MARSBUGS: The Electronic Astrobiology Newsletter Volume 10, Number 8, 24 February 2003. Editor/Publisher: David J. Thomas, Ph.D., Science Division, Lyon College, Batesville, AR 72503-2317, USA. dthomas@lyon.edu Contributing Editor: Julian A. Hiscox, Ph.D., 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 effectively 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/. ________________________________________________________________________ CONTENTS 1) ASSESSMENT OF SCIENCE DATA GAINED DURING COLUMBIA'S MISSION NASA release 03-074 2) THE FUTURE OF FLIGHT: NASA WANTS 4-PERSON SPACE PLANE By Brian Berger 3) NASA'S MARS ODYSSEY POINTS TO MELTING SNOW AS CAUSE OF GULLIES NASA release 2003-021 4) UNDERSEA EXPLORATION PROVIDES TRIAL-RUN FOR SPACE HARDWARE By Leonard David 5) ICE DIARY 1: SHOOTING STARS ON ICE By Andy Caldwell 6) ALIEN TV: SORTING INTELLIGENT SIGNALS FROM WITLESS COSMIC NOISE By Seth Shostak 7) THE GREAT IMPACT DEBATE, PART III: THE LARGE AND THE SMALL Moderated by Don Yeomans 8) ASTEROIDS AND SECRECY: IF END IS NIGH, DO YOU WANT TO KNOW? By Robert Roy Britt 9) COLUMBIA LOST, BUT NOT A NATION By Alan Stern 10) NEW ADDITIONS TO THE ASTROBIOLOGY INDEX By David J. Thomas 11) CONTINUING COVERAGE OF THE COLUMBIA DISASTER By David J. Thomas 12) CASSINI SIGNIFICANT EVENTS NASA/JPL release 13) MARS ODYSSEY THEMIS IMAGES NASA/JPL/ASU release 14) STARDUST STATUS REPORT NASA/JPL release ________________________________________________________________________ ASSESSMENT OF SCIENCE DATA GAINED DURING COLUMBIA'S MISSION NASA release 03-074 19 February 2003 NASA scientists are continuing to assess the status of the data received by the experiments onboard Space Shuttle Columbia (STS-107) during its final mission. Columbia carried more than 80 experiments, science, commercial and student, on a 16-day mission devoted to research, entrepreneurship and education. "For those experiments that received down-linked data during the mission, we estimate that anywhere between 50-90 percent of the data was acquired," said David Liskowsky, STS-107 Program Scientist for NASA's Office of Biological and Physical Research (OBPR). Most of these experiments were in the physical science disciplines of combustion research, material sciences, and fluid physics. For most of the life sciences experiments, data and specimens were to be recovered on landing, so no data are available. The OBPR science project teams report the overall performance of the experimental hardware and equipment employed on the mission was highly successful, with 100 percent operational success being achieved for virtually all of the experiments. "In addition to the scientific data that was collected from the mission, this operational success provides a measure of the robustness and capability of conducting high quality research on the Shuttle," Liskowsky said. During the past week, researchers determined: * The Mechanics of Granular Materials (MGM) investigators estimate that careful analysis of the downlinked data should result in achieving 50 to 60 percent of their science goals. The MGM experiment used the microgravity of orbit to test sand columns under conditions that cannot be obtained from experiments on Earth. The knowledge gained from this will be applied to improving foundations for buildings and increasing understanding of how earthquakes and other forces disturb grains of soil and sand. * Almost all of the data from Critical Viscosity of Xenon, an experiment sponsored by the National Institute of Standards and Technology, was acquired before the end of the mission. This experiment measured the changes in viscosity (resistance to flow) of xenon, a pure fluid with a very simple structure and a critical temperature just below room temperature. The data may help scientists better understand shear thinning in complex fluids such as paints and foods (e.g., whipped cream), which need to flow easily during application and stand firm afterwards. * STARNAV, a star tracker navigation system from Texas A&M University accomplished all of its objectives. This educational experiment was designed to determine precise spacecraft attitude without prior knowledge of position. * SPACEHAB's Space Media commercial payload, STARS, saw many amazing results on this mission. As part of an education program with experiments designed by students, the STARS payload (www.starsprogram.com) received daily downlink of video, photos, humidity and temperature readings. Students from Australia, China, Israel, Japan, Liechtenstein, and the United States designed these six experiments. They were able to achieve approximately 70 percent of their scientific objectives, providing unique insight into the low gravity impact on the behavior and development of ants, bees, silkworms, and fish eggs, the random crystal growth of cobalt and calcium, and the web spinning ability of spiders. * The Solar Constant Experiment (SOLCON), managed by the Royal Meteorological Institute of Belgium and sponsored by NASA, was designed to measure the solar constant and identify variations in the value during a solar cycle. This experiment was a 100 percent success. The data will ensure continuity of the solar constant level obtained by instruments mounted on free flyers, over climate time scale duration. * The Low Power Transceiver (LPT) experiments were completed and 100 percent of the data collected. These experiments demonstrated LPT's ability to do simultaneous communications and on-board navigation in space. The data from this experiment may provide more cost-effective space operations in future satellites * The Mediterranean Israeli Dust Experiment (MEIDEX) acquired an image of a pall of gray smoke hanging above the Amazon rainforest illustrating how complex interactions between smoke and the atmosphere can influence weather and climate. The final results from these and other experiments will be determined in the coming months as the acquired data are analyzed. More information about the research performed by the Columbia crew is available on the Internet at http://spaceresearch.nasa.gov. Contact: Dolores Beasley NASA Headquarters, Washington, DC Phone: 202-358-1753 ________________________________________________________________________ THE FUTURE OF FLIGHT: NASA WANTS 4-PERSON SPACE PLANE By Brian Berger From Space.com 19 February 2003 NASA's top level requirements for the envisioned Orbital Space Plane mandate that the rocket-launched crew transfer vehicle be capable of transporting "no fewer than four" astronauts to and from the International Space Station. That requirement leaves open the possibility that the Orbital Space Plane could carry fewer astronauts than the Crew Rescue Vehicle NASA had originally planned to build for the space station. The Crew Rescue Vehicle, a victim of cutbacks ordered after the discovery of a looming $5 billion space station budget