surveyor Program. The purpose of the Mars Micromission is to increase the quality and quantity of the science and technology data from the Mars Surveyor Program. JPL is a division of the California Institute of Technology, Pasadena, CA. ---------------------------------------------------------------- MARS POLAR LANDER, DEEP SPACE 2 SET FOR ARRIVAL JPL release 25 November 1999 NASA returns to the surface of Mars on December 3 with a spacecraft that will land on the frigid, windswept steppe near the edge of Mars' south polar cap. Piggybacking on the lander are two small probes that will smash into the martian surface to test new technologies. The lander mission is the second installment in NASA's long-term program of robotic exploration of Mars, which was initiated with the 1996 launches of the currently orbiting Mars Global Surveyor and the Mars Pathfinder lander and rover, and included the recently lost Mars Climate Orbiter. Mars Polar Lander will advance our understanding of Mars' current water resources by digging into the enigmatic layered terrain near one of its poles for the first time. Instruments on the lander will analyze surface materials, frost, weather patterns and interactions between the surface and atmosphere to better understand how the climate of Mars has changed over time. Polar Lander carries a pair of basketball-sized microprobes that will be released as the lander approaches Mars and dive toward the planet's surface, penetrating up to about 3 feet (1 meter) underground to test 10 new technologies, including a science instrument to search for traces of water ice. The microprobe project, called Deep Space 2, is part of NASA's New Millennium Program. A key scientific objective of the two missions is to determine how the climate of Mars has changed over time and where water, in particular, resides on Mars today. Water once flowed on Mars, but where did it go? Clues may be found in the geologic record provided by the polar layered terrain, whose alternating bands of color seem to contain different mixtures of dust and ice. Like growth rings of trees, these layered geological bands may help reveal the secret past of climate change on Mars and help determine whether it was driven by a catastrophic change, episodic variations or merely a gradual evolution in the planet's environment. Today the martian atmosphere is so thin and cold that it does not rain; liquid water does not last on the surface, but quickly freezes into ice or evaporates into the atmosphere. The temporary polar frosts which advance and retreat with the seasons are made mostly of condensed carbon dioxide, the major constituent of the Martian atmosphere. But the planet also hosts both water-ice clouds and dust storms, the latter ranging in scale from local to global. If typical amounts of atmospheric dust and water were concentrated today in the polar regions, they might deposit a fine layer every year, so that the top yard (or meter) of the polar layered terrains could be a well-preserved record showing 100,000 years of Martian geology and climatology. The lander and microprobes will arrive December 3, 1999. They are aimed toward a target sector within the edge of the layered terrain near Mars' south pole. The exact landing site coordinates were selected in August 1999, based on images and altimeter data from the currently orbiting Mars Global Surveyor. Like Mars Pathfinder, Polar Lander will dive directly into the martian atmosphere, using an aeroshell and parachute scaled down from Pathfinder's design to slow its initial descent. The smaller Polar Lander will not use airbags, but instead will rely on onboard guidance and retro-rockets to land softly on the layered terrain near the south polar cap a few weeks after the seasonal carbon dioxide frosts have disappeared. After the heat shield is jettisoned, a camera will take a series of pictures of the landing site as the spacecraft descends. These are recorded onboard and transmitted to Earth after landing. As the lander approaches Mars about 10 minutes before touchdown, the two Deep Space 2 microprobes are released. Once released, the projectiles will collect atmospheric data before they crash at about 400 miles per hour (200 meters per second) and bury themselves beneath the martian surface. The microprobes will test the ability of very small spacecraft to deploy future instruments for soil sampling, meteorology and seismic monitoring. A key instrument will draw a tiny soil sample into a chamber, heat it and use a miniature laser to look for signs of vaporized water ice. About 35 miles (60 kilometers) away from the microprobe impact sites, Mars Polar Lander will dig into the top of the terrain using a 6.5-foot-long (2-meter) robotic arm. A camera mounted on the robotic arm will image the walls of the trench, viewing the texture of the surface material and looking for fine-scale layering. The robotic arm will also deliver soil samples to a thermal and evolved gas analyzer, an instrument that will heat the samples to detect water and carbon dioxide. An onboard weather station will take daily readings of wind temperature and pressure, and seek traces of water vapor. A stereo imager perched atop a 5-foot (1.5-meter) mast will photograph the landscape surrounding the spacecraft. All