MARSBUGS: The Electronic Astrobiology Newsletter Volume 9, Number 1, 7 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) ASTROBIOLOGY RESEARCH LOOKS AT CONDITIONS THAT MAKE LIFE POSSIBLE By Karl Hill 2) NASA SENSOR CAPTURES PLIGHT OF PERILED ANTARCTIC PENGUINS NASA/JPL image advisory 3) SIGNS OF LIFE: ON THE LOOKOUT FOR EXTRATERRESTRIAL SWEET SPOTS By Leonard David 4) BIONIC EYES By Steve Price and Tony Phillips 5) "EYES" IN SPACE CHECK SHRIMP FARMS From ESA News 6) SPACE CREW CONDUCTS SHOCKING TEST By Richard Stenger 7) SIESTAS IN SPACE? National Space Biomedical Research Institute release 8) INHERENT SPEED LIMIT GOVERNS HOW QUICKLY LIFE BOUNCES BACK AFTER EXTINCTION, UC BERKELEY RESEARCH SHOWS University of California - Berkeley release 9) NEW ADDITIONS TO THE ASTROBIOLOGY INDEX By David J. Thomas 10) CASSINI WEEKLY SIGNIFICANT EVENTS NASA/JPL release 11) INTERNATIONAL SPACE STATION STATUS REPORT NASA/JSC release 12) STARDUST STATUS REPORT NASA/JPL release _____________________________________________________________________ ASTROBIOLOGY RESEARCH LOOKS AT CONDITIONS THAT MAKE LIFE POSSIBLE By Karl Hill, New Mexico State University release 17 December 2001 This vast universe surely holds plenty of worlds where life can flourish, right? Don't bet on it, says New Mexico State University physicist Slava Solomatov. The more scientists learn about the conditions that make life possible on Earth, the more they realize how complex those factors are--and how a relatively small change in one condition or another could have rendered the planet uninhabitable, Solomatov said. "It's a very finely tuned system," he said. "Some of the factors are well known, but we still don't know what all the factors are." Solomatov has a key part in a NASA-funded astrobiology research project aimed at better understanding the origin of life on Earth and the conditions in which life might be found elsewhere in the universe. The five-year, $4.9 million grant supports the work of a dozen researchers, headed by a team at the University of Washington. The scientists come from a variety of fields, because life requires much more than water and the right mix of elements to survive and evolve into higher forms. Solomatov's part of the project focuses on the role of plate tectonics--the geologic process that results in the shifting of Earth's continental and oceanic plates. Only in recent years have scientists recognized the importance of plate tectonics in maintaining Earth's long-term temperature stability, through global recirculation of carbon dioxide from the planet's interior into the atmosphere, he said. "Because carbon dioxide is a greenhouse gas, it helps to keep our planet warm," he said. "Of course, too much of it is not good, but without this cycle over the centuries the temperature would drop and you might have the 'Snowball Earth' scenario." Plate tectonics also provides diverse geological environments, like mountains, which promote biodiversity, Solomatov said. No other planets are known to have plate tectonics, although some may have had the feature earlier in their evolution, he said. Whether plate tectonics might be essential to the development of higher forms of life is unknown, but Solomatov's theoretical modeling of the complex processes aims to shed light on a number of key questions, including: What planetary conditions allow for the formation of plate tectonics? Are oceans necessary for plate tectonics? When and how did plate tectonics begin on Earth? The question of life on other planets, or even the habitability of other planets, has long captured our imagination, but we tend to be biased in our assumptions, Solomatov said. "We think this is normal and there should be planets all around the universe like Earth," he said. "The more I work in this area, the more I realize the chances really are very slim." It's not enough for a planet to be the right size, to have water, and to be located the right distance from a star of the right size. Without the giant planet Jupiter as a neighbor, and without our moon, Earth might not be the living planet that it is, Solomatov said. Jupiter has protected Earth from too many cataclysmic asteroid collisions, he explained--but on the other hand, a neighbor much larger that Jupiter would not allow formation of an Earth-like planet in the first place. Similarly, our moon is just the right size to help stabilize Earth's spin axis and, as a consequence, the Earth's climate. With a bigger moon or no moon at all, a planet similar to Earth in other respects might not sustain life. The list of critical factors grows longer as scientists learn more. "At the moment there are two camps of believers," Solomatov said. "One believes in the 'Rare Earth' hypothesis and the other thinks