shortfall, was being designed to carry six or seven astronauts away from the station in event of an emergency. Read the full article at http://www.space.com/missionlaunches/space_plane_030219.html. Additional articles on this subject are available at: http://www.cnn.com/2003/TECH/space/02/20/sprj.colu.nasa.orbiter.ap/index .html http://www.spacedaily.com/2003/030219035342.ki29vxhg.html http://www.spacedaily.com/news/osp-03a.html ________________________________________________________________________ NASA'S MARS ODYSSEY POINTS TO MELTING SNOW AS CAUSE OF GULLIES NASA release 2003-021 19 February 2003 [http://jpl.convio.net/images/content/pagebuilder/10131.jpg] Gullies in martian crater. Images from the visible light camera on NASA's Mars Odyssey spacecraft, combined with images from NASA's Mars Global Surveyor, suggest melting snow is the likely cause of the numerous eroded gullies first documented on Mars in 2000 by Global Surveyor. The now-famous martian gullies were created by trickling water from melting snow packs, not underground springs or pressurized flows, as had been previously suggested, argues Dr. Philip Christensen, the principal investigator for Odyssey's camera system and a professor from Arizona State University in Tempe. He proposes gullies are carved by water melting and flowing beneath snow packs, where it is sheltered from rapid evaporation in the planet's thin atmosphere. His paper is in the electronic February 19 issue of Nature. Looking at an image of an impact crater in the southern mid-latitudes of Mars, Christensen noted eroded gullies on the crater's cold, pole-facing northern wall and immediately next to them a section of what he calls "pasted-on terrain." Such unique terrain represents a smooth deposit of material that Mars researchers have concluded is "volatile" (composed of materials that evaporate in the thin Mars atmosphere), because it characteristically occurs only in the coldest, most sheltered areas. The most likely composition of this slowly evaporating material is snow. Christensen suspected a special relationship between the gullies and the snow. "The Odyssey image shows a crater on the pole-facing side has this 'pasted-on' terrain, and as you come around to the west there are all these gullies," said Christensen. "I saw it and said 'Ah-ha!' It looks for all the world like these gullies are being exposed as this terrain is being removed through melting and evaporation." Eroded gullies on martian crater walls and cliff sides were first observed in images taken by Mars Global Surveyor in 2000. There have been other scientific theories offered to explain gully formation on Mars, including seeps of ground water, pressurized flows of ground water (or carbon dioxide), and mudflows caused by collapsing permafrost deposits, but no explanation to date has been universally accepted. The scientific community has remained puzzled, yet has been eagerly pursuing various possibilities. "The gullies are very young," Christensen said. "That's always bothered me, because how is it that Mars has groundwater close enough to the surface to form these gullies, and yet the water has stuck around for billions of years? Second, you have craters with rims that are raised, and the gullies go almost to the crest of the rim. If it's a leaking subsurface aquifer, there's not much subsurface up there. And, finally, why do they occur preferentially on the cold face of the slope at mid- latitudes? If it's melting groundwater causing the flow, that's the coldest place, and the least likely place for that to happen." Christensen points out that finding water erosion under melting snow deposits answers many of these problems, "Snow on Mars is most likely to accumulate on the pole-facing slopes, the coldest areas. It accumulates and drapes the landscape in these areas during one climate period, and then it melts during a warmer one. Melting begins first in the most exposed area right at the crest of the ridge. This explains why gullies start so high up." Once he started to think about snow, Christensen began finding a large number of other images showing a similar relationship between "pasted on" snow deposits and gullies in the high resolution images taken by the camera on Global Surveyor. Yet it was the unique mid-range resolution of the visible light camera in Mars Odyssey's thermal emission imaging system that was critical for the insight, because of its wide field of view. "It was almost like finding a Rosetta Stone. The basic idea comes out of having a regional view, which Odyssey's camera system gives. It's a kind of you-can't-see-the forest-for-the-trees problem. An Odyssey image made it all suddenly click, because the resolution was high enough to identify these features and yet low enough to show their relationship to each other in the landscape," he said. "Christensen's new hypothesis was made possible by NASA's tandem of science orbiters currently laying the groundwork for locating the most interesting areas for future surface exploration by roving laboratories, such as the Mars Exploration Rovers, scheduled for launch in May and June of this year," said Dr. Jim Garvin, NASA's lead scientist for Mars Exploration in Washington, DC. The Jet Propulsion Laboratory manages the Mars Exploration Program for NASA's Office of Space Science in Washington, DC. The new images are available online at: http://photojournal.jpl.nasa.gov/catalog/PIA04408 http://photojournal.jpl.nasa.gov/catalog/PIA04409 More information about the 2001 Mars Odyssey mission is available on the Internet at http://mars.jpl.nasa.gov/odyssey/. Contacts: Mary Hardin Jet Propulsion Laboratory, Pasadena, CA Phone: 818-354-0344 James Hathaway Arizona State University, Tempe Phone: 480-965-6375 Nancy Neal NASA Headquarters, Washington, DC Phone: 202-358-2369 Additional articles on this subject are available at: http://www.cnn.com/2003/TECH/space/02/19/mars.snow.ap/index.html http://www.nytimes.com/2003/02/20/science/20MARS.html?tntemail0 http://science.nasa.gov/headlines/y2003/19feb_snow.htm?list52260 http://www.space.com/scienceastronomy/mars_gullies_030219.html http://spaceflightnow.com/news/n0302/19marssnow/ http://www.spacedaily.com/news/mars-water-science-03f.html ________________________________________________________________________ UNDERSEA EXPLORATION PROVIDES TRIAL-RUN FOR SPACE HARDWARE By Leonard David From Space.com 19 February 2003 A high-tech approach to ocean exploration will not only provide insight into the origin of life on Earth but how to search for life on other worlds. Called Project Neptune, the plan is to convert the Juan de Fuca tectonic plate in the northeast Pacific Ocean and the overlying sea into a suite of undersea observatories. An armada of nautical hardware, including autonomous rovers, would be part of an oceanic toolkit to probe a range of Earth and ocean processes. On the scientific study agenda: monitor submarine volcanoes, home to a bizarre and uncharted biosphere of microbes that thrive on heat and chemicals bubbling up from deep within the Earth. Read the full article at http://www.space.com/businesstechnology/technology/undersea_outerspace_0 30219.html. ________________________________________________________________________ ICE DIARY 1: SHOOTING STARS ON ICE By Andy Caldwell From Astrobiology Magazine 19 February 2003 The "Ice Diary" series explores the adventures of a dedicated group of meteor hunters. The National Science Foundation, NASA and the Smithsonian collect and curate extraterrestrial samples scoured from the South Pole. During the season when the sun never sets, this 12-part expedition series follows their quest step-by-step, as they chase astrobiology's most precious stones: the martian samples. 