Marsbugs: The Electronic Astrobiology Newsletter Volume 10, Number 39, 30 September 2003 Editor/Publisher: David J. Thomas, Ph.D., Science Division, Lyon College, Batesville, Arkansas 72503-2317, USA. dthomas@lyon.edu 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 editor, except for specific articles, in which instance copyright exists with the author/authors. The editor does not condone "spamming" of subscribers. Readers would appreciate it if others would not send unsolicited e-mail using the Marsbugs mailing lists. Persons who have information that may be of interest to subscribers of Marsbugs should send that information to the editor. E-mail subscriptions are free, and may be obtained by contacting the editor. Information concerning the scope of this newsletter, subscription formats and availability of back-issues is available from the Marsbugs web page at http://www.lyon.edu/projects/marsbugs/. ________________________________________________________________________ CONTENTS 1) IF YOU THOUGHT THAT WAS A CLOSE VIEW OF MARS, JUST WAIT NASA/JPL release 2) HIGH TIDE ON EUROPA By Cynthia Phillips and Diane Richards 3) SHENZHOU SECRETS: CHINA PREPARES FOR FIRST HUMAN SPACEFLIGHT By Leonard David 4) WEBCASTS TO FEATURE SCIENTISTS ON A "MARS MISSION" NASA/ARC release 03-75AR 5) PRINCETON PALEONTOLOGIST PRODUCES EVIDENCE FOR NEW THEORY ON DINOSAUR EXTINCTION By Steven Schultz 6) DID A GAMMA-RAY BURST DEVASTATE LIFE ON EARTH? From SpaceDaily 7) THE DRAKE EQUATION REVISITED, PART I By Frank Drake 8) ESA AWARDS THE FIRST AURORA MISSION DESIGN CONTRACTS ESA release 9) NEW ADDITIONS TO THE ASTROBIOLOGY INDEX By David J. Thomas 10) CASSINI SIGNIFICANT EVENTS NASA/JPL release 11) MARS GLOBAL SURVEYOR IMAGES NASA/JPL/MSSS release 12) MARS ODYSSEY THEMIS IMAGES NASA/JPL/ASU release 13) STARDUST STATUS REPORT NASA/JPL release ________________________________________________________________________ IF YOU THOUGHT THAT WAS A CLOSE VIEW OF MARS, JUST WAIT NASA/JPL release 23 September 2003 As Earth pulls away from Mars after last month's close approach, NASA is developing a spacecraft that will take advantage of the next close encounter in 2005. That spacecraft, Mars Reconnaissance Orbiter, will make a more comprehensive inspection of our planetary neighbor than any previous mission. For starters, it will examine landscape details as small as a coffee table with the most powerful telescopic camera ever sent to orbit a foreign planet. Some of its other tools will scan underground layers for water and ice, identify small patches of surface minerals to determine their composition and origins, track changes in atmospheric water and dust, and check global weather every day. "We're reaching an important stage in developing the spacecraft," said James Graf, project manager for Mars Reconnaissance Orbiter at NASA's Jet Propulsion Laboratory, Pasadena, CA. "The primary structure will be completed next month." The structure weighs 220 kilograms (484 pounds) and stands 3 meters (10 feet) tall. At launch, after gear and fuel are added, it will support over 2 tons. Also next month, the mission's avionics test bed will be assembled for the first time and put to use for testing of flight software. Workers at Lockheed Martin Space Systems, Denver, have already assembled the spacecraft structure and will later add instruments being built for it at the University of Arizona, Tucson; at Johns Hopkins University Applied Physics Laboratory, Laurel, MD; at the Italian Space Agency, Rome; at Malin Space Science Systems, San Diego, CA; and at JPL. "In several ways, Mars Reconnaissance Orbiter will advance NASA's follow-the-water strategy for Mars exploration," said Dr. Richard Zurek, project scientist for the mission. Current surveys of Mars' surface composition have found less evidence of water-related minerals than many scientists anticipated after earlier discoveries of plentiful channels that were apparently carved by water flows in the planet's past. A spectrometer on the Reconnaissance Orbiter is designed to identify some different types of water-related minerals and to see smaller-scale deposits. "Instead of looking for something as big as the Bonneville Salt Flats, we can look for something on the scale of a Yellowstone hot spring," Zurek said. Probing below Mars' surface with penetrating radar, Reconnaissance Orbiter will check whether the frozen water that NASA's Mars Odyssey spacecraft detected in the top meter or two (yard or two) of soil extends deeper, perhaps as accessible reservoirs of melted water. Above the surface, an atmosphere-scanning instrument will monitor changes in water vapor at different altitudes and might even locate plumes where water vapor is entering the atmosphere from underground vents, if that's happening on Mars. Mars Reconnaissance Orbiter will stream home its pictures and other information using the widest dish antenna and highest power level ever operated at Mars. "The amount of data flowing back to Earth from Mars will be a giant leap over previous missions. It's like upgrading from a dial-up modem for your computer to a high-speed DSL connection," Graf said. The Mars Reconnaissance Orbiter will lay the groundwork for later Mars surface missions in NASA's plans: a lander called Phoenix selected last month in a competition for a 2007 launch opportunity, and a highly capable rover called Mars Science Laboratory being developed for a 2009 launch opportunity. The orbiter's high-resolution instruments will help planners evaluate possible landing sites for these missions both in terms of science potential for further discoveries and in terms of landing risks. The orbiter's communications capabilities will provide a critical transmission relay for the surface missions. Advantageous opportunities to launch Mars missions come in a rhythm of about every 26 months, shortly before each time Earth overtakes Mars in the two planets' concentric tracks around the Sun. NASA's two Mars Exploration Rovers and the European Space Agency's Mars Express mission were launched during the three months preceding Earth's most recent passing of Mars on Aug. 27. The Mars Reconnaissance Orbiter team has its work cut out for it to have the spacecraft ready for launch on August 10, 2005, which is about 10 weeks before the next close approach. JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter project for NASA's Office of Space Science, Washington, DC. Contact: Guy Webster, JPL Phone: 818-354-6278 An additional article on this subject is available at http://www.universetoday.com/am/publish/mars_reconnaissance_orbiter_next .html. ________________________________________________________________________ HIGH TIDE ON EUROPA By Cynthia Phillips and Diane Richards From Astrobiology Magazine 23 September 2003 Jupiter's large moons, called the Galilean satellites are heated by their orbits, literally. The effect is known as tidal flexing, which arises from their resonant orbits, provides heat for volcanism on Io and could result in the presence of liquid water beneath Europa's icy surface. There is good evidence