MARSBUGS: The Electronic Astrobiology Newsletter Volume 6, Number 13, 21 May 1999. Editors: Dr. David Thomas, Department of Biological Sciences, University of Idaho, Moscow, ID, 83844-3051, USA. Marsbugs@aol.com or davidt@uidaho.edu. Dr. Julian Hiscox, Division of Molecular Biology, IAH Compton Laboratory, Berkshire, RG20 7NN, UK. Julian.Hiscox@bbsrc.ac.uk Marsbugs is published on a weekly to quarterly basis as warranted by the number of articles and announcements. Copyright of this compilation exists with the editors, except for specific articles, in which instance copyright exists with the author/authors. While we cannot copyright our mailing list, our readers would appreciate it if others would not send unsolicited e-mail using the Marsbugs mailing list. The editors do not condone "spamming" of our subscribers. Persons who have information that may be of interest to subscribers of Marsbugs should send that information to the editors. E-mail subscriptions are free, and may be obtained by contacting either of the editors. Article contributions are welcome, and should be submitted to either of the two editors. Contributions should include a short biographical statement about the author(s) along with the author(s)' correspondence address. Subscribers are advised to make appropriate inquiries before joining societies, ordering goods etc. Back issues and Adobe Acrobat PDF files suitable for printing may be obtained via anonymous FTP at ftp.uidaho.edu/pub/mmbb/marsbugs or at the official Marsbugs web page at http://members.aol.com/marsbugs/marsbugs.html. The purpose of this newsletter is to provide a channel of information for scientists, educators and other persons interested in exobiology and related fields. This newsletter is not intended to replace peer-reviewed journals, but to supplement them. We, the editors, envision Marsbugs as a medium in which people can informally present ideas for investigation, questions about exobiology, and announcements of upcoming events. Astrobiology is still a relatively young field, and new ideas may come out of the most unexpected places. Subjects may include, but are not limited to: exobiology and astrobiology (life on other planets), the search for extraterrestrial intelligence (SETI), ecopoeisis and terraformation, Earth from space, planetary biology, primordial evolution, space physiology, biological life support systems, and human habitation of space and other planets. ------------------------------------------------------------------ CONTENTS 1) NASA, USDA WILL BRING SPACE TECHNOLOGY DOWN TO EARTH NASA release 99-58 2) FROM NEAR-EARTH ASTEROIDS TO WATER ON MARS--ASTRONOMERS REVIEW LATEST ISO RESULTS From ESA Science News 3) NEW MARS GLOBAL SURVEYOR IMAGES By Ron Baalke 4) SETI@HOME RELEASED By Dave Watanabe 5) ASTROBIOLOGY'S MOST WANTED--A FAILURE TO RECANT RESULTED IN THE STRANGE CASE OF GIORDANO BRUNO By David Noever and Tony Phillips 6) THE SAGAN CRITERIA FOR LIFE REVISITED: GALILEO'S 1990 CLOSE ENCOUNTER WITH EARTH FRAMED SOME DIFFICULT QUESTIONS FOR ASTROBIOLOGISTS. By David Noever and Tony Phillips ------------------------------------------------------------------ NASA, USDA WILL BRING SPACE TECHNOLOGY DOWN TO EARTH NASA release 99-58 10 May 1999 A new partnership between NASA and the U.S. Department of Agriculture (USDA) could result in updated maps of Yellowstone National Park, a better understanding of wildfires and improved management of California vineyards. Under the partnership, NASA has selected 13 research proposals that will apply remote-sensing data--images of the Earth taken by satellites--to issues on the ground: forest mapping, soil studies, wildfires, range management, flood-plain drainage and crop monitoring. "This new partnership between NASA and USDA demonstrates the diverse and wide-ranging applications of NASA's Earth Science research and its relevance to the American people," said Dr. Ghassem Asrar, Associate Administrator of Earth Sciences, NASA Headquarters, Washington, DC. "The Office of Earth Sciences is eager to form new partnerships with other government agencies, industry and public groups to expand America's use of our Earth Science research." "We in the Department of Agriculture, especially the Cooperative State Research, Education, and Extension Service are very excited about partnering with NASA on these research projects," said I. Miley Gonzalez, Under Secretary for Research, Economics and Education. "We recognized that there were areas of research where images from space combined with ground surveys can greatly benefit our mapping efforts. We are looking forward to these pilot projects and hope they may lead to future partnerships between our organizations to explore land management and precision agriculture topics." The award value for the 13 projects, which involve 11 universities, 11 private companies, 17 federal agency facilities and four state and local governments, is $7 million over three years. NASA selected the 13 projects from 180 proposals. Researchers will use a variety of public and private