MARSBUGS: The Electronic Astrobiology Newsletter Volume 7, Number 33, 4 September 2000. Editors: Dr. David J. Thomas, Math and Science Division, Lyon College, Batesville, AR 72503-2317, USA. dthomas@lyon.edu 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://welcome.to/marsbugs. 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 from 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) THE RISE AND FALL OF MARTIAN LIFE By Julian A. Hiscox 2) NEW CLUES ABOUT MARTIAN METEORITES BAFFLE SCIENTISTS By Greg Clark 3) NASA INDEX USES PLANTS TO SHED NEW LIGHT ON DROUGHTS NASA release 00-132 4) ATLANTIS LIFTOFF SET FOR SEPTEMBER 8 TO OPEN DOORS TO NEW STATION MODULE NASA release 00-134 5) CASSINI WEEKLY SIGNIFICANT EVENTS JPL release 6) ISS STATUS REPORT JSC release 7) MARS GLOBAL SURVEYOR STATUS UPDATE JPL release 8) STARDUST STATUS REPORT JPL release 9) DUXBURY NAMED PROJECT MANAGER OF STARDUST MISSION JPL release --------------------------------------------------------------------- THE RISE AND FALL OF MARTIAN LIFE By Julian A. Hiscox August 2000 The surface of present day Mars is bathed in lethal ultraviolet radiation and probably coated in a layer of peroxides and superoxides. If terrestrial type life were sprinkled on the surface of Mars then it would degrade to dust in a matter of minutes. Data from the two Viking landers, showed that no organic material is present on the martian surface. However, analysis of one of the youngest SNC meteorites indicated that organic material was at least stable below the surface of Mars up until about 150 million years ago. Thus by all accounts the climate of ancient Mars was far more conducive to life than that of present day Mars. The conditions on the surface of Mars have probably been unchanged for the past two billion years or so. The origin of life on Earth let alone Mars has not been elucidated. However, assuming life did arise on Mars, we can make a number of speculations as to its fate. This will help guide future searches for extinct or possibly extant life on Mars. Microbial life on Earth has colonized all manner of niches, from the coldest, driest places on Earth (the rock faces of the Antarctic dry valleys) to thermal springs and hydrothermal vents where viable microorganisms have been isolated living at 113oC. Therefore if life arose on Mars, there are a number of potential habitats where such life may have lived. The migration of life on Mars How life may have originated on Mars is unknown. However, life on Mars may have arisen either at hydrothermal vents and/or in possible martian oceans. (Or all manner of places where liquid water was stable and energy was provided in some form). During the course of martian history, components of hydrothermal centers could have interacted via networks of intersecting faults and fractures. For example, a quantity of water equivalent to a global layer 10 m deep is sufficient to saturate the lower-most 0.8 km of the megaregolith, while a quantity of water equivalent to a 100 m layer would create a global aquifer nearly 43 km deep. Material could be moved within (and perhaps exchanged between) aquifers by hydrothermal convection. This occurs when an aquifer is heated locally, setting up density contrasts in the water and initiating buoyancy-driven flow. On Earth today there are two major sites of hydrothermal convection. First, associated with magmatism, mainly at plate boundaries but also associated with plumes, and second, on the deep sea floor where about twenty times as much water circulates at rather low temperatures driven by heat residing in the oceanic crust. With the possible (but perhaps not!) absence of tectonic and large ocean plates on early Mars, apart from the low temperature aqueous convection in the crust, magmatic activity associated with plumes and impact heating would have been drivers of hydrothermal convection. Magmatic intrusions 1000 cubic kilometers in size could have circulated fluids continuously for ~105 years. Aquifers drawn down by seepage could therefore have been replenished for long periods as hydrothermal convection circulated water into them. Small-scale fluvial activity decreased with time as hydrothermal activity diminished and the atmosphere cooled, although local hydrothermal systems could have accounted for the continuation of isolated fluvial events well into post-Noachian times. However, some volcanic units on Mars may be as young as 100,000 years. Thus the nutrients for life and life itself would have continuously circulated (and indeed percolated!) throughout any martian ocean or where liquid water was present beneath