for liquid water on Europa based on geological evidence from images of Europa taken by the Voyager and Galileo spacecraft. This geological evidence is tantalizing, but incomplete--it suggests that liquid water could be present, but also allows for the possibility that the strange features we see on Europa's surface could all have formed through the motion of soft ice, without any liquid water at all. Fortunately, there are other methods available, in addition to geological techniques, which can provide information about the presence, or absence, of water at Europa. Thermal models of Europa's subsurface are one theoretical way to study what lies beneath Europa's surface, and we will consider them in this article. Models of Europa's gravitational field show that Europa possesses a surface layer about 100 km thick of material with the density of water, on top of a rocky interior and a metallic core. The surface layer is most likely H2O, but since the densities of solid ice and liquid water are very close, gravity models cannot distinguish between the two. So we know that there is about 100 km of some combination of water and/or ice at Europa's surface, but other than knowing that the very top of this water layer is frozen solid, we do not know how thick the surface ice layer is, or if there is liquid water under it at some depth. Thermal models of Europa's subsurface suggest that it is possible, but not definite, that liquid water could be present. Thermal models include sources of heat and methods of cooling, and attempt to determine the thermal gradient and state (solid or liquid) of subsurface materials. In the case of Europa, these models include heating from tidal dissipation and radiogenic sources, and cooling due to conduction and convection of heat. Tidal heating, as discussed in a previous article comes from the flexing of Europa by Jupiter's gravity, as a result of Europa's non-circular orbit due to its resonance with Io and Ganymede. As Europa's distance from Jupiter changes over the course of its orbit, Jupiter's gravitational attraction changes (since gravitational force is dependent on distance), and thus the tidal bulge raised by Jupiter goes up and down. This flexing causes heating of Europa's subsurface. Radiogenic heating is caused by the decay of long-lived radioactive isotopes that were incorporated in Europa when it formed, or brought to it after formation. Conduction is the direct transfer of heat from warmer to cooler regions, while convection is heat transfer due to motion of the materials--warmer materials move upwards, and cooler materials move downwards. Both conduction and convection result in the transfer of heat from Europa's warmer interior to its frigid surface, and the net cooling of Europa as a result. For Europa, thermal models that include all of these effects have been inconclusive. Some models have predicted that convection would remove all the heat from a liquid layer, resulting in Europa being frozen solid rather quickly. Other models have predicted that it would be difficult to produce enough heat to melt a solid ice layer into water, but that if a water layer existed there would be enough heat to maintain it as liquid indefinitely, due to a balance of cooling and heating sources. There are still a number of unknown quantities in these models. For example, tidal heating is the most important heat source at Europa, but also the most poorly known. It is strongly affected by the rheology of ice, which is its behavior when pushed or pulled or squeezed. However, the rheology of ice is difficult to study under conditions similar to Europa, since Europa's surface temperature is a chilly 100 K! It is also hard to study ice being stretched over the long periods associated with Europa's tidal cycle--laboratory measurements are easier to make over time periods of seconds, not days. We also don't know enough about the composition of the ice on Europa-- most models assume that it is pure water ice, but a small amount of other material present in the ice, especially other volatiles such as ammonia or salts, could dramatically alter the rheology of Europa's ice. Most models also assume that the ice layer is solid, but the rheology could be changed if the ice layer is broken or fractured, or if the grain size is different than assumed in the models. So in addition to the geological evidence, thermal models provide one more tantalizing, yet insufficient, clue to Europa's subsurface structure. Water could be present, but is not required. Fortunately, however, we have some more definite evidence for subsurface water on Europa. It comes from an unlikely source--magnetic field measurements. Timely ends The Galileo spacecraft, which officially finishes its mission this week in the Jovian system, took a number of images of Europa's surface between 1995 and 2001 that can be used to study the geology of this small moon and look for evidence of liquid water beneath the surface. The Voyager spacecraft took the first close-up images of Europa in the late 1970's. Before Voyager, little was known about Europa's surface except that it was very bright, and measurements taken from Earth with spectrometers on telescopes suggested that there could be water. Images of Europa taken by Voyager revealed a surface covered with crack-like features, and very few impact craters. The lack of craters was surprising, since all bodies in the solar system are continually hit by debris. This process results in a pockmarked surface like the Moon's unless geologic activity takes place to remove craters from the surface. The relative lack of craters on Europa means that the surface is young, perhaps as young as a few tens of million years. Images of Europa's surface taken by the Galileo spacecraft have shown surface features that could be consistent with the presence of liquid water beneath Europa's surface, but do not prove it. Europa's surface is primarily covered by a vast set of interconnecting cracks and ridges. Also present are areas of disrupted "chaotic terrain", where the surface appears to have been broken up into coherent iceberg-like blocks that seem to have "rafted" into new positions. Such areas can be reconstructed by fitting the preexisting features on the blocks back together like pieces of a jigsaw puzzle. Other features of interest on Europa's surface include regions that could possibly be low viscosity surface flows, and impact craters that are anomalously shallow. A number of models have been proposed for the formation of the variety of features visible in Galileo images of Europa's surface. There is currently no consensus among these often-contradictory views of Europa's geophysics. In general, models of Europa's subsurface fall into two categories, one in which a thin ice layer (at most a few kilometers thick) is present on top of a layer of liquid water, and another in which the surface ice layer is much thicker, perhaps tens of kilometers or more, with liquid water (if it exists) at a much lower depth. Models of the formation of various geologic features on Europa seem