MARSBUGS: The Electronic Astrobiology Newsletter Volume 8, Number 32, 27 August 2001. Editors: Dr. David J. Thomas, 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 monthly 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, the biology of terrestrial extreme environments, planetary biology, primordial evolution, space physiology, biological life support systems, and human habitation of space and other planets. _____________________________________________________________________ CONTENTS 1) ADVANCES IN OUR UNDERSTANDING OF LIFE From the NASA Astrobiology Institute 2) BARLOW: PLENTY OF WATER ON MARS By Susan Loden 3) WELL-PRESERVED METEORITE YIELDS CLUES TO CARBON EVOLUTION IN SPACE Arizona State University release 4) ARTICLE EXPLORES REBIRTH OF AQUATIC LIFE AFTER DEEP-SEA VOLCANIC ERUPTION Rutgers University release 5) GUERRERO NEGRO By Henry Bortman 6) NEW ADDITIONS TO THE ASTROBIOLOGY INDEX By David J. Thomas 7) CASSINI WEEKLY SIGNIFICANT EVENTS NASA/JPL release 8) THIS WEEK ON GALILEO NASA/JPL release 9) ISS STATUS REPORT NASA/JSC release 10) MARS ODYSSEY MISSION STATUS NASA/JPL release 11) STARDUST STATUS REPORTS NASA/JPL releases _____________________________________________________________________ ADVANCES IN OUR UNDERSTANDING OF LIFE From the NASA Astrobiology Institute 21 August 2001 Excerpts from the testimony of Jack D. Farmer, Director and Principal Investigator of the NASA funded Astrobiology Program at Arizona State University, for the "Life in the Universe" hearings before the House Subcommiteee on Space and Aeronautics. Over the past two decades, advances in a number of scientific disciplines have helped us better understand the nature and evolution of life on Earth. These scientific developments also have helped lay the foundation for astrobiology, opening up new possibilities for the existence of life in the Solar System and beyond. A new look at life Carl Woese of the University of Illinois published the first universal tree of life in 1987. The universal tree is based on genetic sequence comparisons, which showed that there are three major domains--Archaea, Bacteria and Eukarya. These three domains consist of dozens of kingdoms, nearly all of which are microbial. This is in contrast to the traditional five kingdom view of the biosphere (Animals, Plants, Fungi, Protists and Monera), where multicellular plants and animals are given prominence. Perhaps one of the most fundamental things we have recognized from the universal tree is that we live on a microbial planet. Microscopic life dominated the first 85% of biospheric history. Evidence from paleontology During Charles Darwin's time, there was limited awareness of the importance of microbial life in the evolutionary history of the biosphere. The oldest fossils known were shelled invertebrates that appeared at the base of the Cambrian Period, now dated at 540 million years. Stromatolites (sediments produced by ancient microbial communities) were first described around 1850, at about the same time Darwin's Origin of Species was published. The interval of Earth history preceding the Cambrian (called the Precambrian) was regarded as being largely devoid of fossils and life. However, in 1993, J. William Schopf of UCLA reported bacterial microfossils from stromatolite-bearing sequences in western Australia dated at nearly 3.5 billion years. Then in 1996, Steven Mojzsis of the University of Colorado described possible chemical signatures for life from 3.9 billion-year-old rocks from Greenland. These are the current record holders for the oldest life on Earth. These advances in Precambrian paleontology have pushed back the record of life on our planet to within half a billion years of the time when the first viable habitats existed on Earth. This suggests that once the conditions necessary for life's origin were in place, it arose very quickly. Exactly how quickly, we don't yet know, but certainly on a geologic time scale, it was much shorter than previously thought. Impact frustration of early biosphere development Prior to 4.4 billion years ago, surface conditions on the Earth were unfavorable for the origin of life. Frequent asteroid impacts produced widespread oceans of molten rock at the Earth's surface. Easily vaporized compounds, like water, and elements important for biology, like carbon, hydrogen, oxygen, nitrogen, sulfur and phosphorous, were lost to space through a combination of volatile escape and impact erosion. About 4 billion years ago, the rate and size of impacts dropped off, allowing the Earth to retain the water and organics delivered by comets and other icy objects. A stable atmosphere and ocean developed, providing the first suitable environments for life. However, models also suggest that as late as 3.8 billion years ago, the emerging biosphere may have experienced one or more giant impacts. These impactors would have been capable of vaporizing the oceans and sterilizing surface environments. The deepest branches of the universal tree--those presumably lying closest to the common ancestor of life--all share an interesting property: a preference for very high temperatures. For some scientists, this implies that life probably got started at high temperatures, perhaps around the deep-sea hydrothermal vents. For others (myself included), it seems more likely that we are not seeing the environment of life's origin, but rather environments that prevailed after the last giant impact. These forms may simply be the descendants of organisms that were able to survive by hiding out in hydrothermal environments. The subsurface biosphere In 1979, oceanographer Robert Ballard and biologist J. Frederick Grassle piloted the deep