the martian surface. If liquid water was abundant, and large bodies of liquid water were stable, then the migration of life toward the surface is relatively easy to accomplish, as presumably rivers fed the ocean(s). Microbial life would therefore have diffused onto the land. If liquid water was not so abundant, the possibility remains that subsurface life could also have spread to the surface of Mars. Assuming terrestrial paradigms are valid, organisms may have been selected for that could grow in brine or (ice covered) lakes, which have been proposed as possible habitats for ancient martian life. On Earth archeabacteria have succeeded in colonizing waters of very high salinity--even the saturated brine of drying seas. They are the only living organisms that still inhabit the Dead Sea and the Great Salt Lake. The detection of sulfur and chlorine and the presence of duricrusts in the martian regolith suggest that brines, concentrated salt solutions, may have been present on Mars in the past but are precluded on present day Mars. The decline of the environment and the implications for life As the atmospheric pressure decreased on Mars, conditions became increasingly deleterious for any surface-based life. Imre Friedmann and Chris McKay and also David Wynn-Williams have outlined four epochs of "water" on Mars. The first three of which have readily identifiable equivalent habitats found in Antarctica today. The four epochs Wynn- Williams outlines in his paper in BIS's "The Search for Life on Mars" symposium proceedings are shown in bold: Epoch 1. Abundant water. Probably necessary for an origin of life event--whether above ground in an ocean or hot spring or deep below the surface. Potential models for wide spread liquid water on Mars are the seasonal melt-water rivers in Antarctica which support photosynthetic cyanobacteria. Epoch 2. Restriction of water to ice-covered lakes (for example, the hypersaline Lake Hoare with benthic cyanobacterial stromatolites). Ice covered lakes can be found in the Antarctic Dry Valleys whose surfaces are frozen all year around. Yet colonies of bacteria live in the liquid below the frozen surface. The temperature in such lakes is probably too cold for an origin of life event to occur, as a hot start was probably required. Therefore, life would have had to have had either migrated to these environments or be "trapped" in them--once the environment declined. Epoch 3. Restriction of water to moisture within porous rocks (as in the Antarctic Dry Valleys). In these environments microorganisms live right at the edge of extinction. These organisms are already as tolerant to desiccation as can be possible. Evolution and adaptation can only go so far before the laws of thermodynamics intervene. Epoch 4. Xeric surface of Mars. The surface of Mars is completely hostile for life. During the period when water was becoming less abundant on the surface of Mars, possible surface organisms might have been selected for which were tolerant of low temperatures and humidity. When the (near) surface became uninhabitable only organisms that lived deep underground would have survived, possibly in chemosynthetic ecosystems. The penetration of the thermal wave of temperatures below 0oC was almost certainly not uniform across the surface of Mars. Hence, some parts of Mars may have become frozen before other parts. The formation of ice would have effectively separated the net transport, both vertically and horizontally between surface dwelling and underground organisms. Also the potential absence of plate tectonics on Mars might have resulted in the formation of two distinct reservoirs of water. Hence, there exists the exciting possibility of both spatial and temporal distribution between different water sources and putative life forms. The differences in freezing over Mars, presumably progressing from pole to equator may have preserved organisms that were at different developmental stages, perhaps protocells to unicellular life, and evidence of this might be found on present day Mars. Table 1 shows the different estimated ages of the martian plains; it may be possible given their geographic distribution that any remains of life could be preserved at different stages. Hesperia Planum, the oldest plain, is situated approximately 20o south of the equator and may therefore have been one of the last places to freeze, and thus may contain remnants of (any of) the most developed martian organisms. Exploring for micro- and molecular fossils on Mars Whether life could have continued in hydrothermal systems on Mars until the present day can only be determined