MARSBUGS: The Electronic Astrobiology Newsletter Volume 9, Number 2, 14 January 2002. 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) RADIATION ZAPS MARS AND EXTRASOLAR PLANETS, AFFECTS BIOLOGICAL EVOLUTION University of Texas at Austin release 2) ANCIENT SUPERNOVA MAY HAVE TRIGGERED ECO-CATASTROPHE Johns Hopkins University release 3) LIFE HITCHING A RIDE TO EARTH: BUGS COULD TRAVEL TO EARTH IN COMFORT ABOARD MARTIAN METEORITES By Anil Ananthaswamy 4) IN SEARCH OF E.T.'S BREATH By Patrick L. Barry 5) ICE EXPLORER CONCEIVED FOR OTHER WORLDS GETS ARCTIC TEST NASA/JPL release 6) PRIMORDIAL EARTH ATMOSPHERE MAY HAVE BEEN BREATHABLE From SpaceDaily 7) NEW ADDITIONS TO THE ASTROBIOLOGY INDEX By David J. Thomas 8) CASSINI WEEKLY SIGNIFICANT EVENTS NASA/JPL release 9) THIS WEEK ON GALILEO NASA/JPL release 10) INTERNATIONAL SPACE STATION STATUS REPORT NASA/JSC release 11) MARS ODYSSEY MISSION STATUS NASA/JPL release 12) STARDUST STATUS REPORT NASA/JPL release _____________________________________________________________________ RADIATION ZAPS MARS AND EXTRASOLAR PLANETS, AFFECTS BIOLOGICAL EVOLUTION University of Texas at Austin release 7 January 2002 Calculations by a team of astronomers at The University of Texas at Austin show that jolts of radiation from space may affect biological and atmospheric evolution on planets in our own solar system and those orbiting other stars. The work by David Smith (a former UT- Austin undergraduate, now a graduate student at Harvard University) and UT-Austin astronomers John Scalo and J. Craig Wheeler is presented today at the American Astronomical Society meeting in Washington, DC. Bursts of radiation that can cause biological mutations, or even deliver lethal doses, can come from flares given off by the planet's parent star or from more remote cosmic events (e.g., supernovae and gamma-ray bursts). The magnitude of the effect on life and evolution on a planet is related to how much protection it gets from its atmosphere. The work presented today concentrates on the transmission of high-energy X-rays and gamma rays through planetary atmospheres. "It's a multi-level calculation," Scalo said. "First you have to determine the spectrum of the source [flare star, supernova, or gamma-ray burst], then you must calculate how the radiation propagates through and disrupts a planet's atmosphere. Then you follow the radiation down to the surface of the planet, even underwater, eventually calculating how strongly it interacts with cellular material. The calculation presented today follows the paths of individual photons as they scatter off electrons bound in molecules and gradually lose energy until they are absorbed by atoms. The result shows just what fraction of the radiation reaches a planet's surface (as function of the intensity and energy of the source and the thickness of the planetary atmosphere)." Today, Mars has a thin atmosphere--about 100 times thinner than Earth's. More than 10 percent of the incident energy reaches its surface for photons with energies above about 100 kiloelectron volts (high-energy X-rays and gamma rays). "Any organisms unprotected by sufficient solid or liquid shields should have been lethally irradiated by cosmic radiation sources many times in the last few billion years," David Smith said. According to John Scalo, "It may have been safe on Mars during the first few billion years, when the planet had a much thicker atmosphere, but today, and probably for the past billion years or so according to current climate evolution models, the planet has had little protection from high-energy radiation. When the atmosphere thinned, any life on the surface was exposed to high-energy radiation from exceptionally strong solar flares and occasional stronger bursts from different astronomical sources throughout the galaxy." The radiation need not be lethal, but may instead induce episodes of intense mutational damage and error-prone repair, leading to interestingly different evolution than on Earth. Mutations are usually deleterious, but they provide the diversity necessary to drive evolution. "Radiation bursts may spur evolution by intermittently enlarging the genomic diversity upon which natural selection is believed to operate," Scalo said. "As an example, chemical pathways adapted to a rapidly fluctuating radiation environment might result in organisms whose signatures of biological activity may be very different from those of terrestrial organisms. "Gamma-ray bursts only last 10 seconds or so," Scalo said, "so the mutations they cause are unlikely to produce direct evolutionary effects." Exposure to gamma-ray bursts will tend to sterilize life on the exposed side of the planet that is not protected under enough rock or water; however gamma-ray bursts may cause long-lived changes indirectly by affecting planetary atmospheres. Significant gamma-ray irradiation from supernova explosions are more frequent and have a much longer duration and may be capable of driving evolutionary effects directly. Both of these distant cosmic sources are capable of delivering atmospherically and biologically significant high- energy radiation jolts every hundred thousand or million years-- possibly hundreds or thousands of such events over the history of a planet. This picture of sporadic zaps of radiation is quite different than when a planet is constantly bathed in radiation from its parent star. "Most stars in our galaxy