to follow either the thin-ice or the thick-ice view. For example, the shapes of Europa's impact craters suggest that they formed within a solid target, but their shallow depths suggest that the surface rebounded somewhat after their formation. Models of this rebound suggest that most craters on Europa formed in a 5-15 km thick brittle surface layer, overlying a lower-viscosity subsurface layer. This subsurface material, however, could either be liquid water or warm, low-viscosity ice. A separate model of central peak formation in Europan craters suggests that the ice crust layer must be at least 3-4 km thick, and a model of crater topography suggests a much thicker ice layer, at least 19-25 km. Cryovolcanic surface flows, made of a mixture of water, ice, and maybe other volatile materials such as ammonia, would be intriguing, but there are very few regions where the shape of surface features is suggestive of flows. There is also a substantial buoyancy problem in their formation, as it is difficult to get liquid water to the surface of Europa since it is denser than ice. One possible such region is visible in the figure, and is about 3 km across. This region could have been formed when some type of fluid-like material covered over pre-existing ridges and other features. Models of ridge formation range from cryovolcanism to tidal squeezing to linear diapirs to compression and plastic deformation. These models range in requirements from a very thin crust overlying liquid water (the tidal squeezing model) to completely solid-state models with a thin brittle crust on top of a lower-viscosity, warm ice layer (diapirism or compression). One interesting feature called cycloidal ridges seem to correspond in orientation and location to cracking of the surface in response to the changing daily tidal stresses. This model would require the existence of a global ocean near the surface to obtain sufficient tidal stresses to crack the ice. Clearly, current models in the literature are contradictory and have very different implications for Europa's subsurface structure. Chaotic terrain was first seen as a "smoking gun" for the presence of liquid water beneath Europa's surface, but formation models that involve only solid materials are also possible. At the liquid end of the spectrum, regions of chaotic terrain are seen as areas of localized heat flow where the ice layer melted all the way to the surface. In this model, the blocks are buoyant remnants of the preexisting icy crust that move about in a slushy matrix, both translating and tilting. Eventually the matrix freezes solid, ending the blocks' motion and preserving their final positions. This model requires localized heating of the crust, but it may be difficult to concentrate the heating in both space and time. The solid-state formation model suggests that ice rises to the surface in a diapir, eventually disrupting the brittle surface. These convective upwellings make it difficult to tilt the blocks as observed, however. A third, intermediate model suggests that runaway melting within rising diapers produces chaos. Thus, models of chaos formation do seem to favor the existence of either water or an ice-water slurry at shallow depths near the surface, but such patches could be localized and not require the existence of a global liquid ocean layer. Europa will never be done Although the Galileo satellite is scheduled to dive into Jupiter's atmosphere on September 21, 2003, Phillips states with confidence that "Europa will never be done," and adds, "I could happily work on Europa for another 20 years." For the next five of those years, she'll be using the Galileo data set, but she acknowledges that this data has limitations. The failure of Galileo's high gain antenna limited the quality of the images. Also, the satellite spent a relatively limited amount of time observing Europa as it orbited Jupiter, imaging the planet and its other moons in addition to the object of her study. The quality of the combined images of Galileo and Voyager is frustratingly inconsistent. "Some areas," she says, "have a resolution of 20 kilometers per pixel some are very sharp, some are very fuzzy." While scientists do have images of the entire surface, some are, in Phillips' words, "pretty lousy." In some areas of Europa, "Voyager 2 images are better than Galileo--we're using these." Phillips worked with the U.S. Geological Survey building a map of Europa, "trying to blend a hodge-podge of images into smoothest map possible." Looking at a globe of the moon, it is possible to see large areas where the features are still sketchy. "There are regions where we just need better data." She eagerly anticipates the next NASA mission to the mysterious planet, tentatively planned as the "Jupiter Icy Moons Orbiter" or JIMO mission, which may launch in "about a decade" and would orbit Europa for up to a month. "JIMO would take a very nice consistent data set of the kind I've been hoping for," she explains. "I'm crossing my fingers." Read the original article at http://www.astrobio.net/news/article603.html. ________________________________________________________________________ SHENZHOU SECRETS: CHINA PREPARES FOR FIRST HUMAN SPACEFLIGHT By Leonard David From Space.com 24 September 2003 After four unmanned trial flights, China's first-ever piloted spacecraft, the Shenzhou 5 is set to soar. When it does, and if triumphant, China will be propelled into an exclusive country club status: the third nation capable of independently rocketing humans into Earth orbit. Although tight-lipped on a range of technical details, Chinese space officials have hinted at a multi-pronged human spaceflight program, including space station construction, as well as eventual travel to the Moon, all by 2020. China's first piloted space journey could occur as early as next month. And as NASA comes to grips with a grounded space shuttle fleet, the Red Dragon is on the rise. Read the full article at http://www.space.com/businesstechnology/technology/shenzhou_tech_030924. html. ________________________________________________________________________ WEBCASTS TO FEATURE SCIENTISTS ON A "MARS MISSION" NASA/ARC release 03-75AR 24 September 2003 NASA and Spanish scientists, who are developing ways to drill into Mars in search of underground life, will take part in eight worldwide, educational webcasts from their project site near Spain's Rio Tinto River from September 29 to October 15. NASA Ames Research Center scientist Carol Stoker will kick off the webcast series on September 29 at 10:00 AM EDT with a talk about the Mars Analog Research and Technology Experiment (MARTE). According to Stoker, mineral deposits like the ones the MARTE project is drilling into may also be found in the martian subsurface. "Searching for subsurface life in the Rio Tinto system can be viewed as a learning experience to teach scientists and technologists how to search for life in the subsurface of Mars," explained Stoker, principal investigator of the three-year experiment. Scientists and engineers from NASA, U.S. universities and the