by direct sampling. However, the longer the time life survived the more chance that an extensive exobiology search has for locating trace fossils or biochemical markers. Where would we look for such molecules? Mike Russell and his colleagues at the University of Glasgow, suggested that life might have emerged from a far-from-equilibrium chemical system coupled to, and driven by, hydrothermal convection. Even on Earth where our oxygenated atmosphere supports a plethora of species, many thermophilic bacteria remain obliged to live at hot springs and seepages. Such coupling can guide our exploration for fossil evidence of life on Mars. For example, Mike Russell suggests that sulfide microbialites, a kilometer or so in length and ten or so meters wide, generated at palaeo hot springs or seepages, might be expected to occur over a fault. On Mars the presence of canyons, channels and out wash fans provides the best evidence for aqueous fluid flow, and it is likely that water continued flowing through the detritus in the base of the channels during the first billion years of the planet's history. The crust of Mars is likely to be composed of mafic or ultramafic rock such as basalt or komatite. Water, carbonated by the CO2 in the early atmosphere, or evolving directly from magma at depth, would have reacted with the mafic debris as it percolated and gravitated to inland seas or lakes, where the meteoric water may have emanated as a buoyant plume. Mike Russell has proposed that the terrestrial site that might provide us the indication of what to expect at such an effluence on Mars is revealed in the Alpine ophiolites, portions of basaltic ocean crust thrust over Eurasia. Some scientists have postulated that the remains of organic compounds on present day Mars might provide clues as to which combination of compounds lead to life and which did not. Although such a question may be unanswerable since different compounds degrade at different rates. Thessa Kanavarioti and Rocco Mancinelli, both at NASA Ames Laboratory, suggested that if organic matter such as amino acids existed on Mars 3.5 Gyr ago then traces that are preserved below the surface oxidizing layer might still be present. Only if the amino acids were located in aqueous or frozen subsurface deposits, such as polar regions, would racemization have been preserved. (All terrestrial life uses one isomer of amino acids for metabolism). Without which it would be very difficult to determine whether the amino acids were of abiotic or biotic origin. In addition, Jeffrey Bada, based upon his estimate of aspartic acid racemization on Mars, suggested that nucleic acid information might also be preserved on Mars under similar conditions as amino acids. However, experimental data indicate that ribose, which makes up the backbone of nucleic acids, has an extremely short half- life--approximately 44 years at 4oC. Therefore genetic information based upon a ribose back bone might not be expected to be found in the same location as amino acids, if at all, even if they were originally present together. Chris McKay and Wanda Davis of NASA Ames suggest that the location of the remains of ice covered lakes which may have persisted during times of climatic hostility would increase the probability of amino acids being preserved until present day. Summary Climatic conditions on early Mars are thought to have resembled some of the conditions on early Earth, thus giving weight to the idea that life may also have arisen on Mars. There are many theories that have been proposed to explain the origin life on Earth, none of which can be proven, and because of its geology Mars provides a unique opportunity to investigate this. Indeed it may be possible that more than one origin of life event occurred on Mars. If life arose on Mars by hydrothermal mechanisms the possibility arises that multiple origin of life centers may have occurred on Mars, and because large bodies of liquid water may have been absent, such centers may have been geographically isolated, thus giving rise to different lineages of life. Recommended reading: Carr, M. H., Water on Mars. Oxford University Press, New York (1996). Davis, W. L., and C. P. McKay, "Origins of Life: A comparison of theories and applications to Mars", Origins of Life and Evolution of the Biosphere, 26, 61-73, (1996). Hiscox, J. A. (Ed), The Search for Life on Mars. British Interplanetary Society, London (1999). McKay, C. P., and C. R. Stoker, "The early environment and its evolution on Mars: Implications for life", Reviews of Geophysics, 27, 189-214, (1989). McKay, C. P., E. I. Friedmann, R. A. Wharton, and