aren't like the Sun," Scalo said. "Most are red dwarfs." These stars have little ultraviolet radiation that can cause mutations, but they flare violently, mostly in X-rays. "Conventional wisdom said that planets orbiting these stars couldn't have atmospheres, that any atmosphere would freeze out because the planet's rotation would be tidally locked," Scalo said. "More recent calculations show these planets can have atmospheres. What might life be like on a planet orbiting a red dwarf with powerful flares and continuous intense coronal X-rays? One possibility is that most of the biosphere would need to be underground or underwater; another is that the challenging mutational radiation environment would accelerate the evolution of life." Future work will focus on the reprocessing of the lost gamma ray and X-ray energy to ultraviolet radiation that can reach the ground. The high-energy photons lose energy to electrons that in turn excite atoms and molecules in the atmosphere. When those atoms de-excite, they can produce substantial ultraviolet radiation that can also affect the biosphere on the surface of the planet. In this case, bursts of cosmic irradiation would be important even when there is a thick atmosphere (like Earth's) that will stop the original X-rays or gamma rays. These jolts of irradiation can cause the formation of a "second ionosphere" at fairly low altitudes and disrupt a planet's atmospheric chemistry. Smith, Scalo, and Wheeler are adding these effects into their calculations. [http://stardate.utexas.edu/pr/pressroom_images/20020107/Scalo_Releas e_Figure.jpg (164KB)] Mars: Atmospheric transmission of high-energy photons as a function of time. Contacts: Rebecca Johnson Phone: 512-475-6763 E-mail: rjohnson@astro.as.utexas.edu Office of Public Affairs University of Texas at Austin P.O. Box Z Austin, Texas 78713-7509 Phone: 512-471-3151 Fax: 512-471-5812 An additional article on this subject is available at http://spaceflightnow.com/news/n0201/11radiation/. _____________________________________________________________________ ANCIENT SUPERNOVA MAY HAVE TRIGGERED ECO-CATASTROPHE Johns Hopkins University release 8 January 2002 An exploding star may have destroyed part of Earth's protective ozone layer 2 million years ago, devastating some forms of ancient marine life, according to a new theory presented at this week's meeting of the American Astronomical Society. The new theory brings together puzzling clues from several different fields of research, including paleontology, geology and astronomy. Narciso Benítez, an associate research scientist in astronomy in the Krieger School of Arts and Sciences at The Johns Hopkins University, says the "missing smoking gun" that brought the clues together was the revelation that a stellar cluster with many large, short-lived stars prone to producing supernovae had passed near Earth's solar system several million years ago. That discovery, made by co-author and Space Telescope Science Institute astronomer Jesús Maíz- Apellániz, led Benítez to check the scientific record for potential effects of nearby supernovae on the Earth. "Nobody had realized that this cluster of stars that Jesús had tracked, which is known as the Scorpius-Centaurus OB association, could have been so close to Earth during the past several million years," Benítez says. "And when I did a search, one of the first things that popped out was a 1999 finding where a team of German astronomers led by Klaus Knie detected the presence of a highly unusual isotope of iron in samples of the Earth's crust drilled from the deep ocean bottom." Knie had proposed that the iron isotope was debris from a recent supernova explosion that took place close to Earth. But astronomers had no plausible candidates for such a nearby explosion until Maíz- Apellániz's work with the Scorpius-Centaurus association, which is also being presented at this week's meeting of the American Astronomical Society. Benítez compared data produced by Maíz-Apellániz and Knie's results, and found "very good agreement, both in the amount of iron deposited and in its time distribution." Benítez consulted with his wife, Matilde Cañelles, an immunologist at the National Institutes of Health who had done her master's thesis on microscopic algae, to learn if the paleontological record included an extinction that had unusual characteristics suggestive of a potential link to a supernova. "Such an extinction would have had especially pronounced effects on the plankton and the marine organisms," Benítez explains. Cañelles pointed out that evidence existed for a widespread extinction of plankton and other marine organisms about 2 million years ago, and noted that scientists are still debating the possible causes of the event. "Based on the minimal distance we expected for a supernova in the Scorpius-Centaurus association at that time, I then did some calculations to explore the potential effects on Earth," says Benítez. He found that cosmic ray emissions from a supernova could have had a potentially devastating effect on the Earth's ozone layer, an upper layer of the atmosphere that absorbs harmful ultraviolet emissions from the sun and other sources. "This would have produced a significant reduction in phytoplankton abundance and biomass, with devastating effects on other marine populations, such as bivalves," Benítez says. Benítez emphasizes that the theory, while provocative, is