21 November, 2002 The adventure has begun. Getting to Antarctica is no easy task. The easiest was flying Denver to Los Angeles in a spacious, uncrowded airplane. In LA, I met the rest of the team except for our guides, who are meeting us in McMurdo. We boarded a Quantas 747 that didn't have one empty seat. I sat next to Dr. Nancy Chabot, our team leader and a good friend. It's difficult to sleep under those conditions, but a 12.5-hour flight is a long time to pass, so I did my best, and felt a little sore and tired after the experience. We landed in Auckland early Wednesday morning, completely bypassing November 19. New Zealand is beautiful, with rolling green fields and sheep... lots of sheep. The air is sweet and moist, but cool. It's summer here, but it feels like a fall day in Seattle. The people couldn't be friendlier, with a smile and an accent that melts your heart. Today we each tried on our extreme cold weather gear. After putting on layer after layer, you couldn't really recognize who was who. We are scheduled to leave at 6:00 AM tomorrow on a C-130, dressing in all of our gear in case we should go down and can't be rescued for a while. There's a good chance that the flight will be delayed, because we hear they are running behind at McMurdo and can't get people out for 2 to 3 days. Given a choice between spending more time here or in McMurdo, New Zealand wins. 22 November, 2002 I'm writing from a crowded bench seat in the hold of a "Kiwi" C-130. The American C-130s were out of service, so the New Zealand Air Force is flying us down. Have I mentioned recently how great the Kiwis are? A C-130 is a 4-turboprop cargo plane that was not designed with comfort and passengers in mind. I heard Dr. Dean Eppler, a member of our team, saying that the reason the Army uses C-130s for paratrooper training is that it is preferable to jump out than to stay in one very long. My body feels like I bought the cheap seats at a baseball doubleheader. We woke to a rainy morning in Christchurch, but were relieved last night to hear that our flight had been delayed from 6:00 AM to 9:00 AM. Nonetheless, many of us woke at a very early hour simply out of anxiety and excitement. As we exited the shuttle to the airport, Dr. Danny Glavin commented to me that he was a little anxious about the flight. I think Danny spoke for all of us, and I felt better knowing I wasn't the only one. The next few hours consisted of "hurry up and wait." We dressed in our ECW (extreme cold weather) gear and waited until afternoon to board the airplane. Apparently, something had to be fixed. The C-130 has few windows, but occasionally we have the opportunity to get glimpses of icebergs through the clouds. We have a ritual where we stand and stretch every hour on the hour. This is a 7-hour flight and would be longer if our C-130 were ski-equipped like the American version. 24 November, 2002 We arrived at McMurdo on a runway carved out of pure ice late Friday night. I was a little anxious about landing on ice, but it was actually one of the softer landings I've experienced. I'm not sure how they stop the plane. If they didn't reverse the engines I believe it would drift for quite a while. This is an amazing place. It is cold here, with daily highs in the upper teens, but not uncomfortable. After a while you realize that nothing is alive out here. There are no plants, and the only animals we've seen are large birds, called skuas, that feast on trash. There aren't even houseplants in any of the buildings. There are no children in McMurdo either. As a teacher, it's hard to adjust to not seeing anyone under 18 years of age. But this is a vibrant community. Three major groups populate McMurdo: scientists, support staff, and military. The scientists are people like the ANSMET team, most of whom are just passing through on their way to another site. McMurdo has complete lab facilities for any scientific group, though. The military is here to handle the transport of goods and services to and from Antarctica. Over 1200 people work here as support staff for the scientists. The majority seem to be in their 20s, but they range in age. They work all sorts of jobs: maintenance, galley, communications, and so forth. Most of these people have worked very hard to get here. There are stories of medical doctors who worked here as truck drivers just to see Antarctica. There's also the story of a woman who was a powerful lawyer, but came here and worked in the cafeteria just so she could see Antarctica. Without this support staff, our expedition would probably not be possible. One of the first things we did in McMurdo was familiarize ourselves with the town. To do this, Dan, Dante, Cady, Diane, and I got certified to drive the vehicles used here. These are not normal vehicles. They use jacked-up 4WD Ford F-350s and 4WD Econoline vans. We took one of the vans for a spin and filled it up with gas. Not even a fill-up is normal in Antarctica. Everything is paid for by the National Science Foundation, so we simply pumped the gas and drove off. I kept checking my mirror to see if we were being pursued for not paying. Helicopters are constantly flying in and out of town, along with the C- 130s that take off and land right on the ice sheet. That will stop by mid-December, when the ice begins to break up. Then they'll have to land on Ross Island. In many ways, McMurdo reminds me of a mining town high in the mountains. It's kind of like Leadville, CO, with the climate and atmosphere of young people. McMurdo has the basic requirements of a town: two places to get carbonated beverages, a "coffee shop", and even a bowling alley (one more than we have in Castle Rock, CO). It also has the southernmost chapel in the world. 