W. L. Davis, "History of water on Mars: A biological perspective", Advances in Space Research, 12(4), 231-(234)238, (1992). Table 1. Ages of martian planes as estimated by Mike Carr of the United States Geographical Survey and the equivalent development of life on Earth and possibly Mars. Plains region Age in 109 years Stage of life on Earth (relative to best estimate) Best estimate Range Mare Acidalium 1.2 0.2-1.7 Increase in diversity Sinai Planum 1.4 0.4-3.0 Origin of eukaryotes Utopia Plantia 1.8 0.6-2.3 Youngest detrital uraninites Noachis Planitia 2.5 0.9-3.6 Oldest heterocyst like cells Amazonis Planitia 2.8 1.0-3.7 As below. Syrtis Major Planum 2.9 1.2-3.7 Diversification of anaerobic prokaryotes Chryse Planitia 3.0 1.2-3.8 Oldest stromatolites Lunae Planum 3.5 1.7-3.8 Oldest fossils Hellas 3.8 2.9-3.9 Earliest biogenic activity (Life on Mars? ALH84001) Hesperia Planum 3.9 3.0-3.9 Origin of life on Earth Note: The shaded area represents the time at which the climates of Earth and Mars were thought to be similar. [This table is best viewed in the PDF version of Marsbugs.] Contact: Dr. Julian A. Hiscox School of Animal and Microbial Life University of Reading Reading, RG6 6AJ, United Kingdom J.A.Hiscox@reading.ac.uk --------------------------------------------------------------------- NEW CLUES ABOUT MARTIAN METEORITES BAFFLE SCIENTISTS By Greg Clark From Space.com 30 August 2000 Analysis of new martian meteorites is confounding planetary scientists with clues that simply don't add up. Rather than clearing up existing questions about the Red Planet, results from the new meteorites seem to be opening up a Pandora's box of questions about Mars. Evidence from the rocks doesn't seem compatible with one of the most trusted scientific conclusions about the planet: that the vast majority of the martian surface is billions of years old. The puzzle came into sharp focus here this week at the annual meeting of the Meteoritical Society, as scientists announced their findings from three recently discovered Mars rocks. The Los Angeles meteorite, which was discovered last fall by a Los Angeles rock hunter, was revealed to be only 175 million years old--contemporary in geologic terms. It is a volcanic rock that crystallized from magma near the martian surface. Larry Nyquist and a research team at NASA's Johnson Space Center and Lockheed Martin in Houston determined the age by measuring the state of certain weakly-radioactive isotopes within the meteorite. Get the full story at http://www.space.com/scienceastronomy/solarsystem/martian_meteorite_0 00830.html. --------------------------------------------------------------------- NASA INDEX USES PLANTS TO SHED NEW LIGHT ON DROUGHTS NASA release 00-132 30 August 2000 NASA has a new tool designed to keep a close watch over our plants. What we see in the reflection of the vegetation may help researchers do a better job of monitoring and, one day, predicting periods of drought. A new Multi-spectral Drought Index measures the impacts of too little water or too much rainfall on vegetation. The index will also be used to verify other existing drought-monitoring products. "What makes this data set unique is its unprecedented detail, which provides a resolution four times that of current drought prediction maps, and it is based on a 20-year data record," said Compton Tucker, the research scientist leading the project at NASA's Goddard Space Flight Center, Greenbelt, MD. The new Multi-spectral Drought Index utilizes and improves the data from the Normalized Difference Vegetation Index (NDVI) and shows deviations from average vegetation levels. The NDVI is an index created by Tucker 20 years ago to measure the absorption and reflectance of sunlight by plants. The NDVI data sets show the greening and browning of plants as they relate to seasonal changes and conditions such as drought or abundant rainfall. The data are gathered by the polar-orbiting satellites built by NASA and operated by the National Oceanic and Atmospheric Administration (NOAA). The satellites measure the reflectance and absorption characteristics of plants at different wavelengths in the electromagnetic spectrum. The data are registered in numerical form, and translated by researchers into monthly maps of vegetation color changes, which in turn indicate how much soil moisture is available to plants. Since the global data set spans a 20-year time period, researchers can better determine what are "normal" levels of plant growth, and what are unusually high or low levels. Sunlight can either be absorbed by leaves and needles or scattered