MARSBUGS: The Electronic Astrobiology Newsletter Volume 10, Number 16, 21 April 2003. Editor/Publisher: David J. Thomas, Ph.D., Science Division, Lyon College, Batesville, AR 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://welcome.to/marsbugs or http://www.lyon.edu/webdata/users/dthomas/marsbugs/. ________________________________________________________________________ CONTENTS 1) MESSAGES IN A BOTTLE From Astrobiology Magazine 2) RESEARCH OPPORTUNITIES IN SPACE LIFE SCIENCES FOR GROUND-BASED RESEARCH IN FUNDAMENTAL SPACE BIOLOGY NASA Research Announcement (NRA) 03-OBPR-03 3) ARECIBO DIARIES (1): LOCATION IS EVERYTHING By Seth Shostak 4) THE STARS OF PROJECT PHOENIX: THE BEST ARE NOT ALWAYS THE BRIGHTEST By Peter Backus 5) NASA ASTROPHYCIST TO DISCUSS STARDUST COMET SAMPLE-RETURN MISSION NASA/ARC release 03-028AR 6) PASSENGER-CARRYING SPACESHIP MAKES DESERT DEBUT By Leonard David 7) ARECIBO DIARIES (2): NARROWING THE SEARCH By Seth Shostak 8) HABSTARS: SPEEDING UP IN THE ZONE From Astrobiology Magazine 9) NEW ADDITIONS TO THE ASTROBIOLOGY INDEX By David J. Thomas 10) CONTINUING COVERAGE OF THE COLUMBIA DISASTER By David J. Thomas 11) CASSINI SIGNIFICANT EVENTS NASA/JPL release 12) MARS EXPLORATION ROVERS: SPACECRAFT AND EXPENDABLE VEHICLES STATUS REPORT By George H. Diller 13) MARS GLOBAL SURVEYOR IMAGES NASA/JPL/MSSS release 14) MARS ODYSSEY THEMIS IMAGES NASA/JPL/ASU release 15) STARDUST STATUS REPORT NASA/JPL release ________________________________________________________________________ MESSAGES IN A BOTTLE From Astrobiology Magazine 15 April 2003 The editors of the Astrobiology Magazine, and its companion Mars Edition, receive a large volume of questions on the new science fields seeking out answers to life elsewhere in the universe. The magazine periodically enhances this dialog by sharing the best of these questions. This feedback not only gauges the depth of interest and knowledge among those who track this field, but also helps define new vistas for investigation. Many of these areas, by their nature, are imprecisely understood. As with most science, such questions spawn new sets of inquiries. The first installment was entitled "The Envelope of Life, Please", to underscore the magnitude of interest in extreme environments and the limits to places where no living organism has gone before (and survived). That fascination with extreme life has continued, and is reflected in many of the questions recently submitted. The magazine received a total of 41,709 questions, and about one in eight (5,731) were not duplicates and ranked most popular. Of these nearly six thousand entrants, the top seventy-five or so are shown below with their reference links [available in the original article] for further exploration. The editors have judged the following question as the most compelling to date, both for its fundamental insight, but also because it is a fertile field of current investigation among astrobiologists. Do lifeforms exist without water? Not so far, at least beyond some exotic sporulating, hibernating or desiccated state. This singular question guides a great deal of how scientists look for habitable zones on other planets: can liquid water exist? Frequently asked questions What is the most extreme temperature in which life is found? 235°F, a hyperthermophilic microbe called Pyrolobus fumarii. What is the most extreme pressure in which life is found? 1200 times atmospheric pressures. In laboratory experiments, around 16,000 sea- level pressures, survival is possible, but it is unknown what kinds of growth and metabolism may be possible under such extreme conditions. What is the biomass below the surface of the Earth? The mass of microorganisms beneath our feet, reaching down miles underground, likely equals or exceeds the mass of all the organisms on Earth's surface. What is the definition of a living organism? It must feed, grow and reproduce. Around 102 specific questions can be asked of a given phenomenon if a classification scheme is imposed. Did ancient oceans exist on Mars? Don't know yet. Snow, frost and gully remnants are fascinating clues to what may also be enough subsurface water to cover the planet knee-deep if equally distributed latitudinally. There is a scientific consensus building around the notion of at least transient gushes to the surface. What were the earliest life forms on Earth? Many think trilobites were the first multi-celled organisms, and cyanobacteria as the first photosynthesizing. Is there life on Europa? Under miles of a frozen ocean, a salty sea may harbor exotic or primitive candidates [but we don't know yet]. What is a galactic habitable zone? A star with planets capable of hosting liquid water. Other constraints may limit the distance the star is away from the high radiation environment of a galactic center versus periphery. Does Saturn's moon, Titan, have an atmosphere? Yes. The Cassini spacecraft will drop a probe down into what some scientists believe is a biochemically rich atmosphere. What is the Fermi paradox? If there is intelligent life out there, why haven't we found it yet? How did our Moon form? New evidence points to "a chip off the terrestrial block", although there are other planets which have captured moons around stray asteroids. How are meteorite searches conducted to find martian fragments? Often times on hands and knees in Antarctica, or even in desert marketplaces where meteorites are sold. What kinds of next generation, planetary rovers are currently being explored? Lots of remote control, autonomous behaviors. Did life originate once or many times on Earth? [At present] all life can be mapped to one tree or web of life. Are strong oxidants thought to exist on the surface of Europa? Evidence from the Voyager and especially Galileo spacecraft missions points towards an ocean whose volume is nearly twice that of all the Earth's oceans combined. [Unfortunately, this doesn't answer the question.] How is mitochondrial DNA used to construct family trees through maternal genes? The energy center for complex cells called the mitochondria carries forward tracer DNA that allows backtracking, and has recently been found in fossils of interest. Could life be transferred from Mars to Earth or vice versa? Perhaps endospores, or fossils. Radiation may be a bigger constraint that temperatures. How many plant and animal species have gone extinct? The majority [of species that ever existed are extinct]. What is the Doppler detection method for finding new planets? A change in color of a star's light to measures changes in the star's velocity caused by the gravitational pull of an orbiting planet. How do scientists apply Occam's Razor to resolve questions with little actual data available? A principle of good science, given multiple possible choices, choose