life is smart and can adapt to extreme conditions." The "Rare Earth" hypothesis, which takes its name from a book by University of Washington scientists Peter Ward and Don Brownlee, holds that microbial life might be common in planetary systems, but advanced life is rare. If pushed into one camp or the other, Solomatov would choose the "Rare Earth" believers. "We don't have enough data yet but all the evidence we have now points out that the Earth is a very special place," he said. "Maybe we should take better care of our planet." Photo caption: [http://kiernan.nmsu.edu/newsphoto/solomatov.jpg] New Mexico State University physicist Slava Solomatov is part of a NASA- funded astrobiology project aimed at better understanding the conditions that make life possible. (NMSU photo by Darren Phillips). Contact: Karl Hill, News Bureau University Communications New Mexico State University Las Cruces, New Mexico Phone: 505-646-1885 An additional article on this subject is available at http://www.spacedaily.com/news/life-02a.html. _____________________________________________________________________ NASA SENSOR CAPTURES PLIGHT OF PERILED ANTARCTIC PENGUINS NASA/JPL image advisory 27 December 2001 A NASA remote sensing instrument is capturing an unfolding ecological disaster affecting hundreds of thousands of penguins at Earth's southern tip. Images from the Multi-angle Imaging SpectroRadiometer, a remote sensor built and managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, are documenting the movement of huge icebergs and spreading sea ice in Antarctica's Ross Sea. These natural phenomena are adversely affecting the region's penguin population, according to a new study funded by the National Science Foundation. Two massive icebergs, initially designated B-15 and C-16, broke away from the Ross Ice Shelf in March 2000 and migrated west to a point northeast of McMurdo Sound. The resulting barrier altered wind and current patterns. In addition, earlier this season sea ice in the region of the main U.S. Antarctic facility, McMurdo Station, expanded from its normal distance of 24 to 32 kilometers (15 to 20 nautical miles) north of the base to approximately 128 kilometers (80 nautical miles). The combination of icebergs and sea ice has made it difficult for entire colonies of penguins to return from their feeding grounds in the open sea to their breeding areas. The result is expected to be a significant reduction in regional penguin populations, with one colony in danger of extinction. An image sequence is available online at http://www.jpl.nasa.gov/images/earth/antarctica. The images, taken between December 2000 and December 2001, depict the rapid motion of the C-16 iceberg in late 2000 and early 2001 and its subsequent stall, as well as the incursion of the B-15A iceberg, a large fragment of the original B-15 iceberg. The increase in sea ice is particularly pronounced in the final image. The Multi-angle Imaging SpectroRadiometer is one of several Earth- observing experiments aboard the Terra satellite, launched in December 1999. The instrument acquires images of Earth at nine angles simultaneously, using nine separate cameras pointed forward, downward and backward along its flight path. More information is available at http://www-misr.jpl.nasa.gov. The National Science Foundation manages the U.S. Antarctic Program, which coordinates almost all U.S. scientific research in Antarctica. More information is available at http://www.nsf.gov. JPL is a division of the California Institute of Technology in Pasadena. Contact: Alan Buis Phone: 818-354-0474 _____________________________________________________________________ SIGNS OF LIFE: ON THE LOOKOUT FOR EXTRATERRESTRIAL SWEET SPOTS By Leonard David From Space.com 3 January 2002 Looking for life elsewhere is a tough task for human or robot. The good news is that the scientific skill and tools to search for, detect and inspect extraterrestrial life are advancing rapidly. A revolution in the field of microbiology is afoot, along with extraordinary progress in understanding the "geobiological" history of Earth. And then there's growing amazement about life on this planet and how it can survive and thrive even in the most extreme and bizarre of environments. For example, within the last ten years alone, more than 1,500 new species of microorganisms have been discovered and genetically sequenced. In a just issued report, Signs of Life, a multidisciplinary group of scientists grappled with techniques and technologies to detect evidence for extraterrestrial life--either on the spot on other worlds, or within prime pickings hauled back to Earth by robotic spacecraft. Get the full story at http://www.space.com/searchforlife/lifesigns_spots_020103.html. _____________________________________________________________________ BIONIC EYES By Steve Price and Tony Phillips From NASA Science News 3 January 2002 Using space technology, scientists have developed extraordinary ceramic photocells that could repair malfunctioning human eyes. Rods and cones--millions of them are in the back of every healthy human eye. They are biological solar cells in the retina that convert light to electrical impulses--impulses that travel along the optic nerve to the brain where images are formed. Without them, we're blind. Indeed, many people are blind--or going blind--because of malfunctioning rods and cones. Retinitis pigmentosa and macular degeneration are examples of two such disorders. Retinitis pigmentosa tends to be hereditary and may strike at an early age, while macular degeneration mostly affects the elderly. Together, these diseases afflict millions of Americans; both occur gradually and can result in total blindness. "If we could only replace those damaged rods and cones with artificial ones," says Dr. Alex Ignatiev, a professor at the University of Houston, "then a person who is retinally-blind might be able to regain some of their sight." Years ago such thoughts were merely wishful, but no longer. Scientists at the Space Vacuum Epitaxy Center (SVEC) in Houston are experimenting with thin, photosensitive ceramic films that respond to light much as rods and cones do. Arrays of such films, they believe, could be implanted in human eyes to restore lost vision. "There are some diseases where the sensors in the eye, the rods and cones, have deteriorated but all the wiring is still in place," says Ignatiev, who directs the SVEC. In such cases, thin-film ceramic sensors could serve as substitutes for bad rods and cones. The result would be a "bionic eye." The Space Vacuum Epitaxy Center is a NASA-sponsored Commercial Space Center (CSC) at the University of Houston. NASA's Space Product Development (SPD) program, located at the Marshall Space Flight Center, encourages the commercialization of space by industry through 17 such CSCs. At the SVEC, researchers apply knowledge gained from experiments done in space to develop better lasers, photocells, and thin films--technologies with both commercial and human promise. Scientists at Johns Hopkins University, MIT, and elsewhere have tried to build artificial rods and cones before, notes Ignatiev. Most of those earlier efforts involved silicon-based photodetectors. But silicon is toxic to the human body and reacts unfavorably with fluids in the eye--problems that SVEC's ceramic detectors do not share. "We are conducting preliminary tests on the ceramic detectors for biocompatibility, and they appear to be totally stable" he says. "In other words, the detector does not deteriorate and [neither does] the eye." "These detectors are thin films, grown atom-by-atom and layer-by- layer on a background substrate--a technique called epitaxy," continues Ignatiev. "Well-ordered, 'epitaxally-grown' films have [the best] optical properties." Crafting such films is a skill SVEC scientists learned from experiments conducted using the Wake Shield Facility (WSF)--a 12-foot diameter disk-shaped platform launched from the space shuttle. The WSF was designed by SVEC engineers to study epitaxial film growth in the ultra-vacuum of space. "We grew thin oxide films using atomic oxygen in low-Earth orbit as a natural oxidizing agent," says Ignatiev. "Those experiments helped us develop the oxide (ceramic) detectors we're using now for the Bionic Eye project." The ceramic detectors are much like ultra-thin films found in modern computer chips, "so we can use our semiconductor expertise and make them in arrays--like chips in a computer factory," he added. The arrays are stacked in a hexagonal structure mimicking the arrangement of rods and cones they are designed to replace. The natural layout of the detectors solves another problem that plagued earlier silicon research: blockage of nutrient flow to the eye. "All of the nutrients feeding the eye flow from the back to the front," says Ignatiev. "If you implant a large, impervious structure [like the silicon detectors] in the eye, nutrients can't flow" and the eye will atrophy. The ceramic detectors are individual, five- micron-size units (the exact size of cones) that allow nutrients to flow around them. Artificial retinas constructed at SVEC consist of 100,000 tiny ceramic detectors, each 1/20 the size of a human hair. The assemblage is so small that surgeons can't safely handle it. So, the arrays are attached to a polymer film one millimeter by one millimeter in size. A couple of weeks after insertion into an eyeball, the polymer film will simply dissolve leaving only the array behind. The first human trials of such