of these instruments are part of an integrated science payload called the Mars Volatiles and Climate Surveyor. Also onboard the lander is a light detection and ranging (LIDAR) experiment provided by Russia's Space Research Institute. The instrument will detect and determine the altitude of atmospheric dust hazes and ice clouds above the lander. Inside the instrument is a small microphone, furnished by the Planetary Society, Pasadena, CA, which will record the sounds of wind gusts, blowing dust and mechanical operations onboard the spacecraft itself. The lander is expected to operate on the surface for 60 to 90 martian days through the planet's southern summer (a martian day is 24 hours, 37 minutes). The mission will continue until the spacecraft can no longer protect itself from the cold and dark of lengthening nights and the return of the martian seasonal polar frosts. Mars Polar Lander and Deep Space 2 are managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington, DC. Lockheed Martin Astronautics Inc., Denver, CO, is the agency's industrial partner for development and operation of the orbiter and lander spacecraft. JPL designed and built the Deep Space 2 microprobes. JPL is a division of the California Institute of Technology, Pasadena, CA. ---------------------------------------------------------------- THREE DAYS ON GALILEO [TWICE] JPL releases 22-24 November 1999 Galileo returns to Io this week for an encounter that is even more daring than its previous close flyby one and a half months ago. This is the 14th and last encounter of the Galileo Europa Mission, a two-year extension of Galileo's primary mission. It is also only the second close flyby of Io by the spacecraft since December 1995. This pair of Io flybys was made possible by the four preceding flybys of Callisto, the outermost Galilean moon, which were used to lower the orbit of Galileo towards Jupiter. Galileo's flyby of Io is a risky endeavor, which also promises a wealth of new information about both Io and Europa. The spacecraft is beginning to show the effects of 10 years in space and dozens of passages through the radiation belts near Jupiter. One example is the Ultraviolet Spectrometer (UVS), which will be turned off in order to protect the instrument from additional radiation damage and to allow for possible annealing of some damaged electronic components. Such problems were anticipated and are the reason the Io encounters were placed at the end of the Galileo Europa Mission. Balanced against these risks are unique data to be obtained from Io, including high-resolution images and spectra of Io's volcanos and plumes, and the only opportunity to determine if Io possesses an intrinsic magnetic field. Encounter activities begin on Wednesday night and continue through Friday night. The bulk of the encounter activities are scheduled for Thursday, with the peak surrounding the close flyby of Io at 8:05 PM PST at the spacecraft's location. The radio signals indicating that the flyby has occurred won't be received on Earth until 35 minutes later, or 8:40 pm PST. The time difference is due to the fact that the spacecraft is approximately 621 million kilometers (386 million miles) from Earth and it will take radio signals just under 35 minutes to travel between the spacecraft and Earth [see Note 1]. The flyby will take the spacecraft to within 300 kilometers (186 miles) of Io's surface. That is closer than the altitude at which the International Space Station flies over the Earth's surface! The flyby is also unique in that the spacecraft will be passing over Io's south pole. This will be the first detailed look at what lies at one of Io's poles. During the previous flyby, the spacecraft flew above Io's equatorial regions. Prior to Wednesday night, the spacecraft activities are focused on preparations for the I25 encounter. Playback of data acquired during Galileo's previous flyby of Io and stored on the spacecraft's onboard tape recorder will complete on Tuesday morning. On Wednesday, the spacecraft performs standard maintenance on its onboard tape recorder, thus preparing it to store data acquired in the following days. The spacecraft also has distant flybys of Jupiter and the other Galilean moons during this encounter. The flyby of Callisto occurs Wednesday afternoon at 3:54 PM PST-SCET (4:29 PST-ERT) at a distance of just over 1.5 million kilometers (950,000 miles). The remaining flybys occur on Thursday, including a relatively close flyby of Europa on Thursday morning at a distance of 8,642 kilometers (5,371 miles) from the moon's surface. Most of this encounter's observations are focused on Io, its interior, its volcanic surface, and its electromagnetic environment. However, given the relatively close flyby distance, a number of observations focus on Europa. The Europa flyby turns out to be the only opportunity of the combined prime and Europa missions that provides a view of the Jupiter-facing hemisphere of Europa at reasonable observation resolutions. Due to Jupiter's size and brightness, this part of Europa's surface is difficult if not impossible to observe from Earth. One observation is initiated on Wednesday evening, just after the start of the encounter. As with previous encounters, the start of this encounter marks the resumption