Spanish Centro De Astrobiología (Center for Astrobiology) hope to show how robot systems could look for life below Mars' surface. Scientists believe liquid water may exist deep underground on Mars. "In addition to looking for evidence of subsurface life, we hope MARTE inspires students to pursue careers in science and engineering," Stoker added. "What's different about this course is that it offers real-time transcription in both Spanish and English. So far, this has only been done before with the French in 1998," said Mark Leon, deputy chief of the NASA Ames education office, which organized the programs. "Not only do we have a live webcast, but we have live captioning," Leon said. NASA will webcast lectures by Stoker and other scientists with subtitles in both English and Spanish. The Internet lecture series has been structured as a three-week, NASA subsidized, interactive course. The series, called NASA Robotics for Research and Exploration, is worth one unit of college credit at San Jose State University, San Jose, CA. San Jose State University students enrolled in the course will be able to ask questions using Internet chat technology. Members of the worldwide Internet audience may monitor thelectures live through the program Web site. The other lecturers and their topics are: * Ricardo Amils of Spain's Centro De Astrobiología--biology and microbiology at Rio Tinto and the role of iron in biology * Todd Stevens of Portland State University, Portland, OR--subsurface life * David Fernandez Remolar of Spain's Instituto Nacional de Tecnica Aerospacial (INTA)--geology of the Rio Tinto region * Brian Glass of NASA Ames--issues and challenges for robotic drilling * Javier Gomez Elvira of INTA--down hole instrumentation for Mars and the borehole inspection system * Kennda Lynch of NASA's Johnson Space Center, Houston--searching for life on Mars and sample handling * Victor Parro of INTA--instrumentation and searching for life on Mars NASA's Astrobiology Science and Technology for Exploring Planets program is funding the project. The Spanish contribution to the project is supported by the Ministerio de Ciencia y Tecnologia, Comunidad de Madrid and the Instituto Nacional de Tecnica Aeroespacial. Educational webcasts enable students to watch live video courses, listen and interact in real time with experts participating in the programs. The schedule for the lectures is accessible on the Internet at http://robotics.nasa.gov/courses/fall2003 and http://www.cab.inta.es. For information about NASA Education programs on the Internet, visit http://education.nasa.gov. Contacts: John Bluck NASA Ames Research Center, Moffett Field, CA Phone: 650-604-5026 or 650-604-9000 E-mail: John.G.Bluck@nasa.gov Juan Bautista Rodriguez Instituto Nacional de Tecnica Aeroespacial (INTA), Spain Phone: 011 34 91 520 1938 An additional article on this subject is available at http://spaceflightnow.com/news/n0309/22marsdrill/. ________________________________________________________________________ PRINCETON PALEONTOLOGIST PRODUCES EVIDENCE FOR NEW THEORY ON DINOSAUR EXTINCTION By Steven Schultz Princeton University release 25 September 2003 As a paleontologist, Gerta Keller has studied many aspects of the history of life on Earth. But the question capturing her attention lately is one so basic it has passed the lips of generations of 6-year- olds. What killed the dinosaurs? The answers she has been uncovering for the last decade have stirred an adult-sized debate that puts Keller at odds with many scientists who study the question. Keller, a professor in Princeton's Department of Geosciences, is among a minority of scientists who believe that the story of the dinosaurs' demise is much more complicated than the familiar and dominant theory that a single asteroid hit Earth 65 million years ago and caused the mass extinction known as the Cretacious-Tertiary, or K/T, boundary. Keller and a growing number of colleagues around the world are turning up evidence that, rather than a single event, an intensive period of volcanic eruptions as well as a series of asteroid impacts are likely to have stressed the world ecosystem to the breaking point. Although an asteroid or comet probably struck Earth at the time of the dinosaur extinction, it most likely was, as Keller says, "the straw that broke the camel's back" and not the sole cause. Perhaps more controversially, Keller and colleagues contend that the "straw"--that final impact--is probably not what most scientists believe it is. For more than a decade, the prevailing theory has centered on a massive impact crater in Mexico. In 1990, scientists proposed that the Chicxulub crater, as it became known, was the remnant of the fateful dinosaur-killing event and that theory has since become dogma. Keller has accumulated evidence, including results released this year, suggesting that the Chicxulub crater probably did not coincide with the K/T boundary. Instead, the impact that caused the Chicxulub crater was likely smaller than originally believed and probably occurred 300,000 years before the mass extinction. The final dinosaur-killer probably struck Earth somewhere else and remains undiscovered, said Keller. These views have not made Keller a popular figure at meteorite impact meetings. "For a long time she's been in a very uncomfortable minority," said Vincent Courtillot, a geological physicist at Université Paris 7. The view that there was anything more than a single impact at work in the mass extinction of 65 million years ago "has been battered meeting after meeting by a majority of very renowned scientists," said Courtillot. The implications of Keller's ideas extend beyond the downfall of ankylosaurus and company. Reviving an emphasis on volcanism, which was the leading hypothesis before the asteroid theory, could influence the way scientists think about the Earth's many episodes of greenhouse warming, which mostly have been caused by periods of volcanic eruptions. In addition, if the majority of scientists eventually reduce their estimates of the damage done by a single asteroid, that shift in thinking could influence the current-day debate on how much attention should be given to tracking and diverting Earth-bound asteroids and comets in the future. Keller does not work with big fossils such as dinosaur bones commonly associated with paleontology. Instead, her expertise is in one-celled organisms, called foraminifera, which pervade the oceans and evolved rapidly through geologic periods. Some species exist for only a couple hundred thousand years before others replace them, so the fossil remains of short-lived species constitute a timeline by which surrounding geologic features can be dated. In a series of field trips to Mexico and other parts of the world, Keller has accumulated several lines of evidence to support her view of the K/T extinction. She has found, for example, populations of pre-K/T foraminifera that lived on top of the impact fallout from Chicxulub. (The fallout is visible as a layer of glassy beads of molten rock that rained down after the impact.) These