within and among them. By using red and infrared wavelengths in the spectrum, multi-spectral imaging measures the absorption rate of sunlight and identifies levels of chlorophyll generated in vegetation. When more sunlight is absorbed, higher levels of chlorophyll are generated in vegetation showing plant growth. Conversely, when a plant is stressed from lack of fertilizer or water, it will limit its chlorophyll production compared to healthy plants. "The new Multi-spectral Drought Index is used to generate better vegetation anomaly maps than before," according to Tucker. Light brown on the drought map means there's diminished plant growth, green on the map indicates a higher than average plant growth. A map generated for July 2000 indicated a drought in the western United States. "The data clearly shows why we're having wildfires," Tucker said. "Soil conditions are dry, and the diminished vitality of vegetation indicates that." Many drought products are based on water availability in soils. The new index maps integrate climate variables such as soil moisture, temperature and precipitation, and show how vegetation responds to environmental conditions around the world. "The bottom line is that the new Multi-spectral Drought Index reflects the actual environmental conditions of the vegetation, and at a much higher resolution than previously available, which will be helpful in supplementing and validating the NOAA drought forecast maps," Tucker said. The first data sets covering North America and Africa and are currently available at: http://earthobservatory.nasa.gov/Drought/ http://svs.gsfc.nasa.gov/imagewall/drought.html Complete data sets including images from all continents are expected to be released to the scientific community early next year. This research is done in support of NASA's Earth Science Enterprise, Washington DC. The Enterprise is dedicated to the long-term study of how human-induced and natural changes affect our global environment. More information about the Enterprise can be found at http://www.earth.nasa.gov. Contacts: David E. Steitz Headquarters, Washington, DC Phone: 202-358-1730 Cynthia M. O'Carroll Goddard Space Flight Center, Greenbelt, MD Phone: 301-614-5563 --------------------------------------------------------------------- ATLANTIS LIFTOFF SET FOR SEPTEMBER 8 TO OPEN DOORS TO NEW STATION MODULE NASA release 00-134 30 August 2000 Following a thorough review of mission preparations yesterday, the launch of Space Shuttle Atlantis has been set for September 8, on a mission that will open the doors to the International Space Station's new living quarters. "This mission begins a series of Station assembly flights aboard the Shuttle during the next year that will be as complex and challenging as anything NASA has ever done, including landing a man on the moon," Space Shuttle Program Manager Ron Dittemore said. "I believe these flights will be as impressive as they are complex. The team has done a fantastic job preparing Atlantis for this mission, and we're excited and ready to get started." Atlantis's liftoff from the Kennedy Space Center on Shuttle mission STS-106 will be targeted for 8:45 AM EDT at the opening of a launch window that will be less than five minutes long. During the planned 11-day flight, the crew of seven will spend a week docked to the International Space Station, unloading more than one and a half tons of equipment and supplies from both the Shuttle and from a docked Russian Progress cargo craft. This mission will set the stage for the arrival of the first resident Station crew, planned to launch and begin living aboard the outpost later this year. Terry Wilcutt will command Atlantis and Scott D. Altman will be shuttle's pilot. The crew also includes mission specialists Edward T. Lu, Richard A. Mastracchio and Daniel C. Burbank. Atlantis will also carry two cosmonauts from the Russian Space Agency who will server as mission specialists, Yuri I. Malenchenko and Dr. Boris V. Morukov. While Atlantis is docked to the Station, Lu and Malenchenko are scheduled to perform one spacewalk to conduct assembly tasks. Atlantis is scheduled to land at the Kennedy Space Center at about 4 AM EDT September 19. Contacts: Kirsten Williams Headquarters, Washington, DC Phone: 202-358-0243 Bruce Buckingham Kennedy Space Center, FL Phone: 321-867-2468) James Hartsfield Johnson Space Center, TX Phone: 281-483-5111 --------------------------------------------------------------------- CASSINI WEEKLY SIGNIFICANT EVENTS JPL release 24-30 August 2000 The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Wednesday, 08/30. The Cassini