detectors will begin in 2002. Dr. Charles Garcia of the University of Texas Medical School in Houston will be the surgeon in charge. "An incision is made in the white portion of the eye and the retina is elevated by injecting fluid underneath," explains Garcia, comparing the space to a blister forming on the skin after a burn. "Within that little blister, we place the artificial retina." Scientists aren't yet certain how the brain will interpret unfamiliar voltages from the artificial rods and cones. They believe the brain will eventually adapt, although a slow learning process might be necessary--something akin to the way an infant learns shapes and colors for the first time. "It's a long way from the lab to the clinic," notes Garcia. "Will they work? For how long? And at what level of resolution? We won't know until we implant the receptors in patients. The technology is in its infancy." Ignatiev has received over 200 requests from patients who learned of the studies from earlier press reports. "I'm extremely excited about this," he says. He cautions that much more research is needed, but "it's very promising." Additional information on this article is available at http://science.nasa.gov/headlines/y2002/03jan_bioniceyes.htm?list6924 7. _____________________________________________________________________ "EYES" IN SPACE CHECK SHRIMP FARMS From ESA News http://www.esa.int 3 January 2002 Shrimps with salad, shrimps with pasta, shrimps with pizza, potted shrimps with toast--if this delicacy has now become fairly common we have the shrimp farmers in Europe, South America and particularly Asia to thank. In the future thanks will also be due to satellites and the important remote sensing data that they provide on aquaculture. Shrimp farming is a thriving business. According to the Food and Agriculture Organization (FAO) aquaculture production has increased rapidly in the past decade while seafood production has remained relatively stable--and shrimp farming is one of the fastest growing sectors of the aquaculture industry. Although shrimp farms can be found all over the world, the main cultured shrimp-producing countries are in Latin America and Asia, and the main markets are the United States, Japan and Europe. In value terms, shrimps are the most important seafood products traded internationally. As often happens, however, its rapid development has been accompanied by controversial debates over the environmental, social and economic impact of shrimp farming. Often, government planning and regulatory frameworks have been unable to keep pace with the rapid rise in shrimp farms. Care is needed to ensure that private returns on shrimp culture can be sustained and to preserve the local environments of mangroves, creeks and lagoons; coastal water quality; and wild shrimp stocks. This is where ESA and the remote sensing data supplied by its satellites can help out. A few years ago ESA, FAO and the Government of Sri Lanka worked together on a remote sensing study to protect and improve shrimp farming. Outbreaks of disease had badly hit the shrimp farmers and one of the causes was thought to be the uncontrolled proliferation of the farms, which had damaged the environment. What was needed was precise regular mapping of the shrimp farms to register their increase and growth, and to monitor encroachment onto reservation areas. ESA's Earth Remote Sensing satellites are continually orbiting around the Earth allowing the equipment onboard to provide constant data, in all weather, on our environment. One of these instruments is called synthetic aperture radar (SAR). This data covers an area of 100 km2 and collects information on the same place on Earth, normally at regular intervals of every 35 days. By comparing SAR data of the selected shrimp farming area in Sri Lanka for the last few years, and then developing the methodology to identify and quantify the surface area enclosed by shrimp farms, it was possible to assess their growth and to monitor their development. Once the satellite data had been interpreted, a random field survey was undertaken to check the accuracy of the methodology. The results were extremely encouraging as the data proved to be more than 90% accurate. The satellite data showed that in three years the area covered by shrimp farms had increased by more than 44%. The high resolution of the SAR data made it possible to pinpoint the areas in which the growth had been most rapid and the remote sensing results showed that the growth had been much greater than estimates carried out by traditional means had led the authorities to believe. As this was the first time that SAR data had been used to inventory and monitor shrimp farms the most demanding part of the study was to develop the methodology to