fossils indicate that this impact came about 300,000 years before the mass extinction. The latest evidence came last year from an expedition by an international team of scientists who drilled 1,511 meters into the Chicxulub crater looking for definitive evidence of its size and age. Although interpretations of the drilling samples vary, Keller contends that the results contradict nearly every established assumption about Chicxulub and confirm that the Cretaceous period persisted for 300,000 years after the impact. In addition, the Chicxulub crater appears to be much smaller than originally thought--less than 120 kilometers in diameter compared with the original estimates of 180 to 300 kilometers. Keller and colleagues are now studying the effects of powerful volcanic eruptions that began more than 500,000 years before the K/T boundary and caused a period of global warming. At sites in the Indian Ocean, Madagascar, Israel and Egypt, they are finding evidence that volcanism caused biotic stress almost as severe as the K/T mass extinction itself. These results suggest that asteroid impacts and volcanism may be hard to distinguish based on their effects on plant and animal life and that the K/T mass extinction could be the result of both, said Keller. Read the original news release at http://www.princeton.edu/pr/news/03/q3/0925-keller.htm. A longer version of this news release appeared in the Princeton Weekly Bulletin (http://www.princeton.edu/pr/pwb/03/0922/). Contacts: Steven Schultz Phone: 609-258-5729 E-mail: sschultz@princeton.edu Princeton University Office of Communications 22 Chambers Street Princeton, New Jersey 08542 Phone: 609-258-3601 Fax 609-258-1301 Additional articles on this subject are available at: http://www.spacedaily.com/news/life-03zw.html http://spaceflightnow.com/news/n0309/26dinosaur/ http://www.universetoday.com/am/publish/dinosaurs_volcanoes_asteroids.ht ml ________________________________________________________________________ DID A GAMMA-RAY BURST DEVASTATE LIFE ON EARTH? From SpaceDaily 26 September 2003 A huge massive burst of gamma-rays 443 million years ago could have caused one of Earth's worst mass extinctions say a group of astrophysicists and palaeontologists in a report carried by this week's issue of New Scientist. Using the pattern of trilobite extinctions at that time the scientists say the pattern meets the expected effects of a nearby gamma-ray burst (GRB). Although other experts have greeted the idea with some skepticism, most agree that it deserves further investigation. GRBs are the most powerful explosions known. As giant stars collapse into black holes at the end of their lives, they fire incredibly intense pulses of gamma rays from their poles that can be detected even from across the universe for 10 seconds or so. All the bursts astronomers have recorded so far have come from distant galaxies and been harmless on the ground, but if one occurred within our galaxy and was aimed straight at us, the effects could be devastating, according to astrophysicist Adrian Melott of the University of Kansas in Lawrence. Read the full article at http://www.spacedaily.com/news/gamma-03m.html. An extended version of this article will appear in the September 27 issue of New Scientist (http://www.newscientist.com). ________________________________________________________________________ THE DRAKE EQUATION REVISITED, PART I By Frank Drake From Astrobiology Magazine 29 September 2003 The Drake equation was developed as a means of predicting the likelihood of detecting other intelligent civilizations in our galaxy. At the NASA forum, Frank Drake, who formulated the equation 42 years ago, moderated a debate between paleontologist Peter Ward, co-author of the book Rare Earth, and astronomer David Grinspoon, author of the forthcoming book Lonely Planets: The Natural Philosophy of Alien Life. In this installment of the series, Dr. Drake explains the history and the content of his famous equation. Dr. Drake is the director for the Center for the Study of Life in the Universe at the SETI Institute in Mountain View, CA. He is also chairman emeritus of the SETI Institute board of trustees and professor emeritus of astronomy and astrophysics at the University of California at Santa Cruz. Subsequent installments will include the comments made by Drs. Ward and Grinspoon, and the question-and-answer period that followed the opening remarks. Frank Drake: It's a pleasure and honor to be with all of you exobiologists tonight. When I started in this game there were no exobiologists. So just seeing you all out there is a lot of progress. I want to start out by giving you a little bit of the history and a brief description of the equation. This all began shortly after I conducted the first search for extraterrestrial intelligent radio signals at the National Radio Astronomy Observatory in Green Bank. That was in 1960. At that very same time, a very seminal paper was published by Philip Morrison and Giuseppe Cocconi, pointing out what I had already realized, and that was that we had the ability to detect reasonable signs of intelligent technology across the distances which separated the stars. This in one way opened the door to detecting life, in this case specifically intelligent life, beyond Earth. A great new window of possibilities was opened, which was slowly recognized at the time and, of course, is widely recognized today. It's expressed by the great growth in the field of astrobiology. Shortly after this, the National Academy of Sciences wanted to convene a small meeting to examine this whole question and propose where we should go from here. They asked me to do this and, indeed, just about 42 years ago at this time I sponsored the first such meeting at Green Bank. I was the entire scientific and local organizing committee, but it wasn't a hard task because I invited every person in the world we knew of who was interested in working in this subject--all twelve of them. And all twelve of them showed up. As I planned the meeting, I realized a few day ahead of time we needed an agenda. And so I wrote down all the things you needed to know to predict how hard it's going to be to detect extraterrestrial life. And looking at them it became pretty evident that if you multiplied all these together, you got a number, N, which is the number of detectable civilizations in our galaxy. This, of course, was aimed at the radio search, and not to search for primordial or primitive life forms. Well, what is the equation? It encapsulates our understanding of the evolution of our galaxy and of our solar system. We know our galaxy is about 14 billion years old and that stars have been created at almost a constant rate. And since very early on those newly formed stars have been accompanied by planetary system--at least in some cases. So the whole equation is based on a continuous production of new planetary systems, and then presumably life, intelligent life and technology-using life. And that tells us, of course, that the number of detectable civilizations is going to be proportional to the