spacecraft is in an excellent state of health and is operating normally. The speed of the spacecraft can be viewed on the "Where is Cassini Now?" web page at http://www.jpl.nasa.gov/cassini/today/. The checkout of the new Command and Data Subsystem (CDS) flight software concluded this week with the successful completion the SSR management and telemetry mode demonstrations and the loading of the emergency RAM. The Periodic Engineering Maintenance (PEM) sequence was executed. PEM activities included Backup ALF Injection Loader (BAIL) maintenance, Engine Gimbal Actuator (EGA) and Reaction Wheel Assembly (RWA) exercises. The C21 instrument power-on and IEB load mini-sequence was approved for uplink to the spacecraft next week. The Preliminary SIV Approval Meeting was held for C22. A Sequence Change Request approval meeting was held for C23 and formally approved one change requested by SCO (AACS). A Jupiter System Assessment Meeting was held to mark the formal completion of development for the Jupiter phase. The Instrument Operations Team Requirements and Design Review for the Tour Phase occurred this week. The review board gave the team high marks for the material presented. An update to the Mission Sequence System was delivered to correct a problem with the C-kernel output file in the Pointing Design Tool. Installation on the Science Operations and Planning Computers at the remote science sites was completed later in the week. A briefing was given to Program Management regarding status of and current challenges in development of the Science Opportunity Analyzer, Pointing Design Tool, and Cassini Information Management System software tools. ULO personnel have proposed a revised sequence development schedule for the post-Jupiter time frame. The new schedule reduces the process to eight weeks by eliminating the overlap of sequence development and execution. This process improvement should result in more efficient operations. A preliminary version of the MSSO Functional Requirements Document (FRD) has been released for review. This document will form the basis of the MSSO Requirements and Design Review planned for September. User access to the Central Database (CDB) was terminated this week with decommissioning of the CDB scheduled for mid-September. The CDB has been replaced by the TMOD provided Distributed Object Manager (DOM) system. --------------------------------------------------------------------- ISS STATUS REPORT JSC release 30 August 2000 With a visit by the Space Shuttle Atlantis a little over a week away, International Space Station flight controllers plan to conduct a final rehearsal of the station's activities for the upcoming docking on Tuesday. This week, station controllers completed transferring propellants from tanks aboard the attached Progress cargo craft to tanks aboard the Zvezda living quarters module. Controllers in the United States and Russia also conducted a test of the efficiency of the solar arrays on the Zvezda and Zarya modules, finding everything in good shape. An evaluation of problems with two batteries on the station--one in Zarya and one in Zvezda--continued this week, although the problems have no impact on any planned station activities. The problem exhibited by the battery in Zarya, labeled Battery 6, is consistent with normal signs of aging, and battery 6 is already planned to be replaced during Atlantis' visit. The problem with the battery in Zvezda, called Battery 4, is believed to be caused by an electronics unit, called the PTAB, that is associated with the battery's charging and discharging. The problem is not believed to be with the battery itself. At present, Battery 4 is not in use, and the PTAB is planned to be replaced during Atlantis' visit. The four other batteries aboard Zvezda are operating normally. Late last week, one of the three flight control computers aboard Zvezda was automatically taken off line. To backup one another, three computers operate simultaneously aboard the module, performing the same functions. The other two computers are on line and continuing to operate well and there is no impact to the station's activities. The station can operate on only one computer if necessary, and the docking of Atlantis could proceed using ground commanding to control the station even if no computer was on-line. Analysts at the Russian Mission Control Center in Korolev have dumped the off-line computer's software and are evaluating it. Since the computer has been off-line, it has remained operating and controllers have seen no other problems. As they continue to evaluate the station's orbit in preparation