submersible Gilliss to sites more than a mile and a half deep on the sea floor. Their mission was to describe in detail the volcanic vents and their associated faunas. At these locations, scientists got a first glimpse of living ecosystems based entirely on chemical energy. As this type of exploration continued, complex vent communities were discovered in virtually every ocean basin, proving the remarkable ability of these organisms to colonize even the most widely dispersed habitats. There are now hints of photosynthetic organisms that are able to utilize the weak thermoluminescent radiation given off by the hot vents. This has opened up the intriguing possibility that photosynthesis may have evolutionary roots in deep-sea vent settings. More recently it was discovered that life also thrives in deep subsurface environments where interactions between water and rock yield available energy. While many subsurface organisms utilize the "filtered-down" organic compounds produced by photosynthetic surface life, some species are able to make their own organic molecules from the purely inorganic substrates that come from simple weathering reactions between groundwater and rock. The extremes of life Microbial species are now known to occupy almost the entire range of pH from 1.4 (extremely acid) to 13.5 (extremely alkaline). Life also thrives in extreme temperatures, with some species showing growth up to 114 degrees C (thermal springs at Vulcano, Italy and deep sea vents) and other species surviving down to -15 degrees C (brine films in Siberian permafrost). Life also occupies an equally broad range of salinity, ranging from fresh water up to sodium chloride saturation (about 300 percent), where salt precipitates. In addition to environmental adaptation, some microbial species show evidence of remarkably prolonged viability. In even the driest deserts on Earth, some species survive by living inside porous rocks where they find a safe haven from UV radiation. They spring to life only when the water needed for growth becomes available. Microbes have been isolated from Siberian permafrost, where they had remained in deep freeze for about 3 million years. Bacteria have been germinated from 30 million-year-old spores that were preserved in amber. Salt-loving microbes have been cultured from rock salt that is hundreds of millions of years old. The search for extraterrestrial life These findings hold special importance with regard to potential habitats for life elsewhere in the Solar System. For example, we must now consider the possibility of a subsurface biosphere on Mars or on Jupiter's moon Europa. Mars may have an extensive ground water system located several kilometers below the surface. This possibility was bolstered by the recent discovery of small channels caused by surface fluid seeps. If liquid water is proven to be the agent that formed these features, then the biological potential for Mars will be dramatically enhanced. Liquid surface water also may have been present at the Martian surface for a few hundred million years early in the planet's history. If surface life developed on Mars during this Earth-like period, it quite likely left behind a fossil record. Refrigeration is known to be an effective means for the preservation of organisms. Carl Sagan first suggested that microorganisms from an earlier period in Martian history might still exist there today in a perpetually frozen state, preserved in ground ice. Could the same hold true for Jupiter's moon Europa? Measurements of the magnetic field of Europa, obtained during the Galileo mission, have strengthened arguments for the existence of a salty ocean lying beneath an exterior shell of water ice. It seems quite plausible that water welling up from below may carry organisms or their by- products. These materials would eventually freeze and become cryopreserved in ices at or near the surface. Conclusion One thing seems clear: on Earth, life occupies virtually every imaginable habitat where liquid water, an energy source, and basic nutrients coexist. Whether or not this is true on other worlds is one of the premier questions facing astrobiology today. While we can effectively build on what we have learned about life on Earth, the question of extraterrestrial life requires exploration. This is perhaps the most compelling aspect of astrobiological science, and a standard by which we can measure our progress. Additional information on this article is available at http://nai.arc.nasa.gov/index.cfm?page=understanding_life. An additional article on this subject is available at http://www.spacedaily.com/news/life-01zd.html. _____________________________________________________________________ BARLOW: PLENTY OF WATER ON MARS By Susan Loden University of Central Florida release 21 August 2001 When we make it to Mars, there's an excellent chance that we will find a vast, easy-access watering hole to help sustain life on the Red Planet. This ice-crusted reservoir was found by Nadine Barlow, director of UCF's Robinson Observatory, and her partners John Koroshetz, a former UCF physics undergraduate student, and James Dohm, a research associate with the University of Arizona's Department of Hydrology and Water Resources. Barlow's use of impact craters to identify a near-surface ice reservoir south of the big canyon system Valles Marineris on Mars is outlined in the August 15 issue of Geophysical Research Letters. "This ice is closer to the surface in the Solis Planum area than ice elsewhere in the equatorial region and our analysis also suggests that an extensive liquid water reservoir underlies this shallow ice deposit" Barlow says. "We believe that nearby, long-term