MARSBUGS: The Electronic Astrobiology Newsletter Volume 8, Number 30, 13 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) SPACE SEEDS RETURN TO EARTH By Patrick L. Barry and Tony Phillips 2) LEARN TO WASTE NOT, WANT NOT ON THE ROAD TO MARS From SpaceDaily 3) SETI AND THE SEARCH FOR LIFE By Christopher F. Chyba 4) NEW WEB SITE FOR HUMAN SPACEFLIGHT From ESA News 5) SCIENTISTS CLAIM EVIDENCE OF LIFE IN OUTER SPACE By Patricia Reaney 6) HOW THE SCUM OF THE EARTH LED TO ADVANCED LIFE By Robert Roy Britt 7) HUNTING FOR LITTLE GREEN MICROBES FROM MARS: 'VERY EXCITING TIME' FOR SCIENTISTS AT ASTROBIOLOGY MEETING By Ruth Schubert 8) ARE WE ALONE? WHERE ARE OUR NEAREST NEIGHBORS? By Edward Weiler 9) MIXED UP IN SPACE By Patrick L. Barry and Tony Phillips 10) ISS TO STUDY OVARIAN CANCER CELLS From SpaceDaily 11) EATING RIGHT FOR LONG-DURATION SPACE MISSIONS From SpaceDaily 12) JIGSAW MODEL OF THE ORIGIN OF LIFE By John F. McGowan 13) KEEP IT CLEAN SAYS NASA From SpaceDaily 14) EXTRASOLAR PLANETS WITH EARTH-LIKE ORBITS By Leslie Mullen 15) LIFE ON ICE By Lee J. Siegel 16) NEW ADDITIONS TO THE ASTROBIOLOGY INDEX By David J. Thomas 17) CASSINI WEEKLY SIGNIFICANT EVENTS NASA/JPL releases 18) THIS WEEK ON GALILEO NASA/JPL release 19) GALILEO MILLENNIUM MISSION STATUS REPORT NASA/JPL release 20) ISS STATUS REPORTS NASA/JSC releases 21) MARS GLOBAL SURVEYOR STATUS REPORT NASA/JPL release 22) STARDUST STATUS REPORTS NASA/JPL releases _____________________________________________________________________ SPACE SEEDS RETURN TO EARTH By Patrick L. Barry and Tony Phillips From NASA Science News 25 July 2001 Seed pods from a commercial gardening experiment aboard the ISS are back on our planet. The far-out pods could hold the key to long-term habitation of space. When the space shuttle Atlantis returned to Earth this morning, it brought home some unusual cargo--seed pods grown in space. They're the harvest of an 8-week-long commercial gardening experiment on board the International Space Station (ISS). Astronauts on the ISS have been tending a batch of fast-growing Arabidopsis plants (better known as "mustard weed") to discover whether plants can complete their entire seed-to-seed life cycle in a weightless environment. Video from the experiment shows that seed pods were produced by the space-borne plants. But scientists aren't yet certain what's inside the pods. "We are waiting for retrieval of the payload to see whether or not seeds are indeed inside the seed pods," says Weijia Zhou, Principal Investigator for the Advanced Astroculture? plant growth chamber that harbored and nourished the seedlings on the ISS. "Personally, I have a very high confidence level that they will have seeds," he added. Zhou is the Director of the Wisconsin Center for Space Automation and Robotics (WCSAR), a NASA Commercial Space Center that built the growth chamber. "This research is a joint endeavor between WCSAR and Space Explorers, Inc. (SEI)," explains Zhou. SEI is a private company specializing in the development of educational products for schools. Data from the Advanced Astroculture? experiment will allow SEI to complete an Internet-based multimedia program called Orbital Laboratory, which students and educators can use to study plant biology in classrooms. If normal, healthy seeds were produced as Zhou suspects, the experiment will be a good sign that future astronauts can grow multiple generations of plants in space. Such self-perpetuating gardens will be a practical necessity for humans as they explore and colonize the solar system. Hardy space plants could provide fresh food, oxygen, and even clean water for explorers living for long stretches aboard orbiting outposts or on the Moon and Mars. Now that the plants are back on Earth, scientists at WCSAR will analyze them to learn if growing in the weightless environment of free-fall had any ill effects "Most importantly, we need to see how many seeds were produced," Zhou says. Comparing the fecundity of the space-grown plants to a control group grown under identical conditions on the ground will tell researchers whether the conditions of growth--such as temperature, moisture, and fertilizer concentrations--were indeed optimal. "The second thing we need to do is conduct a final chemical analysis of the seeds to find out if there was a different phytochemistry involved," Zhou says. (Phytochemistry is a term for the chemical make-up of a plant.) If there is a difference, it would likely be caused by the weightless environment where the plants were gardened, he added. These seeds will be preserved for use in a similar experiment to be flown to the ISS by a shuttle flight currently scheduled for November 2001. Half of the seeds in that experiment will be from this space- grown batch, and the other half will be regular Earth-grown seeds. Comparing the plants and seeds produced in this follow-up experiment will tell scientists whether the conditions of space have any effect on subsequent generations of plants. Eventually gardens could become a routine part of space travel. "NASA has announced a plan to sustain a long-term human presence in space," notes Zhou. What are those astronauts going to eat? "Are they going to eat all dehydrated food, or are they going to get some fresh salad crops?" he asks. Salads and vegetables are not only good nutrition, but they could also offer an important psychological boost to diners who have spent a long time in space. Eating reconstituted foods from plastic bags is bound to grow tiresome eventually. Fresh lettuce or broccoli might be a welcome change--even for kids. Plants in space won't only be a source of food--they'll have other jobs to do as well, playing a critical role in cutting-edge life support systems. On Earth, photosynthetic organisms like plants and algae provide a natural life support system for the planet's many life forms. Plants and algae use energy from light to split water molecules into hydrogen and oxygen. Then they combine the hydrogen with carbon dioxide to make sugars, which serve as food. Oxygen is released into the air as "waste." This serves as a perfect compliment to other life forms such as animals and fungi, which use the oxygen and respire carbon dioxide. Taking a cue from nature, scientists at NASA's Johnson Space Center and Kennedy Space Center are pioneering next-generation "bioregenerative" life support systems, which use plants rather than machines to perform the chemistry of life support. Not only do plants release precious oxygen, they can also help recycle drinking water. After some processing, nutrient-rich wastewater can be used to water and fertilize the plants. Much of the water absorbed by the roots will evaporate from the leaves as pure water vapor. Condensing this water vapor out of the air creates virtually pure, distilled water that can be used for drinking. While elegant in theory, the fine details of such a system must be worked out before plants and people can live in a successful space- symbiosis. Learning to grow many generations of plants in space is an early step toward that goal. Many research teams at NASA and NASA-sponsored university projects are experimenting with plant growth for space missions, but Zhou's team is the only one at the moment that's actually growing plants in space from seed to seed. "What WCSAR and industry are doing is rather unique," Zhou says. But researchers hope it will soon be common. Fast-growing plants that thrive from generation to generation in orbit will surely produce the seeds from which human exploration of space will spring. More information on this article is available at http://science.nasa.gov/headlines/y2001/ast25jul_1.htm?list52260. _____________________________________________________________________ LEARN TO WASTE NOT, WANT NOT ON THE ROAD TO MARS From SpaceDaily 26 July 2001 When the first humans go to Mars, they will need to pack very carefully. Everything for a three-year trip will need to fit into one small spacecraft. Once on the journey, the astronauts will throw nothing away, including human waste. Precisely how to turn such waste into food, oxygen and water is the subject of an ESA project, which is building a small pilot plant outside Barcelona, Spain. The plant is shortly to be scaled-up and tested on real consumers--three rats, whose oxygen demand and carbon dioxide production is roughly equivalent to that of one human. The rats will be kept under close veterinary supervision throughout. "We are creating an artificial ecosystem which uses micro-organisms to process the waste so that we can grow plants," says Christophe Lasseur from the Melissa project team at ESA's technical centre ESTEC in the Netherlands. Melissa (Micro-Ecological Life Support Alternative) goes further than other recycling systems used on Mir or the International Space Station which purify water and recycle exhaled carbon dioxide, but do not attempt to recycle organic waste for food production. Get the full story at http://www.spacedaily.com/news/mars-base- 01b.html. _____________________________________________________________________ SETI AND THE SEARCH FOR LIFE By Christopher F. Chyba From the NASA Astrobiology Institute 30 July 2001 (Excerpts from the written testimony submitted by Christopher F. Chyba, SETI Institute, to the "Life in the Universe" hearings held by the House Subcommitee on Space and Aeronautics on July 12, 2001.) Over the past decade, there has been a rebirth in the scientific study of life elsewhere in the Universe--and for very good reasons. We've learned that organic molecules--the sort of carbon-based molecules all life on Earth is based upon--are abundant not only in our own solar system, but throughout the space between the stars. They are likely to be present in many other solar systems as well. We're finally beginning to discover other planets are out there. While we can't yet detect solar systems like our own, at a minimum we now know that planets are not rare. My own suspicion is that just about every kind of solar system that could be out there, will be out there. Our solar system will prove to be neither common nor rare, but instead just one example of a wide variety of possibilities. Within our solar system we have more and more evidence of other worlds with liquid water, which is an essential ingredient for life as we know it. Water seems to have flowed on the Martian surface in the geologically recent past. There is now strong, though still indirect, evidence for a second ocean in our solar system beneath the ice of Jupiter's moon Europa--the evidence from the Voyager and especially Galileo spacecraft missions points towards an ocean whose volume is nearly twice that of all the Earth's oceans combined. If we want to look for life in our solar system, the importance of Europa can hardly be