MARSBUGS: The Electronic Astrobiology Newsletter Volume 9, Number 23, 24 June 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. Information concerning the scope of this newsletter, subscription formats and availability of back-issues is available from the Marsbugs web page at http://welcome.to/marsbugs or http://www.lyon.edu/webdata/users/dthomas/marsbugs/marsbugs.html. _____________________________________________________________________ CONTENTS 1) TANDEM EVOLUTION By Anne M. Rosenthal 2) THE SEARCH FOR DISTANT EARTHS By Lee J. Siegel 3) STUDY OF DUST IN ICE CORES SHOWS VOLCANIC ERUPTIONS INTERFERE WITH THE EFFECT OF SUNSPOTS ON GLOBAL CLIMATE University at Buffalo, State University of New York release 4) DEFINING LIFE By Leslie Mullen 5) CURIOUS SKELETONS By Karen Miller and Tony Phillips 6) GEARING UP TO HARVEST MARS' WATER RESOURCE By Leonard David 7) ASTEROID 2002MN GIVES EARTH ITS CLOSEST SHAVE IN YEARS Near Earth Object Information Centre release 8) LARGE FORMER LAKE, CATASTROPHIC FLOOD IDENTIFIED ON MARS Smithsonian Institution release 9) INTERNATIONAL TEAM EXPLORES LUNAR BASE PROPOSALS By Leonard David 10) NEW ADDITIONS TO THE ASTROBIOLOGY INDEX By David J. Thomas 11) CASSINI SIGNIFICANT EVENTS NASA/JPL release 12) THE NEXT FOUR WEEKS ON GALILEO NASA/JPL release 13) INTERNATIONAL SPACE STATION SCIENCE OPERATIONS STATUS REPORT NASA/MSFC release 02-155 14) MARS ODYSSEY THEMIS IMAGES NASA/JPL/ASU release 15) STARDUST STATUS REPORT NASA/JPL release _____________________________________________________________________ TANDEM EVOLUTION By Anne M. Rosenthal From Astrobiology Magazine 3 June 2002 Several kilometers beneath the ocean surface a fascinating evolutionary synchrony is occurring. A type of clam that inhabits deep-sea hydrothermal vents is so closely knit with a bacterium living in its tissues that their evolutionary paths, as recorded in their DNA, run in lockstep. Vesicomyid clams are some of the many intriguing animals inhabiting hydrothermal vents. Like other vent fauna, they depend on sulfide-eating microbes for energy. Sunlight does not penetrate to the ocean's depths. In its absence, photosynthesis the powerhouse for food chains on the Earth's surface cannot occur. Instead, the sulfur bacteria obtain energy through a process called chemosynthesis. They oxidize hydrogen sulfide (H2S) from mineral-rich underwater flows, using the energy released by this chemical reaction to build organic compounds. Because higher organisms can use these organic compounds for food, the sulfur bacteria form the base of the food chain for vent fauna. Many hydrothermal vent animals graze on free-living forms of these sulfur bacteria, which grow in such profusion that the colonies appear almost like grass growing around the vents. But vesicomyid clams, like the giant tubeworms and mussels that also inhabit the vents, host sulfur bacteria within their own tissues. In a symbiotic relationship, the bacteria provide their hosts with nutrients while their hosts provide a specialized environment where the bacteria can flourish. A maternal inheritance This symbiosis has intrigued several researchers, including Dr. Robert Vrijenhoek, a biologist at the Monterey Bay Aquarium Research Institute (MBARI), who studies genetic variation among hydrothermal vent organisms. "Symbiosis is interesting because it contrasts with pathogenesis," Vrijenhoek says. "Studying negative and positive interactions between bacteria and hosts can provide insights regarding the evolutionary dynamics of bacteria." Vrijenhoek began looking more closely at the clams and their bacterial guests. In earlier studies, species of sulfur bacteria residing within vesicomyid clams were found only as symbionts, never as free-living organisms. Studies by S. Craig Cary, Professor at the University of Delaware, College of Marine Studies, suggested that rather than obtaining bacteria from the surrounding water, the clams inherited their microbes from their mothers. The eggs from which the clams developed contained bacterial starter cultures. The obligatory symbiosis between the clams and their bacteria neither can survive without the other predisposes them to a tight evolutionary relationship. Vrijenhoek's group, which was then at Rutgers University and included Andrew Peek, Robert Feldman, and Richard Lutz, hypothesized that the two evolved together, a process known as coevolution. Symbiosis is one of the most important issues in coevolution," notes Vrijenhoek, with both the hosts and symbionts evolving to improve the way they cooperate." Over the eons, when one species of clam evolved into two perhaps through the isolation of one population from another, or the colonization of greater depths the bacterial strain riding along would also have split into two lineages that scientists might identify as distinct species. The branching of one or more species from another forms what can be pictured as an evolutionary tree. "The ancestors form the roots, the trunk, and the branches, successively, and modern, that is, living species form the twigs at the ends of this tree. Some branches are broken--species go extinct, terminating a branch--and others proliferate wildly into many twigs since speciation can occur in rapid bursts," Vrijenhoek explains. Vrijenhoek's group proposed that if the clam and bacterial species had coevolved, their evolutionary trees should have the same basic shapes. They used molecular biology techniques to examine the DNA and construct genealogies evolutionary trees of genes for both the clams and their guests. The mechanism by which the clams obtain their bacteria, maternal inheritance, is significant, says Vrijenhoek, because it would tend to preserve any genetic signature of coevolution by the two species. No contamination of the clams with new bacteria from the environment would dilute the signature. Matching trees The first step was to obtain a variety of clam species. Vrijenhoek's group was able to obtain specimens of nine different species from hydrothermal vent communities distributed worldwide. To construct the evolutionary tree for the bacteria, the scientists looked for variations in portions of the bacterial chromosome that code for ribosomes, the cellular structures where amino acid chains are manufactured. For the clams, the scientists chose segments from mitochondrial DNA. Mitochondria are small organelles that exist within the cells of all multicellular organisms. These organelles have their own DNA and are inherited maternally through the egg, similar to the way in which the symbiotic bacteria are inherited from one hydrothermal clam generation to another. Therefore, if coevolution had occurred, changes in bacterial DNA, as mapped in an evolutionary tree, would likely be mirrored in clam mitochondrial DNA. The findings were spectacular. The trees for the clams and their sulfur bacteria matched closely, both in their branching patterns and the evolutionary times when new species developed. Cospeciation--new species arising together--had, indeed, occurred. A different strategy Vrijenhoek's group also wondered about other vent animals with bacterial symbionts. Had coevolution occurred there as well? The group decided to focus next on vestimentiferan tubeworms. In previous studies led by Cary, examination of tubeworm eggs had yielded no bacteria. The scientists worried, however, that perhaps sulfur bacteria were present in those eggs, just difficult to detect with the available techniques. Thus, Cary joined his efforts with Vrijenhoek's group to determine whether the tubeworms obtained their bacteria from surrounding waters. The sulfur bacteria hosted by tubeworms are different than those found in vesicomyid clams. Robert Feldman, then a Rutgers University postdoctoral fellow working with Vrijenhoek and Cary, found that the species of bacterium a tubeworm hosts depends on the worm's habitat. Species of tubeworms that lived on basaltic vents all shared one type of bacterium, while species of tubeworms that lived in muddy sediments all shared another. Using genetic techniques capable of finer levels of discrimination, Carol DiMeo, then a graduate student at the University of Delaware, found that all the tubeworm species living near a particular vent hosted the same set of bacterial strains. "These findings lent further support to the supposition that tubeworms are reinfected in every generation from the surrounding environment," explains Vrijenhoek. Without a means of inheriting their bacteria, the evolution of tubeworm species likely occurred