interpret the data. However, now that this has been developed it is can easily be used in other areas. A further advantage was that the survey found the cost of using satellite data to be relatively modest in comparison to that of aerial photography. The latter also has the drawback of being more difficult to obtain and being unavailable in cloudy weather--a condition common in tropical and subtropical areas. Given the positive results of the Sri Lanka study carried out with ESA's help, FAO prepared a regional project for the inventory and monitoring of coastal and inland aquaculture which it is hoped will come into operation in 2002. India, Indonesia, Malaysia, the Philippines, Thailand and Vietnam have all requested to take part in this study. An important feature of the project will be to train local personnel in the use of the methodology developed in Sri Lanka so that they will be able to interpret the satellite data for themselves. Carlo Travaglia of FAO's Environment and Natural Resources Service expects the number of shrimp farms, as well as other forms of aquaculture, to continue to grow over the next two decades. "A large percentage of global production comes from small producers living in developing countries. Satellites and shrimps are a strange combination but one that is contributing to increasing food security, alleviating poverty and safeguarding our environment". Related links * FAO http://www.fao.org/ * Network of Aquaculture Centres in Asia and the Pacific http://www.enaca.org/ Image captions Image 1: [http://www.esa.int/export/esaCP/ESAAQWZ84UC_index_1.html] Market demand for shrimps continues to increase worldwide. Photo: AP Image 2: [http://www.esa.int/export/esaCP/ESAAQWZ84UC_index_1.html#subhead1] Young boys catching shrimps in Bangladesh. Photo: FAO Image 3: [http://www.esa.int/export/esaCP/ESAAQWZ84UC_index_1.html#subhead2] Map of shrimp farms in the Seguwantiyu test site made with the help of SAR data. By 1999, all available land for shrimp farms had already been used. Credit: FAO Image 4: [http://www.esa.int/export/esaCP/ESAAQWZ84UC_index_1.html#subhead3] Shrimps being left to dry on the roof of a fishing boat. Photo FAO _____________________________________________________________________ SPACE CREW CONDUCTS SHOCKING TEST By Richard Stenger From CNN 3 January 2002 Resuming their scientific work after the holidays, the international space station residents took part in an experiment that delivered quite an electric shock. The test, one of many planned this week, will help measure the effects of space flight on the spinal cord, according to NASA scientists. The electrical pulse was delivered to the back of the knee on test crewmembers. Instruments recorded the resulting contraction of the calf muscle. The response, known as the Hoffmann reflex, resembles the leg twitch that takes place when a doctor taps a patient's knee with a rubber hammer. The greater the jerk, the greater the spinal cord excitability. The human body undergoes numerous physiological changes in the weightlessness of space, affecting the bones, the muscles and the internal equilibrium mechanism, for example. By studying the Hoffman reflex on Alpha residents, Canadian Space Agency researchers hope to find out more information about changes to the human neurological system during long-duration space flights. Get the full story at http://www.cnn.com/2002/TECH/space/01/02/iss.test/index.html. _____________________________________________________________________ SIESTAS IN SPACE? National Space Biomedical Research Institute release 3 January 2002 Brief naps may prevent the effects of chronic sleep loss experienced by astronauts during missions. Studies of astronauts' sleep indicate they average about six hours per day while in orbit, which is below the amount they receive on Earth. Although the reasons for this sleep loss are unknown, it is suspected that excitement, extended work schedules, environmental disturbances and microgravity are leading culprits. "Whatever the cause, extensive ground-based research shows that chronically reduced sleep impairs thought processes and slows reaction times," said Dr. David Dinges, National Space Biomedical Research Institute's (NSBRI) Neurobehavioral and Psychosocial Factors Team Leader. "Mental mistakes and lapses of attention increase. Also, complex problem solving, learning and emotional reactions can be affected." Dinges, also on the NSBRI's human performance team, hopes to find a solution to chronic sleep loss in space. To help astronauts get the most benefit from sleep, Dinges wants to identify the ideal combination of one major, "anchor" sleep period combined with a short nap each day. He is focusing on daily naps because studies have shown greater recovery of sleep's