exaggerated. Perhaps even more astonishing, there is now evidence for subsurface oceans under the ice of two of Jupiter's other large moons, Ganymede and Callisto. We've gone from thinking that Earth's ocean is unique to thinking that our ocean may be one of many. We've also learned that Earth harbors a deep subsurface biosphere, and that the mass of microorganisms beneath our feet, reaching down miles underground, likely equals or exceeds the mass of all the organisms on Earth's surface. This is a dramatically different picture of terrestrial life than the one we experience daily, and makes speculation about subsurface life on Europa or vestigial life on Mars seem much more credible. Our understanding of the Earth helps shape our thinking about other worlds, and vice-versa. The prospects for finding life elsewhere seem better than ever. But we need to remember that prospects are not proof, and it may be possible that Earth is the only planet where life exists. That would seem extraordinary, and I doubt it's likely in a galaxy with 400 billion stars, but the honest answer is that we don't know yet. But we can use scientific exploration to try and find out. The SETI (Search for ExtraTerrestrial Intelligence) Institute is a private scientific institute dedicated to research, education, and public outreach. Its mission is to use scientific methods to investigate the origin, nature, and prevalence of life in the Universe. SETI Institute scientists investigate everything from the formation of stars and planets to the development of advanced technical civilizations. Research topics include, for example, interstellar organic chemistry, planet formation, the search for extrasolar planets, the chemistry of life's origins, microbiology and life in extreme environments, planetary climatology and habitability, Mars and Europa, and the role of asteroid and comet impacts in the history of life on Earth. By understanding the many factors that make a world habitable for complex life, we can put the search for extraterrestrial civilizations into context. For instance, by learning more about the history of life on Earth, we can try to track the events that have led to the development of intelligence. But we don't know whether the evolution of human-style technical intelligence is something that will prove to be incredibly rare or common. Finding evidence for such intelligence elsewhere would have a profound effect on humanity. One of SETI's best-known projects is the search for artificially produced radio signals in the vicinities of nearby stars. Many natural objects in the Universe produce radio waves (including our own Sun), but no naturally occurring source in the Universe is known that produces bandwidths thinner than 300 Hz (Hertz, a measure of frequency equal to one cycle per second). So the first criterion of an artificial signal is a very narrow spectral bandwidth. In fact, we look for bandwidths below about 1 Hz in width. This wavelength of the signal is extremely precise and highly efficient, because narrow- band signals pack a lot of energy into a small amount of spectral space. Any object producing extremely narrow bandwidth signals is either artificial or represents some entirely unknown astrophysical phenomenon. To give some sense of how sensitive our radio searches are, it's worth mentioning that we have for many years tested our system by using the signal transmitted by the Pioneer 10 spacecraft, launched from Earth in 1972 and now traveling beyond our Solar System. Pioneer 10 is at a distance of 6 billion miles from Earth and broadcasting with a power of a few watts--much less than a light bulb in your house, but about the power of a small flashlight. It takes more than 10 hours for Pioneer 10's radio signal, traveling at the speed of light, to reach Earth. Because Pioneer 10 really is an extraterrestrial (even extra-Solar System!) artificial source, it provides an excellent test for our system--and it comes in loud and clear. Since SETI gets so much media attention, it is easy to get the mistaken impression that SETI researchers have searched the galaxy thoroughly for alien radio signals, yet have found nothing. But in fact we've only examined about one-billionth of the galaxy so far. We're looking at the thousand nearest Sun-like stars that lie within about 150 light years of Earth. This is only a tiny fraction of the entire Milky Way galaxy, which contains some 400 billion stars and is 100,000 light years across. Even if alien signals are detected someday, it is unlikely that an interstellar dialogue would occur, except over extremely long time scales. If we detect a signal from a star 100 light years away, that message was sent 100 years ago - so that two-way communication would require 200 years for each reply. It is quite possible that, while we could detect the signal's carrier wave, we would not have the sensitivity to detect whatever message might be carried by that wave. Even if we could, it is difficult to predict how difficult decipherment might prove to be. A possible analogy could be the decipherment of inscriptions left by the ancient Maya, which proved extremely difficult. Even in this case, we had the advantage of being able to apply linguistic knowledge from extant Maya languages. And of course, we share a genetic and sociological heritage with any other human culture that we will not share with an extraterrestrial civilization. Nevertheless, if we detect an extraterrestrial radio signal, we will at least have in common the physics and mathematics that made that transmission possible, and this could be a starting point. The scientific Search for Extraterrestrial Intelligence enjoys great public interest. We see this every day at the Institute, where we serve as a resource for the press covering topics across the range of life in the Universe studies. Our web site (www.seti.org) receives about two million hits per month. We view this kind of interest as a tremendous opportunity to teach students and the general public about science and the scientific method -that blend of openness to new ideas coupled with an insistence on hard evidence and skeptical analysis of data. The goals of the SETI Institute fit naturally with the fundamental questions at the heart of NASA's Astrobiology program: "Does life exist elsewhere in the Universe, or are we alone?" and "What is life's future on Earth and beyond?" Whether any other intelligent civilizations exist elsewhere is a natural extension of these questions. The scientific investigation of these questions is exciting, inspiring, and eventually may help humanity find its place in the Universe. More information on this article is available at http://nai.arc.nasa.gov/index.cfm?page=seti_life. _____________________________________________________________________ NEW WEB SITE FOR HUMAN SPACEFLIGHT From ESA News, http://www.esa.int 31 July 2001 Do you want to know how to be an astronaut, what is going on at the International Space Station or how to carry out research in space? ESA's new site on human spaceflight is now on line and should be able to supply you with most of the answers. The web site of ESA's Directorate of Manned Spaceflight and Microgravity has been redesigned to make it more in line with the ESA Web Portal philosophy: news-oriented, image-rich factual and up-to-date. On the new site information can be found under five main headings: Astronauts, the International Space Station, Research in Space, Education and the Future. The wide variety of subjects covered range from what life is like on a spacecraft; the possibilities of finding life once you get there; to how children, and adults, can have their experiments undertaken on the International Space Station. Sounds interesting? Check it out on Human Spaceflight, http://www.esa.int/export/esaHS/. _____________________________________________________________________ SCIENTISTS CLAIM EVIDENCE OF LIFE IN OUTER SPACE By Patricia Reaney From Reuters/Space.com 31 July 2001 A team of international researchers said on Tuesday they have found what could be the first proof of life beyond our planet--clumps of extraterrestrial bacteria in the Earth's upper atmosphere. Although the bugs from space are similar to bacteria on Earth, the scientists said the living cells found in samples of air from the edge of the planet's atmosphere are too far away to have come from Earth. "There is now unambiguous evidence for the presence of clumps of living cells in air samples from as high 41 kilometers (25 miles), well above the local tropopause (16 kilometers up), above which no air from lower down would normally be transported,'' Professor Chandra Wickramasinghe, an astronomer at Cardiff University in Wales, said in a statement. He presented the findings to a meeting of the International Society of Optical Engineering in San Diego, California. Get the full story at http://www.space.com/searchforlife/bacteria_space_010731.html. _____________________________________________________________________ HOW THE SCUM OF THE EARTH LED TO ADVANCED LIFE By Robert Roy Britt From Space.com 3 August 2001 Look at any stagnant pond and you'll see a reflection of early Earth- -green scum. It's the way things were back before the planet had enough oxygen to allow life to evolve a little, to breathe, to get some legs under it and trot around. Your scummy ancestors had the planet to themselves up to about 2.2 billion years ago. These single- celled organisms were the only things that could survive on a diet nearly bereft of oxygen. But then things changed. Something, someone, or some process suddenly pumped Earth's atmosphere full of oxygen. Life was good, and it flourished. Fossil records show that the first complicated, multi-celled organisms appeared 2.1 billion years ago. Researchers have puzzled for decades over what caused the breath of fresh air. A pair of new studies finds evidence that it was the scum of the Earth itself that made higher life forms possible. Get the full story at http://www.space.com/scienceastronomy/planetearth/life_oxygen_010803. html. _____________________________________________________________________ HUNTING FOR LITTLE GREEN MICROBES FROM MARS: 'VERY EXCITING TIME' FOR SCIENTISTS AT ASTROBIOLOGY MEETING By Ruth Schubert From The Seattle Post-Intelligencer 6 August 2001 When scientists get together to talk about extraterrestrial life, they certainly don't imagine little green men. In fact, our first contact with life beyond our planet probably will involve a microbe. Although it doesn't hold the Hollywood appeal of coming face to face with an alien biped, the search for signs of microbial life in the universe is generating a lot of excitement these days. "Any discovery of extraterrestrial life--even if it's microbial life- -would be among the most