25 November, 2002 Almost everyone who comes to Antarctica is given survival training after arriving on "The Ice." For ANSMET team members, we must do a bit more. This includes a complete "shakedown" overnight trip that will take us on snowmobile about 12 miles from here. There is a great deal of preparation that goes into this. John Schutt and Jamie Pierce are our mountaineering guides and safety experts for our expedition. This truly is an expedition, much like the ones held in the early part of the 20th Century. Despite our technology and knowledge, the same dangers are here that existed 100 years ago. Jamie and John made that very clear to all of us yesterday, giving us a lecture on what can happen to us in the field. There are many hazards in the work that we'll be doing, but as long as we're smart and prepared, the risk should be reduced. However, as John and Jamie showed us, a little first hand experience goes a long way. Jamie needed to demonstrate methods for performing CPR and the Heimlich maneuver, and he used me as the model for this. I trust Jamie, because he is confident and experienced. But at one point Dan Glavin came over to get a feel for where to press when doing CPR, and Dean Eppler nearly had a heart attack himself. He was worried Dan would start CPR on me, which can be deadly to a healthy subject. Luckily, Dan knew this too. We spent the afternoon learning some rope techniques that could save us if any of us should fall into a crevasse. We learned how to put ourselves on a rope securely, and how to climb a rope if necessary. Afterwards, we learned about setting up a pulley system to rescue a victim. I pointed out that we teach the mechanical advantages of pulleys in the 9th grade course, Intro to Physical Science. This brought a good laugh--here was a room of scientists and experienced mountaineers trying to figure out something that 9th graders do. 26 November, 2002 We needed to be ready by 7:30 AM to start loading gear into a truck to bring to the ice edge. This isn't glorified car camping. This means bringing tents, sleds, food, climbing equipment and a host of personal items about a half-mile to the sea ice and the Ski-doos. Once at the edge we learned the art of loading a sled so that it doesn't tip easily. These sleds are large and designed to be pulled by a strong little Ski-doo, but it really makes you appreciate the early Antarctic explorers, who towed sleds with dogs or by themselves. About an hour into the traverse, we stopped at "Castle Rock," a large black rock sticking right out of the snow. Being from Castle Rock, CO, I wanted to compare and contrast this with the one back home. While the Castle Rock I know from home is a conglomerate sandstone about 35 million years old, this one is probably only a few thousand of years old and is made of a rock called hyaloclastite. This igneous rock forms quickly when magma comes in contact with ice. Speaking of volcanism, as our Ski-doos rounded the corner outside of Scott Base, the New Zealand base adjacent to McMurdo, I caught a view of Mt. Erebus, the southernmost active volcano in the world. A plume of steam was rising from the top, producing a long thin cloud against a crystal clear blue sky. This day was cool, but comfortable, and with all of us wearing our gear it felt down right warm by afternoon. We set up camp on the flanks of the volcano, on the Erebus glacier tongue that extends from the volcano to McMurdo Sound and the Ross Ice Shelf. From this elevation, you can see for hundreds of miles. The Ross Ice Shelf is the size of Texas and full of trapped icebergs and pressure ridges. But from here it looks as flat as a calm sea. After camp was set up, we went to a crevasse area and went over the basics of roping up and crevasse rescue. Jamie Pierce and John Schutt are really gifted teachers. They set a good pace and gave us practical experience. But mostly they made it fun with their personalities and stories. We learned everything from how to set up an anchor in the snow, to how to set up a pulley system to raise a victim from a crevasse. I think my favorite part of the day was when we roped up and walked through a field of crevasses and serracs, large chunks of falling glacial ice. At one point, Jaime disappeared into the crevasse on purpose, forcing his team to orchestrate a rescue. I couldn't stop laughing because he looked so funny going over the edge. It was getting pretty late, but it was such a nice evening (and the sun never sets during the summer), so we gave the Ski-doos a real shakedown at a place John calls the Wall of Death. You plunge your snow machine down an embankment and right up a steep wall that underlies a cornice. Then you race up the other side, hoping to "catch a little air." 27 November, 2002 The tents do such a good job of holding in heat, I was almost disappointed that it was so warm (32°F) when I woke up this morning. I've camped in colder weather many times. My tentmate, Jaime, made breakfast and tried to radio McMurdo. We were actually so close that our signal bounced off the ionosphere and passed right over the base. So he had to call a team at the South Pole and have them radio McMurdo to let them know we're fine. We continued our crevasse training by lowering Dr. Carlton Allen of the Johnson Space Center into a crevasse. I hope his wife, Jackie, doesn't kill me for allowing this to happen. Then we used our training to "rescue" Carl from the ice. We constructed pulley systems that worked so well that Dr. Scott Messenger and I were able to pull him out with relatively little effort. Scott and I are not exactly burly, so it's a real testament to the power of the simple machine. It's amazing how often we use what we learned in 9th grade Intro to Physical Science in our lives! We headed out early in the afternoon and stopped by the Happy Camper School. This is where most of the people at McMurdo learn how to survive if caught outside. They build a number of snow structures that fill multiple roles. Igloos look cool (literally) but take a lot of time and effort. A good alternative is a snow dome, where you pile and pack snow on your gear, then pull out the gear and dig a tunnel to the dome. An ice cave or trench is a good structure to make in a hurry if one doesn't have lots of gear, but can be the coldest of all. Arriving in McMurdo meant about two more hours of unloading gear and running it inside. We were exhausted, so some members of our team went to bed by 9:00 PM. But a few of us felt we needed to celebrate with a "carbonated beverage." Read the original article at http://www.astrobio.net/news/article379.html. ________________________________________________________________________ ALIEN TV: SORTING INTELLIGENT SIGNALS FROM WITLESS COSMIC NOISE By Seth Shostak From Space.com 20 February 2003 This is Part 2 of a 3-part series on artificiality. SETI researchers are a bold lot. They've chosen to accept a mission that might dissuade Mr. Phelps. Year after year, they spin their telescopes to the sky, sifting through a broiling rumpus of cosmic static in hopes of finding a signal made by other beings. But how will they know? In our previous