independently of their symbionts. As in the previous study of clams, the group looked at ribosomal DNA for the bacteria, and mitochondrial DNA for their hosts. But unlike the clams and their symbionts, there was no evidence that the mitochondrial DNA of the tubeworms and ribosomal DNA of the bacteria had evolved in tandem. Not only did the evolutionary trees of the tubeworms and their bacteria differ in their branching patterns, but also speciation had occurred over vastly different time spans. Several groups of bivalves hosting chemosynthetic symbiotic bacteria have been studied for possible evidence of cospeciation, but Vrijenhoek's work on the vesicomyids marks the first time that cospeciation has actually been demonstrated, says Colleen Cavanaugh, Professor of Biology at Harvard University and an authority on symbiotic relationships in hydrothermal vent fauna. It was Cavanaugh who confirmed, in 1983, the presence of the symbiotic bacteria in the gill tissue of the vesicomyid clams. The other major groups between which symbioses have been extensively studied are insects and bacteria, especially aphids and the Buchnera bacterium, explains Cavanaugh. Importantly, the genome of the Buchnera symbiont has been sequenced completely, allowing comparisons at many levels, between bacteria that are free-living and those that can only survive as symbionts. Sequencing the genomes of symbionts like those hosted by vesicomyid clams, Cavanaugh adds, could provide enormous insights into these bacteria." Vesicomyid clams and vestimentiferan tubeworms exemplify two contrasting evolutionary strategies for obtaining the bacteria that allow them to survive in the hydrogen sulfide-based vent ecosystem, muses Vrijenhoek. Each strategy confers different benefits and risks to both the host species and the bacterial species residing within them. "Carrying the symbiotic bacterium in its eggs and larvae provides a benefit for clams that need to find far-flung hydrothermal vent habitats in a vast ocean. Dispersing clam larvae arrive at a new vent habitat with everything that's needed to grow and survive," says Vrijenhoek. In contrast, when tubeworm larvae disperse, not only do they have to find hydrothermal vents tiny and ephemeral habitats they also need to incorporate an appropriate species of sulfur-oxidizing bacterium before they can grow, he notes. "Since tubeworms colonize hydrothermal vents in the eastern Pacific more rapidly and effectively than clams, acquiring a symbiont from the environment seems to pay off," Vrijenhoek says. "The clams, on the other hand, appear to wait until conditions are just right for establishment and growth of a new colony. Although the riskier strategy may pay higher rewards for the tubeworms, the safer strategy works for the clams. Both the clams and tubeworms have been participating in their respective symbiotic life style for perhaps as much as 100 million years." What's next? Vrijenhoek's group, including MBARI post-doctoral fellow Steven Hallam, is continuing to look at various aspects of the evolutionary relationship between deep-sea tubeworms and their symbiotic bacteria. Studies submitted for publication examine whether the ratios of bacterial strains within tubeworms are consistent across tubeworm species at a single location. These studies could provide additional insight on environmental acquisition of bacteria. Part of Cavanaugh's current research may aid in learning about the tubeworm bacteria. She is currently funded by NOAA (National Oceanic and Atmospheric Administration) to search for free-living forms of tubeworm symbionts using the Alvin submersible, a search comparable to looking for a potential needle in a haystack. So far, even though all evidence points to environmental transmission of these symbiotic bacteria, no one has isolated them from the environment. Vrijenhoek's interests include how the tubeworm host and its symbiotic bacteria find each other, which, he says, is completely unknown. "We are hoping that the new discoveries being made with pathogenic bacteria of humans and nitrogen-fixing bacteria that infect legumes can help us develop models for environmentally acquired symbionts," says Vrijenhoek. How do the hosts find the bacteria? Or is it the other way around?" Vrijenhoek also wants to look at how the bacteria invade host tissues, including how the host recognizes the invaders as beneficial rather than harmful. Additional information on this article is available at http://www.astrobio.net/news/modules.php?op=modload&name=News&file=ar ticle&sid=221. _____________________________________________________________________ THE SEARCH FOR DISTANT EARTHS By Lee J. Siegel From Astrobiology Magazine 5 June 2002 Imagine trying to see an ant crawling across the headlight of a car miles away. That is the magnitude of the task facing astronomers as they search for small, rocky Earth-like planets around other stars-- planets that might harbor life. "The question is, 'Are Earths frequent or rare in our galaxy?'" says Bill Borucki, an astrophysicist at NASA's Ames Research Center in Mountain View, CA. "If they are frequent, the galaxy is probably full of life. 'Star Trek' will happen. If there are no other Earth- like planets, there can be no 'Star Trek.' There is no place to go." During the next 15 years or so, American and European scientists hope to launch more than half a dozen missions to search our corner of the Milky Way galaxy for terrestrial planets. So far, Earth-based telescopes have found more than 80 planets orbiting relatively nearby stars [now more than 90, see the previous issue of Marsbugs]. Almost all of them, however, are believed to be giant gaseous planets like Jupiter, a few hundred times more massive than Earth, without a solid surface or liquid water. Some are smaller planets located near pulsar stars with radiation that would make life impossible, Borucki says. The traditional ground-based method of looking for extrasolar planets uses the Doppler shift a change in color of a star's light to measures changes in the star's velocity caused by the gravitational pull of an orbiting planet. The technique can detect only Jupiter- sized planets. Finding Earth-sized planets may well require placing telescopes in space, because the Earth's atmosphere blurs and distorts the light from the star and planet, and because daylight, weather and Earth's rotation prevent continuous observations needed for some planet-hunting methods. The United States and Europe plan six space-borne missions in which planet hunting is a major goal. They include France's small-scale COROT, NASA's more-ambitious Kepler mission, the European Space Agency's (ESA) Eddington and NASA's Space Interferometry Mission (SIM). These four missions would set the stage for two more- expensive and sophisticated missions, NASA's Terrestrial Planet Finder (TPF) and ESA's Darwin. The French COROT mission, approved and due for launch in late 2004 or 2005, will study asteroseismology, or oscillations within stars, and likely will be the first orbiting telescope to search for extrasolar planets. It will look at 50,000 to 60,000 stars and should find a few dozen terrestrial planets and several hundred close-in gas-giant planets during a two- to three-year mission, says Pierre Barge, an astronomer at the Laboratory of Astrophysics in Marseille and leader of COROT's exoplanets group. COROT--for Convection, Rotation and Planetary Transits--is a mission of CNES, the French National Center for Space Studies, in partnership with ESA, Italy, Belgium and Germany. When searching for extrasolar planets, COROT's 27-centimeter (10.6-inch) telescope will use a method called photometry, in which sensitive light detectors look for a slight drop in a star's brightness as a small planet "transits" the star (crosses the face of the star as viewed from COROT). "It will be on the edge of possibility as to whether COROT can detect a planet the same size as Earth," says Alan Penny, a space scientist at Britain's Rutherford Appleton Laboratory. Meanwhile, as part of its Discovery Program, NASA has approved a more powerful planet-hunting photometry telescope, named Kepler. The Kepler mission is scheduled for launch into solar orbit in October 2006. Kepler will simultaneously observe 100,000 stars in our galactic "neighborhood," looking for Earth-sized or larger planets within the "habitable zone" around each star--the not-too-hot, not- too-cold zone where liquid water might exist on a planet. To highlight the difficulty of detecting an Earth-sized planet