significant scientific discoveries ever," said Chris Chyba, who holds the Carl Sagan chair at the SETI (Search for Extraterrestrial Intelligence) Institute in Mountain View, California. Chyba is among the scientists gathered at Crystal Mountain this week for the first astrobiology conference held by the University of Washington. Get the full story at http://seattlep- i.nwsource.com/local/34079_spacelife06.shtml. _____________________________________________________________________ ARE WE ALONE? WHERE ARE OUR NEAREST NEIGHBORS? By Edward Weiler From the NASA Astrobiology Institute 6 August 2001 (Excerpts from the written testimony submitted by Edward Weiler, Associate Administrator for Space Science, National Aeronautics and Space Administration, to the "Life in the Universe" hearings held by the House Subcommiteee on Space and Aeronautics on July 12, 2001.) "There are countless suns and countless Earths all rotating around their suns in exactly the same way as the seven planets of our system. We see only the suns because they are the largest bodies and are luminous, but their planets remain invisible to us because they are smaller and non-luminous. The countless worlds in the universe are no worse and no less inhabited than our Earth." These words, written in 1584 by Giordano Bruno, lay out the major challenge of NASA's Origins program--namely, to use 21st century science to discover whether Earth-like planets exist beyond our Solar System and whether any of those planets are habitable, or even inhabited, by primitive life. The public and the scientific response to NASA's search for habitable planets and life has been considerably more enthusiastic than that of Bruno's contemporaries, who had him burned at the stake in 1600. So how do we determine whether or not a planet has life? When the Galileo spacecraft flew by Earth on its way to Jupiter, the spacecraft turned its instruments toward Earth to look for signs of life. Other than the radio signals and the lights being on at night, the signs of life from Earth were surprisingly subtle. There was a complex green color on the continents (which we know are plants) and chemicals like carbon dioxide, oxygen, methane, and nitrites coexisting in the atmosphere--a chemical impossibility unless maintained by something like life. But Earth did not always have this kind of atmosphere. Early Earth hosted a high-temperature, non-photosynthetic biosphere that was rich in carbon dioxide and poor in oxygen. Life on Earth was microbial and acquired energy-consuming hydrogen and sulfide, resulting in a broad array of reduced carbon and sulfur gases. What chemicals would be identifiable signs of life in the early Earth's atmosphere? The challenge to astrobiologists is to determine what biosignatures can be expected on any living planet. To this end, astrobiologists are studying microbial ecosystems in extreme environments here on Earth as microcosms of what might have been on early Earth and what may be possible on extrasolar planets. Techniques currently used in the search for extrasolar planets One of the most successful means of discovering extrasolar worlds is the Doppler technique. The small tug of a planet on its parent star causes a small (only a few miles an hour) variation in the velocity of the star. This variation can be detected by measuring the Doppler shift--the change in frequencies of the light when the star is moving toward us versus moving away from us. To date, we have found almost 75 stars showing significant Doppler variations. From these we have learned that approximately 7 percent of stars like the Sun have large planets located within a few Astronomical Units (the Earth-Sun distance, or AU). These large planets range from 0.2 Jupiter masses to approximately 15 Jupiter masses. Although masses measured with the Doppler technique suffer from an ambiguity related to the orientation of the orbital plane to the line of sight, the vast majority of objects detected to date are certainly much less massive than stars--most are gas giant planets similar to Jupiter or Saturn. The recent measurement of one object that happens to pass directly in front of its star (as seen from Earth) has shown definitively that this object is a planet with a mass slightly smaller than Jupiter's and with the density of a light, gas giant planet like Saturn. More than half of the stars under study may have additional planets on more distant, longer period orbits. The data strongly suggest the existence of a large number of objects that are just below the present limits of detection. While multiple systems eventually may prove to be common, as yet we know of no similar counterpart to our own solar system. Furthermore, the broad range of eccentricities and small orbital radii of the known giant planets may be inconsistent with the stable conditions needed for the formation and survival of habitable, terrestrial planets. Some have argued that these results mean solar systems like our own are rare. However, most scientists would respond that this is because the Doppler technique is fundamentally limited to finding massive planets on short-period orbits. Before being discouraged about the prospects for finding other Earths, we should note that we do not yet have the observational capability to find solar systems like our own! The promise of astrometry A second indirect planet-search technique looks for the positional (astrometric) wobble of a star induced by the presence of a planet. NASA has two complementary astrometric experiments aimed at planet detection: the Space Interferometer Mission (SIM) and the Keck Interferometer (Keck-I). SIM will have the exquisite sensitivity needed to detect planets of just a few Earth masses in 1 to 5 AU orbits around stars as far away as 30 light years. SIM will push the detectable mass limits for planets around the nearest stars into the range predicted for the "rocky" as opposed to "gas giant" planets. Keck-I will be less sensitive than SIM, but because it will operate for up to 25 years, Keck-I will be able to find planets as massive as Uranus on long-period orbits. Together SIM and Keck-I will provide a complete and unbiased census of thousands of nearby stars to determine whether systems more similar to our own are the exception or the rule. The challenge of direct detection and the Terrestrial Planet Finder While indirect techniques are very powerful at finding planets, the search for habitability and for life requires that we directly detect the planets and use spectroscopic analysis to learn about their physical and atmospheric conditions. Thus, the goal of the Terrestrial Planet Finder (TPF) is to find and characterize any Earth-like planets orbiting 250 of the closest stars. This search will focus on the habitable zone, which is defined by the range of temperatures where liquid water, and thus the conditions for the formation of life, might be present. TPF will make detailed observations of the atmospheres of the most promising candidates to search for the spectral signatures of habitability and of life. Understanding the conditions needed for life and identifying promising bio-signatures requires a close and continuing collaboration with biologists, atmospheric chemists, and geologists. NASA's astrobiology scientists have been intimately involved in setting the observing requirements for TPF. While the launch of TPF is more than a decade away, we are not standing still in terms of expanding our scientific knowledge. The results of other projects will help us to understand better the difficulty of the TPF challenge by finding out, for example, the distance to the nearest systems likely to harbor Earths. We are also beginning to think about the next steps beyond TPF, including a "Planet Imager" to provide more detailed images and/or spectroscopy of any planets found by TPF. What will be the legacy of NASA's Origins program as seen from 20 years in the future? We will have a complete census of the planets orbiting thousands of stars over a wide range of periods (from days to decades), planetary masses (from Jupiter's to Earth's), and distances (a few to a few hundred light years). We will have correlated these facts with the properties of the parent stars to develop a deeper understanding of the physical processes controlling the formation and evolution of planetary systems. We will have identified what nearby stars, if any, harbor analogs to our solar system with its stable habitable zone. From this information we will understand whether our Solar System and our Earth are common or rare. And, if we are lucky, we will have found one or more places where the complex physical and chemical processes we call life were able to develop. Through the NASA's Origins program, we are beginning to answer one of the longest standing questions in the history of the human intellect: are we alone? Additional information on this article is available at http://nai.arc.nasa.gov/index.cfm?page=weiler. _____________________________________________________________________ MIXED UP IN SPACE By Patrick L. Barry and Tony Phillips From NASA Science News 7 August 2001 Imagine waking up, startled by the bright flash of a cosmic ray inside your eyes. Groggy from sleep, you wonder... which way is up? And where are my arms and legs? Throw in a dash of vertigo and occasional mild illusions, and you're beginning to sense what it can be like to live in orbit. Of course, it's not always so bad-- otherwise no one would want to become an astronaut! Nevertheless, first-time space travelers can be surprised by some very unearthly sensations that can confuse and amuse the astronauts who feel them. Consider, for example, "up" and "down." On Earth we always know which way is up because gravity tell us. Sensors in the inner ear, which are part of the body's vestibular system, can feel the pull of gravity. They signal the brain with information about our body's orientation. In space, however, the vestibular system doesn't sense the familiar pull of gravity. The world can suddenly seem topsy- turvy. Former shuttle astronaut Robert Parker recalls: "One of the questions they asked us during our first flight was, 'Close your eyes... now, how do you determine up?'" With his eyes closed, he couldn't tell. Up and down had vanished. Another astronaut reported a strange experience when he woke up one day in orbit. As he opened his eyes the room was rotating around him! Or so it seemed. Back on Earth he always slept on his right side. By force of habit his brain expected "up" to be on his left at wake-up time. He awoke in space to find the ceiling directly above his head. And he felt an odd sensation as his brain adjusted. "My reference frame rotated clockwise until [the room] aligned with my own personal sense of up," he recalled. "The