discussion we talked about the criterion of artificiality: some property of a transmission that would tag it as deliberately constructed--the equivalent of finding stacked cannonballs in a field of stone heaps. It sounds easy, but pulsars, discovered in the late 1960s, showed how quickly we could be duped by a completely natural phenomenon. Since then, SETI researchers have expended considerable neural energy in considering what type of radio emissions would unequivocally qualify as artificial. An obvious suggestion--and one that well-meaning folks the world over love to send me in e-mails--is to search for a signal that is branded with a mathematical label. For example, maybe the aliens will tag their transmission with the value of pi. That would clearly bespeak a middle school education, and would prove that the signal comes from thinking beings, rather than witless neutron stars or some other cosmic oddity. More numerate correspondents try to improve on pi. Perhaps the extraterrestrials will preface their message with a string of prime numbers, or maybe the first fifty terms of the ever-popular Fibonacci series. Well, there's no doubt that such tags would convey intelligence. But what if the prime numbers are only broadcast at the start of a 100-hour interstellar screed, and we tune in somewhere in the middle? We'd miss the label. Read the full article at http://www.space.com/searchforlife/seti_artificiality_part2_030220.html. ________________________________________________________________________ THE GREAT IMPACT DEBATE, PART III: THE LARGE AND THE SMALL Moderated by Don Yeomans From Astrobiology Magazine 24 February 2003 Don Yeomans: During last week's debate, there was some disagreement about whether the threat of near-Earth objects deserves the media attention it seems to generate. But I think we all agree that asteroids and comets have impacted the Earth, and there is strong evidence that the extinction event that took place some 65 million years ago (the one that wiped out the dinosaurs) was caused by an impact. As mentioned in our first debate, while there is no definitive evidence for impacts causing the other major extinction events in Earth's history, it seems possible that comet or asteroid impacts at least played a role. Largely as a result of a Congressional mandate, NASA established a "Spaceguard" program with a goal of finding 90 percent of all the near- Earth asteroids (NEAs) larger than 1 kilometer in diameter by the end of 2008. Experts like Al Harris, one of our panel members, have estimated that the total population of NEAs larger than 1 kilometer is about 1,100. Since then, telescopic search programs have found about 640 NEAs, so more than half of the estimate has been found already. As more and more of these objects are found, the search for the missing ones gets tougher and tougher. So while we are more than half way toward meeting the Spaceguard goal in terms of the number of objects, we are not halfway there in terms of the time it will take to find the goal of 90 percent of them. Nevertheless, it seems likely that we will have discovered 90 percent of the NEAs larger than 1 kilometer by sometime not much beyond the 2008 deadline. But there are a vast number of NEAs smaller than 1 kilometer in diameter. There are likely to be more than 300,000 that are about 100 meters long--larger in diameter than a football field. Because there are many more of them, they would be expected to hit Earth far more frequently than the near-Earth asteroids larger than 1 kilometer--once every few thousand years for the 100 meter asteroids, as opposed to every half million years for the 1 kilometer or greater asteroids. Why then is NASA concentrating their discovery efforts upon the larger NEAs? For that matter, why aren't near-Earth comets included in the Spaceguard goal? Clark Chapman: Despite the fluctuating headlines in often inaccurate media stories, estimates of the relative risks due to comets and asteroids of various sizes has changed little in the last decade. Roughly 80 percent of the impact hazard is due to asteroids between 1 and several kilometers in diameter. About another 10 percent is due to an asteroid smaller than a kilometer striking the ocean and causing a tsunami. Roughly another 10 percent is due to comets, and less than 1 percent is due to small asteroids striking the land. So it is sensible that NASA finally decided, in 1998, to endorse the Spaceguard Survey goal of emphasizing searches for the NEAs greater than 1 kilometer (though the survey also finds smaller NEAs and comets). Alan Harris: In considering the relative importance of large versus small impacts, one must keep in mind both the nature and the frequency of the disaster. A large impact from, let's say, an asteroid larger than a mile (1.6 km) in diameter would be a global catastrophe. It would spoil your day, your whole life even, no matter where you live or where it hit. Such an impact would lead to the equivalent of "nuclear winter," causing agricultural failure worldwide and famine that would undoubtedly lead to a billion or more deaths--a significant fraction of the world's population. Events of this magnitude are expected to occur once or twice in a million years. Consider the other end of the impact range. The smallest impactor that can penetrate the atmosphere deep enough to cause any damage on the ground is not much smaller than the "Tunguska" bolide that flattened a couple thousand square miles of Siberian forest in 1908. The area flattened is about equal to the area of the greater Washington DC area, inside the beltway. That asteroid was estimated to be about 50 to 70 meters in diameter. The nature of the destruction is pretty much the same as a Hiroshima-style nuclear air burst, but without the radiation after-effects. It's still not a pretty picture if it happened in your neighborhood. But before rising up and screaming "that's intolerable," we must take a careful look at just how often such a small impact event might be expected in a populated area. I have analyzed the fatality rate of Tunguska-like small impact events over the entire surface of the Earth, given the present population distribution. If you take the fraction of the Earth devastated by the Tunguska impact (about one-millionth of the world's area) and multiply that by the world's population, you can conclude that an "average" small impact event kills about 10,000 people. But the real historical event in Russia may have killed one person, at most. If it had happened over the sea, it wouldn't have killed anyone. So even if these small impacts happen every century, really catastrophic events caused by such impacts are much more rare. I have estimated that the frequency of Tunguska-type impacts worldwide is only about once in a thousand years. That's on the edge of implausible since one happened only a century