benefits during the early hours of sleep. For this reason, dual sleep periods totaling four to six hours are being tested to determine if the combinations will produce the same benefits as a single eight-hour sleep period. "We want to know if these anchor and nap sleep combinations will prevent the harmful effects of reduced sleep that occur when they don't take a nap," said Dinges, who is chief of the Division of Sleep and Chronobiology in the Department of Psychiatry at the University of Pennsylvania School of Medicine. Eighteen combinations of anchor sleep and naps are being studied to establish the best way to reduce sleep debt. The study involves putting diverse groups of healthy men and women into a suite of small rooms for two weeks to simulate space flight's low light, tight quarters and lack of social contact with the outside world. Participants undergo neurobehavioral performance testing and continuous monitoring of brain activity, sleep, body temperature, behavior and mood changes. Samples of key circadian and sleep- regulated regulatory hormones, such as melatonin, cortisol and human growth hormone, are taken to determine whether various sleep combinations adversely affect their secretions. Using statistical modeling, test results will provide information on the most efficient sleep-wake schedules with the goal of minimizing cognitive and physiological deficits. The project also looks at whether age and gender affect results. This research is relevant for space flight ground personnel who must work on round-the-clock schedules. Results will also have important implications for optimizing work-rest scheduling in safety-sensitive industries, such as transportation, military, public safety and health care. Findings could also benefit people suffering from pain, insomnia or other clinical illnesses that disrupt sleep. "There is mounting evidence that the immune system and metabolic processes can be affected by the amount of sleep we obtain," Dinges said. "We are working with investigators at The Children's Hospital of Philadelphia, Harvard Medical School and the NSBRI Immunology, Infection and Hematology Team to study this further." The project is complemented by NSBRI teams looking at other space health concerns such as bone loss, cardiovascular changes, muscle wasting, balance and orientation problems, and radiation exposure. While focusing on space health issues, the Institute will quickly transfer the solutions to Earth patients suffering from similar conditions. NASA funds the NSBRI. The NSBRI's consortium members include Baylor College of Medicine, Brookhaven National Laboratory, Harvard Medical School, The Johns Hopkins University, Massachusetts Institute of Technology, Morehouse School of Medicine, Mount Sinai School of Medicine, Rice University, Texas A&M University, University of Arkansas for Medical Sciences, University of Pennsylvania Health System and University of Washington. Contact: Liesl Owens Communication and Outreach Office National Space Biomedical Research Institute Phone: 713-798-7595 E-mail: lkowens@bcm.tmc.edu _____________________________________________________________________ INHERENT SPEED LIMIT GOVERNS HOW QUICKLY LIFE BOUNCES BACK AFTER EXTINCTION, UC BERKELEY RESEARCH SHOWS University of California - Berkeley release 3 January 2002 The 500-million-year history of life on Earth is a series of booms and busts. But while the busts, or extinctions, can be either sudden or gradual, the booms of diversification of new organisms rarely happen quickly, according to a new study by a University of California, Berkeley, scientist. A statistical analysis of the rates of extinction and origination in the fossil record shows that life seldom rebounds rapidly from an extinction. The results imply that the diversification of life obeys "speed limits" set by evolutionary processes, said study author James Kirchner, professor of earth and planetary science at UC Berkeley. "There seem to be biological mechanisms that limit diversification of new organisms and control which ones become successful enough to persist," he said. "Biodiversity is slow to recover after an extinction." This apparent speed limit on the rate at which surviving organisms evolve and diversify has major implications for present-day extinctions. "If we substantially diminish biodiversity on Earth, we can't expect the biosphere to just bounce back. It doesn't do that. The process of diversification is too slow," Kirchner said. "The planet would be biologically depleted for millions of years, with consequences extending not only beyond the lives of our children's children, but beyond the likely lifespan of the entire human species." The paper by Kirchner appears in the January 3, 2002, issue of the journal