orbiting a distant star, Borucki, Kepler's principal investigator, points out it would take 10,000 Earths to cover the Sun's disk. "It's really very much like if you looked at a big highway from miles away and saw all these cars and headlights coming toward you at night, and looked to see if there was an ant crawling across one of the headlights," Borucki says. One NASA estimate says Kepler should discover 50 terrestrial planets if most of those found are about Earth's size, 185 planets if most are 30 percent larger than Earth and 640 if most are 2.2 times Earth's size. In addition, Kepler is expected to find almost 900 giant planets close to their stars and about 30 giants orbiting at Jupiter-like distances from their parent stars. Because most of the gas giant planets found so far orbit much closer to their stars than Jupiter does to the Sun, Borucki believes that during the four- to six-year mission, Kepler will find a large proportion of planets quite close to stars. If that proves true, he says, "We expect to find thousands of planets." Kepler will also catalog the brightness, temperature, stellar type and other properties of stars orbited by habitable planets, helping to provide targets for later missions. In 2008 or later, the European Space Agency hopes to launch the Eddington mission (named for the late British astronomer Arthur Eddington). Eddington primarily would study stars' interior structures and the processes that govern how stars evolve, but it would spend three years scanning 500,000 stars for planets, including terrestrial planets in habitable zones. Like Kepler and COROT, Eddington would use a camera with a large optical telescope, in this case a wide-field 1.2-meter (47-inch) one, to detect planetary transits using photometry. ESA now lists Eddington as an unfunded "reserve" mission. Penny says Eddington's future will be decided within a year or so. After Kepler, NASA is considering a 2009 launch for SIM, the Space Interferometry Mission. SIM's primary mission will be to measure distances to stars with 100 times greater precision than now is possible. This will improve estimates of the size of the universe and help astronomers determine the true brightness of stars, and thus learn more about their chemical composition and evolution. SIM also will look for Earth-sized planets in the habitable zones around some 200 stars. SIM will be an interferometer, which means it will combine interacting light waves from its three component telescopes. This interaction, called interference, makes the individual telescopes, which are separated from each other on the spacecraft, act as though they were a single, larger telescope with greater light-gathering ability. SIM, in solar orbit, won't actually see Earth-sized planets. Instead, it will use astrometry, measuring the angle between two stars (as viewed from the spacecraft, which will form the third point of a triangle). By repeatedly measuring the angle between a target star and each of several more distant background stars, SIM will be able to determine whether the target star wobbles periodically because of gravity from orbiting planets, including planets as small as Earth. NASA says SIM might detect Earth-sized planets around the nearest stars, identifying potential targets for the later Terrestrial Planet Finder, and Jupiter-size planets at greater distances. Also due for launch in 2009 is the almost $1 billion NASA-ESA Next Generation Space Telescope, or NGST, a near-infrared telescope that will succeed the Hubble Space Telescope. Planet hunting will be "a minor part of its job, " says Penny. Like Hubble, NGST will be a general-purpose telescope with an emphasis on cosmology. But it will investigate stars with dusty disks--the early stage of planet formation--and may also be able to study Jupiter-size planets, Penny says. What's next? Kepler and SIM will serve as precursors if all goes according to plan to a tentatively scheduled 2014 launch for NASA's Terrestrial Planet Finder (TPF), while in Europe, COROT and Eddington will pave the way for ESA's Darwin, also to be sent into solar orbit in 2014 or later. Both instruments will be designed to search for Earth-like planets and to examine their atmospheres for evidence of gasses water vapor, oxygen, ozone and methane are leading candidates that could indicate the presence of life. University of Arizona astronomer Nick Woolf says NASA plans for TPF to look for Earth-like planets around 150 stars within about 50 light years (about 473 trillion kilometers, or 294 trillion miles). The basic design of the telescope is still under discussion. Nor has NASA decided whether TPF will make observations at visible or infrared wavelengths. Woolf states that, with both infrared and visible observations, it would be possible to determine the size, surface temperature and atmospheric pressure of a distant planet like Earth, the abundances of many different gases in its atmosphere, and the presence or absence of Earth-like land vegetation. Telescope design considerations, however, limit observation to either visible or infrared, but not both. Darwin, like NASA's SIM, will be an interferometer, comprised of a flotilla of four 1.5-meter (5-foot) solar-orbiting infrared telescopes. Darwin will look at 1,000 of the closest stars with 10 to 100 times the NGST's ability to see details. Woolf and Penny say needed technology still must be developed before either TPF or Darwin is feasible and they question whether either mission can be mounted for what historically has been the standard cost of a big orbiting telescope: about $1 billion. Woolf, a member of the TPF science working group, wonders whether it's even a good idea to build a large, expensive planet-hunting mission. He would prefer to see "something much smaller, cheaper and as soon as possible." Additional information on this article is available at http://www.astrobio.net/news/modules.php?op=modload&name=News&file=ar ticle&sid=222. _____________________________________________________________________ STUDY OF DUST IN ICE CORES SHOWS VOLCANIC ERUPTIONS INTERFERE WITH THE EFFECT OF SUNSPOTS ON GLOBAL CLIMATE University at Buffalo, State University of New York release 11 June 2002 University at Buffalo scientists working with ice cores have solved a mystery surrounding sunspots and their effect on climate that has puzzled scientists since they began studying the phenomenon. The research, published in a paper in the May 15 issue of Geophysical Research Letters, provides striking evidence that sunspots--blemishes on the sun's surface indicating strong solar activity--do influence global climate change, but that explosive volcanic eruptions on Earth can completely reverse those influences. It is the first time that volcanic eruptions have been identified as the atmospheric event responsible for the sudden and baffling reversals that scientists have seen in correlations between sunspots and climate. "Knowing the mechanisms behind past climate changes is critical to our understanding of possible future changes in climate, such as global warming, and for assessing which of these changes are due to human activities and which arise naturally," explained co-author Michael Stolz, doctoral candidate in the Department of Physics in UB's College of Arts and Sciences. According to the UB researchers, their work reveals two different mechanisms by which climate is affected by cosmic rays, charged particles that stream toward Earth and which are strongly influenced by solar activity. "For a long time people have tried to find out whether, for example, periods of maximum sunspots will influence the climate to behave in a certain way," said Michael Ram, Ph.D., professor of physics at UB and co-author on the paper. "Whenever scientists thought they had discovered something, say, they were seeing a positive correlation between temperature and sunspots, it would continue like that for several years and, all of a sudden, there would be a reversal and, instead, they would start to see a negative correlation," said Ram. "There seemed to be no consistent relationship between what the sun was doing and what the climate was doing," he said. To truly confirm any connection between sunspots and climate, a consistent correlation would have to be observed over a long period, covering many solar cycles, Ram explained. That's what he and his graduate students and co-authors have done with their study of ice cores, long cylinders of ancient ice from Greenland that serve as a frozen archive in that they record climate