spaceborne and aircraft-mounted Earth-observing instruments along with ground observations in their studies. For forestry studies, NASA, the U.S. Forest Service and universities will use the recently launched Landsat 7 and other satellites to create valuable new maps of Yellowstone and other public lands. Satellite imagery also can provide researchers at the Forest Service and universities with maps of vegetation in areas prone to wildfires-- firefighters can determine which types of plants are more likely to fuel wildfires and better predict what paths such fires may take. Using airplanes and spacecraft that observe characteristics of grape vines invisible to the naked eye, researchers can "see" when vines are ill, allowing vintners to act before many vines are lost to disease. This research will allow America's billion- dollar wine industry to manage its vineyards more cost- effectively. Additional information on the research projects, including the names of the universities, companies and federal facilities involved, can be found on the Internet at http://earth.nasa.gov/nra/archive/nra98oes09/winners.html The partnership between the space program and USDA is part of NASA's Earth Science enterprise, a coordinated research program that studies the Earth's land, oceans, ice, atmosphere and life as a total science system. The initiative is part of an aggressive new strategy devoted to significantly increasing the application of NASA remote sensing data, information, science and technologies to societal needs, ensuring maximum return on taxpayer investments. ------------------------------------------------------------------ FROM NEAR-EARTH ASTEROIDS TO WATER ON MARS--ASTRONOMERS REVIEW LATEST ISO RESULTS From ESA Science News http://sci.esa.int 11 May 1999 Near-Earth Asteroids--asteroids whose orbits bring them close to Earth--very likely originate from collisions between larger asteroids that orbit the Sun between the planets Mars and Jupiter. This result, obtained by ESA's infrared space telescope, ISO, was presented yesterday at the workshop on ISO results on Solar System, held at ESA's Villafranca Satellite Tracking Station in Spain. Other findings related to the atmosphere of Mars and the giant planets--Saturn, Jupiter, Neptune and Uranus--were also presented during a press conference yesterday morning. About 250 Near-Earth Asteroids (NEA) are known so far, with sizes ranging from one to 40 kilometers in diameter. But according to Alan Harris, of the German Aerospace Centre (Berlin), there are more than 2000 NEA not yet identified. Their origin is still unclear, but scientists are working with two main ideas: many probably originate from collisions among the larger bodies in the Main Belt of asteroids, between Mars and Jupiter, while others might be old, "dead" comets that have undergone so many fly-bys of the Sun that they have lost all their coma--the beautiful comet tail of dust and gas. The infrared observations made by Harris with ISO provide information about the surface and mineralogy of the NEAs, and confirm that many are fragments of larger asteroids. ISO sees a rocky surface without much residual dust; a dusty surface is what would be expected if the NEA were "dead comets." Harris, however, is still analyzing the data and has not yet ruled out the possibility of finding traces of dust in one of the asteroids observed, the orbit of which is very similar to that of a comet. As Harris points out, knowledge on the composition of these objects is necessary to predict the consequences of a future impact on the Earth. "We still know just a few of them, and although the odds that any one will hit the Earth in the near future are very low, there's a possibility. Therefore, the more we know about these objects, the better", he said. The new data about Mars refer to the water in the atmosphere: ISO sees that it condenses and freezes close to the planet's surface. This result will help to understand the behavior of the martian atmosphere. "We got these observations while NASA's Mars Pathfinder mission was also studying the planet, and the results of both missions are in agreement. ISO confirms the Mars Pathfinder data", said Therese Encrenaz, of the Observatoire de Paris-Meudon. Encrenaz also described the detection of new molecules in the atmospheres of the giant planets, mainly hydrocarbons like the radical CH3•, never detected before, and benzene. Benzene is a common molecule on Earth (in petrol for instance), but is apparently less common on other planets. ISO's spectrometers see it now in Saturn. The discovery of water in the atmosphere of Saturn's largest moon, Titan, was also reviewed by Athena Coustenis of the Observatoire de Paris-Meudon. Useful links for this story ISO Science Homepage http://www.iso.vilspa.esa.es/ ISO Data Centre http://www.iso.vilspa.esa.es/users/idc/IDC.html Images supporting this article are available at http://sci.esa.int/story.cfm?TypeID=1&ContentID=4850&Storytype=18 ------------------------------------------------------------------ NEW MARS GLOBAL SURVEYOR IMAGES By Ron Baalke 11 May 1999 The following new images taken by the Mars Global Surveyor spacecraft are now available. "Looking Into" Martian Craters South Melea Planum, By The Dawn's Early Light The images reside on the Mars Global Surveyor web site at http://mars.jpl.nasa.gov/mgs/msss/camera/images/index.html The image captions are appended below. 