consistent with the paleontological evidence, and also with the pattern of movement of the Scorpius-Centaurus group, which would have been at its closest to Earth at that time. He concedes, though, that more evidence will be needed to firmly establish the theory. In particular, more detailed searches for supernova-produced isotopes in the geological record would show whether there was a tight temporal correspondence between the supernova explosion and the extinction event. Isotope searches could also offer crucial information about the physical processes involved in supernova explosions. "People study supernovae using telescopes and supercomputer simulations. In the future, some of the most relevant information in this field may be found in the deep ocean floor," says Benítez. While the new theory may further heighten concern about human impacts on the ozone layer today, Benítez and Maíz-Apellániz say there's no need to worry about another supernova in the Scorpius-Centaurus group affecting Earth in the near future. The next star due to explode in the association, Antares, is now located at a distance of almost 500 light-years, which is too far away to have a significant effect on our planet. This research was funded by an Advanced Camera for Surveys grant from NASA, the Johns Hopkins Center for Astrophysical Sciences, and a grant from the Space Telescope Science Institute. Contacts: Michael Purdy Phone: 410-516-7906 E-Mail: mcp@jhu.edu Office of News and Information Johns Hopkins University 3003 North Charles Street, Suite 100 Baltimore, Maryland 21218-3843 Phone: 410-516-7160 Fax: 410-516-5251 An additional article on this subject is available at http://www.spacedaily.com/news/supernova-02a.html. _____________________________________________________________________ LIFE HITCHING A RIDE TO EARTH: BUGS COULD TRAVEL TO EARTH IN COMFORT ABOARD MARTIAN METEORITES By Anil Ananthaswamy From New Scientist http://www.newscientist.com 9 January 2002 For the first time, millions of bacterial spores have been purposely exposed to outer space, to see how they are affected by solar radiation. The results support the idea that life could have arrived on Earth in the form of bacteria carried from Mars on meteorites. The idea that life started elsewhere and spread through space is called panspermia. It was first proposed in 1903 by the Swedish chemist Svante Arrhenius, who suggested that solar radiation might propel single spores across solar systems. Then, in the 1970s, astronomers Fred Hoyle and Chandra Wickramasinghe studied the infrared spectra of interstellar grains of dust and concluded that they were dried, frozen bacteria. They put forward the controversial suggestion that life on Earth originated when such bacteria arrived from space. But critics of their work said that cosmic rays and ultraviolet radiation from the Sun would kill unprotected spores. Recent discoveries of Martian meteorites that have reached Earth have raised the possibility that bacterial spores could have hitched a ride on these rocks (New Scientist, 15 January 2000, p 19). Most meteorites spend millions of years in space, but meteorites taking a direct route would make it from Mars to Earth in just a few years-- too short a time to experience much damage from deadly cosmic rays. The Sun's UV radiation might still pose a danger, however. To assess its effects, Gerda Horneck of the German Aerospace Centre in Cologne and her colleagues carried out a series of remote-controlled two-week experiments aboard the Russian Foton satellite. They started by exposing nearly 50 million unprotected spores of the bacterium Bacillus subtilis outside the satellite. This is the first time any living organism has been purposely released into space. "You are not allowed to do that if you have a human mission, but we could do it on a Russian satellite," says Horneck. UV radiation from the Sun killed nearly all the spores, confirming that single bacteria would not survive long enough in space to travel from one planet to another. The same happened when the spores were behind a quartz window, so the researchers did the rest of their experiments with the spores confined under quartz. To test whether meteorites might protect the bacteria on their journey through space, Horneck and her colleagues mixed samples of 50 million spores with particles of clay, red sandstone, Martian meteorite or simulated Martian soil, to make small lumps a centimeter across. In most of the samples, between 10,000 and 100,000 spores of the original 50 million survived. And when mixed with red sandstone, nearly all survived. The results suggest that even meteorites as small as a centimeter in diameter could carry life from one planet to another, if they completed the journey within a few years. "Early in the history of Mars and Earth, there could have been an exchange of biological material between the two planets," agrees Benton Clark, a Mars exploration specialist at Lockheed Martin in Colorado. More information can be found at: Origins of Life and Evolution of the Biosphere (Volume 31, page 527) New Scientist issue 12 January 2002 Contact: Claire Bowles New Scientist Press Office, London Phone: +44(0)20 7331 2751 E-mail: claire.bowles@rbi.co.uk An additional article on this subject is available at http://spacedaily.com/news/020109190132.qacp4k89.html. _____________________________________________________________________ IN SEARCH OF