the simplest one with the fewest assumptions-- to paraphrase. What organic compounds have been found in meteorites? The Murchison meteorite showed evidence for protein building blocks, and some amino acids thought not to occur terrestrially. What space probes are planned to explore Europa? The Europa Orbiter is tentatively planned for 2010. So far much compelling data has been collected by the Galileo spacecraft's fly-by mission. What is considered the one animal that can survive the harshest extreme environment? Tardigrade or water bear. What is the saltiest environment that living cells are found to grow? Halophiles, or salt-loving, microbes have been found in water with 25% salt content. What was the Miller-Urey experiment? In the classic 1953 experiment, complex molecules such as amino acids and sugars were produced by electrical discharges in a primeval atmosphere replete with gases such as methane, hydrogen, ammonia and water. What are the three domains of life? Archaea (including life in extreme environments), prokaryotes (lacking a cell nucleus) and eukaryotes (having a cell nucleus) like plants, animals and humans. Some consider viruses a fourth domain. Are their organisms that don't use DNA for code storage? RNA viruses like common cold. What are the most promising martian landing sites? Dry lakebeds or where the water-forming minerals like hematite are expected. More than a hundred sites have been considered relatively promising but differ in mission risks and rewards. What killed the dinosaurs? Climate change and perhaps an asteroid strike where the present day Gulf of Mexico is. This K/T impact occurred 65 million years ago. What science is available to predict what aliens might look like? None, generally, but if advanced intelligence, there are clues to how long such a civilization might need based on what we know about Earth. What was special about the Tagish meteorite? It landed on a frozen lake in Canada, and is considered well-preserved. What was special about the Allan Hills meteorite? It's a martian meteor which showed curious rod-like deposits and magnetic properties. What was special about the Murchison meteorite? It showed evidence of amino acids. What was on the golden record sent out on the Voyager spacecraft? A combined message-in-a-bottle featuring music, images, and greetings. What is the "typical" weather like on Mars? Atmospheric pressure at 0.6 percent that of the Earth's surface, an average temperature of -60 degrees C (-140°F) and a thin atmosphere of 95 percent carbon dioxide. The lack of a protective atmosphere may make radiation hazards considerable. What is the expected lifetime of our Sun? Around another 7 billion years before it enters its Red Giant phase of rapid expansion. What are the scientific chances of a large meteor or comet striking Earth? Around 1000 near earth objects a kilometer or larger in size, with an impact capable of killing 100,000 people occurring about once every 40,000 years. Have any comets or asteroids ever hit planets besides Earth? In 1994, the Hubble Telescope photographed the dramatic impact of Comet Levy/Shoemaker as it exploded into Jupiter's atmosphere. What are the prospects for life on Jupiter's moon, Io? Europa is a better bet because of its salty ocean, and Io is volcanic. What is meant by the panspermia hypothesis? Sowing the seeds of life with organic molecules or simple life transported on meteors or comets. Are electrical storms on Mars a risk for spacecraft and rover electronics? Mission planners are testing against this hazard. What is the driest place on Earth? At high altitude between northern Chile and Bolivia (Atacama), and Antarctica. Could bacteria survive on present-day Venus? The surface is too hot, but cloud colony theories have been proposed. Who is Matthew Golombek? Mars Pathfinder (1997) Project Scientist, Jet Propulsion Laboratory. What are nanobes? What is the smallest organism on the planet? Nanobacteria, or life at the limits of being able to encapsulate its own DNA. What are the two typical structures for viruses? Rods or icosahedral. What will animals will like in a million years? Impossible to speculate, but some scientists imagine on time scales as short as a thousand years, humans will be frequently space-faring which introduces rapid adaptations in a hostile environment. Is there water on Venus? The surface is hot enough to melt lead, but atmospheric layers may be temperate in a stratified way. [Another case of a question unanswered.] What is Dollo's law in evolution? An organ never returns to an antecedent structure. What is meant by the Snowball Earth theory? A geological phase where the oceans freeze. Was there life on earth before the formation of our own Moon? Unlikely, since the Earth was hot and molten, and above the boiling point of liquid water. What are the individual probabilities for intelligent life based on the Drake equation? A series of probabilities based on the number of stars, but with the least well-known factor may well be the lifetime of a technological civilization. What is the age of the universe? 13.7 billion years, according to levels of background microwave radiation. What happened to cause the Cambrian explosion of different life forms on Earth? Don't know exactly, but genetic cross-over of material played a larger role compared to just mutations in evolving species more rapidly. What do planet discoverers mean when they refer to "hot Jupiters"? Gas giants very close to their parent stars, and unlikely to harbor habitable conditions. Could life form today from "scratch" given current the current Earth's atmosphere, composition and temperature? Life scientists are trying some ambitious lab experiments [but current theory indicates that life could not re-start under current planetary conditions]. What weather modifications are needed to terraform Mars? Greenhouse creation, most likely with chlorofluorocarbons, or CFCs. It might take at least 40 years depending on the inputs, and how well-controlled a runaway hot Mars might behave. The greening of a rusted, red planet is being actively studied, although the requirements for bacteria are quite different from more complex life. How many extrasolar planets have been found so far? Around 105. Why is the mineral, hematite, considered important to finding evidence for ancient water on Mars? Red hematite is found in certain regions and on Earth is formed in combination with water deposits. What are psychrophiles? Cold-adapted bacteria that often live in permafrost at -20°C. How are tidal forces considered an alternative heat source when solar heat is insufficient? Akin to frictional heating, strong tides provide a heat source particularly for Jupiter's moons, such as Europa. Honorable mentions. A new honorable mention category