volcanic activity has concentrated the volatiles in this region, due to various episodes of uplifting and tilting of the groundwater table. Heating associated with the volcanism has also kept the water liquid for longer time periods," The team poured over Mars surface images from two 1970s-era Viking Orbiters, taking a closer look at the smooth plains of Solis Planum, which is pocked with craters formed by meteorite impact. They evaluated crater shapes and the ejecta deposits thrown from the craters when they were created. The locations and diameters of hundreds of craters were evaluated, mapped and cataloged. Excavation depths of the craters were obtained from the crater diameters using relationships derived from the laser altimeter data taken by the Mars Global Surveyor (MGS) spacecraft, which has been orbiting Mars since 1997. More analysis of this area is continuing with the MGS Mars Orbiter Camera data. The character of craters and deposits is believed to indicate what might be beneath the surface. In particular, the fluidized appearance of ejecta deposits surrounding fresh impact craters on Mars is commonly believed to indicate impact into subsurface ice and or water. Barlow believes ice and water are just below the surface in the Solis and Thaumasia Planae region. The tip-off is smaller than average onset-diameters for single-layer craters, strongly suggesting a supply of ice about 360 feet from the surface there, compared to approximately 650 feet elsewhere in the equatorial region. The team will now try to estimate how much ice and water the reservoir holds, while their find attracts media attention. Space.com was first to interview Barlow after she reported on the reservoir at a workshop last year. A report on her paper can be found at http://space.com/scienceastronomy/solarsystem/mars_ice_010813.html MSNBC and UPI have also reported on the discovery. Images supporting this release are available at http://www.news.ucf.edu/FY2001-02/010821a.html. _____________________________________________________________________ WELL-PRESERVED METEORITE YIELDS CLUES TO CARBON EVOLUTION IN SPACE Arizona State University release 23 August 2001 The first results are in from the organic analysis of the Tagish Lake Meteorite, a rare, carbon-rich meteorite classified as a "carbonaceous chondrite" that fell on a frozen Canadian lake in January 2000 and is the most pristine specimen ever studied of this group of important space objects. Carbonaceous chondrite meteorites contain vital clues to the evolution of carbon compounds in our solar system preceding the origin of life. The analysis, conducted by a team headed by chemist Sandra Pizzarello, a research scientist at Arizona State University, on 4.5 grams taken from the sealed interior of the meteorite, found organic compounds in the meteorite with some similarities to other known carbonaceous chondrites, but also clear differences--most notably the near-absence of the amino acids found in some meteorites studied before. In an article scheduled to appear in the August 24 issue of the online journal Science Express (with publication in Science to follow) the team notes that the chemistry of the Tagish Lake Meteorite appears to preserve organics that accumulated or developed in the early history of the Solar System--including molecular bubbles of carbon (fullerenes or "buckyballs") containing the noble gasses helium and argon in a ratio similar to the gas and dust cloud that formed the planets--and thus perhaps reflects an early stage in a process of evolution of complex carbon compounds in space. "The chemistry here is different from that we have seen in any other meteorite," said Pizzarello. "It's simple, when compared with Murchison (a famous carbon meteorite found in Australia in 1969 that contained numerous amino acids and a variety of other organic compounds) and probably represents a separate line of chemical evolution. However, it still includes compounds that are identical to biomolecules." Other members of the research team include Yongsong Huang from the Department of Geological Sciences at Brown University; Luann Becker from the Institute for Crustal Studies at the University of California Santa Barbara; Robert J. Poreda from the Department of Earth and Environmental Sciences, University of Rochester; George Cooper from the NASA Ames Research Center; and Ronald A. Nieman and Michael Williams, both also from ASU. The Science paper notes that many of the organic compounds found in the Tagish Lake sample have also been found in other meteorites, but that the distribution of compounds is different, particularly for the amino acids and carboxylic acids. "Some people have been disappointed that we found virtually no amino acids, but scientifically this is very exciting," Pizzarello said. "This meteorite shows the complexity of the history of organic compounds in space--it seems to have had a distinct evolution." "We found some compounds identical to some in Murchison that show the same 'interstellar connection' in their abundance of deuterium (heavy hydrogen), while some others differ from Murchison in amounts and variety," said Pizzarello, meaning that for some groups of organic molecules, only the simplest species were found in Tagish Lake, as opposed to a broader distribution of species found in Murchison. "Overall, Tagish Lake represents a simpler, more unaltered stage than we have seen before." What emerges from the analyses is evidence for what Pizzarello calls "a different outcome" of organic chemical evolution in space likely to have happened during the formation and development of the solar system, "but one that still might have contributed molecular precursors