sensation was so definite and strong that I could almost feel myself [turning] counterclockwise." Space travelers in science fiction rarely have such problems. On Star Trek's USS Enterprise, for example, artificial gravity provides direction cues for the crew. Captain Kirk never gets out of bed upside-down. Without artificial gravity, however, the designers of the real-life International Space Station and the Space Shuttle must rely on different tricks to establish a common sense of "up". For example, all of the modules on the ISS will have a consistent "up" orientation. And the writing on the walls points in the same direction, too. Shuttle mission specialist John-David Bartoe remembers his first days in orbit: "I followed the advice from my commander, Gordon Fullerton. He recommended that for the first few days we always keep ourselves oriented up with respect to the writing on the walls and with respect to the other crewmembers. This worked fine for me. After day two I was more adventurous and would turn upside down for fun--I had no problem!" The vestibular system isn't the only one affected by the absence of weight. The proprioceptive system--that is, nerves in the body's joints and muscles that tell us where our arms and legs are without having to look--can also be fooled. Without the stresses in the joints usually caused by the pull of gravity, this sense is sometimes dampened. "The first night in space when I was drifting off to sleep," recalled one Apollo astronaut, "I suddenly realized that I had lost track of... my arms and legs. For all my mind could tell, my limbs were not there. However, with a conscious command for an arm or leg to move, it instantly reappeared--only to disappear again when I relaxed." Another astronaut from the Gemini program reported waking in the dark during a mission and seeing a disembodied glow-in-the-dark watch floating in front of him. Where had it come from? He realized moments later that the watch was around his own wrist. These sorts of mismatches between what the eyes see and what the body feels can trigger a malady called "space sickness." Scientists think it's much like "car sickness," which you can get right here on Earth by trying to read in a moving car. The inner ear detects the motion of the car but the eyes--staring at a page filled with unmoving words--do not. "When people go up into space, many will immediately get space sickness," says Dr. Victor Schneider, research medical officer for NASA's Biomedical Research and Countermeasures Program. While a few astronauts are apparently immune, most can experience symptoms ranging from mild headaches to vertigo and nausea. In extreme cases prolonged vomiting can make an astronaut dehydrated and malnourished. Fortunately, the brain quickly adapts. It learns to trust the eyes and reprograms signals from the vestibular system to reconcile the mismatch. "Space sickness relieves itself after about 3 days, although individual astronauts and cosmonauts may have a relapse at any time during their mission," Schneider says. Indeed, space sickness is capricious--when it will happen and who will get it can be hard to predict. Some astronauts who show an exceptional tolerance to motion sickness when flying jets suffer the worst symptoms upon arriving in space. "This occurs on Earth as well," adds Schneider. "For example, gymnasts who perform acrobatics and do not get motion sick may get sick on a roller coaster or in the back seat of a moving car." Figuring out how to prevent space sickness--and how to treat it when it happens--is a high priority for NASA. For that reason, in 1997, NASA helped establish the National Space Biomedical Research Institute (NSBRI) where researchers study how humans adapt to weightlessness and develop "countermeasures" against maladies like space sickness. Much of the NSBRI's research is conducted on Earth and can directly benefit millions of patients that never leave our planet. For example, an estimated two million American adults suffer chronic impairment from dizziness or difficulty with balance. And nearly one quarter of all emergency room visits include a complaint of dizziness. Figuring out why we're mixed up in space can have some down-to-Earth benefits! Key issues under investigation at the NSRBI include the psychology of long-term space flight, physical changes to bones and muscles in weightlessness, and of course the adaptation of the vestibular system. Science@NASA will explore these questions and more in a series of ongoing articles about humans in space. More information on this article is available at http://science.nasa.gov/headlines/y2001/ast07aug_1.htm?list52260. _____________________________________________________________________ ISS TO STUDY OVARIAN CANCER CELLS From SpaceDaily 8 August 2001 When the space shuttle Discovery blasts off on its next mission (scheduled August 9), it will take ovarian cancer into space for the first time. Part of a joint project between University of South Florida College of Medicine and the National Aeronautics and Space Administration, the ovarian cancer cells are headed to the International Space Station to grow for two weeks in a near-gravity- free environment. The goal is to develop three- dimensional cancer cell clusters that function more like cancer in humans than the two- dimensional cell cultures traditionally grown in petri dishes. Get the full story at http://www.spacedaily.com/news/iss-science- 01b.html. _____________________________________________________________________ EATING RIGHT FOR LONG-DURATION SPACE MISSIONS From SpaceDaily 8 August 2001 During long-duration space flights, astronauts often don't eat as much as they should, which can cause weight loss and other nutritional concerns, such as low levels of vitamin D. In a recent study astronauts who lived aboard the Russian space station Mir, and counterparts living in seclusion on Earth, has validated a tool for measuring astronauts' dietary intake during long space flights. "We have developed a program that helps us ensure that crewmembers go to space with an optimal nutritional status, and that we do everything we can to help them remain healthy while they are there," said Dr. Scott M. Smith, lead author on the paper and a nutritionist in the Life Sciences Research Laboratories at the NASA Johnson Space Center (JSC) in Houston, Texas. Get the full story at http://www.spacedaily.com/news/food-01f.html. _____________________________________________________________________ JIGSAW MODEL OF THE ORIGIN OF LIFE By John F. McGowan 8 August 2001 It is suggested that life originated in a three-step process referred to as the jigsaw model. RNA, proteins, or similar organic molecules polymerized in a dehydrated carbon-rich environment, on surfaces in a carbon-rich environment, or in another environment where polymerization occurs. These polymers subsequently entered an aqueous environment where they folded into compact structures. It is argued that the folding of randomly generated polymers such as RNA or proteins in water tends to partition the folded polymer into domains with hydrophobic cores and matching shapes to minimize energy. In the aqueous environment, hydrolysis or other reactions fragmented the compact structures into two or more matching molecules, occasionally producing simple living systems, also known as autocatalytic sets of molecules. It is argued that the hydrolysis of folded polymers such as RNA or proteins is not random. The hydrophobic cores of the domains are rarely bisected due to the energy requirements in water. Hydrolysis preferentially fragments the folded polymers into pieces with complementary structures and chemical affinities. Thus the probability of producing a system of matched, interacting molecules in prebiotic chemistry is much higher than usually estimated. Environments where this process may occur are identified. For example, the jigsaw model suggests life may have originated at a seep of carbonaceous fluids beneath the ocean. The polymerization occurred beneath the sea floor. The folding and fragmentation occurred in the ocean. The implications of this hypothesis for seeking life or prebiotic chemistry in the Solar System are explored. The full article is available at http://www.jmcgowan.com/JigsawPreprint.pdf. _____________________________________________________________________ KEEP IT CLEAN SAYS NASA From SpaceDaily 8 August 2001 The Aerospace Corporation has landed a follow-on effort with NASA's Jet Propulsion Laboratory (JPL) to continue researching the effectiveness of spacecraft cleaning methods used by NASA in missions to planets and moons that could harbor life. A second $50,000 task came to Aerospace as a result of successful research in the same area that was completed for JPL in October 2000. "Sterilization of spacecraft is very important for NASA missions to planets and moons that could potentially harbor life," explained Dr. Carl Palko, a project engineer involved in the research. "Outbound sterilization and cleaning is important to prevent both the accidental contamination or infection of alien worlds with terrestrial organisms and the accidental contamination of extraterrestrial soil or ice samples being returned to Earth with terrestrial organisms that could be mistaken as evidence for alien life," Palko said. Get the full story at http://www.spacedaily.com/news/life-01zc.html. _____________________________________________________________________ EXTRASOLAR PLANETS WITH EARTH-LIKE ORBITS By Leslie Mullen From the NASA Astrobiology Institute 8 August 2001 Most of the planets discovered outside our solar system don’t have orbits like Earth’s. Either the planets are closer to their stars, with orbital periods of only a few days, or they have highly elliptical orbits--some of which better resemble the paths of comets. Recently, however, a team of astronomers from the Geneva Observatory in Switzerland announced they had discovered a planet with an orbital path very similar to Earth’s. Dubbed HD 28185 b, this planet has a nearly circular orbit and is about the same distance away from its star as the Earth is from the Sun. HD 28185 b is 150.6 million kilometers from its star; the Earth is 149.6 million km from the Sun--a difference of only 1 million kilometers. HD 28185 b takes 385 days to orbit its star, twenty days longer than the orbital period of Earth. An Earth-like orbit would tend to give a planet relatively stable temperatures. This would increase the chances that any water on the planet would be able to remain in liquid form. Finding planets with liquid water is one of the key goals of astrobiology, because water is believed to be essential for life. Because of this very Earth-like orbit, is it possible that HD 28185 b could harbor life? At present, there’s no way to