details from thousands of years ago. "This is the beauty of working with ice cores," said Ram. "They go back 100,000 years, so we can study how dust concentrations vary along the ice core, reflecting past-atmospheric dust concentrations." Plain old dust, Ram added, holds the key in these experiments because it reflects how dry conditions were in a particular year. "Dust is a very sensitive parameter of climate," he explained. Drawing on climate data derived from ice cores obtained through the Greenland Ice Sheet Project 2, (GISP2), the scientists used laser- light scattering techniques to determine the level of dust in the atmosphere for roughly the past 300 years, which is how far back sunspot data have been recorded. The scientists started out with the assumption that a low level of cosmic rays on Earth resulting from high sunspot activity would lead to less cloud cover and less rain, with resulting high dust levels. "This was true for the first three or four solar cycles we studied, from about 1930 to 1962, but then the correlation reversed itself, demonstrating that the mechanism couldn't be what we thought," said Ram. It turned out that during those 32 years of positive sun/dust correlation, there was relatively little explosive volcanic activity worldwide. The researchers found that the same conditions existed between 1860 and 1882. Each of these relatively "quiet" periods came to an end with increased volcanic activity. For example, in 1883, the Indonesian volcano Krakatau erupted in one of the deadliest volcanic disasters, killing 36,000 people. At exactly the same time, the data started to exhibit low dust concentration whenever there was high sunspot activity, a correlation that violated the scientists' original assumptions. "By carefully studying the timing of other volcanic eruptions, we found that they coincided with all of the correlation reversals between sunspots and climate," said Ram. A chart in the paper shows how six major volcanic eruptions between 1800 and 1962 occurred during precisely the same years when there were reversals in the correlation between sunspot activity and climate. That revelation provided a further insight into how sunspots affect climate. "All energy comes from the sun, but the change in visible radiation from the sun during any one solar cycle is less than one half of a percent," explained Stolz. "Scientists have said it's impossible that so small a change could influence any signal in the climate. But here we have evidence to show that it's not just radiation energy from the sun that is affecting climate, it's the solar-modulated cosmic rays that have a strong influence because of their impact on cloud cover." With fewer clouds, and therefore less rain, the scientists reasoned, maximum sunspots should cause levels of atmospheric dust to rise. "That is true sometimes," said John Donarummo, Jr., UB doctoral candidate in the UB Department of Geology and a co-author on the paper. But, the researchers discovered, during periods of high volcanic activity, high sunspot activity also results in high levels of atmospheric dust. According to Donarummo, it long has been known that volcanoes add more dust and more sulfates to the atmosphere. The UB team discovered that these additional sulfates cause cosmic rays to have a more pronounced effect on Earth by spurring the formation of small droplets in the atmosphere that, in turn, cause the formation of a type of cloud that does not produce rain. "During these times of high volcanic activity, the sunspot/climate correlation reverses and dust levels rise, even in the absence of high sunspots," explained Stolz. The work was funded in part by National Science Foundation. Contact: Ellen Goldbaum Phone: 716-645-5000 x1415 Fax: 716-645-3765 E-mail: goldbaum@buffalo.edu An additional article on this subject is available at http://www.spacedaily.com/news/climate-02u.html. _____________________________________________________________________ DEFINING LIFE By Leslie Mullen From Astrobiology Magazine 19 June 2002 What is life, exactly? This is a question that keeps biologists up at night. The science of biology is the study of life, yet scientists can't agree on an absolute definition. Are the individual cells of your body, with all their complex machinery, "alive?" What about a computer program that learns and evolves? Can a wild fire-- which feeds, grows, and reproduces--be considered a living entity? Trying to define life is not just a philosophical exercise. We need to understand what separates living creatures from non-living matter before we can claim to find life elsewhere in the Universe. In 1944, the physicist Erwin Shrodinger defined living matter as that which "avoids the decay into equilibrium." This definition refers to the Second Law of Thermodynamics, which says that entropy always increases. Entropy is often referred to as chaos or disorder, but really it is the spreading out of energy towards a state of uniformity. This law can be seen in a cold glass of water that slowly grows warmer until it is the same temperature as the surrounding air. Because of this trend toward equilibrium, the Universe eventually will have a complete lack of structure, consisting of evenly spread atoms of equal warmth. But living things, said Shrodinger, are able to postpone this trend. Consider: while you are alive your body maintains its structure, but once you die your body begins to break down through bacterial action and chemical processes. Eventually the atoms of your body are evenly spread out, recycled by the Earth. To die is to submit your body to the entropy of the Universe. Living things resist entropy by taking in nutrients. This biochemical process of taking in energy for activities and expelling waste byproducts is known as a "metabolism." If metabolism is a sign of life, scientists can look for the waste byproducts of a metabolism when searching for life on other worlds. At least, that was the idea behind the Viking Lander's Labeled Release Experiment, conducted on Mars in 1976. This experiment tested for metabolic clues to life by adding radioactively labeled liquid nutrients to a sample of Martian soil. If these nutrients were consumed by life forms, any gases released as waste byproducts would also be radioactively labeled. After the nutrient was injected, there was a rapid increase in carbon dioxide (CO2) gas. Because this gas had the radioactive label, scientists at first concluded that organisms in the Martian soil were eating the nutrient and releasing the CO2 as a waste byproduct. However, the Martian soil turned out to have a unique soil chemistry that could produce a metabolic-like reaction. Although the test remains inconclusive, most scientists believe that non-living, chemical processes in the Martian soil caused the "metabolic" reaction. The Viking experiments showed that while metabolism may be a quality of life, it is not a narrow enough guideline to search for life elsewhere. Another quality of all life on Earth is a dependence on water. Since water plays such a crucial role in all known life forms, many scientists believe that water-use will be a quality universal to all life. But Benton Clark, an astrobiologist with the University of Colorado and Lockheed Martin, says that water is really a side issue. "Water doesn't define life, it is just an aspect of our environment," says Clark. Life on Earth evolved with water, and so today life on Earth is dependent on that resource. But we cannot say that without water, life is impossible. On Earth, life has been able to adapt to the harshest environments, so it is possible that life may have found a way to survive on worlds that have no liquid water. Steven Benner, an astrobiologist with the University of Florida, agrees that water is not necessarily a universal quality of life. "We can conceive of chemistries that might occur in sulfuric acid as a solvent--as on Venus--or in methane-ammonia mixtures--as on Jupiter," says Benner. "Discovering these would have a profound impact on our view of life, however, as well as the way that NASA looks for it." A recent definition of life created by Gerald Joyce of the Scripps Research Institute doesn't mention either metabolism or water. This definition says that life is "a self-sustaining system capable of Darwinian evolution." But Clark says most life forms technically are not self-sustaining. Animals feed on plants or other animals, plants need microorganisms at their roots to take up nutrients, and bacteria often live inside other organisms, relying