of biomolecules to the origins of life," she noted. Contact: James Hathaway Phone: 480-965-6375 E-mail: Hathaway@asu.edu _____________________________________________________________________ ARTICLE EXPLORES REBIRTH OF AQUATIC LIFE AFTER DEEP-SEA VOLCANIC ERUPTION Rutgers University release http://ur.rutgers.edu/medrel/viewArticle.phtml?ArticleID=1641 23 August 2001 The rapid revival of life around hydrothermal vents on the floor of the Pacific Ocean after a lava flow had appeared to exterminate it is the subject of an article co-authored by Rutgers researcher Richard A. Lutz in the September-October issue of American Scientist magazine. Lutz is director of the Center for Deep Sea Ecology and Biotechnology at Rutgers Institute of Marine and Coastal Sciences. The magazine is published by Sigma Xi, a scientific research society based in Research Triangle Park, NC. As described in the article, "Life after death in the deep sea," Lutz first encountered the strange ecology of hydrothermal vents in the late 1970s off the coast of the Galapagos Islands. On a subsequent expedition in 1991 to hydrothermal vents more than 2,550 meters below the surface off the coast of Mexico, the scientists found themselves in the middle of a volcanic eruption. A blanket of fresh lava killed the sea life the researchers hoped to study. Many of the creatures, such as giant tubeworms, clams and fish, were instantly incinerated by lava. In the article, Lutz details how he led a series of return trips over a nine-year period that shocked the scientific world: not only did the researchers find new geological formations that scientists had formerly believed took eons to evolve, the scientists found an explosion of new biological life, including new life forms ranging from microscopic crustaceans to two new species of octopus. The creatures living around thermal vents function without light and near vent water that would seem too hot and toxic to support life, reports Lutz. Among them are worms, clams, mussels, mollusks, octopuses, fish, crabs and other crustaceans. To date, he notes in the article, more than 500 new species have been found at vent sites throughout the world's oceans. Some of the strangest are two kinds of vent worms: the tubeworm (Riftia pachyptila), which can grow to 6 feet tall, yet has no eyes, mouth, stomach or gut, and the hairy, 5- inch Pompeii worm (Alvinella pompejana), which lives in the hottest environment of any animal on Earth, he notes. Lutz's co-authors are Timothy M. Shank, an assistant scientist in the department of biology at the Woods Hole Oceanographic Institution in Woods Hole, MA, and Robert Evans, a free-lance writer based in California. The research was supported by the National Science Foundation, the National Oceanic and Atmospheric Administration's National Sea Grant College Program, and the National Aeronautics and Space Administration. Contact: Kevin P. Hyland Phone: 732-932-7084 x633 E-mail: khyland@ur.rutgers.edu _____________________________________________________________________ GUERRERO NEGRO By Henry Bortman From the NASA Astrobiology Institute 27 August 2001 Guerrero Negro, a small town of 10,000 located halfway down Mexico's Baja peninsula, is a popular destination for ecotourists. They come to gaze at the gray whales, or to marvel at the diverse population of shorebirds. But in June, Dr. David Des Marais and his colleagues headed to the area to investigate an ecosystem not likely to be mentioned in any travel guide. Des Marais is a senior research scientist at the NASA Ames Research Center in Mountain View, CA, and a member of the NASA Astrobiology Institute. His research team made the trek south to study microbial mats, colonies of microscopic organisms 1- to 10-cm thick, inhabitants of a series of salt evaporation ponds that run along the Pacific shoreline near Guerrero Negro. The Guerrero Negro investigation is a long-term project to study this primitive ecosystem. Des Marais and his colleagues believe the mats may hold important clues to what life was like on early Earth. They also hope to gain insight into how to search for signs of life on planets around distant stars. Many scientists believe that for some 3 billion years after life first evolved on Earth, microbes were the only forms of life around. Only fragmentary evidence of that early life remains today, but geologists have found rocks that do provide such evidence. Known as stromatolites, these ancient fossils are notable because their layered appearance is reminiscent of the layering found in modern-day microbial mats. "We focus on microbial mats," Des Marais explains, "because we have specific geologic evidence for their antiquity. We can go back to rocks that are almost 3.5 billion years of age and see films and features that are strongly consistent with microbial mat ecosystems." But it's not that easy to find microbial mats these days. In most environments, microbes are eaten by other organisms or crowded out by plants before they can form stable mat communities. Only in certain extreme environments, too harsh for most of these grazers to live, can one find nearly pure microbial ecosystems. Guerrero Negro fits the bill because the water in the evaporation ponds there is so salty that microbial mats can compete successfully. The mats under study live in water 2 to 3 times as salty as seawater. Because these modern mat communities are believed to function much like the ancient microbial communities from which stromatolites formed, says Des Marais, "they're good test beds for understanding early evolution." But microbiologists can't just scoop up a piece of the mat, take it back to the lab and analyze it organism by