tell for sure. There is no evidence of water existing on HD28185 b. In fact, the planet is massive enough to be a gas giant resembling Jupiter, and if water was present on the planet it would most likely not resemble the bodies of water found on Earth. The extrasolar planet does share another life-friendly condition with Earth: Just as the orbit of HD 28185 b is similar to the Earth’s, the star it orbits is very similar to our Sun. Like our Sun, the star HD 28185 is a G-class main sequence yellow star. The "G" refers to the temperature of the star (other temperature classes are O, B, A, F, K and M). A "main sequence" star is a star in the middle of its life cycle. The Sun and HD 28185 are not exactly the same temperature however--HD 28185 is a G5 star, whereas our Sun is a G2 (which means our Sun is hotter). Only one other extrasolar planet that we know of--iota Hor b, discovered in 1999--has orbital conditions similar to the Earth’s. That planet has an orbital period of 320 days, and orbits about 145 million kilometers away from its star, a G5 yellow star named iota Horologii. Like HD 28185 b, iota Hor b is probably a gas giant planet similar to Jupiter. Iota Hor b has a mass of at least 2.26 times that of Jupiter, or 720 times the mass of Earth. HD28185 b has a minimum mass of 3.5 times that of Jupiter, or about 1000 times that of the Earth. Many scientists agree that life is unlikely to appear on giant gaseous planets. "The very large mass of this planet would almost certainly preclude the development of multicellular life," says Peter Ward, planetary geologist with the University of Washington and member of the NASA Astrobiology Institute. "While there might be some possibility of microbial life, even that seems a bit unlikely, because of the high pressures." For life as we know it to survive in these distant solar systems, extrasolar worlds would need to be terrestrial rather than gaseous, says Ward. "The planet should be stony like ours," says Ward. He also says an extrasolar planet able to sustain complex life should, "have water, and have the phenomena known as plate tectonics--which on Earth acts as our planetary thermostat." Such conditions could potentially be met on any moons that may orbit these extrasolar planets. Moons tend to be rocky, and water and tectonics on moons are possible. It is thought that Jupiter’s moon Europa, for instance, may have a liquid water ocean and possibly even some sort of tectonic activity. Extrasolar moons of HD 28185 b and iota Hor b, if they exist, would have the additional advantage of getting enough solar radiation to support Earth-like temperatures. This would help keep water liquid, although it may not be necessary for life to appear. According to Chris Chyba, director of the Center for the Study of Life in the Universe at the SETI Institute, while it is important to have temperatures above the freezing point of water at least some of the time, stable temperatures are not needed for life to gain a foothold. "I don’t see any reason to think that widely varying temperatures are a problem for the origin of life, and they may be an advantage," says Chyba. "Freeze-thaw cycles might help provide higher concentrations of prebiotic organic molecules needed for the origin of life." However, says Chyba, "it is difficult to know to what extent wide temperature fluctuations would inhibit multi-cellular life from flourishing." So, although any moons orbiting HD 28185 b in the Earth-zone would not necessarily have an edge in the emergence of life, their position would help keep water liquid and would seem to be more amenable to sustaining any complex multicellular life that might evolve there. But according to Ward, extrasolar moons have other qualities that would make sustaining complex life a tricky proposition. "The problem is that any such moon would probably be tidally locked, where the same side is always facing the larger planet," says Ward. This would mean that some parts of the moon would always be exposed to sunlight, while other parts would be perpetually cold and dark. But Chyba disagrees. "I see no reason whatsoever why it would matter to the prospects of either simple or complex life on a Moon orbiting a giant planet whether or not that Moon were tidally locked," he says. Ward says another limitation is that "large Jupiters tend to get bombarded more than smaller planets. Because of this, any moons would likely be subject to repeated bombardment, which is not good for complex life." But Chyba says that moons orbiting Jupiter-like planets are not necessarily more prone to get hit by asteroids and comets. "The impact rate for kilometer-sized bodies to strike Europa is perhaps once every couple of million years--this is a bit less than the impact frequency of kilometer-sized objects hitting Earth," says Chyba. The discoverers of HD 28185 b are Michel Mayor, Dominique Naef, Francesco Pepe, Didier Queloz, Nuno Santos, Stephane Udry, and Michel Burnet. The astronomers used the radial velocity technique to find the planet. This technique looks for a wobble in a star caused by the gravity of the orbiting planet. The wobble shows up as a periodic change in the spectrum of the star’s light. This change can be measured by high-resolution spectrographs mounted on telescopes. The scientists measured the shift of HD 28185 using the CORALIE spectrometer on the Swiss 47-inch (1.2-meter) Leonard Euler telescope at the European Space Observatory's La Silla Observatory. Instruments on telescopes at the Haute-Provence Observatory in France and on the twin Keck telescopes on Mauna Kea, Hawaii were also used to verify the findings. A puzzle astronomers need to solve is how these two gas giant planets ended up in such Earth-like orbits. Many of the extrasolar planets with circular orbits found thus far have been extremely close to their stars, with orbits of only a few days. The current model for these short-orbit "hot Jupiters" is that they formed in the colder regions of their solar system and then migrated in, because the regions where they are now located are too warm for gas giant planet formation. Perhaps the two Jupiter-mass planets in Earth-like orbits will help scientists better understand the evolution of such extrasolar planets. What’s next? A fundamental limitation of the radial velocity method is that it doesn’t allow astronomers to determine the inclination of the planetary orbit relative to Earth. As a result, only lower limits can be set for the masses of planets found using this technique. The astronomers at the Geneva Observatory plan to use new interferometer systems on telescopes to better determine the masses of the extrasolar planets. According to Laurance Doyle of the SETI Institute, it may also be possible to read the spectrum of light reflecting off HD 28185 b. This could tell us whether or not the planet’s atmosphere is favorable to any forms of life. "The reflected light spectral lines from the planet will be Doppler- shifted away from those of the star," says Doyle. Thus, they will be visible as a distinct signature. Doyle also says that although detecting any moons orbiting HD 28185 b would be difficult, it could be done indirectly. The moons would have the effect of causing an apparent delay in the orbit of the planet. "I've calculated that the moon Callisto by itself would delay Jupiter's transit by about 8 seconds, so perhaps this also is a possible way to detect moons around giant [extrasolar] planets," says Doyle. More information on this article is available at http://nai.arc.nasa.gov/index.cfm?page=earth_zones. _____________________________________________________________________ LIFE ON ICE By Lee J. Siegel From the NASA Astrobiology Institute 10 August 2001 From Arctic sea ice to Antarctic lakes and dry valleys, scientists study microbes that tolerate freezing temperatures on Earth to learn where to look for life on other worlds. Among the possibilities are fossils in ancient Martian lakebeds and bacteria wrapped in mucus and ice on Jupiter’s moon Europa. "It’s terribly important that we learn more about cold-adapted microbes because all the environments we even contemplate for supporting life elsewhere [in our solar system] are cold," says microbiologist Jody W. Deming, an oceanography professor at the University of Washington in Seattle. "We need to know how all forms of life are managing at supercold temperatures in our search for extraterrestrial life. The surfaces of Mars and Europa are both very, very cold, so any samples we might ever obtain from Mars or Europa are going to be frozen." Cold-loving or psychrophilic organisms--psychro is the Greek word for cold--are microbes that can grow and replicate at temperatures between 15 degrees Celsius (59 degrees Fahrenheit) to about minus 15C (5F), and can survive at even frostier temperatures, Deming says. She says researchers routinely store bacteria in the lab at minus 80C (minus 112F), and some survive. True psychrophiles die when it gets warmer than about room temperature (20C, or 68F), so most of those on Earth live in ocean watersaquatic environments such as the ocean, where temperatures that remain much coolerremain stable, says biologist and NASA Astrobiology Institute member Imre Friedmann, of NASA’s Ames Research Center in Mountain View, CA. Because land temperatures fluctuate, he explains, "in terrestrial environments, there are practically no psychrophiles," only "psychrotolerant" organisms that can survive either cold or warm temperatures. Earth’s psychrophilic and psychrotolerant organisms include archaea-- the most primitive bacteria-like life forms--bacteria, algae, cyanobacteria (nicknamed blue-green algae) and fungi. Most thermophiles, or heat-loving organisms, are primitive and evolved soon after the origin of life on Earth, perhaps near seafloor volcanic vents. But cold-adapted organisms occur in different groups on the evolutionary tree, so Friedmann believes the ability to adapt to cold evolved independently in different organisms. On Earth, many cold-loving and cold-tolerant microbes live in large masses in the oceans, some forming blooms, such as toxic cyanobacteria responsible for killing seals in the North Sea, says microbiologist David Wynn-Williams, astrobiology project leader for the British Antarctic Survey. Cold-tolerant algae are responsible for red-tinged snow in glaciers and polar ice. Other psychrotolerant microbes live within the fabric of rocks in the Antarctic desert and at the edge of the Antarctic ice sheet, as well as and onthe floors bottoms of ice-covered Antarctic lakes. Deming believes "sea ice is a seed bed for cold-adapted microbes that appear everywhere else in the ocean." She and her colleagues use snowmobiles and sleds to sample Arctic sea ice off Barrow, Alaska, in winter. Deming says