ago, but I think anything more often than once a century is inconsistent both with historical records and with observations of NEAs in space. Assuming that such Tunguska events occur once in a millennium, a small impactor that hits an area populated enough to kill 1,000 people is expected only once in about 8,000 years. A small impactor that hits a mid-range population, killing 100,000 people, is expected about every 40,000 years. And a small impactor that directly hits a major population center, killing perhaps a million people, has a chance of occurring only a couple times in a million years. I don't mean to trivialize the human loss of such disasters. In the case of a 1,000-death disaster, similar disasters happen almost annually from floods, earthquakes, and so forth, or at least several times per decade. The middle example--of 100,000 deaths--is comparable to the loss of life in some of the greatest natural disasters of the last century. But such an event caused by a small asteroid is expected to only occur once in 40,000 years--a longer time period than all of recorded history. Clark Chapman: In facing a hazard, whether as an individual or as collective society, we want to allocate our limited resources as effectively as possible. We would wish to address the core problem, and we would want to work first on what is most easily and cheaply accomplished. NASA's investment, which represents most of the world's investment, has been very modest: only a few million dollars a year. But they also leverage technological investments--for example, using Air Force imaging technology that was developed for other purposes. In addition, unpaid volunteer efforts by amateur and overseas astronomers make up part of this investment. It is a no-brainer that over a decade, the investment of perhaps $10,000 per expected life saved is a real bargain, especially with the added possibility of saving all of civilization. Indeed, a much more ambitious program would be easily justified. The cost-effectiveness drops as one tries to deal with smaller asteroids or with comets. Smaller asteroids constitute only about 10 percent of the hazard, yet detecting them requires new, larger, more expensive telescopes. Detection of long-period comets may require very expensive, state-of-the-art telescopes in order to give us sufficient warning time to respond. At some point, it becomes prohibitively expensive to protect ourselves from every last near-Earth object (NEO). I don't know where the crossover point is. Benny Peiser: There seems to be a real paradox with our perception of the impact hazard. While three-quarters of the overall NEO risk is due to large asteroids, the most likely impact to occur in the foreseeable future will be caused by a small asteroid. According to traditional risk analysis, it simply does not make any sense to fund a search for smaller NEOs. The cost of such a search is exceedingly disproportionate to the economic cost caused by small and medium-scale impacts. In other words, as the price tag for the search goes up, the extent of the damage you prevent goes down. If we stringently stick to this line of argumentation, we might just as well stop funding any NEO searches beyond, say, objects smaller than 200 meters. In a nutshell, this seems to be what Al and Clark are suggesting. The logical conclusion of this simplistic cost-benefit analysis is straightforward: the estimated 100,000 NEOs in the 50 to 200 meter class should be ignored altogether, because they pose no greater risk than the other major disasters that we have come to accept. Now the societal and political problem with such an attitude is that we are constantly bombarded by smallish NEOs. In contrast to more familiar natural disasters, impacts are totally random in time, location, and degree, and therefore are much more petrifying than anything else nature is throwing at us. The more our astronomical and space technologies advance, the more we become aware of the considerable number of small impacts that occur each year in the Earth's atmosphere. From time to time, a small object hits the ground with a boom. Nobody knows when or where this is going to happen, but happen it will. Thus there is the realistic risk that NASA--and much more so those space agencies that are inactive regarding NEO searches--will be brought to task for failing to pay attention to small NEOs. Apart from the monetary, social, and military risk small impacts pose to our fragile societies, there also potentially seems to be a political cost for inaction. Clark Chapman: Maybe society should spend the same resources per life saved on mitigating small asteroid impacts that we do on airline safety or safety of nuclear power plants, in which case we need to do much more. Or maybe, when analyzing the facts, our political leaders will choose instead to give small asteroids the same priority they give to protecting agricultural workers and miners from the hazards they face, or the priority given to protecting susceptible people from the flu--in other words, next to nothing. This is a country where more attention was given (in autumn 2001) to half-a-dozen deaths due to anthrax than to the more than 30,000 preventable deaths due to the flu. It is up to the citizens of the world, through their political processes, to decide how to deal with the impact hazard. For every impact-produced tsunami that might kill hundreds of thousands or a million people, there will be hundreds of equally deadly earthquakes, floods, and other natural disasters. That doesn't mean that we should do nothing about asteroid tsunamis, but it puts the problem into perspective. Alan Harris: As Clark says, it's a "no-brainer" to make the case for finding the majority of asteroids greater than 1 kilometer in diameter. It's more questionable whether it makes sense economically to find much smaller ones. But as Clark points out, what societies demand and what policy makers choose are not always rationally justifiable. It is no more than coincidence that the maximum risk is from the largest objects. It could just as well be the other way around. In that case, discovering the larger asteroids would only modestly reduce risk. The biggest risk reduction would have to wait for more capable surveys. But luckily in the case of the impact hazard, the greatest risk happens to reside in the easiest (largest) bodies to discover. In this case we face a very rapidly diminishing return. Joe Veverka: While a survey of objects 1 kilometer in diameter or larger can be carried out in a moderately short time, I think cataloging objects in the 100-meter category is much more important. First of all, these smaller objects have about a hundred times greater chance of causing mischief by interacting with Earth. Also, it is more useful for us to worry about 100-meter objects, since we can imagine potentially