organism. Most of the hundreds of different types of organisms that live in the Guerrero Negro environment have never been identified--and may not ever be. To identify them, at least by traditional means, scientists must isolate and culture them. But because they require the environment of the mat to survive, they're difficult to culture. And it's often difficult to figure out the precise mix of conditions that each different organism requires. "For most organisms," said Des Marais, "being in a pure culture is an extraordinarily stressful situation. It's like putting you in a spacecraft and sending you to Mars with nobody around you. Extraordinarily stressful. You're a social organism. These guys are social, too. Their version of being social is a bit different from ours, though. It has a lot to do with sharing sunlight and exchanging chemicals between neighbors." Moreover, he adds, "We're discovering that the very organisms that are the most important in this community are the hardest ones to grow in pure culture. Surprise, surprise: these are the best team players, therefore they have the hardest time living by themselves." Life, fundamentally, is chemistry. All living creatures, from microbes to mammals, take in chemical nutrients and energy from the environment, reorganize it through a series of chemical reactions into useful forms and get rid of what they don't need. The basics of this process are well understood. The devil is in the details. It is these details that Des Marais and his colleagues hope to tease out of the microbial mats in Guerrero Negro. They want to understand the inner workings of the biochemical cycles that are active in the mat community. By placing probes into the mat at different depths, they are investigating how various chemicals--the most important are compounds containing carbon, oxygen and sulfur--cycle through the system; how they are combined and recombined by the interactions of the mat organisms with each other and with their environment; how gases such as oxygen, methane and carbon dioxide build up and dissipate at different depths within the mat. "How you actually control everything in response to environmental constraints is the essence of survival," says Des Marais. "And so the essence of ecological interaction is really the same thing: How are all these processes regulated as they interact with each other?" Among the questions they are trying to answer is how the biochemical activity of the community changes over the course of a day. For example, the primary producers of organic material for the community are photosynthetic cyanobacteria. These organisms live at the top of the mat, where sunlight is available. They take in carbon dioxide from the atmosphere and the mat community and, using energy from sunlight, convert it to the organic carbon compounds that are the building blocks of living cells. In the process, they release oxygen. Thus, during the daylight hours, oxygen builds up in the upper layers of the mat. But at night, this photosynthesis shuts down and other processes become dominant. The oxygen in the mat decreases as it is used by other organisms. These, in turn, release other gases, such as methane. In an effort to quantify this process, Des Marais and his colleagues camped out near the salt ponds for several days and nights, carefully taking measurements every few hours, to learn how these interactions shift over the course of a 24-hour period. One of the early results from the June expedition, Des Marais says, is that although the mats are submerged in oxygen-rich water, "a centimeter or two above the mat actually goes anoxic at nighttime. So oxygen is not available even to the surface of the mat at nighttime, which has to have some important implications for the organisms that can live there. For example, if you're an organism and you can't stand sulfide because sulfide is poisonous to you, you've got a problem living at the surface of the mat, because every night sulfide gets up into the water column." Researchers also measured the gases drawn from the atmosphere into the mat community, and emitted by the community back into the atmosphere. This information may shed light on a long-standing scientific debate: What was the composition of the atmosphere on early Earth and how did it change over time? "There's the whole tapestry of early evolution that's wrapped up in understanding how these organisms interact and made this very efficient system work over a long period of time," Des Marais explains. "And then, of course, in so doing they leave markers of their remains in the sediments that you find them in, or they put gases into the atmosphere, which modifies the atmosphere." Understanding the interaction of the mat community with the atmosphere may also help scientists who are planning a new generation of telescopes that will search for signs of life on distant worlds. Within the next decade, space-borne telescopes should be capable of detecting Earth-like planets around other stars. But even with the powerful new telescopes, each planet will appear as nothing more than a tiny colored dot. To detect life on these as-yet-undiscovered worlds, the telescopes will make measurements that will indicate the presence or absence of certain atmospheric gases. If they find a world whose atmospheric composition mirrors Earth's, it will be a strong indication that life, perhaps even complex life, exists there. But many scientists believe that for the first two billion years of life on Earth, our planet's atmosphere was very different than it is today. Studying the gases emitted by the Guerrero Negro microbial mats may help in determining what atmospheric signals