is appended for specialty categories, such as the most humorous and the most surprising. Can humans live after being frozen? Is a camel just a horse designed by a committee? Intra-species human communication The most unexpected lines of questions hold future promise for humans communicating with our own species, as a large number of readers seek out new space-related ringtones for their cellphones. These requests have come from around the world, including Serbia, Turkey, Marathi (India), Armenia, Japan, Telugu (southern India), Punjabi, Persia, Cantonese, Vietnam, Nepal, Kannada (India), Korea, Poland, Arabic, and Uganda. Fortunately all these are available from adaptations of the Voyager spacecraft's golden record that was sent as a partial history of diverse languages and greeting to a future receiver of that message-in- a-bottle. Read the original article at http://www.astrobio.net/news/article429.html. ________________________________________________________________________ RESEARCH OPPORTUNITIES IN SPACE LIFE SCIENCES FOR GROUND-BASED RESEARCH IN FUNDAMENTAL SPACE BIOLOGY NASA Research Announcement (NRA) 03-OBPR-03 15 April 2003 This National Aeronautics and Space Administration (NASA) Research Announcement (NRA) solicits proposals in the following research areas: Molecular Structures and Physical Interactions, Cellular and Molecular Biology, Organismal and Comparative Biology, Developmental Biology, and Gravitational Ecology. Proposals are solicited for ground-based research. Beginning April 15, 2003, this NRA and other relevant information will be available electronically via the Internet at http://research.hq.nasa.gov/code_u/nra/current/NRA-03-OBPR- 03/index.html. Notices of Intent due: May 15, 2003 Proposals due: July 15, 2003 If you have any questions pertaining to NRA-03-OBPR-03, please contact Dr. David Liskowsky at 202-358-0220 or dliskows@hq.nasa.gov. All categories of institutions are eligible to submit proposals in response to this NRA, but only approved research proposals from U.S. institutions will be selected for funding. This research supports NASA's mission and the Office of Biological and Physical Research (OBPR). Paper copies of the Announcement are available starting April 15, 2003 to those who do not have access to the Internet by calling 202-479-9030 x277 and leaving a voice mail message. Please leave your full name, address with zip code, telephone number with area code, and the NRA number (NRA-03-OBPR-03). ________________________________________________________________________ ARECIBO DIARIES (1): LOCATION IS EVERYTHING By Seth Shostak From Space.com 15 April 2003 At first glance, Puerto Rico seems a strange place to eye the sky. A tilted block of land guarding the eastern end of the Greater Antilles, this island boasts no soaring mountains on which an optical telescope could perch, nor an unpopulated outback that would suit the signal- sensitive ears of a radio array. What Puerto Rico does have is geology and location. Stretching across the island's northern edge from the suburbs of San Juan to the western town of Aguadilla is a bumpy, limestone terrain known as karst. Pockmarked from thousands of millennia of rain, the karst is a jumble of haystack hills and broad sinkholes. One of the latter, about 8 miles south of the coastal city of Arecibo, is a perfect natural dimple to house the world's biggest single-dish antenna: the Arecibo radio telescope. Read the full article at http://www.space.com/searchforlife/shostak_arecibo_1_030415.html. ________________________________________________________________________ THE STARS OF PROJECT PHOENIX: THE BEST ARE NOT ALWAYS THE BRIGHTEST By Peter Backus From Space.com 17 April 2003 April nights at Arecibo find Orion the Hunter high overhead. Red Betelgeuse (the eastern shoulder) and blue-white Rigel (the western knee), plus the three stars of Orion's belt form an easily recognized and spectacular constellation from any latitude. Here, away from bright city lights, Orion and the Milky Way's hazy band of star clouds stand out against a black velvet sky. So many stars! So little telescope time! Unlike other SETI programs, Project Phoenix targets individual stars rather than scanning the sky, which is mostly "blank," from our point of view. In a vast sky full of stars, only a fraction are likely to have life-supporting planets and be near enough for us to detect radio waves transmitted at a reasonable power. Therefore, the SETI Institute conducts a "targeted" search of selected stars. This strategy has many advantages over scanning the sky. By choosing particular, relatively close stars and observing each star for a long time, we are sensitive to lower power transmitters over a wider range of frequency channels for more types of signals. Read the full article at http://www.space.com/searchforlife/seti_stars_030417.html. ________________________________________________________________________ NASA ASTROPHYCIST TO DISCUSS STARDUST COMET SAMPLE-RETURN MISSION NASA/ARC release 03-028AR 17 April 2003 Humanity' first opportunity to study the original material from which our solar system was built will be the subject of a free public lecture at Foothill College on Wednesday, April 23 at 7:00 PM PDT. The talk is entitled "The Stardust Mission: Bringing Home a Comet." Stardust mission co-investigator Dr. Scott Sandford of NASA Ames Research Center, located in California's Silicon Valley, will describe the sample-return mission to a comet. Launched in 1999, the mission will rendezvous with a comet in 2004 and return samples of cometary dust to Earth in 2006. The Stardust mission is the first return of a sample from outside the Earth's moon system. "NASA Ames is pleased to co-sponsor the popular Silicon Valley Astronomy Lecture Series, which exemplifies excellence in science outreach," said NASA Ames Research Center Director G. Scott Hubbard. "This is one important element of our efforts to inspire the next generation of space explorers." Sandford is a renowned expert in the field of meteoritics, the study of rocks that fall from space. He has helped discover a number of such rocks in Antarctica. Among his other scientific interests is the study of molecules in clouds of interstellar dust from which new stars and planets form. This is the fourth year of the Silicon Valley Astronomy Lecture Series, which is co-sponsored by NASA Ames, Foothill College's Division of Physical Science, Mathematics and Engineering, the Astronomical Society of the Pacific and the SETI Institute. The lecture series is held at Foothill College's Smithwick Theater in Los Altos Hills. From Interstate 280, exit at El Monte Road and travel west to the campus. Visitors must purchase a one-day campus-parking permit for $2. Seating is on a first-come, first-served basis. Young