on the internal environment of their host. He says the only truly self-sustaining organisms are chemolithotrophs and photolithotrophs, and they are relatively rare. Clark says that Darwinian evolution is another problematic criteria. How could you tell if something has undergone Darwinian evolution? The time scales involved are enormous--scientists would need a complete understanding of an organism's fossil history before being able to declare that the object is, indeed, alive. According to Clark, living organisms exhibit at least 102 observable qualities. Adding all these qualities together into a single--if exceedingly long--definition still does not capture the essence of life. But Clark has picked out three qualities from this list that he considers universal, creating a new definition of life. This definition says that "life reproduces, and life uses energy. These functions follow a set of instructions embedded within the organism." The instructions are the DNA and RNA "letters" that make up the genetic code in all organisms on Earth. A wild fire, one might say, reproduces and uses energy. So do crystals and various chemical reactions. In fact, Benner says that, "every spontaneous chemical process must expend free energy, living or not." But Clark says none of these phenomena are "alive" because none of them have the embedded instructions of a genetic code. We know there are no instructions, because there has not been any mutation over the years. They follow the rules of physics rather than embedded instructions, and so they behave the same every time. Mutation, says Clark, is the key to understanding whether or not something has embedded instructions. Not all living things are capable of reproduction, however. Mules are born sterile. Most honeybees do not reproduce: only the Queen bee has that honor. Many human beings live their entire lives without producing offspring, and no one would argue that such people were not therefore alive. But Clark says that reproduction and energy-use need not both occur for life to exist. He divides life into two categories: "organisms" and "life forms." Organisms channel energy according to embedded instructions, and this energy allows the organism to perform certain activities. A life form, says Clark, is a broader category that encompasses organisms and makes reproduction possible. "What I am proposing is that the individual physical entities should be called 'organisms,' but it sometimes takes a collection of organisms, the 'life form,' to achieve reproduction," says Clark. There have been many definitions of life created over the years, but there has yet to be a single definition accepted by all. Every definition has had to face down challenges to its validity. According to Carol Cleland of the University of Colorado, this is because definitions are concerned only with language and concepts; they can't expand our understanding of the world. We can only define things we already understand. Cleland says that scientists in the seventeenth century had the same problem trying to define water. There are many descriptions of water--it's wet, thirst-quenching, it freezes and turns into vapor-- but other substances also have these qualities. Once scientists discovered molecular chemistry, they could define water to everyone's satisfaction as one oxygen atom coupled with two hydrogen atoms (H2O). Perhaps we need a similar revolution in scientific thought in order to define life. "Current attempts to answer the question, 'What is life?' by defining life in terms of features like metabolism or reproduction--features that we ordinarily use to recognize samples of terrestrial life--are unlikely to succeed," says Cleland. "What we need to answer the question, 'What is life?' is a general theory of living systems." What next? Could we use Clark's definition to find life on other worlds? The Viking Lander already looked for energy-use in the form of a metabolism, and the results were inconclusive. To search for this criterion as a means for finding life, we would need to consider other ways life could use energy. The problem with searching for life forms with embedded instructions, says Clark, is that the criteria may be too specific. The only instructions we know of are DNA and RNA--there may be other genetic systems possible in the Universe that do not resemble the system found here on Earth. Additional information on this article is available at http://www.astrobio.net/news/modules.php?op=modload&name=News&file=ar ticle&sid=226. _____________________________________________________________________ CURIOUS SKELETONS By Karen Miller and Tony Phillips From NASA Science News 19 June 2002 Sculptor Kenneth Snelson's "Needle Tower" is a fragile-looking thing. Criss-crossing rods suspended by taut wires soar perilously upward 20 meters high. Surely it ought to crumble or fall over. Yet it doesn't. When the wind blows, the Needle Tower bends, not breaks. When someone shoves it, it shoves back. The tower is lightweight, strong and curiously beautiful. Just like the skeletons of cells. That's right, cells have skeletons. They're not made of calcium like the bones that rattle on Halloween. Cell skeletons--biologists call them cytoskeletons--consist of protein molecules arranged into chains. Cytoskeletons give cells their shape, help cells move, and hold the nucleus in place. Like Snelson's sculptures, cytoskeletons have tensegrity--short for tensional integrity. They balance compression with tension, and yield to forces without breaking. In the Needle Tower, the wires carry tension and the rods bear compression. In a cytoskeleton, protein chains--some thin, some thick and some hollow--take the place of wires and rods. Linked together they form a stable, but flexible, structure. NASA is interested in cytoskeletons because cytoskeletons respond to gravity. Weight can provide both tension and compression. But what happens (during space travel, for example) when weight vanishes? Do cells behave differently when their cytoskeletons relax? Harvard cell biologist Don Ingber is a leader among researchers who have been working to find out. "The cytoskeleton perceives gravity--or any force--through special proteins known as integrins, which poke through the cell's surface membrane," explains Ingber. Inside the cell, they're hooked to the cytoskeleton. Outside, they latch onto a framework known as the extracellular matrix--a fibrous scaffolding to which cells are anchored in our bodies. Ingber and his colleagues have shown that when integrins move, the cytoskeleton stiffens. They did it by coating small magnetic beads, about 1 to 10 microns in size, with special molecules that bind to integrins. They attached the beads to the integrins and then applied a magnetic field. "The beads turned and tried to align with the field, just like a compass needle would want to align with the earth's magnetic field," explains Ingber. The beads twisted the integrins and, in turn, tweaked the cytoskeleton. As more stress was applied, the cytoskeleton became stiffer and stiffer. In fact, it become so stiff that the beads couldn't be turned much past a few degrees! Tugging on integrins not only caused the cytoskeleton to stiffen, it also activated certain genes. "Activating a gene" means coaxing a gene to generate RNA and proteins. That's important because proteins are little messages that signal the cell to take action. Tickling the cytoskeleton, it seems, can make cells switch between different genetic programs. Even before the magnetic bead experiment, Ingber's group at Harvard had already discovered a link between cell geometry and cell behavior. In one experiment they forced living cells to take on different shapes--spherical or flattened, square or round--by placing them on tiny adhesive islands of extracellular matrix. Cells that were flat and stretched tended to divide. Cells that were round and cramped tended to die. Says Ingber, "Mechanical restructuring of the cell and cytoskeleton apparently tells the cell what to do." Very flat cells with taut cytoskeletons somehow sense that more cells are needed--to cover a cut, for example. Rounder, cramped cells might sense an overpopulation problem and decide it's time to die and make room for others. In either case, they are responding to a control system in which the shape-shifting cytoskeleton serves as a switching mechanism. The potential implications of this research are vast--and not limited to space travel. It has already led to a prospective cancer treatment based on