from a remote planet might indicate a world more like that of early Earth than present-day Earth. Other scientists on the Guerrero Negro expedition studied related questions. Jack Farmer, from Arizona State University (ASU), for example, looked at how sediments trapped by the mats form its characteristic layering. This may help in understanding the conditions that caused the layers seen in stromatolites. Farmer also collected samples that he will examine for evidence of microscopic worms living within the mats. Some scientists speculate that these worms closely resemble the first animals to evolve on Earth, and that mat ecosystems were their first homes. Another ASU scientist, Ferran Garcia-Pichel, took DNA samples from the cyanobacteria living in the mat. By sampling at different depths and over a wide surface area, he is hoping to learn which cyanobacteria are living where. This will aid future research at Guerrero Negro. Garcia-Pichel is currently examining the DNA of the cyanobacteria to see how uniform their populations are from one location to another within the mat. If the populations of cyanobacteria are highly uniform within areas several meters square, Des Marais says, researchers at different labs will be able to examine different samples from the mat with a reasonable degree of certainty that "they are looking at the same ecosystem." Pieter Visscher, from the University of Connecticut, and David Stahl and Matt Dillon, from the University of Washington, are performing similar studies of the bacteria that reduce sulfate and thus provide various sulfur species and gases to other members of the mat community. Norman Pace and John Spear, from the University of Colorado, collected DNA from these mats to determine the variety, or "richness," of the microbial species present. What's next? The work at Guerrero Negro will continue for many years to come. Genomics is one component that will be expanded in future visits to the region. This work will be headed by Mitch Sogin of the Woods Hole Oceanographic Institution. Sogin hopes to discover which genes are being expressed at different locations in the mats at different times of day. By combining this data with that of Des Marais' and Pace's groups, investigators hope to create a more complete picture of how the organisms in the mat community interact. More information on this article is available at http://nai.arc.nasa.gov/index.cfm?page=gn. _____________________________________________________________________ NEW ADDITIONS TO THE ASTROBIOLOGY INDEX By David J. Thomas http://www.lyon.edu/webdata/users/dthomas/astrobiology/astrobiology.h tml 27 August 2001 Articles about astrobiology, exobiology and terraformation http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_article s1.html A. J. S. Rayl, 2001. Water, and life, on Mars? The Scientist, 15(6):10. Articles about evolutionary biology and chemistry http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_article s5.html J. Farmer, 2001. Advancing our understanding of life. SpaceDaily. B. A. Palevitz, 1999. Missing links and the origin of biochemical complexity. The Scientist, 23(8):8. _____________________________________________________________________ CASSINI WEEKLY SIGNIFICANT EVENTS NASA/JPL release 16-22 August 2001 The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Wednesday, August 22. The Cassini spacecraft is in an excellent state of health and is operating normally. Information on the spacecraft's position and speed can be viewed on the "Present Position" web page at http://www.jpl.nasa.gov/cassini/english/where/. Recent spacecraft activities include a Magnetospheric and Plasma Science observation, an Ultraviolet Imaging Spectrometer Interplanetary Hydrogen Survey and Periodic Instrument Maintenance, a Radio and Plasma Wave Science (RPWS) High Frequency Receiver calibration, and an autonomous Solid State Recorder Memory Load partition repair. Real-time commands were uplinked to the spacecraft as planned to transition to the Reaction Wheel Assembly for attitude control and to perform a Command & Data Subsystem Memory Readout of the Non-Interfering Error Log. Instrument Operations (IO) Radio Science Subsystem conducted a test of the X-band Traveling Wave Tube Amplifier (TWTA) as part of the second Gravitational Wave Experiment System Test, which began this week. The X-band TWTAs were placed in standby mode for 18 hours, then warmed up for 2 hours and turned on again. This was done to obtain thermal information relevant to operations mode development. A similar test was performed the following day with the Ka-Band TWTA, to obtain thermal information that will be useful for tour development. The Science Planning Team began holding weekly Target Working Team (TWT) meetings to integrate science activities for the entire tour. In addition to the Titan Orbiter Science and Satellite Orbiter Science Teams (TOST and SOST), the four new teams responsible for integrating segments of the tour are the Saturn, Magnetosphere, Rings, and Cross-Discipline TWTs. The TWT meetings are held Monday through Thursday and will continue for the next three years or until the tour has been completely integrated. Additional tour planning took place at an all-day SOST meeting, which was held to continue work on integrating the targeted icy satellite flybys. The Spacecraft Operations Office (SCO) held the third in a series of Maneuver Automation Tool progress briefings. There has been substantial progress and the prototype scripts and block are well along in development. The developer is preparing for formal delivery of the software and documentation in January 2002. The Navigation team delivered the Cassini orbit