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 Global Surveyor Mars Orbiter Camera MOC "Looking Into" Martian Craters MGS MOC Release Nos. MOC2-123, MOC2-124, MOC2-125, 11 May 1999 During the first week of May 1999, the Mars Orbiter Camera (MOC) spent some time peering into martian impact craters. Three examples are shown here. The first crater (on left, MOC2-123) is located on a plain west of the Tartarus Montes (east of Elysium Mons volcano). The crater is about 2.7 kilometers (1.7 miles) across. Illumination is from the left. The second crater (middle, MOC2-124) is located in south-central Syria Planum and is about 7.0 kilometers (4.4 miles) across. Illumination is from the upper left. The third crater (right, MOC2-125) is found on Hesperia Planum and is 7.3 kilometers (4.5 miles) across. Illumination is from the upper left. If you have ever visited the famous Meteor Crater in northern Arizona, U.S.A., then you are aware of its immense size on a human scale. The Arizona crater, however, is only 1 kilometer across (0.62 miles), whereas the first crater above (left) is nearly three times that size, and the other two are seven times wider. The impact and explosion of a meteorite at some time in the martian past formed each crater. After each crater formed, wind and erosion modified it. The craters show deposits of sand and dust on their floors and in low areas around their rims, they also typically have boulders and other debris that has slid down the inside walls of the crater; and some crater walls show exposures of bedrock. Mars Global Surveyor Mars Orbiter Camera South Melea Planum, By The Dawn's Early Light MGS MOC Release No. MOC2-126, 11 May 1999 MOC "sees" by the dawn's early light! These two pictures were taken over the high southern polar latitudes during the first week of May 1999. The areas shown are currently in southern winter darkness. Because sunlight is scattered over the horizon by aerosols--dust and ice particles--suspended in the atmosphere, sufficient light reaches regions within a few degrees of the terminator (the line dividing night and day) to be visible to the Mars Global Surveyor Mars Orbiter Camera (MOC) when the maximum exposure settings are used. The picture on the left (MOC2-126a) shows a polygonally-patterned surface on southern Malea Planum. At the time the picture was taken, the sun was more than 4.5° below the northern horizon. The scene covers an area 3 kilometers (1.9 miles) wide, with the illumination from the top of the picture. The image on the right (MOC2-126b) shows a bright, wispy cloud hanging over southern Malea Planum. This cloud would not normally be visible, since it is currently in darkness. At the time this picture was taken, the sun was more than 5.7° below the northern horizon. The scene covers an area 3 kilometers (1.9 miles) wide. Again, the illumination is from the top. In both frames, the surface appears a relatively uniform gray. At the time the pictures were acquired, the surfaces were covered with south polar wintertime frost. The highly reflective frost, in fact, may have contributed to the increased visibility of these surfaces. This "twilight imaging" technique for viewing Mars can only work near the terminator; thus in early May only regions between about 67°S and 74°S were visible in twilight images in the southern hemisphere, and a similar narrow latitude range could be imaged in the northern hemisphere. MOC cannot "see" in the total darkness of full-borne night. ------------------------------------------------------------------ SETI@HOME RELEASED By Dave Watanabe 14 May 1999 SETI@home is a scientific experiment that will harness the power of hundreds of thousands of Internet-connected computers in the Search for Extraterrestrial Intelligence (SETI). You can participate by running a program that downloads and analyzes radio telescope data. There's a small but captivating possibility that your computer will detect the faint murmur of a civilization beyond Earth. Get it now (Macintosh & Windows software), and help contribute. More information and downloadable software are available at http://exosci.com/news/155.html and http://setiathome.ssl.berkeley.edu/. ------------------------------------------------------------------ ASTROBIOLOGY'S MOST WANTED--A FAILURE TO RECANT RESULTED IN THE STRANGE CASE OF GIORDANO BRUNO By David Noever and Tony Phillips From NASA Space Science News 21 May 1999 "Innumerable suns exist; innumerable earths revolve around these suns in a manner similar to the way the seven planets revolve around our sun. Living beings inhabit these worlds." From On the Infinite Universe and Worlds, Giordano Bruno, 1584 When astronomers recently