people over the age of 13 are welcome. More information is available by calling the series hotline at 650-949-7888. For more information about the Stardust mission, visit http://stardust.jpl.nasa.gov/. Contact: Kathleen Burton NASA Ames Research Center, Moffett Field, CA Phone: 650-604-1731 or 650-604-9000 E-mail: kburton@mail.arc.nasa.gov Read the original release at http://amesnews.arc.nasa.gov/releases/2003/03_28AR.html. ________________________________________________________________________ PASSENGER-CARRYING SPACESHIP MAKES DESERT DEBUT By Leonard David From Space.com 18 April 2003 What has been billed as the "First Private Manned Space Program" and a new, never-seen spaceship, was unveiled today by noted design wizard Burt Rutan and his company, Scaled Composites, Inc. Aggressive work on a passenger-carrying sub-orbital craft has been active and hidden from public view for two years. Labeled as the SpaceShipOne Project, the unveiling took place here about 80 miles north of Los Angeles before a large crowd of journalists and invited guests. The company plans to use the craft to compete for the X Prize, a $10 million cash prize that will be awarded to the first team that successfully launches three people to an altitude of 62.5 miles (100 kilometers) returns the safely to Earth and then repeat that feat with the same vehicle within two weeks. Read the full article at http://www.space.com/businesstechnology/technology/rutan_scaled_0304187. html. ________________________________________________________________________ ARECIBO DIARIES (2): NARROWING THE SEARCH By Seth Shostak From Space.com 18 April 2003 ...By 1611, Galileo had built a yard-long, tubular instrument fronted by a small, bubbly, one-inch lens. It boasted an unimpressive 20x magnification. Peering through this toy-like device, he was able to see the four large moons of Jupiter. This discovery changed our paradigm for the solar system, and earned Galileo endless column inches in astronomy textbooks. For Galileo, setting up for observing was pretty straightforward: (1) Take telescope outdoors, (2) position eyeball near the small end, and (3) make groundbreaking finds. ...For SETI, it's different. We're hunting for narrow-band signals--the very same type as the man-made interference that fills the airwaves. This RFI (Radio Frequency Interference) can clearly frustrate our search. To avoid this problem, we take a cue from Charles Messier, the 18th century French astronomer who tried to help comet seekers by cataloging all the potentially confusing fuzzy objects in the sky. On our first day out, the Project Phoenix team points the telescope overhead, and locks it down. We then do "RFI scans" by slowly stepping up the microwave dial and noting all the narrow-band signals, and even some (such as GPS broadcasts) that are a bit less narrow. These are cataloged into an on-line database that can be used during the search to identify (and quickly toss out) persistent terrestrial signals. Read the full article at http://www.space.com/searchforlife/shostak_arecibo_2_030418.html. ________________________________________________________________________ WORKSHOP ON COMETARY DUST IN ASTROPHYSICS LPI/University of Washington release http://www.lpi.usra.edu/meetings/stardust2003/ 20 April 2003 Workshop on Cometary Dust in Astrophysics Crystal Mountain, Washington Hosted by University of Washington August 10-15, 2003 First Announcement Sponsored by: University of Washington Lunar and Planetary Institute NASA Johnson Space Center Meeting Organizers: Don E. Brownlee Lindsay P. Keller Scott R. Messenger Scientific Organizing Committee: Don E. Brownlee, University of Washington John P. Bradley, Lawrence Livermore Laboratory Lindsay P. Keller, NASA Johnson Space Center Martha S. Hanner, Jet Propulsion Laboratory Scott R. Messenger, NASA Johnson Space Center Scott Sandford, NASA Ames Research Center Rens Waters, University of Amsterdam When and where? Cosmic Dust in Astrophysics I will be held August 10-15, 2003, at the Crystal Mountain Lodge near Mount Rainier in Washington State. Attendance will be limited to 80-100 participants and limited funds are available to support graduate student travel to the workshop. Crystal Mountain Lodge is located approximately two hours southeast of Seattle. The locality is a ski resort on the slope of Mount Rainier and its isolation and facilities provide an excellent Gordon Conference-like environment where attendees have maximum opportunities for interactions at meals, breaks, hikes, etc. Scope and purpose The collection and return of dust from Comet Wild 2 by the Stardust spacecraft promises to connect a range of scientific disciplines related to the origin and evolution of stars, the solar system, and interstellar matter. The comet studies also have strong ties with astrobiology because of the roles that comets, asteroids, and dust might play in transporting "biogenic elements" and compounds to Earth-like planets residing in stellar habitable zones. Cometary Dust in Astrophysics I will bring together researchers from the fields of observational astronomy, sample science, and laboratory astrophysics in an informal workshop approximately four months prior to the Wild 2 flyby by Stardust. The purpose of the meeting will be the integration of astrophysical observations of comets and interstellar/circumstellar dust with laboratory analyses of interplanetary dust particles, stardust, and meteorites, and to discuss what we hope to learn from comet samples to be returned by Stardust in 2006. This is a timely meeting, following the recent rendezvous with Comet Borrelly by Deep Space 1 and preceding the imminent arrival of Stardust at Comet Wild 2 and return of Genesis samples. Several new missions will launch in the next few years (e.g., Rosetta, MUSES-C). In addition, significant new observational data is provided by the Infrared Space Observatory (ISO), HST NICMOS, along with new data to be added with the SIRTF, SOFIA, ABE, and new groundbased IR capabilities. All these advances are occurring at a time when laboratory analyses of extraterrestrial materials have achieved an unprecedented level of sophistication such that the physical and chemical properties of materials can be determined at nearly the atomic scale. This is a remarkable time for synergy between the fields involved. ________________________________________________________________________ HABSTARS: SPEEDING UP IN THE ZONE From Astrobiology Magazine 21 April 2003 Jill Tarter and Margaret Turnbull have a wish list. To maximize the search for extraterrestrial technological signals, the SETI researchers know where the next generation radio telescopes should start pointing. Their HabCat, or Catalog of Nearby Habitable Systems, was created from what is known about habitable