determination quarterly update, which covered the data arc from April 2001 to July 2001. The predicted Saturn encounter is several thousand kilometers from the Trajectory Correction Maneuver 17 aimpoint due to normal TCM-17 delivery dispersions and spacecraft thruster activities including the safing event earlier this year. However, this is well within expected trajectory variations at this point in the mission, and will have no noticeable effect on subsequent maneuvers. The Thermal Devices team has completed the analysis of the Reaction Control System catalyst bed heater tests performed in cruise sequence C26. The results of both tests were normal and validate the 32- minute warm-up time and the thermal stability of having both branches powered simultaneously. The Uplink Operations office completed system testing for Mission Sequence Subsystem (MSS) D7.6, including Integration Test Laboratory and High Speed Simulator retest of modules for MSS D7.6. The integrated retest was completed last weekend, and the MSS D7.6 Delivery Coordination Meeting took place this week. The new delivery includes significant updates to Science Opportunity Analyzer, Pointing Design Tool, and the MSS modules, both ground-expanded and on-board. IO installed and performed initial testing of a new Remote Terminal Interface Unit (RTIU) for the RPWS team. Testing of the RTIU was successful with individual commands, and further work and testing is planned for more complex commanding. The Mission Planning (MP) team held a review of Saturn Orbit Insertion planning status. Discussion included the recommendation to use the High Gain Antenna (HGA) to protect the spacecraft during ring plane crossings. The group decided to hold a half-day debris hazard review in conjunction with the upcoming October Project Science Group meeting. MP also received reports from main-engine nozzle testing at White Sands Test Facility, and negotiated with propulsion experts for a September reassessment of Cassini nozzle vulnerability. Mission Assurance completed generation of a Mission Operations Assurance Plan (MOAP) for the program. This plan documents the Operations Assurance effort for Cassini and relies heavily on the synergistic relationship between Mission Assurance and Systems Engineering. Detailed role statements for both Mission Assurance and Systems Engineering are provided, with traceability to both the Mars Climate Orbiter Failure Review Board recommendations and the JPL Design Principles. The MOAP is currently being tailored by Cassini Systems Engineering and should be released to the Flight Team within a few weeks for review. Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, CA, manages the Cassini mission for NASA's Office of Space Science, Washington, DC. _____________________________________________________________________ THIS WEEK ON GALILEO NASA/JPL release 20-26 August 2001 Another very quiet week of cruise activities is in store for the Galileo spacecraft. On Thursday, a test of the on-board gyroscopes is conducted. The electronic circuits governing these gyros have shown sensitivity to the intense radiation experienced as we fly close to Jupiter. Periodically running these tests allows us to determine if the software scale factors that are applied to the gyro measurements need to be updated to correctly interpret the information. The last such test was performed on August 7, just after the flyby, and this test will show to what extent the circuits have recovered from the radiation effects in the intervening two weeks. Continued playback of the data stored on the tape recorder during the Io flyby occupies the Galileo science community this week. Data from the Solid State Imaging camera, the Near Infrared Mapping Spectrometer, and the instruments that measure the electromagnetic fields and particles of the Jupiter environment are on tap. This week's playback should include the measurements taken just as Galileo reached its closest approach to Io, at a distance of 200 kilometers (124 miles), including views of the Isum, Tvashtar, and Prometheus volcanoes. 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 _____________________________________________________________________ ISS STATUS REPORT NASA/JSC release 23 August 2001 Just hours after the return of the Expedition Two crew to the Kennedy Space Center, the Expedition Three crew aboard the International Space Station (ISS) received new supplies and fuel this morning following the flawless docking of a Progress resupply freighter. The unmanned Progress 5 craft linked up to the aft docking port of the Zvezda Service Module at 4:51 AM Central time (951 GMT) after an automated two-day excursion following its launch Tuesday from the Baikonur Cosmodrome in Kazakhstan. The docking occurred over Central Asia. Within a few minutes after docking, hooks and latches were commanded to close between the Progress and Zvezda, forming a hard mate and a tight seal between the two craft. Hatches between the two vehicles will be opened later today, enabling Station Commander Frank Culbertson, Pilot Vladimir Dezhurov and Flight Engineer Mikhail Tyurin to unload some 3000 pounds of supplies and personal effects. The arrival of the Progress vehicle at the Station sets the stage for the launch of the next module for the outpost next month--the Russian Docking Compartment named Pirs, the Russian word for pier. The Docking Compartment will automatically link up to the nadir, or earthward facing docking port of Zvezda two days after launch, providing an additional docking port for future Russian vehicles arriving at the ISS. At the Kennedy Space Center, Expedition Two Commander Yury Usachev and Flight Engineers