E.T.'S BREATH By Patrick L. Barry From NASA Science News 10 January 2002 Advanced space telescopes might soon probe far-off worlds for the chemical signatures of alien life. If "E.T." is out there, whether in the form of intelligent beings or much simpler organisms, we may soon be hot on its trail. For the first time in history, the dream of searching for signs of life in other solar systems belongs not only on the philosopher's wish list, but on the list of doable and planned human endeavors. Momentum is gaining rapidly. Only 6 years ago, the first planet around another Sun-like star was discovered by scientists using Doppler detection--a method that reveals Saturn-sized (or larger) planets close to their parent suns. Today, we know of more than 80 candidates for such worlds, and more are being found all the time. Scientists crossed a new frontier in "exo-planet" research just last year when, using the Hubble Space Telescope, they detected sodium in the atmosphere of a large alien world orbiting the star HD 209458. The Hubble data not only revealed that exo-planets have atmospheres, but also that we can analyze them from a distance. For the first time, humans are discovering and exploring worlds outside the solar system. So far, all known extra-solar planets are gas giants--unlikely abodes for life as we know it. In fact, some are so large that they might not be planets at all, but a kind of failed star called a "brown dwarf." Of greater interest are Earth-size planets, which are too small for even the Hubble Space Telescope to detect. Nevertheless, astronomers believe they exist. Enter Kepler, a space telescope approved recently by NASA. Beginning in 2006, Kepler will monitor about 100,000 nearby stars, searching for the slight dimming that occurs when an orbiting planet blocks some of the parent star's light. Because Kepler will be sensitive enough to detect planets as small as Earth, this celestial survey will give scientists an idea of how common Earth-like planets are--and identify candidates for further study. If all goes as planned, an important new tool for exploring such planets will be operating by the end of this decade. Called the Terrestrial Planet Finder (TPF), this space telescope will use a technique called "interferometry" to dramatically reduce the obscuring glare from the planet's parent star, allowing scientists to see the planet itself. The Web site for the European Space Agency's similar Darwin project notes that, "Looking for planets around nearby stars is like trying to discern, from a vantage point 1000 km away, the feeble light from a candle next to a lighthouse." It is indeed a daunting challenge, but worth the effort. The goal is nothing short of finding worlds that could support life--and perhaps some that do. Seeing E.T.'s "breath" Planets circling other stars are many light years away. (A light- year is the distance that light travels in a year--about 9.5 trillion km.) Even with the TPF's advanced optics, Earth-like worlds would appear as a single pixel of light. How, then, will it be possible to learn much about them? Amazingly, that tiny speck of light can speak volumes about the planet from which it came. Embedded in that light are the "fingerprints" of the chemicals that have touched it, including the gases in the planet's atmosphere. By splitting the light into its component frequencies--which for visible light creates the familiar rainbow of colors--scientists can reveal these "fingerprints" and learn about the chemistry of the planet's atmosphere. If life is widespread on a planet, its atmosphere should show signs of life's presence. Just as the air you exhale has more carbon dioxide and less oxygen than the air you inhale, the combined "breathing" of all the life on a planet will change the chemistry of its atmosphere. If life is plentiful on the planet, these changes may be large enough to notice. A simple premise--but what would E.T.'s breath look like? Which gases should we search for? We know the answers for our own world, but predicting how an alien biology might interact with its atmosphere is no simple matter. "As astrobiologists we've got to be sure that we're not too Earth- centric," says Michael Meyer, senior scientist for astrobiology at NASA Headquarters in Washington, DC. The possibility that life elsewhere has a biology that's radically different from our own is perhaps the most exciting and challenging part of astrobiology (not to mention a ubiquitous theme of science fiction). If life evolves by random mutations and natural selection, why should we expect alien life forms to be even remotely similar to Earthly life? "We have to be very careful about how foreign biology might be different from our own, especially when you get to the bigger molecules" such as DNA, says David Des Marais, principal investigator for the Ames Research Center team of NASA's Astrobiology Institute. For example, people have speculated that silicon, a primary component of sand and a close cousin to carbon, could form the basis of an extraterrestrial biology. Alien life might forgo sunlight and depend instead on the geothermal energy in hydrogen and sulfur compounds emitted from the planet's interior, much like the deep-sea vent ecosystems here on Earth. Or maybe the chemistry of alien life will be utterly different and unimaginable. Fortunately, the chemical constraints within which life must function make it likely that