Karen Junge, a doctoral student at Washington, found evidence of bacteria surviving- -and even metabolically active--at minus 20 C (minus 24 F) in winter sea ice. Survival strategies Deming says some bacteria survive in sea ice by secreting antifreeze chemicals called she calls "exopolymers" or "organic goop." "A layman’s word is mucus," she says. "The bacteria just surround themselves with mucus. It keeps them in a fluid environment. It protects them against freezing, against actual ice crystal damage to their cell walls," and against high salt concentrations. "We think this mucus also keeps the pore spaces inside the ice large enough so the bacteria aren’t crushed by the ice," she adds. If mucus-coated microbes live within the upper layers of the sea ice believed to cover Europa, Deming speculates, the exopolymers might change reflectance of the ice in a way orbiting spacecraft could detect--a possibility that requires more research. Many terrestrial organisms, including some yeasts and nematode worms, survive extreme cold by producing trehalose, a sugar that replaces water and prevents vital proteins such as enzymes from collapsing, enabling them to survive when conditions are cold and dry, Wynn- Williams says. Deming says Junge’s research has uncovered another survival trick: "Something like 99 percent of the active bacteria in wintertime sea ice are attached to some surface," either pore walls within ice, mineral grains or salt crystals. "This becomes very exciting in searching for life on Europa because the surface of Europa is peppered with dark red-brown areas where planetologists think salt has been deposited," Deming says. She suspects cold-loving bacteria adhere to surfaces for the same reason microbes grow on the walls of sewage pipes: liquid flowing through ice pores delivers nutrients and carries away wastes. Wynn-Williams, a member of the NASA Astrobiology Institute (NAI), notes that cold-tolerant microbes also survive because their cell membranes "remain relatively fluid at low temperatures." Yet another survival technique is suspended animation. Wynn-Williams says a pond in Antarctica’s Taylor Dry Valley is saturated with so much calcium chloride that it does not freeze until minus 53C (minus 63F), yet bacteria survive there--barely. "They are not doing anything," says Wynn-Williams. "Microbes that live inside rock ridges in the Antarctic dry valleys take 10,000 years to metabolize a single molecule of carbon dioxide." It’s cold out there Antarctica’s Lake Vostok, some 23 kilometers (14 miles) long, is permanently covered by a 3.7-kilometer (2.3-mile) layer of ice. Bacteria have been found in this overlying ice, but Wynn-Williams wants to look for microbes in lake-floor sediments, which are at least 500,000 years old and free from human contamination. He says Vostok "is a Europa analog. You’ve got to go through an ice sheet, through a water column and down to the bottom sediments." Wynn-Williams expects that on Europa heat-loving microbes living near seafloor hot-water vents are more likely than cold-tolerant organisms. Yet he says cold-tolerant microbes might have evolved if any heat-loving bugs near Europa’s seafloor were carried upward to the ice. Friedmann is less optimistic. He doubts there is volcanism or adequate convection for either heat- or cold-loving life on Europa. He thinks that even if conditions for life are present, it’s difficult to imagine how life could have originated on Europa or transported there from Earth or from Mars. Antarctica also offers environments similar to habitats on Mars, in which cold-adapted organisms once lived--or might still be living. If life evolved on Mars, it may have done so earlier than life on Earth, because Mars cooled earlier to a temperature that could support a biosphere. Earth was remelted 4.55 billion years ago, after it first cooled, by a massive collision with another object. (That collision formed the Moon.) But because Mars is so much smaller than Earth, it continued rapidly cooling and eventually froze, dying volcanically and biologically while Earth remained alive, says Chris McKay, a planetary scientist at Ames Research Center and an NAI member. The last surviving organisms on Mars likely were adapted to low temperatures. "Mars would have gotten cold," McKay says. "It would have become like the Antarctic dry valleys. Organisms we find in the cold desert regions of Earth are the best models for what life may have been like on Mars early in its history." Antarctica’s dry valleys "are so dry because there is very little precipitation and the mountains block the flow of ice from elsewhere," he says. Yet annual summertime glacial runoff maintains ice-covered lakes that harbor algae and bacteria, which collect in lakebed sediments. Wynn-Williams says that as Mars cooled and dried up, "the abundant water available originally would have receded into ice-covered lakes like [those that exist today] in the dry valleys." Then, after these Martian lakes evaporated, "it is conceivable that organisms were alive in rocks, like in Antarctic rocks," which harbor algae, fungi, bacteria and cyanobacteria, Friedmann says. But "one of the best places too look for evidence of life on Mars is to look for ancient lakebeds that would have been ice-covered lakes billions of years ago," says McKay, noting 20 such lakebeds have been identified so far. "We should land on these lakebeds and dig, dig, dig." More information on this article is available at http://nai.arc.nasa.gov/index.cfm?page=coldlovers. _____________________________________________________________________ NEW ADDITIONS TO THE ASTROBIOLOGY INDEX By David J. Thomas http://www.lyon.edu/webdata/users/dthomas/astrobiology/astrobiology.h tml 13 August 2001 Articles about astrobiology, exobiology and terraformation http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_article s1.html Associated Press/CNN, 2001. Scientist claims 25-year-old data show signs of life on Mars. CNN. L. David, 2001. Scientists say Mars Viking mission found life. Space.com. H. Franzen, 2000. From Mars to Earth in a meteorite? Scientific American. H. Franzen, 2001. Scientists say they have found extraterrestrial life in the stratosphere but peers are skeptical. Scientific American. R. Schubert, 2001. Hunting for little green microbes on Mars. Seattle Post-Intelligencer. SpaceDaily, 2001. Keep it clean, says NASA. SpaceDaily. Articles about the biology of extreme environments (on Earth) http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_article s2.html G. Geraci, R. del Gaudio and B. D'Argenio, 2001. Microbes in rocks and meteorites: a new form of life unaffected by time, temperature, pressure. Rendiconti Accademia Nazionale dei Lincei, 12(9):51-64. S. Graham, 2001. Scientists discover mechanism by which plants hold water during drought. Scientific American. P. Reany, 2001. Scientists claim evidence of life in outer space [upper atmosphere]. Space.com. E. M. Rivkina, E. I. Friedmann, C. P. McKay and D. A. Gilichinsky, 2000. Metabolic activity of permafrost bacteria below the freezing point. Applied and Environmental Microbiology, 66(8):3230-3233. K. Wong, 2000. Lost city of hydrothermal vents. Scientific American. Articles about human space exploration and the microgravity environment http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_article s3.html P. L. Barry and T. Phillips, 2001. Mixed up in space. NASA Science News. P. L. Barry and T. Phillips, 2001. Space seeds return to Earth. NASA Science News. SpaceDaily, 2001. ISS to study ovarian cancer cells. SpaceDaily. SpaceDaily, 2001. Learn to waste not, want not on the road to Mars. SpaceDaily. SpaceDaily, 2001. Eating right for long-duration space missions. SpaceDaily. Articles about the search for extraterrestrial intelligence (SETI) http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_article s4.html S. Graham, 2001. SETI will begin to look for optical beacons from alien worlds. Scientific American. Articles about evolutionary biology and chemistry http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_article s5.html R. R. Britt, 2001. How the scum of the Earth led to advanced life. Space.com. D. C. Catling, K. J. Zahnle, C. P. McKay, 2001. Biogenic methane, hydrogen escape, and the irreversible oxidation of early Earth. Science, 293(5531):839-843. K. Leutwyler, 2001. Are we alien life? Scientific American. J. F. McGowan, III, In press (2001). Jigsaw model of the origin of life. In Instruments, Methods, and Missions for Astrobiology IV, R. B. Hoover, Editor, Proceedings of SPIE, 4495. K. Wong, 2000. Ancient soils suggest earlier terrestrial life. Scientific American. _____________________________________________________________________ CASSINI WEEKLY SIGNIFICANT EVENTS NASA/JPL releases 19-25 July 2001 The most recent spacecraft telemetry was acquired from the Canberra tracking station on Wednesday, July 25. 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, http://www.jpl.nasa.gov/cassini/english/where/. Recent spacecraft activities include clearing the Attitude Control Subsystem (ACS) Highwater Marks, a Command & Data Subsystem Solid State Recorder Memory Load Partition repair, testing of the Radio and Plasma Wave Science (RPWS) Instrument Expanded Blocks, and an RPWS High Frequency Receiver calibration. The Spacecraft Operations Office (SCO) performed two ACS Reaction Control Subsystem Controller tests to investigate possible ways to decrease thruster cycles and hydrazine use. The SCO team also completed the first of three instrument muting tests in support of future Huygens Probe checkouts. A Delivery Coordination Meeting was held for version 4.1 of the Visual and Infrared Mapping Spectrometer Flight Software. The delivery was accepted and the software released for testing in the Integrated Test Laboratory, with a planned uplink in late August. Training was conducted for team members from Instrument Operations, Composite Infrared Spectrometer, Imaging Science Subsystem, and Mission Support & Services Office. Classes introduced personnel to the Cassini Help Desk; Science Opportunity Analyzer; the JPL Problem Reporting System; the Uplink Process; Spacecraft, Planet, Instruments, C-matrix, and Events (SPICE) kernels; and Cassini's Distributed Object Manager file repository. The Cross-Discipline and Magnetosphere Target Working Teams met to discuss the integration of the Tour segments allocated to these teams. Cassini management staff supported a meeting with a subset of the board from the NASA Independent Annual Review to discuss board findings. Two new Cassini slide sets have been posted on the web. "A Trip to Saturn" chronicles the assembly, launch, and journey of Cassini- Huygens to the Saturn System. "The Saturn System" is a compilation of images of Saturn, its moons, rings, and magnetospheres as seen by Voyager and the Hubble Telescope. "A Trip to Saturn" and "The Saturn System" slides can be viewed at http://www.jpl.nasa.gov/cassini/english/pic/trip2saturn.html and http://www.jpl.nasa.gov/cassini/english/pic/saturnsystem.html. 26 July - 1 August 2001 The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Monday, July 30. 