Jim Voss and Susan Helms are in excellent shape, readapting to gravity and enjoying life back on Earth after167 days in space, 163 days of which were spent aboard the ISS. They are scheduled to return to Ellington Field in Houston late this afternoon with their Discovery crewmates, Commander Scott Horowitz, Pilot Rick Sturckow and Mission Specialists Pat Forrester and Dan Barry following yesterday's landing of Discovery at the Florida spaceport. In addition to attending to the newly arrived Progress craft, the Expedition Three crew continues to oversee a variety of science investigations. Oversight from the ground is handled by the Payload Operations Center at NASA's Marshall Space Flight Center in Huntsville, AL, except for the Human Research Facility, which is monitored and controlled from the Telescience Support Center (TSC) at the Johnson Space Center, Houston. For details on ISS science, visit http://www.scipoc.msfc.nasa.gov. The International Space Station (ISS) is orbiting at an altitude averaging 240 miles (385 km). Sighting opportunities from the ground for many cities around the world can be viewed at http://spaceflight.nasa.gov/realdata/sightings/. The next ISS status report will be issued next Wednesday, August 29, or earlier, if events warrant. _____________________________________________________________________ MARS ODYSSEY MISSION STATUS NASA/JPL release 20 August 2001 NASA's 2001 Mars Odyssey spacecraft, now 18.5 million kilometers (11.5 million miles) from Mars on its way to a rendezvous with the red planet on October 23, remains in overall good health. Flight controllers have turned off the Martian radiation environment experiment after the instrument did not respond during a downlink session last week. Following unsuccessful attempts to reset the radiation instrument, the mission manager and project officials have decided to form a team to further study the anomaly over the next several weeks and propose a course of action to recover the instrument following Mars orbit insertion on October 23. Managers suggested that the most important thing now is for the team members to devote their attention to achieving a successful Mars orbit insertion, a demanding maneuver that will require a focused team effort over the next few months. "We have limited information on the nature of the problem with the radiation experiment. The investigative team will develop a fault tree containing a list of potential causes for the behavior," said David A. Spencer, Odyssey's mission manager at NASA's Jet Propulsion Laboratory, Pasadena, CA. The spacecraft's other science payloads are working as expected. The thermal emission imaging system is made up of an infrared imager and a visible camera, and the gamma ray spectrometer instrument package contains a gamma ray sensor, neutron spectrometer and high-energy neutron detector. On Friday, August 17, the team opened and closed the valves in the spacecraft's main engine to verify that it is working properly prior to Mars arrival. On October 23, the main engine will burn for 24 minutes so the spacecraft will be captured into orbit around the planet. Today, Odyssey is traveling at 24 kilometers per second (54,600 miles per hour) relative to the Sun. The 2001 Mars Odyssey mission is managed by JPL for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology in Pasadena. The Odyssey spacecraft was built by Lockheed Martin Astronautics, Denver. NASA's Johnson Space Center, Houston, built and manages the Martian radiation environment experiment. The thermal emission imaging system is managed by Arizona State University, Tempe, and the gamma ray spectrometer is managed by the University of Arizona, Tucson. _____________________________________________________________________ STARDUST STATUS REPORTS NASA/JPL releases 21 August 2001 The Stardust spacecraft went into safe mode last Thursday, August 16. Communications with the spacecraft has been re-established and fault data has been downloaded to confirm that an error occurred onboard the spacecraft. On Monday, August 20, the Stardust spacecraft was placed back into its normal operations mode. As previously planned, two software patches will be transmitted to the spacecraft tomorrow during the normal Deep Space Network (DSN) pass, and we expect good results. 24 August 2001 The regularly scheduled Deep Space Network (DSN) pass on Tuesday, August 21 was used to restart the revised background sequence and install two flight software patches. A third flight software patch was also installed to correct a Cometary and Interstellar Dust Analyzer (CIDA) command timeout concern. The flight software code needed a longer delay time to ensure that CIDA had sufficient time to respond to commands sent to it. CIDA completed its second interstellar dust collection period on August 12. The instrument was going to remain powered on until September 12, since the spacecraft's attitude is still favorable for analyzing interstellar dust particles. Now, CIDA will remain powered off until power conditions allow it to be turned on again, probably in January 2003. For the next 15 months Stardust will be in deep space--more than 2.2 AU from the Sun--and will not have sufficient Sun power to continuously operate the science instruments. The Spacecraft Test Laboratory computer that executes simulations received a new processor card, increasing its computing capacity by approximately 25%. The existing processor was operating at its maximum capacity, and created unreliable timing performance. Testing is in progress to determine if the new processor has corrected this concern. 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, Volume 8, Number 32.