simple molecules such as oxygen and carbon dioxide will play the same roles in an extraterrestrial biology as they do on Earth. "Suppose," says Meyer, "that there is silicon-based life. [It might be] photosynthetic, and you would still end up with oxygen in the atmosphere. You could go there and the life could be completely different, but some of the chemistry could still be the same [as on Earth]." "The small molecules are going to be more universal," agrees Des Marais. "Large molecules like DNA and chlorophyll represent later, highly significant innovations of life on Earth, but also the ones that may have differed elsewhere." For this and other reasons, the exploration of distant Earth-like planets with TPF will focus on simple gases such as oxygen, ozone, carbon dioxide, methane, and, of course, water vapor. Oxygen and its tag-along cousin ozone will top the list of target molecules. Without life, oxygen should be rare on rocky worlds. A small amount of it can be created without life by ultraviolet radiation that splits water vapor into hydrogen and oxygen. But that oxygen would be readily consumed by rocks and minerals on the planet's surface in the "oxidizing" reactions that produce, for example, rust. Volcanic gases also react with oxygen and remove it from the atmosphere. Geological processes alone usually work against the accumulation of oxygen. An oxygen-rich atmosphere is, therefore, out of chemical equilibrium, suggesting that some active agent--namely photosynthetic life--is constantly replenishing the supply. As Carl Sagan noted in a 1997 Scientific American article, "the great concentration of oxygen (20 percent) in Earth's dense atmosphere is very hard to explain by [any means other than life.]" The same would be true of planets around other stars. Next on the list of target molecules is methane. Scientists suspect that for roughly the first billion years of its history, life on Earth had not yet evolved oxygen-producing photosynthesis. Instead, the microorganisms that then dominated the planet tapped the energy in gases leaking out of the Earth's interior, with some microbes creating methane as a byproduct. On a planet with a similar geology to Earth, methane levels greater than about 100 parts per million would suggest the presence of life. But methane would be a more ambiguous discovery than oxygen, because planets of a different geological make-up might produce abundant methane without life. Other details about these planets--such as their size, their distance from the parent star, their carbon dioxide and water vapor levels, and their reflectivity--will help scientists accurately interpret a methane or oxygen discovery. These other details can also be measured (or at least estimated) using TPF and other telescopes. Some of these ideas have already been tested on a planet known to support life--Earth. In 1990, the Galileo spacecraft made a flyby of our planet on its circuitous journey to Jupiter. As it passed, Galileo's sensors detected high levels of oxygen and methane in Earth's atmosphere and signs of chlorophyll on the ground. Chlorophyll, which absorbs light at the far-red end of the visible spectrum, is a "red flag" for life. The TPF won't be sensitive to chlorophyll on a planet's surface because atmospheric water vapor, which is opaque in the mid-infrared frequency range that TPF will observe, will hide the surface below. Even without chlorophyll, signs of oxygen and methane--which TPF can detect--would make a persuasive case for life. If the TPF finds a habitable planet with lots of oxygen and some methane in its atmosphere, it would be a momentous discovery. But would such data really prove life is there? "Proof" is always a tall order in science, especially when discussing extraterrestrial life. Nevertheless, say astrobiologists, such evidence would be "very compelling." One day it might happen, and after catching its first whiff of E.T.'s breath, humanity won't likely give up the chase. The next step would be an even larger space telescope that could see the planet as more than one pixel, allowing scientists to see surface features such as continents and to observe the changing of the planet's seasons. And perhaps by the end of the next decade it would be possible to send a probe across interstellar space to take a close-up look, which could finally provide incontrovertible evidence. Proof will be for the patient; even using advanced propulsion technologies, a probe might take decades to reach a neighboring star. But to answer a profound question that's been asked by humanity for centuries, perhaps that isn't too long to wait. More information on this article is available at http://science.nasa.gov/headlines/y2002/10jan_exo- atmospheres.htm?list69247. _____________________________________________________________________ ICE EXPLORER CONCEIVED FOR OTHER WORLDS GETS ARCTIC TEST NASA/JPL release 10 January 2002 Robots that melt their way through ice may one day explore below frozen surfaces of other worlds, based on a pioneering version that successfully bored into an Arctic glacier in an adventurous field test. NASA teamed with the Norwegian Polar Institute and Norwegian Space Center to use the ice-penetrating robot, or Cryobot, for the first time on a glacier on the island of Spitsbergen, far above the Arctic Circle in the Norwegian-administered international territory of Svalbad. Researchers from NASA's Jet Propulsion