changes in cell shape. And it could provide new treatments for osteoporosis, cardiac disease, lung problems and developmental abnormalities. Every tissue in the body, says Ingber, has some disease that results from cells responding abnormally to mechanical forces. "By pursuing the question of [how cells sense] gravity we've uncovered entirely new aspects of cell regulation." Ingber believes that tensegrity is a core organizing principle of the entire physical world. Self-stabilizing structures form spontaneously at every scale--cytoskeletons are merely one example. Another would be spherical carbon molecules called "BuckyBalls" that look like atomic soccer balls. Clay molecules also arrange themselves into tensegrity patterns that some researchers think harbored the first microscopic life forms on Earth. Even the universe itself, with its black holes (compression) and gravitationally linked galaxies (tension), may be a tensegrity structure. "I gave a talk once at NASA on evolutionary biology," he recalls. "The last slide of my talk was a picture of the universe: super clusters of galaxies. Next to it was a one of capillary cells in a dish, formed into networks. The two pictures looked identical." Additional information on this article is available at http://science.nasa.gov/headlines/y2002/19jun_cytoskeletons.htm?list6 9247. _____________________________________________________________________ GEARING UP TO HARVEST MARS' WATER RESOURCE By Leonard David From Space.com 19 June 2002 Scientists have found Martian terrain that is hydrogen-rich, an indicator of water ice. The most abundant reservoirs of that near- surface water stretch from the planet's poles to within about 50 degrees of the equator. The amount of hydrogen detected is huge. So much so that one brimming bucket of ice-rich polar soil, when heated, can yield more than half a bucket of water. That's big news for Mars water reclamation experts. As a watering hole to sustain an expeditionary crew, Mars must now be approached with an eye on how to tap into the invaluable resource. Scientists and engineers have begun charting how this watery commodity can nourish the human drive to distant Mars. Get the full story at http://www.space.com/businesstechnology/technology/mars_ice_tech_0206 19-1.html. _____________________________________________________________________ ASTEROID 2002MN GIVES EARTH ITS CLOSEST SHAVE IN YEARS Near Earth Object Information Centre release 20 June 2002 On Friday 14 June, an asteroid the size of a football pitch made one of the closest ever recorded approaches to Earth. Astronomers working on the LINEAR search program, near Socorro, New Mexico first detected the giant rock on 17 June, a few days after its close approach. The Near Earth Object, known to astronomers as "2002MN", was travelling at over 10 km/s (23,000 miles per hour) when it passed Earth at a distance of around 120,000 km (75,000 miles), bringing it well inside the Moon's orbit. The last time a known asteroid passed this close was back in December 1994. Asteroids are typically too small and distant to measure their size directly from Earth, so scientists use the amount of light they reflect, along with a basic understanding of the materials they are made of, to estimate their size. With a diameter between 50-120 meters, 2002 MN is a lightweight among asteroids and incapable of causing damage on a global scale, such as the object associated with the extinction of the dinosaurs. However, if it had hit the Earth, 2002MN may have caused local devastation similar to that which occurred in Tunguska, Siberia in 1908, when 2000 square kilometers of forest were flattened. Whilst the vast majority of NEOs discovered do not come this close, such near misses do highlight the importance of detecting these objects. This reminder comes in a week when the UK telescopes on La Palma are being tested to search for NEOs. Brief description of object Object Designation: 2002MN Date of First Observation: 17 June 2002 Number of Observations: 14 Search Team: LINEAR (Lincoln Near Earth Asteroid Research) Date of Closest Approach: 14 June 2002 Closest Approach Distance: 0.000797 AU or 119,229 km (0.3 Lunar Distances) Asteroids Velocity Relative to Earth at Closest Approach: 10.58 km/s (23,667 miles per hour) Estimated Diameter of Asteroid: 50-120 meters Orbital Period: 894.9 days For further information contact: Kevin Yates (Project Officer) Near Earth Object Information Centre Phone: +44(0)116 2582130 or 07740 896141 E-mail: keviny@spacecentre.co.uk Additional articles on this subject are available at: http://www.cnn.com/2002/TECH/space/06/20/asteroid.miss/index.html http://www.space.com/scienceastronomy/solarsystem/asteroid_miss_02062 0.html http://spacedaily.com/news/020620121339.dc05vk7l.html http://story.news.yahoo.com/news?tmpl=story&cid=624&ncid=624&e=4&u=/a p/20020621/ap_on_sc/asteroid_close_call_4 _____________________________________________________________________ LARGE FORMER LAKE, CATASTROPHIC FLOOD IDENTIFIED ON MARS Smithsonian Institution release 20 June 2002 Geologists at the Smithsonian's National Air and Space Museum have discovered a large former lake in the highlands of Mars that would cover an area the size of Texas and New Mexico combined, and which overflowed to carve one of that planet's largest valleys. The findings will appear in the June 21 issue of the journal Science. The flood channel, Ma'adim Vallis, is more than 550 miles long and up to 6,900 feet deep, making it larger than Earth's Grand Canyon. "Imagine more than five times the volume of water in the Great Lakes being released in a single flood, and you'll have a sense of the scale of this event," said Ross Irwin, a geologist in the museum's Center for Earth and Planetary Studies (CEPS) and the paper's lead author. Mars is now a cold desert planet but its many dry valleys could indicate that water once flowed on its surface. Recent results from the Mars Odyssey spacecraft have found evidence of water trapped in the near surface of the polar regions. "The size of this lake-1,400 miles long-suggests Mars was warmer and wetter than previously thought," said Robert Craddock, a CEPS geologist and co-author of the paper. Former lakes are considered the most likely places to preserve the record of any past Martian life. Calm water would allow sediments to be deposited slowly, preventing small organisms from being destroyed. The source of water to carve the flood channel had long been a mystery to scientists, who had known very little about Mars' topography prior to the Mars Global Surveyor mission, which has been orbiting Mars since 1997. Detailed elevation data from the Mars Global Surveyor shows the large valley originated nearly full-size at a ridge, much like the spillway of a dam. Late in the lake's history, rising water levels overflowed the lake basin rim, releasing the huge flood as the river cut into this former dividing ridge. What remained was "some of the best geological evidence for a lake found to date on Mars, including clear indications of the former shoreline," Irwin says. Two other smaller lake basins were identified in the region by paper co-author Alan Howard, a geologist at the University of Virginia. All three lakes shared the same water level prior to the flood, indicating the possibility of an ancient water table and suggesting the locations of other dry lake basins on Mars. Such information could be important in determining where to land robotic probes in coming years. CEPS is the scientific research unit within the Collections and Research Department of the National Air and Space Museum. CEPS performs original research and outreach activities on topics covering planetary science, terrestrial geophysics, and the remote sensing of environmental change. Media contact: Peter Golkin Phone: 202-357-1552 Public information: 202-357-2700 http://www.nasm.si.edu/ceps/research/mars/irwin_lakes.htm An additional article on this subject is available at http://spaceflightnow.com/news/n0206/23marslake/. _____________________________________________________________________ INTERNATIONAL TEAM EXPLORES LUNAR BASE PROPOSALS By Leonard David From Space.com 20 June 2002 A first-of-its-kind workshop is underway in Europe to blueprint extraterrestrial bases for human settlement of the Moon. The international lunar base design study involves the talents of engineers, architects, industrial designers and specialists in medicine and psychology. The multi-nation moon base conference is being held at the European Space Agency's (ESA) European