effective and affordable defenses against such impactors. However, when it comes to bodies 1 kilometer in diameter--which on average will be one thousand times more massive--the idea of diverting them or blowing them up in the foreseeable future still borders on the fantastic. Alan Harris: It is only logical to start with the easiest measures, and then if resources are available, advance on to the more challenging measures. In this case, find the big objects first and then work down to smaller sizes. Of course, the present surveys don't just search for large bodies. That's just a natural consequence of optical surveys that the larger objects are easier to find. It's like fishing: you catch what you catch. And we certainly are not "throwing the little ones back." We catalog everything we can find. Benny Peiser: The Spaceguard search program should and most likely will evolve gradually. Pragmatically speaking, the goal for the next 15 years should be to extend the terrestrial searches to smaller objects. This is more or less in line with the far-sighted proposals made by the UK Task Force on near-Earth objects. More importantly, we should make every effort to exploit the decreasing cost of satellites launches in order to establish the first tier of an effective space-based NEO detection system. This would guarantee that we could gradually address the potential threat of cometary impacts, as well. Read the original article at http://www.astrobio.net/news/article382.html. ________________________________________________________________________ ASTEROIDS AND SECRECY: IF END IS NIGH, DO YOU WANT TO KNOW? By Robert Roy Britt From Space.com 24 February 2003 Suppose a giant asteroid is heading toward Earth right now. Impact is certain. The consequences are expected to be globally devastating, with the human race among the casualties. The chances of doing anything about it are zero, the government decides. Would you want to know? Or would you prefer the Feds keep the information secret and spare you and your neighbors a bunch of pointless worrying? In essence, the question concerns whether you'd prefer to die in ignorant bliss, or if you'd like some options. The alternatives might include dying in a panic, calmly making peace with your Maker, finally taking the kids to Disneyland or--who knows?--making a last-ditch effort to fight odds your elected leaders say are wholly against you. Read the full article at http://www.space.com/scienceastronomy/asteroid_secrecy_030224.html. ________________________________________________________________________ COLUMBIA LOST, BUT NOT A NATION By Alan Stern From SpaceDaily 24 February 2003 The sad and sudden demise of the space shuttle Columbia and her crew on the frontier of space on February 1st provided a sharp reminder of the risks of spaceflight. The deep, heartfelt U.S. reaction to this accident that has been expressed in so many ways in the days since Columbia was lost illustrates the intimate connection that Americans have with frontiers in general, and space exploration in particular. Space exploration is indeed a characteristically American endeavor, going far beyond the sporadic prominence it often receives in mainstream media. That popularity is evidenced by the blockbuster popularity of numerous motion pictures-from Star Wars to Apollo 13, to recent polls expressing widespread desires for public space travel, and the virtually ubiquitous interest of our children in space exploration. When American's are asked how they picture the future, the reply very often includes a vision of routine spaceflight and distant exploration. This does not surprise. The United States is a nation bred from generations of explorers from every walk in life, who emigrated to and settled a raw continent, and then built a society brimming with success and innovation on the fruits of those explorations. Read the full story at http://www.spacedaily.com/news/oped-03r.html. ________________________________________________________________________ NEW ADDITIONS TO THE ASTROBIOLOGY INDEX By David J. Thomas http://www.lyon.edu/webdata/users/dthomas/astrobiology/astrobiology.html 24 February 2003 Astrobiology, exobiology and terraformation articles http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_articles1. html Associated Press, 2003. Study: Mars snow boosts life prospects. CNN. L. David, 2003. Trickle down theory of melting snow may support life on Mars. Space.com. NASA, 2003. Melting snow could be cause of gullies on Mars. Spaceflight Now. NASA, 2003. Snow gullies on Mars. NASA Science News. J. N. Wilford, 2003. Photos bolster idea of water, and possibly life, on Mars. New York Times (20 Feb 2003). Terrestrial extreme environments articles http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_articles2. html A. Caldwell, 2003. Ice diary 1: shooting stars on ice. Astrobiology Magazine. L. David, 2003. Undersea exploration provides trial-run for space hardware. Space.com. Search for extraterrestrial intelligence (SETI) articles http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_articles4. html S. Shostak, 2003. Alien TV: sorting intelligent signals from witless cosmic noise. Space.com. Planetary protection articles http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_articles6. html R. R. Britt, 2003. Asteroids and secrecy: if end is nigh, do you want to know? Space.com. D. Yeomans, 2003. The great impact debate, part III: the large and the small. Astrobiology Magazine. ________________________________________________________________________ CONTINUING COVERAGE OF THE COLUMBIA DISASTER By David J. Thomas 24 February 2003 The investigation of the Columbia tragedy continues to make headlines in both space and general media. I have included (below) a non-exhaustive list of links to recent articles on the subject. http://www.cnn.com/2003/TECH/space/02/20/sprj.colu.investigation.ap/inde x.html http://www.nytimes.com/2003/02/20/national/nationalspecial/20INQU.html?t h http://www.space.com/missionlaunches/sts107_updatepm_030218.html http://www.space.com/missionlaunches/sts107_meteor_030218.html http://www.space.com/missionlaunches/sts107_debris_request_030219.html http://www.space.com/missionlaunches/sts107_landgear_030219.html http://www.space.com/missionlaunches/sts107_theories_030219.html http://www.space.com/missionlaunches/sts107_iss_030220.html http://www.space.com/missionlaunches/sts107_debris_030221.html http://www.space.com/businesstechnology/technology/shuttle_laser_030221. html http://www.space.com/missionlaunches/sts107_nevada_030223.html http://www.space.com/missionlaunches/sts107_history_030224.html http://www.space.com/missionlaunches/sts107_emailok_030224.html http://www.spacedaily.com/2003/030223232648.ra18gqcz.html http://www.spacedaily.com/news/oped-03r.html http://spaceflightnow.com/news/n0302/18osp/ http://spaceflightnow.com/shuttle/sts107/030218caib/ http://spaceflightnow.com/shuttle/sts107/030219science/ http://spaceflightnow.com/shuttle/sts107/030220exp6/ http://spaceflightnow.com/shuttle/sts107/030221emails/ http://spaceflightnow.com/shuttle/sts107/timeline/ http://spaceflightnow.com/shuttle/sts107/030221tpsrepair/ http://spaceflightnow.com/shuttle/sts107/030221telemetry/ ________________________________________________________________________ CASSINI SIGNIFICANT EVENTS NASA/JPL release 13-19 February 2003 The most recent spacecraft telemetry was acquired from the Madrid tracking station on Wednesday, February 19. 