Laboratory and the California Institute of Technology coped with fading daylight, frequent snow and severe cold while camping on the Longyearbreen glacier for more than a week. Migrating polar bears were also a concern, particularly during the team's late-night and early-morning vigils of the warm- nosed robot probe. Despite these obstacles, the test was completed, with the probe successfully melting down 23 meters (75 feet) into the glacier. "The test showed the design has viability. It established a bold foothold for opening up new, below-the-surface environments for scientific study," said Lloyd French, Cryobot task manager at JPL. "In exploring outer planets, we have observed from two environments: space orbits and planet surfaces. Now we have a potential third: subsurface." The Cryobot began at JPL as a concept for examining what's under the surface of Jupiter's moon Europa. NASA's Galileo spacecraft, orbiting Jupiter since 1995, has accumulated strong evidence that Europa has a deep saltwater ocean below the ice, making that moon a prime target for studies of possible extraterrestrial life. "In developing ideas for exploring Europa, we realized the same technology could be applied to icy environments elsewhere--ice on Earth, the polar icecaps on Mars," French said. "There's never been a probe before that does what this one can," said Wayne Zimmerman, lead engineer for the task. "Earlier probes were much larger, required more power, did not carry a full navigation and control system, could not manage sediment buildup in front of the probe, and had limited science-payload capacity." The first prototype of the Cryobot is a cylinder about 1 meter (3.3 feet) long and 12 centimeters (5 inches) in diameter. Heated water at the downward end melts ice, and gravity provides the propulsion. Instruments such as a camera and chemical sensor ride aboard to study the deep layers without the need to hoist a core to the surface. A tether behind the vehicle provides an electronic link to the onboard instruments and carries electricity from the surface to supply heat in the Cryobot. On deeper descents, ice would be allowed to refreeze behind the robot, but in the first field tests, the borehole was reopened for retrieving the equipment. "By no means is Earth merely a testing ground for Europa and Mars, said JPL's Dr. Frank Carsey, Cryobot task scientist. There are many interesting environments on Earth where a Cryobot could be the best technology for conducting safe and effective scientific studies." For exploring lakes that lie under permanent ice, a Cryobot would have an advantage over rotary drilling or hot-water drilling, which leave a hole open. Allowing ice to refreeze behind the descending Cryobot would minimize contamination of the lake, Carsey said. Antarctica has at least 70 lakes under ice, including Earth's fourth- largest lake, Lake Vostok. Choosing the Longyearbreen glacier for the first Cryobot field test took advantage of the Norwegian Polar Institute's research infrastructure and logistical support in Svalbard. "In the past, the United States and Norway participated in a global race for the North Pole on Earth. Now, with the help of the Norwegian Polar Institute and Norwegian Space Center, we're cooperating on a possible way to explore another north pole, on Mars," said French. A mission proposal called Cryoscout will compete with other Mars Scout proposals to be chosen by NASA for a 2007 launch to Mars. Cryoscout is one of 10 Mars Scout concepts selected last year for further study. It proposes using a Cryobot to descend through Mars' polar ice cap. "If you want to learn about the climate history of Mars, which is important in the search for life, you want to examine the layers of the polar caps, and this is how you can do it," said Scott Anderson, a geophysicist on the Cryobot field-test team. Work also continues on developing plans for how a Cryobot could be used on icy worlds such as Europa or Titan, though NASA has no specific plans at this point for landing a spacecraft on either. A Europa Orbiter mission is under development at JPL with a launch target of 2008. JPL, a division of the California Institute of Technology in Pasadena, manages Cryobot development for the NASA Office of Aero- Space Technology's Cross-Enterprise Technology Program, NASA Office of Space Science and NASA Office of Earth Science, in Washington, DC. Contact: Guy Webster Phone: 818-354-6278 More information on the Cryobot is available at http://fuego.jpl.nasa.gov/. _____________________________________________________________________ PRIMORDIAL EARTH ATMOSPHERE MAY HAVE BEEN BREATHABLE From SpaceDaily 11 January 2002 The Earth may have had an oxygen-rich atmosphere as long ago as three billion years and possibly even earlier, three leading geologists have claimed. Their [hypothesis] challenges long-held ideas about when the Earth's atmosphere became enriched with oxygen, and pushes the likely date for formation of an atmosphere resembling today's far back into the early history of the planet. It may also revolutionize the worldwide search for gold and other minerals, and raises new questions about when and how life could have arisen. Get the full story at http://www.spacedaily.com/news/early-earth- 02a.html. _____________________________________________________________________ NEW ADDITIONS TO THE ASTROBIOLOGY INDEX By David J. Thomas