Nature (Evolutionary speed limits inferred from the fossil record, http://www.nature.com/cgi- taf/DynaPage.taf?file=/nature/journal/v415/n6867/abs/415065a_fs.html) . Kirchner has been mining a fossil database created by the late University of Chicago paleontologist Jack Sepkoski, who catalogued the genera and families of fossil marine animals over the past 530 million years, from the Cambrian to the present. Using a technique called spectral analysis, Kirchner has looked for patterns in the rates at which new organisms appear or disappear. Last year Kirchner and colleague Anne Weil reported that the Earth needs, on average, about 10 million years to recover from global extinctions, whether they involve the loss of most life on Earth or wipe out far fewer species. This was much longer than most scientists thought. The new results come from asking a related question. How do rates of extinction and diversification vary, and how are they related? This is important because, if rapid diversification is possible, biodiversity might be able to rebound quickly from a global extinction. Kirchner's analysis found that extinction rates and diversification rates are about equally variable over long spans of geological time. Over shorter periods, however, diversification rates vary much less than extinction rates do. That means that evolution doesn't accelerate quickly in response to rapid bursts of extinction. One possible explanation for why diversification takes so long to rev up after an extinction is that extinction eliminates not merely species or groups of species, but takes away ecological niches. It eliminates both organisms and the roles those organisms played in the ecosystem. Recovery thus becomes more complicated. "This shows that extinction is not like knocking chess pieces off a chessboard, with the empty squares ready for you to plunk down new pieces," Kirchner said. "Extinction is more like knocking down a house of cards. You only have places to put new cards as you rebuild the structure of the house." It's as if the ecosystem must bootstrap its way to the level it was at before. "For a new kind of organism to evolve and survive long enough for us to notice it--for it to become common enough to leave a fossil record--requires that it have an evolutionary niche. The organism has to have some role in order to succeed in its ecosystem," he said. "As a result, the ecosystem must first increase in complexity so there are niches for new organisms to fill, which is probably a very complicated process. "At a fundamental biological level it takes time to build niches, evolve new organisms and filter out unsuccessful ones, although it's not yet clear what all the limiting factors are." The work was supported by grants from the National Science Foundation and the University of California. James Kirchner can be reached at (510) 643-8559 or via e-mail at kirchner@seismo.berkeley.edu. Contact: Robert Sanders University of California - Berkeley Phone: 510-643-6998 E-mail: rls@pa.urel.berkeley.edu _____________________________________________________________________ NEW ADDITIONS TO THE ASTROBIOLOGY INDEX By David J. Thomas http://www.lyon.edu/webdata/users/dthomas/astrobiology/astrobiology.h tml 7 January 2002 Articles about astrobiology, exobiology and terraformation http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_article s1.html L. David, 2002. Signs of life: on the lookout for extraterrestrial sweet spots. Space.com. K. Hill, 2002. A universe of life: maybe not. SpaceDaily. Articles about human space exploration and the microgravity environment http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_article s3.html R. Stenger, 2002. Space crew conducts shocking test. CNN. Articles about evolutionary biology and chemistry http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_article s5.html J. W. Kirchner, 2002. Evolutionary speed limits inferred from the fossil record. Nature, 415(6867):65-68. _____________________________________________________________________ CASSINI WEEKLY SIGNIFICANT EVENTS NASA/JPL release 27 December 2001 - 2 January 2002 The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Wednesday, January 2. The Cassini spacecraft is in an excellent state of health and is operating normally. See the "Present Position" web page at http://www.jpl.nasa.gov/cassini/english/where/. Recent instrument activities include two Radio and Plasma Wave Science High Frequency Receiver calibrations. Engineering activities taking place onboard the spacecraft this week include an Attitude Control Subsystem (ACS) high-water mark clear. Execution of C29 continues normally with the ongoing Gravitational Wave Experiment, of which 37 days out of 40 days have been completed. Spacecraft health remains excellent, maintaining a quiet spacecraft on RWA control. Instruments remain quiet as well with MAPS data being collected and downlinked. On December 29, continuous DSN coverage in place for the GWE was interrupted by a predicted lunar occultation lasting 1 hour and 24 minutes. All ground operations for loss and re-acquisition of signal after the occultation proceeded normally. 