Space Research Technology Centre (ESTEC) in Noordwijk, The Netherlands, from June 10-21. Experts are hammering out concepts for bases to support a human return to the Moon. A trio of Moon base scenarios is at the core of the 2002 Lunar Base Design Workshop. Each case study focuses on a 2020 timeframe to establish a small permanent habitat on the lunar surface. Study teams are comprised of students with a bachelor's degree or higher, versed in a variety of disciplines. Get the full story at http://www.space.com/scienceastronomy/solarsystem/lunarbase_euro_0206 20.html. _____________________________________________________________________ NEW ADDITIONS TO THE ASTROBIOLOGY INDEX By David J. Thomas http://www.lyon.edu/webdata/users/dthomas/astrobiology/astrobiology.h tml 24 June 2002 Astrobiology, exobiology and terraformation articles http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_article s1.html H. Bortman, 2001. Focus on Europa. Astrobiology Magazine. L. Mullen, 2002. Defining life. Astrobiology Magazine. National Air and Space Museum, 2002. Evidence found of lake, catastrophic flood on Mars. Spaceflight Now. L. J. Siegel, 2002. The search for distant Earths. Astrobiology Magazine. Terrestrial extreme environments articles http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_article s2.html R. Friedman, 2002. Bugs from hell. Astrobiology Magazine. R. A. Kerr, 2002. Deep life in the slow, slow lane. Science, 296(5570):1056-58. L. Mullen, 2001. From lightbulbs to life. Astrobiology Magazine. L. Mullen, 2002. Living in the dark. Astrobiology Magazine. L. Mullen, 2002. A pothole in the road of life. Astrobiology Magazine. A. M. Rosenthal, 2002. Tandem evolution. Astrobiology Magazine. Human space exploration and microgravity effects articles http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_article s3.html L. David, 2002. Gearing up to harvest Mars' water resource. Space.com. L. David, 2002. International team explores lunar base proposals. Space.com. Search for extraterrestrial intelligence (SETI) articles http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_article s4.html SETI Institute, 2001. Scientists hunt for light flashes from extraterrestrial civilizations. Astrobiology Magazine. Evolutionary biology and chemistry articles http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_article s5.html S. Hart, 2002. Evolution's slow recovery. Astrobiology Magazine. L. Mullen, 2002. Unfamiliar life. Astrobiology Magazine. D. Tenenbaum, 2002. Biological diversity: fact or artifact? Astrobiology Magazine. _____________________________________________________________________ CASSINI SIGNIFICANT EVENTS NASA/JPL release 13-19 June 2002 Cassini is currently maintaining 24-hour Deep Space Network coverage in support of the Radio Science Solar Conjunction Experiment. The most recent spacecraft telemetry confirms the Cassini spacecraft is in an excellent state of health and is operating normally. Information on the present position and speed of the Cassini spacecraft may be found on the "Present Position" web page located at http://saturn.jpl.nasa.gov/cassini/english/where/. On-board activities this week included uplink of the High Water Mark clear, and the first conjunction test commands. When the separation angle reached about 3 degrees, the project began uplinking a command file consisting of 10 no-op commands sent every 5 minutes. The file is uplinked 10 times daily. These commands have been sent to the spacecraft each time Cassini enters Solar Conjunction. The previous occasion was in June of 2001 and the next opportunity will be July of 2003. The purpose of the test is to accumulate statistics for uplink reliability at decreased separation angles. Saturn Orbit Insertion will occur on July 1, 2004 and conjunction will follow within 7 days. Knowledge of how conjunction affects commanding will be crucial at that time. The Radio Science Subsystem Solar Conjunction Experiment continued this week. The Ka-band transmitter at DSS-25 tripped due to a heater exchanger problem. Facilities and maintenance engineers have been working to correct the problem but have been unable to bring the transmitter back on-line. The minimum separation angle occurs on Friday June 21. C33 is currently in the preliminary Sequence Integration and Validation Phase. This week a meeting was held with the Spacecraft Office (SCO) and interested instruments to discuss a SCO request to include an in-flight gyro calibration of scale factor, misalignment, and biases to correct an error in flight software. SCO needs to perform the calibration prior to C36 so updates may be included in the next software build. The test has been tentatively scheduled for mid July pending resolution of a number of action items. Program Management approved Mission and Science Planning's design for the C34 sequence at a Project Briefing held this week. C34 will observe 30 targets, execute a Probe receiver test, and perform a compatibility test for a new ESA tracking station at New Norcia, Australia. C34 provides an opportunity for a loading test of the flight team's ability to manage an increased number of targets. It was observed at the briefing that the number of activities planned in C34 is at least twice that of previous cruise sequences, and emulates a modest plan for a tour sequence. The first input port occurred this week for the Science Operating Plan integration of tour sequences S9 and S10. The files have been delivered to AACS for processing. Science Planning (SP) held a Target Working Team/Orbiter Science Team process improvement meeting. The meeting went well. Participants felt that in general the process is working well and that only a few areas needed to be targeted for improvement. All teams and offices supported the Cassini Monthly Management review. A new Cassini Science and Uplink Office Manager has been appointed. Transition plans are still to be developed. System Engineering (SE) began assisting teams in bringing training plans and schedules up to date to support Verification and Validation activities, and V&V, Approach Science, and Tour operations readiness reviews. Initial activities included meeting with Uplink Operations Personnel to identify training needs and document training plan guidelines. The guidelines will be presented to the Program next week. Outreach personnel attended the NASA OSS Conference in Chicago, Illinois. 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. _____________________________________________________________________ THE NEXT FOUR WEEKS ON GALILEO NASA/JPL release 17 June - 14 July 2002 The Galileo spacecraft has now rounded the corner in its longest looping orbit around Jupiter and is again heading back in towards the giant planet and a close flyby of the tiny moon Amalthea in November. This past week brought good news about the on-board tape recorder. On April 12, during a routine maintenance activity, the tape appears to have stuck to the record or playback heads. After five preliminary tests to characterize the problem, on Saturday, June 8, the tape was successfully pulled free and we now expect it to be operational. On Tuesday, June 18, the recorder will be commanded back to the beginning of the tape and the tape position counter will be reset. From there we can safely command the tape as we have in the past without worrying that tape-position errors will trip fault protection routines in the spacecraft software. Subsequent activities are still in the planning stage. They may include slowly traversing the entire length of the tape several times, gradually increasing the distance and speed of motion until we are confident the recorder can again be used freely and reliably to record our final set of encounter data in November. On Friday, June 21, and Monday, July 8, routine maintenance of the propulsion system is performed. On Monday, July 1, the spacecraft performs a nearly 11 degree turn in place to keep the communications antenna pointed towards Earth. This turn positions the spacecraft to comfortably ride out an upcoming period called solar conjunction. During conjunction, Jupiter and Galileo appear to pass behind the Sun as seen from Earth. With the Sun still relatively near the peak of its 11-year activity cycle, interference from the dynamic solar wind scrambles the radio signal sent from the spacecraft. Between July 9 and July 28, the spacecraft will be within 7 degrees of the Sun, and communications are expected to be completely blocked. We are already seeing occasional degradation of the signal that we think can be attributed to solar activity. On Monday, June 24, we reconfigure the radio signal from the spacecraft to help improve our ability to communicate during this turbulent time. With the spacecraft well outside the magnetosphere of Jupiter on the sunward side of the planet, continuous data collection by the Magnetometer, the Dust Detector, and the Extreme Ultraviolet Spectrometer instruments provides scientists with information about the interplanetary medium. During the solar conjunction period, the Magnetometer data collection is suspended, but the Dust Detector and Extreme Ultraviolet data will collect in an on-board computer memory buffer to be returned once communication is re-established in late July. 