rate of star formation, which we write as R*, because the more stars you make, the more civilizations there will be, eventually. That's an easy one. We've known for a long time that about 20 new stars are produced per year in our galaxy, and that has been the case for many billions of years now. But over time, we've become a little bit more sophisticated in defining what this factor means. Twenty stars per year are produced, but we realize not all of them could produce an intelligent species. Some burn out their hydrogen cores extremely fast, in literally millions of years--no time to evolve intelligent species. If we take all of those away, the fast-burning stars, we're left with 19 stars per year. Of those, about four are like the sun. So is the right number for R* four per year? This is still one of the big questions in astrobiology, and one of the challenging ones. What are the other 15? They're all very small red dwarf stars, stars known as M dwarfs to astronomers. For a long time we believed that they could not be abodes of intelligent life because, indeed, they could have planetary systems (although none has ever been detected yet), but even if there were planets there, they would be so close to the star that, just as our moon keeps one face to the Earth, they would keep one face to their star. And we thought this would create a situation where, on the dark side of these planets, it would be so cold that the atmosphere would freeze out. There would be no atmosphere and therefore no possibility of life arising. Well, now that belief has been challenged and it has been shown that with a properly massive atmosphere this freezing out of the atmosphere will not occur. So perhaps the M stars and their planets, after all, are abodes of life. So what is R*? Well maybe it's 4, and maybe it's 19 stars per year. If we multiply by the fraction of those stars which have planets, fp, we get the rate of production of new planetary systems per year. So what is that? Well, for a long time we have had nothing but theories to go on. We thought perhaps 50 percent of the stars had planets. That was based on the fact that half the stars are binary systems, and the other half must have something else, something small, a planet. Of course, one of the great discoveries of the last century, which only ended about three years ago, was the detection of other planetary systems. This is one of the greatest discoveries in the history of science. We now know of over 100 such systems. Most all of them have what you might call "giant Jupiters" in them, not planets suitable for life on Earth. But we know this is the tip of the iceberg, because this is the only kind of planet we can detect. About 5 percent of the stars have such planets. What do the other 95 percent have? Perhaps Earth- like planets, or planets suitable for life. We also ask whether these giant planets have habitable satellites. In any case, the primary detector of these stars, Geoff Marcy at UC Berkeley, estimates that about 50 percent of the stars have planetary systems. If we multiply that by the next factor, which is written ne, the number of planets in the ecosphere, a term we don't use any more--nowadays we call it the continuously habitable zone--we get the rate of production of possible life-bearing planets. This is a complex subject, very much more complex than was first imagined. Early on it was thought that the planet had to be at such a distance from the star that liquid water could exist. Not too close, not too far. You had to be Goldilocks, to give rise to life. Now we realize that the nature of the planet can greatly affect the distance at which it can be from a star and still be habitable. A prime example is Europa, far out where it's very, very cold on its surface, and yet there is a potential biosphere on that object. A deep atmosphere, through the greenhouse effect, can also make a planet far out from its star nevertheless habitable. So, again, this is a factor we don't know very well. The next factor, fl, is the fraction of potentially habitable planets that actually give rise to life. That one we seem to know something about, because the chemists have found a multitude of chemical pathways to the origins of life. Life seems inevitable on any planet with suitable characteristics. And what are those? They seem to be very simple: liquid water, organic molecules and a source of energy. The real question is not whether life arises, but how it really happens. The present consensus is that life does arise in a body of water, perhaps in Darwin's "warm little pond," or the deep-sea vents, the froth of ocean waves--these have all been suggested--or on the molecular templates of clay minerals. We think that fraction is close to one. Our next fraction, fi, is the one which describes what fraction of systems of living things give rise to an intelligent species. This fraction is trying to give the answer to the question: Does evolution converge or diverge? There is much evidence for convergence in intelligence, including the growth in brain size seen in the fossil record, but is an intelligent brain really contingent on things we're not quite sure about? For instance, does it require the evolution of a means of sophisticated communication, one of the possible contingent situations which may limit the frequency with which intelligence arises? That one is a big unknown. The next, fc, is the fraction of intelligent civilizations which give rise to a technology which we might detect, or which might communicate-- that's what the "c" means. It seems that fc should be close to one. Once you have enough intelligence in a creature whose anatomy allows the use of tools, you should get technology. Technology has, in fact, developed in many places on Earth in humans independently. The prime drivers are pretty obvious. The drivers were to provide food, leading to the development of agriculture and the tools of agriculture; to provide the ability to live in otherwise uninhabitable regions, such as artic regions, polar regions; and, of course, for the development of weapons. At this point, you multiply this all together and you get the rate of production of detectable civilizations in the galaxy. Now, we don't believe, being conservative, that they remain detectable forever. Perhaps they destroy themselves through nuclear folly, or through destruction of their environment. Perhaps they suffer a cosmic catastrophe, like the K/T event [the asteroid impact that caused dinosaurs to go extinct]. More likely, at least to the optimists such as myself, they come upon the scene, they are detectable, and then they disappear, because they become more sophisticated technologically. They've stopped releasing energy into space. At the present time we are very detectable, primarily through our television broadcasts. But we see television going to cable, and especially to the direct-to-home transmission of television from satellites. This is terrifying to people like me. The ordinary over-the-air television transmitter transmits a million watts. It makes a very detectable