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, http://www.jpl.nasa.gov/cassini/english/where/. Recent spacecraft activities include two Radio and Plasma Wave Science High Frequency Receiver calibrations and two Cassini Plasma Spectrometer data set collections. The Composite Infrared Spectrometer was powered on for instrument muting tests, and the second of the three muting tests was completed this week. These tests are being conducted by the Spacecraft Operations Office (SCO) in support of future Huygens Probe checkouts. The SCO also completed an Attitude Control Subsystem Reaction Control Subsystem calibration. The Critical Design Review (CDR) for the Cassini Ground Data System (GDS) was held, which included a system-level design overview from each office and updates of the Cassini software inventory, subsystem interfaces, and data flow. In support of the C28 sequence development, the preliminary Sequence Integration & Validation Package was created and released. The C29 Science Planning Virtual Team (SPVT) Project Briefing was held, with the Project approving the integrated plan for implementation. The first product input port for this process falls within the next week, and the entire C29 SPVT phase will be complete in early September. Meetings of both the Magnetosphere and Cross-Discipline Target Working Teams were held last week. Discussion included data input to the Cassini Information Management System as well as MAPS campaigns and Saturn imaging movies. The last updates of the D27 Multi Mission Image Processing Laboratory software were delivered for testing. These updates are evolutionary updates to both Uplink and Downlink support software. Cassini Outreach personnel gave a three-hour presentation and demonstration of Cassini educational resources to participants in a NASA NEWEST workshop. The workshop was sponsored by the Educator Resource Center in Pomona, California and attended by 30 educators from throughout the US. 2-8 August 2001 The most recent spacecraft telemetry was acquired from the Madrid tracking station on Wednesday, August 8. 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, http://www.jpl.nasa.gov/cassini/english/where/. Recent spacecraft activities include the conclusion of a Magnetospheric and Plasma Science observation, a Radio and Plasma Wave Science (RPWS) High Frequency Receiver Calibration, powering off the Composite Infrared Spectrometer, and an autonomous memory load partition repair of Solid State Recorder-B. The third and final of the instrument muting tests was completed this week. This test puts Cassini in a position to perform future Probe Checkouts with the instruments placed in a sleep state and having their Bus Interface Unit's transmission port 'muted'. Prior to these tests, Probe Checkouts required the Cassini instruments to be powered off for the duration of the activity. This new capability will allow the instruments to avoid incurring an undesired cycle as they are powered off and on again. In support of the C28 sequence process, the "b" version of the C28 sequence products was released, as was the draft package for the Preliminary Sequence Integration and Validation meeting. A meeting was held to define the Integration Test Laboratory (ITL) simulation support for Flight Software Normalization activities for the Cosmic Dust Analyzer (CDA) and Visual and Infrared Mapping Spectrometer. Also discussed were the results of the successful instrument mute tests and the corresponding impact on C28 testing. A preliminary package of the Command and Data System Version 9 Flight Software was delivered to the ITL for Huygens Probe relay testing. Probe relay testing has begun in subsystem mode with this new build of the flight software. The entire set of modules for Mission Sequence Subsystem (MSS) D7.6 has been successfully tested both individually and in small groups by the ITL and High Speed Simulator, and an integrated retest is planned for later this week in preparation for the MSS D7.6 delivery. The CDA Remote Terminal Interface Unit (RTIU) has been successfully tested, and the new RTIU for RPWS is scheduled to begin testing later this week. The RTIU converts the 1553 real-time instrument data interface to an Ethernet interface for data processing and performance testing with the instrument engineering model. An on-line Risk Management Tool has been completed for Cassini. Mission Assurance has begun the process of entering data from the Significant Risk List, for risk tracking and assessment. Following a few additional modifications and data entry, the tool will be rolled out for use by the Cassini Risk Team. A delivery review for the Advanced Multi-Mission Operations System V26.2 release was held this week. This version implements necessary capabilities for the Gravitational Wave Experiment. The Program Review Plan has been updated and distributed to the flight team for review by Mission Assurance. The plan reflects the high-level review process to assess readiness for SOI, probe relay, and Saturn tour operations, and includes an integrated schedule of program level reviews. The Cassini Design Team met to collect comments from Cassini personnel on the review process for the Ground Data System and Tour Downlink Operations Concepts reviews. These "lessons learned" comments are being collected by System Engineering for evaluation and implementation in future reviews. The Mission Planning team held a review of the Cassini navigation tracking requirements. Topics included having ranging "on" at all times as a default, reductions in the 2-way Doppler requirement, and alternative solutions to a requirement that one third of all Cassini DSN support come from the Madrid tracking station. A Cassini image of Jupiter is featured in the September issue of Sky and Telescope Magazine. 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 30 July - 3 August 2001 This is the last week before the August 4 start of Galileo's next encounter with the volcanic satellite Io. As playback of data from the May flyby of Callisto winds down, the final observations to be returned come from the Near Infrared Mapping Spectrometer (NIMS) and the Solid State Imaging camera (SSI). NIMS data concentrates on Jupiter atmospheric observations, including a global map of the giant planet. NIMS takes detailed looks at some persistent hot spots in the turbulent clouds and at the region trailing the Great Red Spot. SSI will be returning global color pictures of Ganymede, Jupiter's largest satellite. While the Flight Team makes final preparations for next week's Io flyby, the spacecraft undertakes a few last housekeeping tasks to get ready. On Thursday, routine maintenance of the on-board tape recorder is performed. On Friday, playback is stopped, and the final targeting orbit trim maneuver is executed. This engine burn could last as long as six hours, and ensures that Galileo reaches its scheduled rendezvous with Io at the correct time and place. Six hours may seem like a long time to run the engine, but remember that Galileo is like a large gyroscope, spinning at a stately 3 revolutions per minute. In order to nudge the path of the 1300 kilogram (2870 pound) spacecraft in a particular direction, a set of small 10 Newton thrusters (about 2.2 pounds of thrust each) are fired for less than one second per pulse on each revolution. Galileo has twelve such thrusters, some pointing forward, some backward, and some to the sides. The choice of which thrusters to fire and when to fire them determines what direction the spacecraft moves. They can also be used to turn the spacecraft in place, pointing its antenna in a new direction, with no change to its orbital path about Jupiter. Typically, final targeting maneuvers such as this one change the spacecraft velocity by a few tenths of a meter per second. Compare this to the 7.1 kilometers per second speed of Galileo as it flies by Io. These are truly gentle nudges in the grand scheme of things! After the maneuver, the tape is repositioned to the correct starting place to begin recording the next set of data from the upcoming Io flyby. It's about to get busy again! 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 _____________________________________________________________________ GALILEO MILLENNIUM MISSION STATUS REPORT NASA/JPL release 6 August 2001 NASA's Galileo spacecraft has successfully completed a flyby of Jupiter's moon Io, skimming about 200 kilometers (124 miles) above the surface of the highly volcanic moon at 04:59 Universal Time today (9:59 PM Sunday, Pacific Daylight Time). Engineers at NASA's Jet Propulsion Laboratory in Pasadena, CA, said that signals confirming the veteran spacecraft's basic health were received five and a half hours after the flyby via a Goldstone, CA, antenna of the Deep Space Network. As of 17:00 UT (10:00 AM PDT) today, the spacecraft had recorded about three-fourths of the scientific data that its instruments had been programmed to collect during this swing through the inner portion of the Jovian system. Besides studying Io, Galileo has made observations of cloud patterns on Jupiter. Initial telemetry did not reveal whether or not Galileo passed through a volcanic plume on Io. Galileo's route went directly over a volcano named Tvashtar, which had been spouting a tall plume of gases when last observed seven months ago. "As expected, we don't have any sign at this point that the plume was still active, but whether it was or not, we expect this flyby will give us valuable new information about changes in the Tvashtar area from recent activity," said JPL's Dr. Eilene Theilig, Galileo project manager. The area was to be examined by Galileo's camera and near-infrared mapping spectrometer. Galileo's camera, which has had an intermittent electronic problem for more than a year, appears not to have been working during the closest part of the flyby. Engineers have narrowed the cause of the problem to one of two electronic components probably damaged by radiation from Jupiter's radiation belts. Nine or more of the camera's 16 planned observations during the encounter period were probably lost, Theilig said. Engineers are attempting to restore the camera to functioning status in time for more-distant observations planned for Tuesday and Wednesday. Recorded data from the camera and Galileo's other instruments will be transmitted to Earth over the next two months. "We're looking forward to getting data back from the