stars, or "habstars", near our sun. Seventy-five percent are within 140 parsecs, or around 450 light years. These Sun-like, habitable stars have just the right distance, constancy, and light to qualify in a forthcoming enlarged radio search. A former list of 2000 targets guided the search for Project Phoenix, a privately funded All-Sky-Survey that continued NASA's High Resolution Microwave Survey (HRMS). In 1993, that mission commenced to search for continuous and pulsed radio signals from extrasolar civilizations. Each year, the Phoenix Project buys three weeks of telescope time to observe 200 stars using the world's largest capable dish, the Arecibo Observatory in Puerto Rico. All [of] that is about to change in the next two years. Tarter and Turnbull are preparing for much bigger and faster searches. In 2005, a joint effort by the SETI Institute and the University of California-Berkeley expects to increase the speed of this search by 100 times or more (~20,000 stars per year). But even without their help, this faster search would begin to exhaust nearby habstars. The new shortlist of habstars has grown nearly 9-fold. Their article, "Target Selection for SETI: I. A Catalog of Nearby Habitable Stellar Systems," published in the Astrophysical Journal, identifies 17,129 potentially habitable hosts for complex life. The co- authors plan a follow-up article that will prioritize which habstars to target first. The creation of the Catalog of Habitable Stellar Systems was motivated by the ongoing and rapid development of a network of 350 radio antenna dishes. Called the Allen Telescope Array (or ATA), the network ties together 6.1 meter (~20 foot) diameter dishes for a total surface area as large as eight football fields. In 2005, the telescope will be completed using commercial satellite dishes and be located 290 miles northeast of San Francisco. Tarter and Turnbull winnowed down about 120,000 Hipparcos stars to those that could be habitable to life as we know it for observation during the first few years of ATA operation. In evaluating Sun-like targets as suitable hosts for communicating life forms, one recurring theme is defining habitability. At the very least, candidate stars need terrestrial planets. For life to develop on Earth, liquid water and certain heavy atomic elements like phosphorus were also needed. Stars with very low metal content probably formed from a cloud that did not have enough heavy metals to make planets or life forms. These needs refined the HabCat list to only those stars exceeding a lower limit on stellar metallicity, about 40 percent that of the sun. Planets and water might be enough for simple life, but stars also must remain nearly constant in brightness over billions of years for complex life to have time to develop. On Earth, single cells may have developed after only 800 million years or so, but the fossil record indicates that it took another 3 to 4 billion years before multi-cellular life flourished. The authors write that accurate luminosities are "perhaps the most important information we use in determining the habitability of nearby stars" for complex life, because luminosity indicates which phase of life the star is in, and that in turn dictates how long the star will remain stable. Our own sun follows an 11-year, "bright and dark" cycle (the sunspot cycle), yet its luminosity fluctuates over that time by only 2 parts per 10,000 (0.02 percent). A drop in solar radiance of half a percent or less locked terrestrial life into the coldest years of the Little Ice Age (1550-1700 A.D.). Turnbull and Tarter took on the daunting task of evaluating 118,218 nearby stars, using membership criteria of constant luminosity and potential habitable zones. A database search gave them their first cut, which they call the "Celestia sample." If a star fluctuated by 3 percent in its luminosity, the level of variability detectable to Hipparcos, complex life would be imperiled. Stars that don't twinkle A star's twinkle in the night sky is due to the distorting effects of our atmosphere. If stars like our sun actually varied or twinkled that much, life as we know it would cease to exist. For that reason, Tarter and Turnbull are not interested in sifting through what they term, "the cataclysmic, eruptive, pulsating, rotating, or X-ray" stars. If those stars had planets, their climate would prove a quick killer. Such stars are relatively common, so after eliminating such stars from the search, the Celestia sample totaled about half of the original list, or 64,120 candidate stars. The remaining stars could be narrowed down even further based on mass, color, and age. The final list of candidates needed to have just the right size and composition. If, for example, a habstar expanded or shrank over the required 3 billion years for complex life to develop, then orbiting planets would experience ice ages and runaway greenhouses. Another two-thirds (64%) of the HabCat candidates fell off this wish list because, while it may be possible for advanced life to survive, the stars posed a threat to well-known biological sensitivities. For example, the excessive ultraviolet (UV) radiation of a star could cause DNA to fragment or mutate. However, Tarter and Turnbull note that these assumptions may change in the future with additional data. The scientists also excluded young star systems. Young stars typically have high rotations, they emit soft X-rays above and beyond their estimated temperatures, or they haven't burned through enough light elements to produce metals (heavy elements like iron). The survivors in the catalog at this point numbered only one in six stars, or 20,814 potential candidates. Favorable stars as loners After eliminating the variable, low metallicity or very young stars from HabCat, Turnbull and Tarter took on the binary and multiple star systems. As disquieting as a dual sunrise and sunset might prove to our own biorhythms, there are a great number of multiple star systems where such broken days occur. The fraction of solar-type stars in binary or multiple systems has been estimated to be two out of every three stars. These stars have fewer stable orbits for hosting planets with liquid water, and planets would have a higher danger of either spinning out of the system (ejection) or spiraling into one of the stars (accretion). Very elliptical orbits also cause climatic chaos. Turnbull and Tarter examined the "habitable zone" (where liquid water can exist on an Earth-like planet) around each potential habstar that was part of a binary or multiple sytem. By eliminating systems where the habitable zones were not stable, about 2200 of 3500 stars in binary or multiple systems were kept in the HabCat. The HabCat inventory was nearly finished, their final cut done. It takes a planet to feed a