signal. The transmitters which transmit television to those little dishes on people's homes only transmit 10 watts, far less than a million, and make a signal which is totally undetectable at interstellar distances. So, we have to worry: civilizations may be thriving, with a tremendous quality of life, and yet be very hard to detect. And we must account for that by saying, okay, they exist but they only last some limited amount of time, which we will call L, the longevity. L is dominated by those civilizations with very large Ls, because L is the average lifetime of a civilization. Just as a numerical example, given 100 civilizations, if 99 are detectable for only 100 years, and 1 is detectable for a billion years, then L turns out to be 10 million years. And so L may be larger than what our intuitive thoughts might be. So that's the equation. But before we move on, I'll offer a few comments that are evident but somehow not really seen. One is that every factor in the equation appears to the first power. There are no exponentials, no powers, no power laws, no logarithms. Every one is equally important. And, in the same vein, the overall error in the result is controlled by the biggest uncertainties, which are probably fi and L. Thirdly, the uncertainties grow as we go from the left to the right of the equation, from the astronomical and chemical factors to the social ones. And, finally, we ask whether we need some other factors. I get letters every week suggesting such. Particularly that we need a factor for the ignorance of politicians. However, all the other ones so far proposed are subsumed within the traditional ones. But the future could well reveal the need for an enlarged equation. Read the original article at http://www.astrobio.net/news/article610.html. ________________________________________________________________________ ESA AWARDS THE FIRST AURORA MISSION DESIGN CONTRACTS ESA release 29 September 2003 A major milestone in ESA's long-term Aurora program of Solar System exploration has been passed with the announcement of the winners of competitive contracts for two of the program's key robotic missions-- ExoMars and Earth re-entry Vehicle Demonstrator (EVD). Alenia Spazio (Italy), Alcatel Space (France) and EADS Astrium (France) are heading the three industrial teams selected to carry out a full mission design for ExoMars, the Aurora exobiology mission to Mars. At the same time, two industrial teams, headed by EADS LV (Launch Vehicles) of France and Surrey Satellite Technology Limited (SSTL) of the United Kingdom respectively, have been selected for the pre-development phase (officially known as Pre-Phase A) of the EVD mission. "Following the Invitations to Tender (ITTs) for these contracts, issued in April-May 2003, there was an overwhelming and enthusiastic response from industry," said Bruno Gardini, Aurora Project Manager. "We were delighted by the number and the excellence of the proposals received," he added. "It was also pleasing to see that many of them included new, innovative ideas from industry." ExoMars The ExoMars mission, to be launched in 2009, is the first of the major Flagship missions in the Aurora program. It includes an orbiter and a descent module that will land a large (200 kg), high-mobility rover on the surface of Mars. After delivery of the lander/rover, the ExoMars orbiter will also operate as a data relay satellite between the Earth and the vehicle on the martian surface. The primary objective of the ExoMars rover will be to search for signs of life, past or present, on the Red Planet. Additional measurements will be taken to identify potential surface hazards for future human missions, to determine the distribution of water on Mars and to measure the chemical composition of the surface rocks. Three parallel Phase A studies for the ExoMars Mission will be carried out by industrial teams that include companies from ESA member states and Canada: * Alenia Spazio (Italy) with subcontractors OHB (Germany), GMV (Spain), SEA (UK), SSC (UK) and Laben (Italy). * Alcatel Space (France) with subcontractors Deimos (Spain), ETCA (Belgium), Fluid Gravity Engineering (UK), Kayser Threde (Germany), Laben (Italy), MD Robotics (Canada), NGC Aerospatiale (Canada), QinetiQ (UK), Vorticity (UK). * EADS Astrium (France) with subcontractors Astrium Ltd. (UK), EADS LV (France) and SAS (Belgium). The contracts cover the design of the entire ExoMars mission, from launch, through the long interplanetary voyage to the landing of the rover on the planet. "This is an exciting landmark for the Aurora program, since these are the first contracts dedicated to mission development rather than technical studies," said Gardini. "With the participation of all major European aerospace companies, the proposed concepts will make the best use of their extensive experience, gathered over many years, in the design and development of interplanetary missions," he said. "The studies will also bring to fruition several years of efforts from national and international programs in investigating and planning Mars missions. "From the quality of the proposals, the agency is very confident that the technical baseline will be fully consolidated by the end of the Phase A studies and that the spacecraft design will then be defined to a level of detail commensurate with a prompt start of Phase B." Depending on the availability of funding, the Phase B studies for ExoMars are planned to start in 2004. Earth re-entry Vehicle Demonstrator (EVD) The second Aurora Flagship mission is a Mars Sample Return (MSR), planned for 2011. Its main goal will be the retrieval of rock samples from the martian surface and subsurface for subsequent analysis in laboratories on Earth. In order to ensure the success of this challenging mission, a number of new technologies will have to be developed and tested. Conceived as a small, technology-driven Arrow- class mission, the Earth re-entry Vehicle Demonstration will be used to validate the design of the small MSR capsule that will bring back the precious samples of martian soil. The EVD is expected to be launched in 2007. The baseline mission foresees the insertion into a highly elliptical Earth orbit of a small spacecraft carrying a re-entry capsule. In order to reproduce the final phase of a typical Mars return mission, the capsule will then carry out a ballistic re-entry into Earth's atmosphere at speeds of up to 45,000 km/h. Two industrial teams have been selected for the parallel EVD mission Pre-Phase A studies. The concept presented by the industrial team, under the leadership of EADS LV (France) with the participation of OHB System (Germany) and Plansee (Austria) is solidly based on the experience of past projects. The industrial team led by SSTL (UK), a company well known for its experience in small highly integrated spacecraft, has devised a very innovative concept well adapted for a small technology mission. The participation of highly specialised companies, Fluid Gravity Engineering (UK), Kayser Threde GmbH (D) and Vorticity Ltd. (UK) ensures an excellent coverage