announced the discovery of a new planetary system, the greatest dangers they faced were the ones that come with fame in the Information Age: calls from the press, web pages to edit, and speeches to deliver. Nowadays discovering planets is a tiring business, but relatively safe as jobs go. Four hundred years ago the search for life among the stars was considerably riskier. Consider, for example, the strange case of Giordano Bruno, who could be considered one of the Western World's first astrobiologists. Many Renaissance scholars regard Bruno as a forerunner, if not a founder, of modern science and philosophy. Many credit him with greater influence in his day than better known Italian philosophers who were his contemporaries, including Copernicus. Renowned for his gifts of memory, Bruno memorized vast amounts of text, whether written in Italian, English, French or German. One of his amusements was an abstract model of the solar system itself and a mnemonic wheel, The Memory Wheel, having a circular shape with 7 concentric layers like the orbits of the 7 known planets of the time. Bruno's extraordinary skill in the art of memory attracted the attention of patrons, and he was brought to Rome to demonstrate his abilities to the Pope. Later, thanks to his unorthodox tendencies and outspoken nature, he also attracted the attention of the Inquisition in Naples. In 1576 he left to escape persecution. When the same thing happened in Rome, he began a 15- year journey across Europe, teaching and writing under the sponsorship of various patrons. No Labor Entirely Lost While excommunicated to England, he is largely credited with inspiring the character Berowne in one of William Shakespeare's first London plays, "Love's Labor's Lost." In the story, Berowne was a sharp-witted attendant of King Ferdinand who pledged to devote himself to study for a period of three years without the intrusion of such physical pleasures as adequate sleep, enough food, or the company of women. When "Lost" first played, Bruno had already lived in London for two years. Scientifically, Bruno advocated a radical view of a universe extending everywhere in all directions, echoing what later would become a detailed mathematical theory and Einstein's special relativity. "There is no absolute up or down, as Aristotle taught; no absolute position in space; but the position of a body is relative to that of other bodies. Everywhere there is incessant relative change in position throughout the universe, and the observer is always at the center of things." But for many, Bruno is considered the first Westerner to publish a position that entertained the possibility for not only the Earth as a planet orbiting around a sun, but for many such planets harboring conditions compatible with life. A single sentence summarized his outcast life that crossed with the then prevailing view, until he himself was caught in the cross-hairs of a different and dangerous kind of sentence--death by burning. "Innumerable suns exist; innumerable earths revolve around these suns in a manner similar to the way the seven planets revolve around our sun. Living beings inhabit these worlds." From On the Infinite Universe and Worlds, published in 1584 In 1591, in Venice, he was arrested by the Inquisition and tried. For eight years he was imprisoned and eventually declared a heretic. Bruno was burned at the stake on the Campo dei Fiori in Rome, February 17, 1600. Accused for his views including ideas that now would be called astrobiology, the defiant Bruno answered the pronounced sentence of death by fire, "Perhaps you, my judges, pronounce this sentence against me with greater fear than I receive it." Nearly 400 years after Bruno's execution, the fast-paced discovery of new solar systems makes his own sentence resonate in time as something more than just a labor lost. In only four years, more than 20 giant planets have been found orbiting nearby suns. Some are within the "habitable zones" of their stars, i.e., within a range of orbital distances where water could exist and, presumably, life could flourish. Conventional wisdom has it that gas giants like Jupiter are unlikely abodes for life, but their moons may be a different story. In the solar system astronomers have found that the larger the gas giant is, the more mass there will be in its system of moons. If this holds true for other solar systems, then some of the newly discovered planets which are many times more massive than Jupiter could have moons as large as Mars. Do these moons exist? Are they Earth-like? No one knows, but Giordano Bruno thought he had the answer 4 centuries ago. "Innumerable suns exist..." There are several hundred billion stars in the Milky Way galaxy alone. "...innumerable earths revolve around these suns in a manner similar to the way the seven planets revolve around our sun." The recent discovery of 3 planets around Upsilon Andromedae makes this assertion seem more likely than ever. "Living beings inhabit these worlds." The proliferation of life in the Universe remains a tantalizing