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 An additional article on this subject is available at http://www.spacedaily.com/news/galileo-02b.html. _____________________________________________________________________ INTERNATIONAL SPACE STATION SCIENCE OPERATIONS STATUS REPORT NASA/MSFC release 02-155 19 June 2002 The new Expedition Five crew's main science activity this week involved activation and maintenance of a new liver cell research experiment. The StelSys experiment was among the new payloads ferried to the Station by Space Shuttle Endeavour last week. Liver cells have remained frozen in a liquid nitrogen thermos-type container since launch on June 5. On Tuesday, the crew transferred liquid nutrient pouches, in which the liver cells will be processed, from a refrigerator to an incubator. Today and again on Thursday, the crew will be injecting the cells into the nutrient pouches in the incubator to begin a reactivation process. "After two, six, 24, and 48 hours, the incubation process in different cell cultures will be stopped by transferring the processed cells to a freezer. On Friday, the last set of cells will complete processing and the experiment will be concluded," StelSys President and CEO Dr. Paul Silber said. "Cellular products will be analyzed upon the return of the samples to Earth on the STS-114 mission." One of the specialized functions of the human liver is to break down drugs or toxins into less harmful and more water-soluble substances that are more easily excreted from the body. The StelSys experiment- -a joint study by NASA and Baltimore-based biotechnology research company StelSys, LLC--will test this function of human liver cells in the microgravity environment of the Station and compare the results to the typical function of a similar experiment conducted on Earth. The findings of this experiment will provide information about the effects of microgravity and shear force on proper function of human liver cells as well as maintaining the health of humans living and working in space. Research in this area could lead to earlier and more reliable drug candidate screening for patients in need of liver and kidney treatments prior to transplant. It could also accelerate development of new life saving drugs by pharmaceutical companies. The experiment was designed by StelSys scientists and is managed by the Cellular Biotechnology Program Office at NASA's Johnson Space Center in Houston. A variety of other new Expedition Five experiments are functioning normally this week. The Protein Crystal Growth Single Thermal Enclosure System (PCG STES) experiment was activated June 9. The Advanced Astroculture (ADVASC) experiment was activated June 11, and the science team reported this week that all the soybean plants have sprouted and are visible from images made by a camera within the ADVASC growth chamber. The Solidification Using a Baffle in Sealed Ampoules (SUBSA) and the Pore Formation and Mobility Investigation (PFMI) experiments are awaiting setup and activation next month of the new Microgravity Science Glovebox (MSG) facility. These two experiments are studying production of semiconductor materials and the formation of molten materials in space. Both require use of a furnace and take advantage of the enclosed hands-on workspace of the Glovebox. The Glovebox facility was designed and built by the European Space Agency (ESA) based upon science and design requirements formulated in a cooperative arrangement between NASA and ESA. Also awaiting activation is the Microencapsulation Electrostatic Processing System (MEPS), and new samples in the Zeolite Crystal Growth (ZCG) experiment, which requires a 20-hour post-activation period of minimum microgravity disturbance. The crew reported last Friday that they completed EVA Radiation Monitoring (EVARM) sessions for all three of last week's spacewalks by STS-111 crewmembers Franklin Chang-Diaz and Philippe Perrin. This experiment uses dosimeter badges worn inside astronauts' spacesuits to measure radiation absorbed by various areas of the body during spacewalks. Other planned human life sciences investigations include Renal Stone and the Pulmonary Function in Flight experiments devoted to a potential preventative for kidney stones and improving lung function in space crews. The first Crew Earth Observations (CEO) photography subjects were transmitted to the Station on Monday, including dust and smog over the Eastern Mediterranean, air quality over Italy and the U.S. eastern seaboard, high central Andean glaciers, and icebergs in the Gulf of St. Lawrence. Aboard Space Shuttle Endeavour for return to Earth are several completed Expedition Four Station experiments including: Protein Crystal Growth Enhanced Gaseous Nitrogen dewar, Commercial Protein Crystal Growth High Density, Commercial Generic Bioprocessing Apparatus, Experiment on Physics of Colloids in Space and the Biomass Production System. The Payload Operations Center at NASA's Marshall Space Flight Center in Huntsville, AL, manages all science research experiment operations aboard the International Space Station. The center is also home for coordination of the mission-planning work of a variety of international sources, all science payload deliveries and retrieval, and payload training and payload safety programs for the Station crew and all ground personnel. Contact: Steve Roy Media Relations Department Phone: 256-544-0034 E-mail: Steve.Roy@msfc.nasa.gov Web links Status Report http://www1.msfc.nasa.gov/NEWSROOM/news/releases/2002/02-155.html ISS Science Operations News http://www.scipoc.msfc.nasa.gov/ ISS Science Operations Photos http://www.scipoc.com/photoschron.html StelSys Fact Sheet http://www.msfc.nasa.gov/NEWSROOM/background/facts/stelsys.html _____________________________________________________________________ MARS ODYSSEY THEMIS IMAGES NASA/JPL/ASU release 17-21 June 2002 Canyons and Mesas of Aureum Chaos (Released 17 June 2002) http://themis.la.asu.edu/zoom-20020617a.html Ariadnes Colles Chaos (Released 18 June 2002) http://themis.la.asu.edu/zoom-20020618a.html Galle Crater (Released 19 June 2002) http://themis.la.asu.edu/zoom-20020619a.html Claritas Fossae (Released 20 June 2002) http://themis.la.asu.edu/zoom-20020620a.html Coprates Chasma (Released 21 June 2002) http://themis.la.asu.edu/zoom-20020621a.html All of the THEMIS images are archived at http://themis.la.asu.edu/latest.html. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. Dr. Philip Christensen leads the THEMIS investigation at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey 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. _____________________________________________________________________ STARDUST STATUS REPORT NASA/JPL release 21 June 2002 There were two Deep Space Network (DSN) tracking passes in the past week and all subsystems are performing normally. The European Space Agency's new 35-meter (deep space tracking station in Perth, Australia, called New Norcia) performed its first tracking test using Stardust's spacecraft signal. During a normal communications session between the Stardust and the DSN station in Canberra, Australia, the New Norcia station was also successful in detecting and tracking Stardust's signal for 2 hours. A recent study to determine if Stardust flew closely by any of about 50,000 asteroids during the remainder of its mission found that 1,334 asteroids passed within 0.1 astronomical units (just over 900,000 miles, or 1.5 million kilometers). Of the closest of these encounters, only the Asteroid 5535 Annefrank flyby occurs before Stardust plans to encounter Comet Wild 2. After the Comet Wild 2 flyby in 2004, the Stardust spacecraft will be put into a low maintenance mode until its Earth return in 2006. 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 23.