village Even if a star is classified as "habitable", the orbiting planets might not be. Our neighboring planet, Venus, has a surface hot enough to melt lead. Presumably, any carbon-based intelligence capable of communication needs some solid ground from which to broadcast. In 1993, Project Phoenix began looking at 2,000 candidate stars for signs of life. Since then, a revolution in astronomy has taken place. Scientists have discovered and catalogued an ever-increasing number of extrasolar planets. Of the 17,000 or so habstars in our neighborhood of the galaxy, 55 harbor already-discovered planets. Owing to the challenges of detecting a relatively tiny pale blue dot, all of these planets are hugely massive. The least massive one identified so far (HD 49674), is about a tenth the mass of our own Jupiter--a so-called gas giant. Gas giants are unlikely to support Earth-like life. Cutting the stars whose giant planets interfered with the habitable zone (which could otherwise contain habitable terrestrial planets), the final HabCat was ready for press. It includes 17,129 habstars, all ready for investigation with the Allen Telescope Array. As Turnbull and Tarter note: "Despite the broad array of data used to assemble this catalog, this exercise has forced us to admit that we are defining habitability from a position of considerable ignorance... For SETI this humbling situation is amplified when we consider that we have no indisputable definition for life itself, to say nothing of the precise conditions that are necessary and sufficient for life to evolve into a technological civilization detectable by a SETI search program." Turnbull and Tarter took time from their busy preparations to outline for Astrobiology Magazine the highlights of how they built HabCat and what they plan next. Turnbull (Steward Observatory, University of Arizona, Tucson) and Tarter (SETI Institute, Mountain View, California) broadly described their insights into galactic habitability. Interview with Margaret Turnbull and Jill Tarter Astrobiology Magazine (AB): How did work on the new HabCat begin? Jill Tarter (JT): This paper [Target Selection for SETI] is part of [Margaret's] thesis in Astrobiology at the University of Arizona. The need for a larger target list is driven by the desire to do simultaneous radio astronomy and SETI observing at the same time. AB: What was the primary motivation--to expand the 2000 Phoenix targets to 17,000 HabCat targets for the Allen Telescope Array (ATA)? Does this derive in part from the enhanced search capabilities expected from the new array? Margaret Turnbull (MT): Absolutely. Whereas Project Phoenix has been observing about 200 stars per year, the ATA will be capable of observing 10,000 or more, at three times the frequency coverage and four times the spectral resolution of Project Phoenix. Observing this many targets annually means that HabCat will have to be supplemented by even larger target lists, and currently we are assembling a list of about 100,000 stars from the Tycho-2 catalog. Such a list will not be nearly as "refined" as HabCat due to a severe lack of parallax and spectral data, but we will do our best to keep our targets on the main sequence. JT: With 6-meter telescopes, the primary field of view of the array is about 3 degrees across at 1 gigahertz, but it shrinks by factor of ten at 10 gigahertz, so to have enough targets to always find one or more in the preferred field of view requires very large lists. The lifecycle of the ATA will be long, and we'll start at lower frequencies where the beamsize is larger. AB: Where is the Allen Telescope Array in its current development timeline? JT: ATA completion is probably 2005. MT: The Prototype Test Array at Hat Creek now has three antennas. Ultimately it will consist of 350 individual 20-foot antennas, providing a larger total collecting area than the Green Bank Telescope in West Virginia and higher resolution than the Arecibo dish. AB: How did the target list prioritize its selections for HabCat? MT: We are currently working on a prioritization algorithm for all of our SETI targets, including several subsets of objects not included in HabCat, to be published in a second paper. AB: Your first paper weights candidate stellar systems for X-ray luminosity, rotation, spectral types, kinematics, metallicity, and Strömgren photometry, correct? That's the long equation for acceptance. MT: For the HabCat stars, inclusion in the catalog was based on the X- ray and other data you mentioned, but priority will be assigned based on location in the color-magnitude diagram [CMD] and on distance. A plot of the CMD score would look like a bull's-eye centered on the sun's absolute visual magnitude and B-V color, with the highest score at the center. The distance scoring will go as the inverse square of distance, or the detectability of a given signal. We are still considering how to weight these two factors, but most likely the distance score will dominate within a certain distance. One idea is that, given the first terrestrial transmissions of a century ago, HabCat stars within the possible ETI [extraterrestrial intelligence] response distance of 50 light years should have scores dominated by distance. AB: What is the significance of excluding, or annotating the catalog with, binary and ternary stellar systems? Is this because an orbital instability is incompatible with habitability criteria? MT: In fact, we included in HabCat approximately 2,200 stars that are members of known binary or triple systems, and each of these systems has passed our test for dynamical stability of the habitable zone. For 3,500 candidate habstars in multiple systems, we mapped out the location of the habitable zone according to work done by Kasting, Whitmire and Reynolds [1993, Icarus, 101:108]. To determine if that location is dynamically stable in the presence of the companion stars, we used the stability criteria developed by Holman and Wiegert [1999, Astrophysical Journal, 117:621]. It turned out that many binary and triple systems were habitable, including 21 tight binaries where the habitable zone encompasses both stars. AB: So what's planned in forthcoming projects? MT: This work falls within the broader themes of, first, the overall habitability of the Milky Way, and, second, the remote sensing of biosignatures. My dissertation work includes topics such as characterizing the Earthshine signal, including spectral signatures of life; constraining the fraction of habitable stars in the solar neighborhood; identifying suitable targets for the Terrestrial Planet Finder mission; and examining the concept of a habitable belt in the Galaxy. JT: We were sorry to see FAME [Full-sky Astrometric Mapping Explorer] cancelled, since it would have provided 40 million parallaxes [or star