mystery. Will Bruno be vindicated once again? Only time will tell. [See http://science.nasa.gov/newhome/headlines/ast21may99_2.htm for more information on this story.] ------------------------------------------------------------------ THE SAGAN CRITERIA FOR LIFE REVISITED: GALILEO'S 1990 CLOSE ENCOUNTER WITH EARTH FRAMED SOME DIFFICULT QUESTIONS FOR ASTROBIOLOGISTS. By David Noever and Tony Phillips From NASA Space Science News 21 May 1999 "It is now clear that organic chemistry has run rampant through the solar system and beyond." Carl Sagan, Scientific American, 1997 When the Galileo space probe flew by Jupiter's moon Callisto earlier this month, the detection of life on that strange and distant world was not among the scientific objectives. After all, Callisto's heavily cratered surface is a frigid -220°F and is scarcely protected from the ravages of space by an extraordinarily thin CO2 atmosphere. Indeed most astrobiologists concur that Callisto is an unlikely abode for life. But even if Callisto was wet and warm and teeming with life, would Galileo have noticed? The question brings to mind an earlier Galileo flyby of another curious planet--Earth. When the Galileo space probe swooped by Earth in 1990, all its instruments were pointed towards us. As Galileo flew toward our planet, the Earth was centered in the windshield and then again in the rear-view mirror as Galileo continued on its journey to Jupiter. Galileo's close encounter with Earth framed one of the most difficult questions in astrobiology. Can a modern space instrument tell if the Earth, or any planet, is a good candidate for harboring life? To put the 1990 flyby in perspective, the late Carl Sagan and his colleagues published a 1993 Nature article on this question. According to Sagan, the Galileo spacecraft found clear signs of life during its flight past the earth including: 1. strong absorption of light at the red end of the visible spectrum, particularly over the continents. The light-absorbing pigment that causes this is chlorophyll, a molecule essential to plant life and photosynthesis. (Plants appear green because chlorophyll reflects green light and absorbs red and blues.) 2. spectral absorption features caused by molecular oxygen in Earth's atmosphere. The amount of O2 in our atmosphere is many orders of magnitude greater than is found on any other planet in the Solar System. An oxygen-rich atmosphere is a curiosity because oxygen slowly combines with rocks on the earth's surface. Maintaining the oxygen content requires some replenishing mechanism, in this case photosynthesis by plants--the action of life. 3. infrared spectral lines caused by methane in the atmosphere. Although the amount of methane Galileo saw was miniscule--about 1 part per million--it is still important. In an oxygen-rich atmosphere like Earth's, methane should rapidly oxidize into water and CO2. Not a single molecule of methane would remain in equilibrium. Biological action such as bacterial metabolism in bogs replenishes the supply. 4. modulated narrowband radio transmissions. These emissions look nothing like natural sources of radio waves like lightning and plasma instabilities in Earth's magnetosphere. They are clear signs of a technological civilization. Galileo's flyby of Earth was just the beginning of the first-ever control experiment in astrobiological remote sensing. The second part happened two years later, in 1992, when Galileo returned for a flyby of the moon. While Earth is known to be teeming with life, the Moon is believed to be the exact opposite--cold, barren, and lifeless throughout its long geological history. What did Galileo see when it passed by the moon? "Nothing," says David Noever, a NASA astrobiologist. "There was no evidence for life. No chlorophyll, no oxygen-methane atmosphere, no artificial radio transmissions. It was just as we would have expected, and consistent with the Sagan criteria." Caveat Lunar The Galileo flybys showed that we know how to identify life at a distance, at least the kinds of life we're familiar with here on Earth. However, things may not be as simple as they seem. Organic compounds have been discovered in some unlikely--and almost certainly lifeless--places, including amino acids in meteorites, organic molecules in interstellar clouds, and organic compounds called porphyrins in lunar soil. The example of porphyrins on the Moon is particularly intriguing in the context of the Galileo flybys and Sagan's subsequent criteria for life. Porphyrins are the building blocks of brightly pigmented biomolecules such as hemoglobin and chlorophyll, which reflect only certain wavelengths of visible light. Chlorophylls, for example, are greenish pigments that contain a porphyrin ring. This is a stable ring-shaped molecule around which electrons are free to migrate. Because the electrons move freely, the ring has the potential to gain or lose electrons easily, and thus the potential to provide energized electrons to other molecules. This is the fundamental process by which chlorophyll captures or harvests