observations to confirm that the scientific instruments worked as planned," Theilig said. The flyby's polar route was selected so Galileo could collect magnetic measurements that might indicate whether Io generates its own magnetic field, like the Earth, Jupiter, and Jupiter's moon Ganymede. That information could give scientists a better understanding of what goes on deep inside Io, the most volcanically dynamic world in the solar system. The magnetometer and other instruments for studying fields and particles appear to have been working during the flyby. Coming close enough to Jupiter to approach Io subjects Galileo to intense natural radiation from Jupiter's radiation belts, increasing the risk to the spacecraft's electronics. "Galileo has already performed much longer than expected, so we're pleased every time it completes another encounter without showing new problems," Theilig said. "We're especially satisfied to get the magnetic field measurements that were the highest priority science objective for this flyby." Galileo has already received more than three times the cumulative radiation exposure it was designed to withstand and has continued making valuable scientific observations more than three years after its original two-year mission in orbit around Jupiter. Galileo will fly near Io again, over the south pole instead of the north, on October 16, 2001. Additional information about the mission is available at http://galileo.jpl.nasa.gov. Galileo was launched from NASA's Space Shuttle Atlantis on October 18, 1989. It began orbiting Jupiter on December 7, 1995. JPL, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, DC. _____________________________________________________________________ ISS STATUS REPORTS NASA/JSC releases 1 August 2001 A week and a half removed from the most recent shuttle visit to the International Space Station, the Expedition Two crew continues preparations for ending its mission aboard the complex as Discovery is readied for the STS-105 launch a week from tomorrow at 4:38 p.m. Central time to deliver supplies, logistics and the next crew to live aboard the orbiting outpost. Almost immediately after Atlantis departed following its mission to install an addition on the home in space, station Commander Yury Usachev, and Flight Engineers Jim Voss and Susan Helms began unpacking and stowing supplies delivered by Atlantis, while at the same time beginning to prepare for the arrival of their replacement crew. The Expedition Three crew consists of Commander Frank Culbertson, Pilot Vladimir Dezhurov and Flight Engineer Mikhail Tyurin. The three will be delivered aboard Discovery by its crew of Commander Scott Horowitz, Pilot Rick Sturckow and Mission Specialists Dan Barry and Pat Forrester. The STS-105 and Expedition Three crews will travel to the Kennedy Space Center in Florida Sunday and the countdown begins Monday. While Discovery's countdown to launch to the ISS is set to begin, half a world away at the Baikonur Cosmodrome in Kazakhstan, the fifth Progress supply craft is being readied for launch August 21 followed September 15 by the launch of the next station component--a Russian docking compartment named Pirs, the Russian word for pier. 8 August 2001 With Discovery poised on Launch Pad 39-A at the Kennedy Space Center for liftoff tomorrow to the International Space Station, Expedition Two Commander Yury Usachev and Flight Engineers Jim Voss and Susan Helms completed the packing of personal items and hardware for their return to Earth after more than five months in orbit and awaited the arrival of their replacements. The STS-105 mission to deliver the third resident crew to the ISS is scheduled to launch tomorrow at 4:38 PM Central time as the ISS sails over the Southern Ocean south of Adelaide, Australia at an altitude of around 240 statute miles. Discovery's Commander, Scott Horowitz, Pilot Rick Sturckow, and Mission Specialists Pat Forrester and Dan Barry are ready to ferry Expedition Three Commander Frank Culbertson, Pilot Vladimir Dezhurov and Flight Engineer Mikhail Tyurin to the Station for a four-month mission, succeeding Usachev, Voss and Helms, who have been aloft since March 8. Discovery was cleared for launch earlier this week by Shuttle managers after reviewing the status of fuel injector units used in the hydraulic power units that steer the Shuttle's solid rocket booster nozzles during the first two minutes of powered flight. Last night aboard the ISS, one of three command and control computers (C & C 1) which is used as a backup for the operation of some Station systems experienced a problem reading its hard drive, or Mass Storage Device. The hard drive stores commands for a variety of vehicle activities on the U.S. segment of the complex. Flight controllers attempted to reboot the computer with no success and are continuing efforts to bring it back into operation. This computer has lost only some of its functional capability. The Station's primary computer (C & C 3) is operating normally, however, and a third computer (C & C 2) is being transitioned from standby status to act as the backup for C & C 3. A newly refurbished command and control computer had already been manifested to be launched on Discovery to the ISS as a spare, and would be installed for operation, if required. The backup computer glitch has had no impact on Station operations and will not affect the joint mission to deliver the new Expedition crew to the orbital outpost. As Usachev, Voss and Helms prepared to handover command of the Station to a new crew, Russian engineers prepared two vehicles for launch right after the STS-105 mission. At the Baikonur Cosmodrome in Kazakhstan, a Progress resupply ship is being readied for launch on August 21 to deliver food, fuel and supplies for the new Expedition Three crew. It is scheduled to dock to the aft docking port of the Zvezda Service Module on August 23, one day after the current Progress attached to the ISS is jettisoned. And the newest ISS module, a Russian Docking Compartment named Pirs, the Russian word for pier, is in the final stages of preparation for launch on September 15 to link up to the earthward facing docking port of Zvezda. It will provide a new docking port for future visiting Russian vehicles. In addition to packing to come home, the Expedition Two 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 after the STS-105 mission. Subsequent ISS status updates will be contained within the mission status reports for Discovery's flight. _____________________________________________________________________ MARS GLOBAL SURVEYOR STATUS REPORT NASA/JPL release 25 July 2001 Launch / Days since Launch = November 7, 1996 / 1722 days Start of Mapping / Days since Start of Mapping = April 1, 1999 / 846 days Total Mapping Orbits = 10,642 Total Orbits = 12,325 Recent events The spacecraft is operating nominally in performing daily recording and transmission of science data. The mm151 sequence has performed well since it started on 01-200 (7/19/01). It terminates on 01-227 (8/15/01). Dust storms spreading across the planet are making narrow-angle photographic imaging of Mars impracticable. Therefore, ROTO operations remain suspended until the global dust storms subside. MGS has completed 155 ROTOs to date. A second in-flight MOLA diagnostic test (MZ116) was performed on 01- 206 (7/25/01) to gain more insight into the MOLA anomaly. Detailed analyses will be performed after the recorded data is transmitted to Earth on 01-207 (7/26/01). Spacecraft health All subsystems report good health and status except for the MOLA payload instrument that malfunctioned on 01-181 (6/30/01). The MOLA instrument team is still investigating the anomaly. Uplinks There have been 6 uplinks to the spacecraft during the past week, including instrument command loads and the MZ116 MOLA diagnostic test. 5,506 command files have been radiated to the spacecraft since launch. Upcoming events A Bistatic Radar experiment is planned for 01-217 (8/5/01). The first of several Delta-DOR experiments will take place on 01-236 (8/24/01). _____________________________________________________________________ STARDUST STATUS REPORTS NASA/JPL releases 27 July 2001 There were two Deep Space Network (DSN) tracking passes this week and all subsystems are performing normally. The Cometary and Interstellar Dust Analyzer (CIDA) continues to observe the interstellar dust stream with an optimal spacecraft attitude when not in communication with Earth. The Spacecraft Test Laboratory (STL) computer, located on the ground in Denver, Colorado, that went down at the end of last week, was brought back up by replacing a board. The Stardust project is in search of an old SGI Challenger series computer that has more capability than our current but even older SGI Onyx computer. Both share the same operating system. 3 August 2001 There were two Deep Space Network (DSN) Trakcing passes this week and all subsystems are performing normally. These passes have been kept simple and at off hours in anticipation of the Genesis launch planned this week. The Cometary and Interstellar Dust Analyzer (CIDA) instrument continues to observe the interstellar dust stream with an optimal spacecraft attitude when not in communication with Earth. The older Silicon Graphics Onyx computer in the Spacecraft Test Laboratory will be upgraded by replacing the 200 Mhz processor with a 250 Mhz processor within the next month. There are still major issues with this old computer with replacement options being explored. 10 August 2001 There was one Deep Space Network (DSN) tracking pass this week and all subsystems are performing normally. Spacecraft contact and operations were minimized for the past two weeks to give priority to DSN and flight teams on Wednesday's successful NASA Discovery Genesis launch. There have been no interstellar dust particle hits on the Cometary and Interstellar Dust Analyzer (CIDA) instrument during the last two months. Commands were successfully sent to increase the sensitivity of the CIDA detection target to produce additional science data. This second CIDA interstellar collection period will end next month: the instrument will be turned off to conserve power, since the spacecraft is out beyond 2.4 AU (about 359 million kilometers, or 223 million miles) from the Sun. The project was able to report excellent status of its resources, schedule and technical accomplishments at the quarterly Governing Program Management Council (GPMC) review by NASA and JPL management. The search for a replacement SGI Challenger computer for the Spacecraft Test Laboratory has been stopped. Instead, the current SGI Onyx 200 MHz CPU boards will be upgraded to 250 MHz under full configuration management and test processes. 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 30.