of the magnetospheric survey performed by the Fields and Particles instruments. The Fields and Particles instruments are comprised of the Dust Detector, Energetic Particle Detector, Heavy Ion Counter, Magnetometer, Plasma Detector, and Plasma Wave instrument. During the survey, the instruments take measurements of plasma, dust, and electric and magnetic fields. These measurements are not recorded on board, but rather are processed and returned to Earth in near real time. This survey has been repeated from encounter to encounter allowing scientists to study the long-term variations within the inner portions of Jupiter's magnetosphere. The measurements will also provide a broader context for higher resolution measurements made by the Fields and Particles instruments later in the encounter period. 26-28 November 1999 Galileo wraps up its encounter with the Jupiter system on Friday, just a few short hours after passing within a few hundred kilometers of Io's south pole. Friday's activities include one observation by the Solid-State Imaging camera (SSI), one by the Extreme Ultraviolet Spectrometer (EUV), and the continuation of the Fields and Particles low resolution survey of the Jovian magnetosphere. Playback of the data stored on the spacecraft's onboard tape recorder during the last few days is initiated today at 4:30 PM PST-SCET (5:05 PM PST-ERT, see Note 1). The next few days see the return of observations performed by the Near-Infrared Mapping Spectrometer (NIMS) and Fields and Particles Instruments. Data return is interrupted once. On Sunday morning, the spacecraft performs a standard gyroscope performance test. Friday's SSI observation captures Amalthea, one of Jupiter's minor moons. The observation will provide the best resolution ever of the moon at 3.7 kilometers (2.3 miles) per picture element. Later in the day, the Extreme Ultraviolet Spectrometer (EUV) obtains data by looking at the Io torus. The Io torus is a doughnut-shaped region with its inner edge bounded by Io's orbit. It is a region of intense plasma and radiation activity, in which there are strong magnetic and electric fields. Similar observations have been performed during Galileo's previous encounters, and the data set will allow scientists to examine long term variations in the torus' size and shape, with the goal of understanding energy transfer between the torus and the overal Jovian magnetosphere. NIMS returns the first observation on the playback schedule. The observation was designed to capture information on surface properties near a hot spot called Tiermes. The remaining observation on this week's is the first portion of a 49 minute recording by the Fields and Particles instruments made as the spacecraft flew closest to Io. The recording contains measurements describing the plasma, dust, and electric and magnetic fields surrounding Io. The primary purpose of this observation is to determine if Io possesses its own internally- generated magnetic field, similar to both the Earth and to another Galilean satellite, Ganymede. Note 1. Pacific Standard Time (PST) is 8 hours behind Greenwich Meridian Time (GMT). The time when an event occurs at the spacecraft is known as Spacecraft Event Time (SCET). The time at which radio signals reach Earth indicating that an event has occurred is known as Earth Received Time (ERT). Currently, it takes Galileo's radio signals 35 minutes to travel between the spacecraft and Earth For more information on the Galileo spacecraft and its mission to Jupiter, please visit the Galileo home page at one of the following URL's: http://galileo.jpl.nasa.gov http://www.jpl.nasa.gov/galileo http://galileo.ivv.nasa.gov ---------------------------------------------------------------- GALILEO MISSION STATUS JPL release 25 November 1999 NASA's Galileo spacecraft has completed the closest-ever encounter with Jupiter's volcanic moon Io, but not before giving ground controllers a Thanksgiving day white-knuckler. The spacecraft dipped to the planned 300 kilometers (186 miles) above Io at 8:40 PM Pacific Standard Time on Thursday, November 25. Only four hours before the flyby, while Galileo was being bombarded by strong radiation near Io, its onboard computers reset and placed the spacecraft into standby mode. Onboard fault protection software told the spacecraft cameras and science instruments to stop taking data and enter a safe state until further instructions were received from the ground. Galileo engineers at NASA's Jet Propulsion Laboratory sprang into action, scrambling to send new commands to the spacecraft and bring it out of safe mode in order to save the flyby. "With so little time to spare, it would have been easy to think 'no way' can we do this," said Galileo project manager Jim Erickson. "But our team members jumped to the challenge, in some cases leaving behind half-eaten Thanksgiving dinners." "We were prepared, because we knew this high-radiation Io flyby posed a risk to spacecraft components, and in fact we saw that the radiation caused some glitches during the October 10th Io flyby," Erickson said. "This planning paid off in a big way." The team finished sending new computer commands to Galileo, which were received and executed by the spacecraft at 8:45 PM PST, four minutes after the closest approach to