positions]. [To further refine HabCat], in FAME's absence we'll have to use reduced proper motions and color-color relationships from the Tycho- 2 Catalog while waiting for SIM [NASA's Space Interferometry Mission] and GAIA [European Space Agency's Galactic Census Project]. Editor's Note: For HabCat the current best set of stellar distances comes from what astronomers call Hipparcos parallax measurements, which give values accurate to ~1 milli-arcsecond. Several new astrometric satellites are now being planned to measure star distances. The most ambitious planned star cataloguing projects are NASA's Space Interferometry Mission and ESA's Galactic Census Project, or GAIA mission, which may yield large numbers of parallaxes with precisions better than ~10 micro-arcseconds. SIM is scheduled to operate from 2006 to 2011 while GAIA, if accepted by ESA, could launch in 2009 with a 5 year lifetime. SIM would provide astrometric measurements of 10,000 stars and GAIA would measure around 10 billion positions. The next scheduled astrometry mission, however, was the now cancelled FAME (Full-sky Astrometric Mapping Explorer), which was scheduled to be launched in 2004. What's next? Conservatively as catalogued so far, the preferred habstars must be 3 billion years old, stable, and support liquid water on the surface of whatever planets are properly distanced. These planets reside in a habitable zone, satisfying the precondition for complex life to develop. Three out of four reside within a communication neighborhood spanning around 450 light years. When the Allen Telescope Array turns on in 2005, its transmitter powers will be comparable to the Arecibo planetary radar (1 megawatt) and thus could search to the farthest of 17,000 habstars, just beyond 300 parsecs. For those search distances, an electromagnetic communication, if detected, would have begun broadcasting a millennium ago, just about 1000 AD on a terrestrial calendar (a transmission 978 light-years old). Read the original article at http://www.astrobio.net/news/article436.html. ________________________________________________________________________ NEW ADDITIONS TO THE ASTROBIOLOGY INDEX By David J. Thomas http://www.lyon.edu/webdata/users/dthomas/astrobiology/astrobiology.html 21 April 2003 Astrobiology, exobiology and terraformation articles http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_articles1. html Astrobiology Magazine, 2003. Messages in a bottle. Astrobiology Magazine. Human space exploration and microgravity effects articles http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_articles3. html L. David, 2003. Passenger-carrying spaceship makes desert debut. Space.com. Search for extraterrestrial intelligence (SETI) articles http://www.lyon.edu/webdata/users/dthomas/astrobiology/online_articles4. html Astrobiology Magazine, 2003. Habstars: speeding up in the zone. Astrobiology Magazine. P. Backus, 2003. The stars of Project Phoenix: the best are not always the brightest. Space.com. S. Shostak, 2003. Arecibo diaries (1): location is everything. Space.com. S. Shostak, 2003. Arecibo diaries (2): narrowing the search. Space.com. Astrobiology and extreme environments book list http://www.lyon.edu/webdata/users/dthomas/astrobiology/astrobiology_book s.htm National Research Council, 2003. Life in the Universe: An Assessment of U.S. and International Programs in Astrobiology. National Academy Press, Washington, DC. ________________________________________________________________________ CONTINUING COVERAGE OF THE COLUMBIA DISASTER By David J. Thomas 21 April 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/04/14/sprj.colu.shuttle/index.html http://www.cnn.com/2003/TECH/space/04/15/sprj.colu.shuttle.probe.ap/inde x.html http://www.cnn.com/2003/TECH/space/04/17/sprj.colu.shuttle.investigation .ap/index.html http://www.nytimes.com/2003/04/17/science/space/17CND- SHUT.html?tntemail0 http://www.space.com/missionlaunches/sts107_columbia_030414.html http://www.space.com/missionlaunches/nasa_okeefe_030417.html http://www.space.com/missionlaunches/sts107_caib_030417.html http://www.space.com/missionlaunches/dittemore_resign_030420.html http://spaceflightnow.com/shuttle/sts107/030415breach/ http://spaceflightnow.com/shuttle/sts107/030415search/ http://spaceflightnow.com/shuttle/sts107/030417recommend/ http://spaceflightnow.com/shuttle/sts107/030419dittemore/ http://www.spacedaily.com/2003/030420150526.2gkjhgxx.html http://www.spacedaily.com/2003/030417214042.gsn7ppok.html http://www.spacedaily.com/2003/030416201756.vi1qh5hl.html http://www.spacedaily.com/news/shuttle-03l1.html ________________________________________________________________________ CASSINI SIGNIFICANT EVENTS NASA/JPL release 10-16 April 2003 The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Wednesday, April 16. 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. Command and Data Subsystem (CDS) Flight Software (FSW) checkout activities continued this week with playback of data from last week's Probe Solid State Recorder Dual Record Demo, enabling of the CDS Solid State Recorder (SSR) Auto-Repair function, a RADAR Instrument Expanded Block (IEB) Exercise with Telemetry Mode Checkout, power on and IEB checkouts for Radio and Plasma Wave Science (RPWS) and Magnetospheric Imaging Instrument (MIMI), clearing of the Attitude Control System (ACS) high water marks, and powering on of the Magnetometer Subsystem (MAG) and Composite Infrared Spectrometer (CIRS). The IEB checkouts for RADAR, RPWS, MAG, and CIRS activities were nominal. Due to a timing error, MIMI rejected the commands comprising the IEB load test. The cause is understood and the test will be repeated in a later sequence. No recovery commanding is necessary. On DOY 098, an absolute timed mini-sequence and an Immediate/Delayed Action Program (IDAP) were executed on the spacecraft to perform a test of the Probe Relay telemetry mode with SSR Dual Record. The execution of the mini-sequence was very similar to the Probe Relay critical sequence, with fault protection and other critical commands removed. The purpose of the playback was to demonstrate the priority playback capability of Probe data over two separate passes. The play back and downlink were completely nominal. However, the Real-Time broadcast of Probe data to the Huygens Probe Operations Center (HPOC) failed. The problem was identified as a telemetry broadcast buffer overflow, caused by a mismatch in data rates between the spacecraft data rate and the data lines to HPOC. Post pass querying of the playback data by HPOC was successful. Spacecraft Office, Mission Support and Services Office, Instrument Operations, System Engineering, and Huygens personnel at JPL are working the issue. Plans are already in place to test a higher capacity data line to HPOC which