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 completion of the Command & Data Subsystem (CDS) flight software Assisted Load Format (ALF) procedure to uplink ALFs to the Solid State Recorder (SSR). Once in place the backup Attitude Control Subsystem (ACS) Flight Computer (AFC) was loaded with new version A8 flight software, and the AFC was swapped to place A8 onto the prime AFC. Then the new backup AFC was loaded with A7 flight software off of the SSR. Additional activities included an update of Trickle Telemetry on the backup AFC, an A8 Flight Software parameter Memory Readout, checkout of the new ACS Telemetry Schedules, an ACS Reaction Control Subsystem checkout, and clearing of the high water marks on both the prime and backup AFCs. The port 2 merge for C37 has been completed. All SEQGEN products have been posted to the Distributed Object Manager, and an updated time ordered listing, data volume report, and DSN allocation files are on the C37 web site. All but 3 data files from a collection of ~500 acquired during GWE #2 have been locally archived. Inquires are underway to determine if the missing files are recoverable. The greatly increased speed and efficiency in completion of this task as compared to data acquisition and archiving for GWE1 and the Solar Conjunction Experiment is due to improved data query software installed on the RSS Operations machines prior to GWE2. The Radio Science Systems Group has launched a redesigned web site at http://www.radioscience.jpl.nasa.gov/. The site includes recent news stories relating to radio-science, as well as technical documentation, staff information, mission contributions, and science goals of radio- science. The Radio Science Subsystem (RSS) team made an initial delivery of archived Gravitational Wave Experiment (GWE) #1 data to the Planetary Data System (PDS) node for radio science (RS) data. The PDS advisor for RS data has made suggestions on how to enhance the quality of the archived data. This delivery by RSS not only fulfills a commitment to deliver the data within one year of the end of the experiment, but it also provides a pathfinder experience for the Cassini project on the process for preparing and delivering archived data. A Visual and Infrared Mapping Spectrometer science team meeting was held this week in Tucson, Arizona. The Spacecraft Operations Office (SCO) has upgraded the Cassini Operational Reference Encyclopedia (CORE) software to Version 3.1. V3.1 contains the revised command definitions for the new Attitude Control and Command and Data Subsystem flight software. Installation on the Cassini Web server by Mission Support and Services Office personnel is now complete. SCO delivered version 8.2 of the Kinematic Predictor/Inertial Vector Propagator tool set. This version contains enhanced flight rule checking and the new algorithms which will support the "Star Identification Suspend" activity to be used during orbital operations. Science Opportunity Analyzer (SOA) version 3.0 has been delivered to Cassini. This version of SOA will be released in March with the MSS D8 adaptation for PC and Linux, and then again in MSS D9.1 with the latest adaptation for Solaris 7, PC and Linux. Composite InfraRed Spectrometer flight software version 2.0 was reviewed at a Software Requirements Certification Review meeting, and approved for testing in SCO before uplink to the spacecraft on May 19. Uplink Operations personnel provided a Cassini Information Management System (CIMS) introductory user training class to members of the Science Planning team, Mission Support and Services Office (MSSO), and SCO. This class is part of ongoing training provided to new Cassini flight team members. A special demonstration was given of the new prime/rider notification features in CIMS. Principal Investigators, Co-Investigators, Team Leads, Team members, Interdisciplinary Scientists, and others who participate in the Target Working Team and Orbiter Science Team integration effort benefited from learning how to use this science-team- requested capability. MSSO personnel hosted an Infrastructure Status Review. Some of the topics addressed included current infrastructure and support, planned implementation of project budget guidelines, changes in network infrastructure, upgrades to sustain existing workstations, and upcoming changes to maintenance and support. Outreach reported that the Cassini web development team has launched an "Image of the Week" campaign. Each week a new image will highlight a different aspect of Cassini's journey to Saturn. Images will rotate between categories as diverse as mission highlights, historical photos, mission and spacecraft technology, and outreach activities. Check out the latest image on the main web site (http://saturn.jpl.nasa.gov/). 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 ODYSSEY THEMIS IMAGES NASA/JPL/ASU release 18-21 February 2003 Crater Wall and Floor (Released 18 February 2003) http://themis.la.asu.edu/zoom-20030218a.html Granicus Vallis (Released 19 February 2003) http://themis.la.asu.edu/zoom-20030219a.html Freedom Crater (Released 20 February 2003) http://themis.la.asu.edu/zoom-20030220a.html Mamers Vallis (Released 21 February 2003) http://themis.la.asu.edu/zoom-20030221a.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 21 February 2003 This past week, the Stardust flight team used the antennas of JPL's Deep Space Network on one occasion. Data relayed from the spacecraft during that contact indicated Stardust is healthy and all subsystems continue to run normally. The Stardust team is planning to send those images of the Pleiades star cluster that are stored in the spacecraft's memory. These Pleiades images were taken by Stardust's navigation camera and will be used to evaluate performance of the spacecraft camera's periscope. This data transfer will occur in early March. The team is also completing preparations for a series of evaluations of the command sequence to be used during Stardust's encounter with Comet Wild 2. These evaluations, or "tabletops", will be used to analyze and streamline the sequence of commands the Stardust spacecraft will execute during encounter. 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. 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 8.