for the rendezvous of Atlantis, station flight controllers will make a final decision this weekend on whether a final engine firing tentatively planned next week will be needed. On Tuesday, controllers will briefly maneuver the station to the orientation required for the Shuttle docking in a test of the docking procedures. On Thursday, the day Atlantis is planned to launch from the Kennedy Space Center, station controllers will turn on heaters to begin warming up the Unity module in anticipation of the seven-member crew's arrival. With a launch on Thursday, Atlantis is scheduled to dock with the station at 1:12 AM CDT September 10. Now in an orbit with a high point of 228 statute miles and a low point of 222 statute miles, the 67-ton, 143-foot long International Space Station can easily be viewed from the ground under proper lighting conditions. To see when the station is visible, check the human space flight web site at http://spaceflight.nasa.gov/realdata/sightings/. For updates on all aspects of human space flight, visit http://spaceflight.nasa.gov. --------------------------------------------------------------------- MARS GLOBAL SURVEYOR STATUS UPDATE JPL release 30 August 2000 Launch / Days since Launch = November 7, 1996 / 1393 days Start of Mapping / Days since Start of Mapping = April 1, 1999 / 517 days Total Mapping Orbits = 6,617 Total Orbits = 8,220 Recent events The spacecraft continues to operate nominally in performing the beta- supplement daily recording and transmission of science data. The mm064 sequence executed successfully from 00-237 (8/24/00) through 00-239 (8/26/00). The mm065 sequence has performed well since it started on 00-240 (8/27/00). It terminates on 00-243 (8/30/00). The mm066 sequence, successfully uplinked on 00-242 (8/29/00), begins executing on 00-244 (8/31/00). The mz054 mini-sequence containing the MOLA Polar Scans was uplinked 00-241 (8/28/00). Between 00-243 (8/30/00) and 00-246 (9/2/00) MGS will specifically target the North and South poles with the laser altimeter during thirteen orbits covering 360 degrees of latitude. Spacecraft health All subsystems report nominal health. As MGS approaches aphelion, the average energy margin per orbit is dropping as expected. Power projections indicate that the average energy margin per orbit will drop below the 40 Watt-hour threshold between early September 2000 and mid-January 2001. Though the spacecraft is capable of operating nominally below this threshold, the project has elected to maintain the average energy margin at or above 40 Watt-hours. The on-board command scripts that control solar array motion will be modified to provide the desired margin. This change will take effect 00-251 (9/7/00). Uplinks There have been nine uplinks to the spacecraft during the last week, including new star catalogs and ephemeris files, instrument command loads, and the background sequences cited above. There have been 4,813 command files radiated to the spacecraft since launch. Upcoming events The mm067 background sequence will be uplinked 00-245 (9/1/00). Radio Science Occultation Egress Scans, scheduled for 00-252 (9/8/00) through 00-253 (9/09/00), are contained in the mz055 mini-sequence. It will be uplinked 00-250 (9/6/00). MOC Focus Calibrations are scheduled for 00-262 (9/18/00) through 00-272 (9/28/00). --------------------------------------------------------------------- STARDUST STATUS REPORT JPL release 1 September 2000 There were two Deep Space Network (DSN) tracking passes during the past week. All subsystems onboard the spacecraft are performing normally. During the last 2 passes using the Medium Gain Antenna (MGA) and Solid State Power Amplifier 1 (SSPA 1), power started off normally but dropped 2 dB during each pass. The SSPA's have been powered off between passes during the last year because this drop in gain would always occur when the SSPA's were left on for long periods of time after launch. This will be studied because of the potential for the SSPA's to not recover this loss of gain when powered off. A Dust Flux Monitor (DFM) checkout test was successfully performed to verify the instrument would still provide more than thirty minutes of nominal operation. This was the first time the DFM had been powered on since September 1999. The DFM operated nominally for 36.5 minutes when it entered its noisy state and was then powered off. The noisy state is associated with an abrupt instrument operating change where there are rapid fluctuations in current. This test successfully verified that more than thirty minutes of nominal operation is still possible, sufficient to