http://www.lyon.edu/webdata/users/dthomas/astrobiology/astrobiology.h tml 14 January 2002 Articles about astrobiology, exobiology and terraformation http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_article s1.html P. L. Barry, 2002. In search of E.T.'s breath. NASA Science News. Articles about evolutionary biology and chemistry http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_article s5.html Agence France-Presse, 2002. Bugs-from-space theory gets a boost. SpaceDaily. SpaceDaily, 2002. Ancient supernova may have triggered eco- catastrophe. SpaceDaily. SpaceDaily, 2002. Primordial Earth atmosphere may have been breathable. SpaceDaily. Spaceflight Now, 2002. Radiation zaps planets, affects biological evolution. Spaceflight Now. _____________________________________________________________________ CASSINI WEEKLY SIGNIFICANT EVENTS NASA/JPL release 3-9 January 2002 The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Wednesday, January 9. The Cassini spacecraft is in an excellent state of health and is operating normally (http://www.jpl.nasa.gov/cassini/english/where/). Execution of C29 continues to proceed normally. Cassini's Gravitational Wave Experiment (GWE) completed on Jan 5. The Radio Science team was very pleased with the effort, reporting they collected over 90% of the possible Ka-Band GWE data. At the completion of the GWE, instruments that were quiet due to the experiment resumed normal operations. Additional instrument activities include Radio and Plasma Wave Science Periodic Instrument Maintenance, write protect bit clear, and two High Frequency Receiver calibrations. The Ultraviolet Imaging Spectrometer (UVIS) completed an observation of Alpha CMA. Commands to activate Latchup detection algorithm and thresholds for the Cosmic Dust Analyzer, and Command & Data Subsystem Enable CDA fault protection were successfully uplinked and executed. Engineering activities this week included transition to the Reaction Control Subsystem following 40 days on wheels to support the GWE, a Reaction Wheel Assembly bias unload and readout of parameters, an Attitude Control Subsystem high-water mark clear, and an autonomous Command & Data Subsystem Solid State Recorder memory load partition repair. The Sequence Team held a Final Sequence Integration and Validation meeting for C30. The sequence has been approved for uplink along with the Imaging Science Subsystem decontamination and Composite Infrared Spectrometer functional test mini-sequences. All files will be sent to the spacecraft next week. Science Planning reported completion of Satellite Orbiter Science Team (SOST)/ Science Uplink Verification (SUPV) activities. Within the next two weeks a package will be produced documenting results and lessons learned. In addition, the Science Planning Virtual Team kicked off development of the C32 sequence. Tour phase mission risks that require a rapid response and that currently need development work was the topic at this week's Mission Planning Forum. At the Cassini Design Team meeting, presentations included the development schedule and System Overview presentation package for the Uplink Critical Design Review to be held in February, and the Instrument Expanded Block strategy operations concept. A suite of Cassini training classes has been scheduled for next week to coincide with the Program Science Group meeting to be held at JPL. Mission Sequence Subsystem version D7.7 has been installed on all online Science Operations and Planning Computers. Cassini Outreach met this week to discuss completion of the Cassini Replan and timelines. 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 7-13 January 2002 This is the last week of orbital cruise activities for the Galileo spacecraft before it shifts into high gear for the next and final Io flyby. This week the distance between Galileo and Jupiter shrinks by nearly half, from 90 Jupiter radii (6.4 million kilometers or 4 million miles) on Monday, January 7, to 50 Jupiter radii (3.6 million kilometers or 2.2 million miles) on Sunday, January 13. On Thursday the spacecraft orientation is shifted by 2 degrees to keep the communications antenna pointed towards Earth. On Saturday the sequence of commands that will govern spacecraft activities during the Io flyby will be transmitted to Galileo from the 70-meter (230-foot) diameter communications antenna near Madrid, Spain. On Sunday the Extreme Ultraviolet Spectrometer instrument (EUV) is turned off. The instrument has been collecting data on interplanetary hydrogen and helium abundances since October 29. Since EUV shares data processing resources on the spacecraft with the Heavy Ion Counter instrument (HIC), EUV now turns over the reins to HIC, which will participate in the study of charged particles in the Io environment during the flyby. In the meantime, playback of the data recorded during the last Io flyby in October comes to a conclusion. This final week of playback will be used to help fill in gaps in previous playback data for the Solid State Imaging camera, the Near Infrared Mapping Spectrometer, and the Fields and Particles suite of instruments. Finally, on Sunday the playback process is halted to get ready for the recording activities to come. 