of the mission's most critical technologies. "The expectations are for highly competitive and exciting Pre-Phase A studies," said Gardini. The next Aurora contract for Phase A studies will concern the Mars Sample Return mission. Industrial proposals were submitted on 1 August and the evaluation is nearly completed. The names of the selected companies are expected to be announced in early October. Read the original news release at http://www.esa.int/export/esaCP/SEM4YL0P4HD_index_0.html. An additional article on this subject is available at http://spaceflightnow.com/news/n0309/29aurora/. ________________________________________________________________________ NEW ADDITIONS TO THE ASTROBIOLOGY INDEX By David J. Thomas http://www.lyon.edu/projects/marsbugs/astrobiology/astrobiology.html 30 September 2003 Astrobiology and planetary engineering articles http://www.lyon.edu/projects/marsbugs/astrobiology/online_articles1.html C. Phillips and D. Richards, 2003. High tide on Europa. Astrobiology Magazine. Terrestrial extreme environments articles http://www.lyon.edu/projects/marsbugs/astrobiology/online_articles2.html NASA Ames Research Center, 2003. Scientists practice Mars drilling near acidic river. Spaceflight Now. SETI articles http://www.lyon.edu/projects/marsbugs/astrobiology/online_articles4.html F. Drake, 2003. The Drake equation revisited, part I. Astrobiology Magazine. Evolution (biological, chemical and cosmological) articles http://www.lyon.edu/projects/marsbugs/astrobiology/online_articles5.html SpaceDaily, 2003. Did a gamma-ray burst devastate life on Earth? SpaceDaily. S. Schultz, 2003. Dinosaurs killed by volcanoes and asteroids? Universe Today. S. Schultz, 2003. Paleontologist: new theory on dinosaur extinction. Spaceflight Now. S. Schultz, 2003. Paleontologist offers new theory on dinosaur extinction. SpaceDaily. ________________________________________________________________________ CASSINI SIGNIFICANT EVENTS NASA/JPL release 18-24 September 2003 The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Monday, September 22. 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/operations/present-position.cfm. On-board activities this week included data playback of last week's Probe checkout, a Magnetospheric Imaging Instrument fight software checkout and Ultraviolet Imaging Spectrograph Hydrogen Deuterium Absorption Cell conditioning. A Trajectory Correction Maneuver (TCM) approval meeting was held for TCM 19B. The maneuver has been approved and will execute on October 1. Preliminary and official port 2 deliveries were completed as part of the Science Operations Plan (SOP) implementation process for tour sequences S01 and S02. In addition, the SOP implementation process for S03 and S04 has concluded and the sequences archived. Imaging Science Subsystem personnel delivered the Imaging Science Subsystem Pre-commanding Tool (ISSPT) V1.0. This program allows the user to design imaging observations using the Imaging Science Subsystem on the Cassini spacecraft. ISSPT allows the user to adjust and optimize camera settings, calculate image brightness and content based on pointing, and produce an Instrument Operations interface output file suitable for building camera command sequences. Members of the International Astronomical Union recently passed a resolution during their meeting in Sydney, Australia: Observations of the saturnian system IAU Commission 16 (Physical Study of Planets and Satellites) endorses astronomical observations of the Saturnian system at the time of the NASA and ESA Cassini/Huygens mission to the Saturnian system. The attention of the worldwide astronomical community is drawn to the unique scientific opportunities presented by the presence of a long-lived orbiting spacecraft in the Saturnian system and a Titan Probe. Observations of all types, ground- and space-based, are encouraged during the course of the mission (nominally 2003-2008), including observations of Saturn, the rings, Titan, and the icy satellites." 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. ________________________________________________________________________ MARS GLOBAL SURVEYOR IMAGES NASA/JPL/MSSS release 18-24 September 2003 The following new images taken by the Mars Orbiter Camera (MOC) on the Mars Global Surveyor spacecraft are now available. Defrosting Patterns (Released 18 September 2003) http://www.msss.com/mars_images/moc/2003/09/18/index.html Eroded Crater (Released September 2003) http://www.msss.com/mars_images/moc/2003/09/19/index.html Ceraunius Caldera Floor (Released 20 September 2003) http://www.msss.com/mars_images/moc/2003/09/20/index.html Exhumed Ridge Pattern (Released 21 September 2003) http://www.msss.com/mars_images/moc/2003/09/21/index.html Ancient Valley (Released 22 September 2003) http://www.msss.com/mars_images/moc/2003/09/22/index.html Defrosting Richardson Dune (Released 23 September 2003) http://www.msss.com/mars_images/moc/2003/09/23/index.html Melas Dust Storm (Released 24 September 2003) http://www.msss.com/mars_images/moc/2003/09/24/index.html All of the Mars Global Surveyor images are archived at http://www.msss.com/mars_images/moc/index.html. Mars Global Surveyor was launched in November 1996 and has been in Mars orbit since September 1997. It began its primary mapping mission on March 8, 1999. Mars Global Surveyor is the first mission in a long-term program of Mars exploration known as the Mars Surveyor Program that is managed by JPL for NASA's Office of Space Science, Washington, DC. Malin Space Science Systems (MSSS) and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO. ________________________________________________________________________ MARS ODYSSEY THEMIS IMAGES NASA/JPL/ASU release 23-26 September 2003 A Crater Split In Two (Released 23 September 2003) http://themis.la.asu.edu/zoom-20030923a.html Niger Vallis (Released 24 September 2003) http://themis.la.asu.edu/zoom-20030924a.html Terra Sirenum (Released 26 September 2003) http://themis.la.asu.edu/zoom-20030926a.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, DC. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen 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 26 September 2003 The Stardust team had one period of communications with the spacecraft in the past week. Telemetry relayed from the spacecraft indicates it is healthy and all subsystems continue to operate normally. Information on the present position and orbits of the Stardust spacecraft and comet Wild 2 may be found on the "Where Is Stardust Right Now?" web page located at http://stardust.jpl.nasa.gov/mission/scnow.html. A formal peer review of the Comet Wild 2 dust model was held recently. Thirteen internationally renowned comet experts reviewed and discussed the mission's 'model' for dust location and size for Comet Wild 2. The current project model was validated with unanimous consensus to use as is for mission planning. The Stardust team will now incorporate the Comet Wild 2 dust model into their final planning for encounter. 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 10, Number 39.