capture 95% of the expected Comet Wild 2 encounter science data. After a few minutes DFM was powered on again for 1 minute to see if power cycling the DFM would reset the instrument to normal operations. Normal operations did not return after power cycling, therefore DFM is expected to only be powered on for 20 minutes at Earth flyby this coming January and at the Comet Wild 2 encounter in 2004. The last two images of the Navigation Camera Charge Couple Device (CCD) heater test were taken. The pre-test, 1, 2, 4, 8-hour and part of the 16-hour image sets have now been transmitted to the ground. Next week, the remaining 32, 56, 100, 144, and 341-hour image sets will be transmitted. The Cometary Interplanetary Dust Analyzer (CIDA) was power off and the flight processor clock speed was reduced to 10 MHz. These actions were taken to keep the Command and Data Handling (CDH) temperature below 43°C. Flight experience has shown that Payload Attitude Control Interface (PACI) card resets occur when the CDH temperature is between 43-45°C. As internal temperatures are rising to near this temperature range as the spacecraft comes closer to the Sun on its way to an Earth flyby in January, thermal analysis indicates that by powering off the CIDA and reducing the clock speed the CDH temperature will remain below 43°C. Next October, CIDA will return to operation and the clock speed increased to 20 MHz, which will push the CDH temperature to above 45°C, thus keeping the temperature outside of the region where PACI resets occur. 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. --------------------------------------------------------------------- DUXBURY NAMED PROJECT MANAGER OF STARDUST MISSION JPL release 30 August 2000 Thomas Duxbury has been named project manager of NASA's Stardust mission to collect a comet sample and return it to Earth. The mission is managed by the Jet Propulsion Laboratory, Pasadena, CA. Duxbury, who has served as Stardust's acting project manager for the past year, replaces Dr. Kenneth Atkins, who now heads a JPL program to develop the leadership of the Laboratory's projects. Duxbury joined the Stardust project as mission manager in 1996 and was responsible for a wide range of elements including navigation, mission design, the ground data system, science data management and archive and mission operations. Stardust, launched in February 1999, is en route to Comet Wild-2 to capture a sample of material and then return the sample to Earth in 2006. A native of Fort Wayne, IN, Duxbury attended Purdue University in West Lafayette, IN, where he earned his bachelor's and master's degrees in electrical engineering. Upon graduating in 1966, he started work at JPL in the field of optical navigation on the Mariner 6 and 7 missions to Mars. Duxbury has served on numerous planetary mission teams including the Mariner 6, 7, 9 and 10 missions; the Mars Viking mission that sent two landers and two orbiters to Mars; the Pioneers 10 and 11 missions to Jupiter and Saturn; Voyagers 1 and 2 to the outer planets; the Soviet Phobos Mission to Mars; the Mars Observer mission; the Department of Defense/NASA Clementine mission that studied the Moon; and the Russian Mars 1996 mission. He has served on many NASA panels and working groups such as the NASA Planetary Cartography and Geologic Mapping Working Group and the Russian/U.S. Joint Working Group on Solar System Exploration for Mars Mission Coordination and Science Data Exchange. In addition to his new Stardust role, Duxbury is a member of the science teams for the Mars Global Surveyor's laser altimeter and the European Space Agency's Mars Express orbiter and lander. He is also the lead scientist for geodesy and cartography in the Mars Exploration Office. His roles on past missions have included engineering and scientific data analysis on highly irregularly shaped and rotating planetary bodies. For his pioneering work in characterizing Mars' moons Phobos and Deimos, Duxbury received the NASA Medal for Exceptional Scientific Achievement. He has also received eight NASA Group Awards and the Institute of Navigation Burka Award. He received the Soviet Flight Control Center Medal, being the only American in Moscow supporting the Phobos '88 encounter and landing operations. He is listed in American Men and Women in Science and in Who's Who in America. He lives in Pasadena with his wife, Dr. Natalia Duxbury, a scientist at JPL. Stardust is managed by JPL for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology. --------------------------------------------------------------------- End Marsbugs, Volume 7, Number 33.