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 _____________________________________________________________________ INTERNATIONAL SPACE STATION STATUS REPORT NASA/JSC release 11 January 2002 The Expedition Four crew is completing its fifth week in space aboard the International Space Station, continuing preparations for the first spacewalk of the five-month mission. The six-hour spacewalk by Commander Yury Onufrienko and Flight Engineer Carl Walz is scheduled to begin at 2:56 PM CST, Monday, January 14. This week, with the assistance of their crewmate, Flight Engineer Dan Bursch, the two spacewalkers outfitted and tested their Russian Orlan spacesuits and prepared the tools and equipment they will use on Monday. After exiting the station from the Russian Pirs docking compartment, Onufrienko and Walz will use a Russian cargo crane that is already installed on Pirs to relocate a similar crane from the station's Pressurized Mating Adapter 1 onto Pirs. On future spacewalks, the two cranes, called Strela (the Russian word for "arrow"), can be used to maneuver equipment and spacewalkers on the station's exterior. Onufrienko and Walz also will install an amateur radio antenna on a handrail at the end of the Zvezda service module. Monday's spacewalk will be the thirty-second in support of the assembly of the International Space Station, the seventh such excursion conducted from the station itself, and the sixth based out of the station's Russian segment. A second spacewalk this month--to be conducted by Onufrienko and Bursch--is targeted for January 25. The plan for this spacewalk currently includes the installation of thruster deflector shields on the end of Zvezda. In addition to preparing for next week's spacewalk, the Expedition Four crew continued a series of upgrades to the station's computer hardware. The crew also completed the first session of a Human Life Sciences experiment called Renal, which is investigating ways to prevent the formation of renal stones during long-duration spaceflights. For the latest information on the crew's activities aboard the space station, future launch dates and times, as well as station sighting opportunities from anywhere on the Earth, please visit the Web at http://spaceflight.nasa.gov. Details on station science operations can be found on the Web site of the Payload Operations Center at NASA's Marshall Space Flight Center in Huntsville, AL at http://www.scipoc.msfc.nasa.gov. The next ISS status report will be issued January 14 after completion of the spacewalk. _____________________________________________________________________ MARS ODYSSEY MISSION STATUS NASA/JPL release 11 January 2002 Flight controllers for NASA's Mars Odyssey spacecraft sent commands overnight to raise the spacecraft up out of the atmosphere and conclude the aerobraking phase of the mission. At 12:18 AM Pacific time January 11, Odyssey fired its small thrusters for 244 seconds, changing its speed by 20 meters per second (45 miles per hour) and raising its orbit by 85 kilometers (53 miles). The closest point in Odyssey's orbit, called the periapsis, is now 201 kilometers (125 miles) above the surface of Mars. The farthest point in the orbit, called the apoapsis, is at an altitude of 500 kilometers (311 miles). During the next few weeks, flight controllers will refine the orbit until the spacecraft reaches its final mapping altitude, a 400- kilometer (249-mile) circular orbit. "The successful completion of the aerobraking phase is a major milestone for the project. Aerobraking is the most complex phase of the entire mission and the team came through it without a hitch," said David A. Spencer, Odyssey's mission manager at JPL. "During the next month, we will be reconfiguring the spacecraft to begin the science mapping mission." The science mission is expected to begin in late February. During the aerobraking phase, Odyssey skimmed through the upper reaches of the Martian atmosphere 332 times. By using the atmosphere of Mars to slow down the spacecraft in its orbit rather than firing its engine or thrusters, Odyssey was able to save more than 200 kilograms (440 pounds) of propellant. This reduction in spacecraft weight enabled the mission to be launched on a Delta II 7925 launch vehicle, rather than a larger, more expensive launcher. JPL manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, DC. Principal investigators at Arizona State University in Tempe, the University of Arizona in Tucson, and NASA's Johnson Space Center, Houston, Texas, operate the science instruments. Additional science investigators are located at the Russian Space Research Institute and Los Alamos National Laboratories. Lockheed Martin Astronautics, Denver, CO, is the prime contractor for the project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena. NASA's Langley Research Center in Hampton, VA, is providing aerobraking support to JPL's navigation team during mission operations. _____________________________________________________________________ STARDUST STATUS REPORT NASA/JPL release 11 January 2002 There were two Deep Space Network tracking passes in the past week and all subsystems are performing normally. Stardust reached its maximum distance, 3.594 AU (334 million miles, or 538 million kilometers) from Earth. A signal takes 59 minutes 47 seconds to travel from Earth to spacecraft and back to Earth. Preparations for Deep Space Maneuver 2 (DSM-2), scheduled for next week, are in the final stages. DSM 2, also the seventh trajectory correction maneuver, will be a 2.65-meter-per-second (5.9-mile-per-hour) burn. 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 9, Number 2.