the energy of sunlight--a kind of powerstation molecule underlying all life seen on earth. The first 3 of Sagan's 4 criteria for life, as gleaned from Galileo's Earth flyby, are all related to porphyrins through the action of chlorophyll. Chlorophyll and photosynthesis are responsible for the spectral colors of plant-covered continents, for the oxygen content of the atmosphere and for its methane balance. Galileo didn't detect porphyrins during its flyby of the Moon, but they were there in quantities too small to see. Here on Earth porphyrin organic compounds are useful biomarkers. For example, petroleum hunters look for porphyrins as markers of oil deposits and thermal maturity. They can be detected remotely without extracting organic matter to reveal oil shales and source rock that came from the decay of green plants. Does the presence of porphyrins mean that there is or has been life on the Moon? Not at all. The 1969 discovery of lunar porphyrins probably says less about the chances for biochemistry there, than about how common their generation may be elsewhere in the universe. In 1978 Simionescu et al. were able to produce porphyrins under laboratory conditions similar to those of primeval Earth, before the genesis of life. They summarized the results in the journal Origins of Life. "Experiments with gas mixtures intended to simulate the primeval atmosphere of the Earth yielded many biologically important chemicals. Investigations into the synthesis of porphyrin-like compounds from methane, ammonia and water vapor were carried out by using high frequency discharges. Microanalyses of porphyrins showed that porphyrin-like pigments were formed in this way. The presence of divalent cations in the reaction system increased the yield of porphyrin-like pigments also involving the direct synthesis of their metal complexes. The ready formation of these compounds in abiotic conditions is significant, suggesting the possibility of their appearance during the early stage of chemical evolution." The idea that the "stuff of life" is common even in lifeless places like the Moon is gaining momentum. On February 19th of this year an article in Science magazine reported one group's attempt to mimic an organic chemistry lab in outer space. The research team included a new breed of astrochemists--including Scott Sandford at the NASA Ames Research Center and the SETI Institute, both in Mountain View, CA, and lead author of the Science paper, Max Bernstein of Stanford University. Their experiments involved a class of complex carbon and hydrogen molecules, called polyaromatic hydrocarbons, or "PAHs." Like the porphyrins, these molecules are also part of the so-called CHNOPS elements--carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur. To reproduce the chemistry of an interstellar molecular cloud, Bernstein's group followed a simple recipe. 1. mix carbon and hydrogen molecules, the PAHs, with water ice at minus 440 degrees Fahrenheit, the temperature inside an interstellar cloud; 2. place these ice grains in a vacuum; 3. shine ultraviolet light on them, the same type of radiation put out by nearby stars and re-radiated by glowing hydrogen gases. Because of the extreme conditions, the likelihood of more complex, biologically useful molecules being formed seemed as remote as space itself. Instead, about 10 percent of the PAHs were converted to more biologically useful molecules such as alcohols, ketones and esters. "These experiments take molecules that only an astrophysicist could love and transform them into something that ought to fascinate astrobiologists," comments Thomas Wdowiak, an astrophysicist at University of Alabama at Birmingham. "This shows there is a process that takes a rather abundant substance that exists in the universe and converts it to the kinds of things that are susceptible to the origin-of-life scenario." Earth as we, the aliens, might see it... On Christmas Eve 1968, Apollo 8 completed 10 orbits around the Moon and returned live television pictures back to our planet. Over half a billion people watched as Earth rose on the Moon's horizon. For many observers it was a transforming perspective. Poet Archibald MacLeish wrote, "...to see the earth as it truly is, small and blue and beautiful in that eternal silence where it floats, is to see ourselves as riders on the earth together..." For astrobiologists, the Galileo flyby invoked a similar transformation--a first-time view of the Earth as an alien world. It affirmed that standards of proof might be the most interesting--and vexing--piece of the puzzle in the search for life among the stars. Meanwhile, scientists continue to push the limits of their understanding of both the biological and pre- biotic envelope for life, as we might know it, and how we might see it remotely from space--even when looking back directly at ourselves. [See http://science.nasa.gov/newhome/headlines/ast21may99_1.htm for more information on this topic.] ------------------------------------------------------------------ End Marsbugs Vol. 6, No. 13