will be installed later this year. The Huygens Team has begun to review the data from the dual record demonstration, and perform gap analysis at their facility in Europe. Analysis is expected to be complete next week. Testing of the first five days of the C37 background sequence, and Trajectory Correction Maneuver (TCM)-19 in system mode have completed successfully in the Integrated Test Laboratory. The preliminary Sequence Integration & Validation package for C37 was also released for review, and a waiver approved for the CIRS FSW checkout activity. Contingency planning for the TCM-20 timeframe has been completed. The plan deals with potential issues in the operation of the Main Engine Assembly cover and with pyro sequence for bringing the oxidizer side of the bi-propellant system online. Science Planning Virtual Team development for the C39 sequence kicked off this week. C39 will use the 2-port, 8-work-weeks cruise development process. The process will conclude in mid June. A project briefing for this sequence will be held in two weeks. Multimission Image Processing Laboratory (MIPL) personnel performed a short performance test of downlink and reconciliation processing. The test was monitored and analyzed by system analysis software. The results showed that the machine loading expected during the tour will be adequately accommodated by planned hardware procurements. Acceptance testing has begun for MIPL D30 software. D30 is scheduled for delivery in July of this year. System engineering held a meeting for team, office, and project management to present options and recommendations for ground data system workstation operating system migration. The decision was reached to proceed with Mission Sequence Subsystem (MSS) and Kinematic Prediction Tool-Inertial Vector Propagator (KPT-IVP) development on the Solaris 7 environment for delivery in mid-July. The developers will then port these tools to either Solaris 8 or Solaris 9, depending upon the results of concurrent Solaris 9 testing. A delivery coordination meeting was held for the Navigation Ancillary Information Facility toolkit version N0055. 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 EXPLORATION ROVERS: SPACECRAFT AND EXPENDABLE VEHICLES STATUS REPORT By George H. Diller NASA/KSC release 14 April 2003 Mission: Mars Exploration Rovers (MER-1/MER-2) Launch Vehicles: Delta II/Delta II Heavy Launch Pads: 17-A/17-B Launch Dates: June 6/June 25 Launch Times: 2:12:44 PM/12:38:16 AM EDT The beginning of the launch period for the first of NASA's two Mars Exploration Rover missions will be rescheduled until no earlier than June 6 to allow time to address a potential problem raised during pre- launch tests of the spacecraft over the weekend. The concern regards cabling that connects the spacecraft's main computer, which is inside the rover, to peripherals in the cruise stage, lander and small deep space transponder. The connection to the cruise stage is severed during approach to Mars and the connection to the lander is severed before the rover drives off. Pre-launch testing revealed a potential problem in how the spacecraft interprets signals sent when the cables are severed. The problem will require fixing on both rovers. The work is not expected to effect the launch period for the second rover mission which is scheduled to open June 25 and close July 15 for a landing Jan. 25, 2004. However, the second mission cannot launch until 10 days after the first one. The remedy will require some disassembly of the spacecraft at NASA's Kennedy Space Center, Cape Canaveral, FL. The work cannot be done within the schedule of preparations for the original May 30 opening of the launch period. The mission will have two launch opportunities each day during the launch period, which is scheduled to close on June 19. Arrival at Mars is set for January 4, 2004, regardless of launch date within that period. On Cape Canaveral Air Force Station, first and second stage processing activities for the MER-A vehicle continues in Hangar AO and erection on Pad 17-A is planned to begin April 22. Erection of the vehicle for MER- B is planned to begin May 24. Contact: George H. Diller NASA Kennedy Space Center Phone: 321-867-2468 Additional articles on this subject are available at: http://www.cnn.com/2003/TECH/space/04/15/mars.rovers.ap/index.html http://www.nytimes.com/2003/04/16/science/16MARS.html http://www.space.com/marsrover/ http://www.space.com/missionlaunches/mer_disassembly_030414.html http://www.space.com/businesstechnology/technology/rover_overview_030416 .html http://www.space.com/businesstechnology/technology/rover_sidebar_030416. html http://www.spacedaily.com/2003/030416015022.ifjd9uij.html ________________________________________________________________________ MARS GLOBAL SURVEYOR IMAGES NASA/JPL/MSSS release 15-18 April 2003 The following new images taken by the Mars Orbiter Camera (MOC) on the Mars Global Surveyor spacecraft are now available. Defrosting North Polar Dune Field (Released 15 April 2003) http://www.msss.com/mars_images/moc/2003/04/15/index.html Daedalia Planum Wind Streak (Released 16 April 2003) http://www.msss.com/mars_images/moc/2003/04/16/index.html Lava Flow and Impact Crater (Released 17 April 2003) http://www.msss.com/mars_images/moc/2003/04/17/index.html North Polar Dust Storm (Released 18 April 2003) http://www.msss.com/mars_images/moc/2003/04/18/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 14-18 April 2003 Textured terrain (Released 14 April 2003) http://themis.la.asu.edu/zoom-20030414a.html Medusae Fossae Yardangs (Released 15 April 2003) http://themis.la.asu.edu/zoom-20030415a.html Ascraeus Mons (Released 16 April 2003) http://themis.la.asu.edu/zoom-20030416a.html Northeastern Meridiani (Released 17 April 2003) http://themis.la.asu.edu/zoom-20030417a.html Lucus Planum (Released 18 April 2003) http://themis.la.asu.edu/zoom-20030418a.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 18 April 2003 Over the past week, the Stardust team completed the first Comet Wild 2 encounter sequence test in the Spacecraft Test Laboratory. This testing is in support of Stardust's historic encounter with Comet Wild 2 in January of next year. The success of last year's Annefrank flyby is still positively affecting the Stardust mission. Stardust made a close pass of asteroid Annefrank back on November 2, 2002. During this flyby many spacecraft functions that will be employed during Stardust's encounter with Comet Wild 2, were proven to be operational. This positive confirmation of both the vehicle and team's performance now allows the Stardust team to look beyond the Wild 2 encounter to the challenging operations required for Earth return in 2006. Information on the relative positions 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 16.