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. _____________________________________________________________________ INTERNATIONAL SPACE STATION STATUS REPORT NASA/JSC release 4 January 2002 The International Space Station's Expedition Four crew began a new year in space this week conducting a variety of experiments, testing new techniques with the station's robotic arm and beginning to prepare for a spacewalk planned later this month. Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch observed a quiet New Year's holiday in orbit, spending time relaxing and communicating with family and friends. Later in the week, work resumed as the crew operated two experiments that study astronauts' reactions to weightlessness. Walz and Bursch both participated in the H-Reflex experiment, a study that gauges the effects of weightlessness on spinal cord excitability and reflexes, and the Pulmonary Function experiment, a study of the effects of space flight and spacewalks on lung function. Bursch and Walz had an opportunity to train in the operation of the station's robotic arm, the Canadarm2, while maneuvering the arm on Thursday to latch on to fixtures on the exterior of the station. In addition to providing training for the crew, the arm operations tested a new technique being developed to alleviate tension that has been seen as the arm releases its latch on a fixture. The tests provided valuable data for engineers on the ground developing those techniques, and similar tests may be repeated later in the mission. The crewmembers have virtually completed unpacking and stowing the more than three tons of supplies and equipment brought to the station with them aboard the space shuttle in early December. Their attention next week will turn to an upcoming milestone for their flight--the first of two planned this month and as many as four spacewalks that are planned during their five-month stay aboard the station. Walz and Onufrienko are planned to conduct a spacewalk for up to six hours tentatively beginning at about 2:50 PM CST January 14. This weekend, the crew will begin shifting their sleep period later to adjust for the timing of the upcoming spacewalk, and, next week, checkouts will begin of the spacesuits and spacewalking gear that will be used for the work outside. The spacewalk will use Russian Orlan space suits and originate from the Russian Pirs docking compartment airlock. Onufrienko and Walz will reposition an exterior Russian strela cargo crane from the station's pressurized mating adapter 1 to the station's Zarya module, moving it within reach of a similar crane on the Pirs compartment. The move will allow the cranes to be used in tandem to maneuver equipment on the station's exterior during future spacewalks. 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/. Overall coordination of the research aboard the space station is the responsibility of the Payload Operations Center at NASA's Marshall Space Flight Center in Huntsville, AL. Details of station science operations can be found on the Web at http://www.scipoc.msfc.nasa.gov. The next ISS status report will be issued January 11, 2002. _____________________________________________________________________ STARDUST STATUS REPORT NASA/JPL release 4 January 2002 There were three Deep Space Network tracking passes in the past week, and all subsystems are normal. Now that Stardust has left solar conjuction and is no longer within 3 degrees of the Sun, its command loss timer was lowered back to 17 days. Stardust successfully performed a 180-degree yaw maneuver before, during and after its time close to the Sun. During the conjunction, the spacecraft passed behind the Sun, and from the spacecraft's point of view the Sun moved from the -X (left-hand, if you were looking at the spacecraft) side of the spacecraft to the +X (right-hand) side. However, since the attitude subsystem had been commanded to keep the Sun on the -X side, the on-board software made the spacecraft slowly perform a 180-degree roll to keep the Sun on the proper side. The spacecraft is commanded to keep the Sun on the -X side to eliminate any potential solar array shadowing from the Whipple shield. Preparations continue for Deep Space Maneuver 2, slated for January 18. The maneuver will be approximately 3 meters per second (8.5 miles per hour.) 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 1.