Io. This enabled the spacecraft to complete more than half of its planned observations of Io and its plasma torus (a doughnut-shaped region brimming with electrified particles), and all the planned observations of another Jovian moon, Europa. If all goes according to plan, the data will be transmitted to Earth over the next several weeks, and it will then undergo processing and analysis. The October 10th Io flyby was performed at an altitude of 611 kilometers (380 miles). Pictures and other scientific information from that flyby provided fascinating new views of Io, which has more than 100 active volcanoes. Scientists hope that by learning more about volcanic activity on Io, we may learn more about volcanoes on Earth. Additional information about the Galileo mission may be accessed at http://galileo.jpl.nasa.gov . Galileo has been orbiting Jupiter and its moons since December 1995. The spacecraft is approaching the end of its two-year extended Galileo Europa Mission, a follow-on to the primary mission that ended in December 1997. Because of the radiation risks to the spacecraft, the Io flybys were scheduled as a daring venture to cap the extended mission, after Galileo had already returned an immense amount of scientific information. JPL, a division of the California Institute of Technology in Pasadena, California, manages the Galileo mission for NASA's Office of Space Science, Washington, DC. ---------------------------------------------------------------- NEW MARS GLOBAL SURVEYOR IMAGE By Ron Baalke 22 November 1999 The following new image taken by the Mars Global Surveyor spacecraft is now available: Layers of the South Polar Layered Deposits The image resides on the Mars Global Surveyor web site at http://mars.jpl.nasa.gov/mgs/msss/camera/images/index.html The image caption is appended below. Mars Global Surveyor was launched in November 1996 and has been in Mars orbit since September 1997. It began its primary mapping mission on March 8, 1999. Mars Global Surveyor is the first mission in a long-term program of Mars exploration known as the Mars Surveyor Program that is managed by JPL for NASA's Office of Space Science, Washington, DC. Malin Space Science Systems (MSSS) and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO. Mars Global Surveyor Mars Orbiter Camera Patterned Ground of the Martian Antarctic MGS MOC Release #MOC2-189, 15 November 1999 Remnant frost from the retreating south polar ice cap, trapped in cracks, enhances the visibility of polygonal patterns in this new picture of Malea Planum in the far southern regions of Mars. This scene, taken by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) in October 1999 shows a relatively smooth portion of Mars (a plain) that is covered with polygons both at large and small scales. Smaller polygons are mostly found on the surfaces of old, mantled impact craters (e.g., top and lower center), while larger polygons are evident on the surfaces between the craters. (Note: The polygons are too small to see in the icon--click on it to see the full-resolution image and the polygons). It is spring in the southern hemisphere of Mars, and the region shown here has recently emerged from beneath a winter coating of frost. Patches of frost (bright material) remain in the cracks that make up the edges of each polygon in the picture. The image covers a narrow strip of martian terrain only 1.5 km (0.9 mi) across at a resolution of 3 meters (10 ft) per pixel. Polygons such as these are common in Earth's arctic and antarctic regions (see descriptions of Antarctic research and Antarctic pictures), and they usually indicate the presence of ice (i.e., frozen water) in the ground. Polygons form from the cycle of freezing and thawing of ground ice over the course of years, decades, and centuries. The fact that polygons are found on all surfaces in the Malea Planum scene shown here indicates that the ice is not too deeply buried because only a thin veneer (a few meters--or yards) of material appears to have covered the crater at the top of the scene. Image credit: NASA/JPL/Malin Space Science Systems ---------------------------------------------------------------- STARDUST STATUS REPORT JPL release 24 November 1999 The Stardust spacecraft continues to perform normally in cruise. Nine Navigation Camera star images were transmitted to Earth where they are being analyzed in detail. The camera used two different exposures, all 8 filters and moved the mirror to about 90 degrees so that the images were not taken through the periscope. At first look, the star images appear to be dimmer than expected, but more analysis need to be performed before this can be verified. The command load for the next cruise sequence was successfully transmitted to the spacecraft by the flight team at Lockheed Martin Astronautics (LMA). The Lead Scientist of the German Cometary and Interstellar Dust Analyzer (CIDA) instrument visited JPL along with the LMA Flight Systems Manager to review the flight operations of CIDA. CIDA has been performing well. For more information on the Stardust mission--the first ever comet sample return mission--please visit the Stardust home page at http://stardust.jpl.nasa.gov. ---------------------------------------------------------------- End Marsbugs Vol. 6, No. 39