MARSBUGS: The Electronic Exobiology Newsletter Volume 5, Number 5, 6 March, 1998. Editors: David Thomas, Department of Biological Sciences, University of Idaho, Moscow, ID, 83844-3051, USA, thoma457@uidaho.edu or Marsbugs@aol.com. Julian Hiscox, Division of Molecular Biology, IAH Compton Laboratory, Berkshire, RG20 7NN, UK. Julian.Hiscox@bbsrc.ac.uk or Marsbug@msn.com 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. E- mail subscriptions are free, and may be obtained by contacting either of the editors. 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 may be obtained via anonymous FTP at: ftp.uidaho.edu/pub/mmbb/marsbugs. 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. Exobiology 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 proper (life on other planets), the search for extraterrestrial intelligence (SETI), ecopoeisis/ terraformation, Earth from space, planetary biology, primordial evolution, space physiology, biological life support systems, and human habitation of space and other planets. ------------------------------------------------------------------ INDEX 1) NAKHLA MARS METEORITE AVAILABLE FOR SCIENTIFIC STUDY by Monica Grady 2) CLUES TO POSSIBLE LIFE ON EUROPA MAY LIE BURIED IN ANTARCTIC ICE by Dave Dooling 3) PALEOCLIMATOLOGY--DECIPHERING MYSTERIES OF PAST CLIMATE FROM ANTARCTIC ICE CORES from the American Geophysical Union 4) CASSINI MISSION STATUS JPL release 5) STARDUST STATUS REPORT by Ken Atkins ------------------------------------------------------------------ NAKHLA MARS METEORITE AVAILABLE FOR SCIENTIFIC STUDY by Monica Grady 4 March, 1998 Nakhla is a 1300 million year old Martian meteorite, the first one in which carbonates were identified. Nakhla fell as a shower of stones in 1911; several of the stones are in the collection of the Natural History Museum in London. One completely fusion-crusted stone has been kept unbroken since its acquisition in 1913. The Natural History Museum is now prepared to offer samples of this stone to scientists for appropriate analyses. The Antarctic Meteorite Processing Group had kindly agreed to allow the stone to be broken and sub-divided at the Curatorial Facility at the Johnson Space Center in Houston, prior to the LPSC in March. There is no formal deadline for sample requests, but the material available is limited. Coordinated approaches from groups of scientists undertaking complementary studies are encouraged. Those requests submitted to the Museum by April 3 will be processed in April. Those arriving later will be delayed for several months. For further details and to submit requests, contact: Dr. Monica M. Grady Department of Mineralogy The Natural History Museum Cromwell Road London SW7 5BD E-Mail: mmg@nhm.ac.uk ------------------------------------------------------------------ CLUES TO POSSIBLE LIFE ON EUROPA MAY LIE BURIED IN ANTARCTIC ICE by Dave Dooling 5 March, 1998 More than a century ago, science fiction pioneer Jules Verne wrote about people swept "Off on a Comet" and into space where they lived more or less happily ever after. Verne's 1877 book (also published as "Hector Servadac") was a bit fanciful, but it had an element of truth: life may have hitchhiked across the solar system. The proof may be found at the ends of the Earth. This week, American and Russian scientists are examining deep ice from the Antarctic and hoping to find clues that fungi, bacteria, and even diatoms could survive conditions in icy solar system bodies. This would help make the South Pole one of the first destinations for the growing field of astrobiology. "It's possible to say that ancient impacts of asteroids on the Earth could have ejected soil, rocks, and seawater containing terrestrial microorganisms into space, and that they may have made it to other places in the solar system," explained Richard Hoover at NASA's Marshall Space Flight Center. Hoover is an X-ray astronomer who is also is internationally known for his work on diatoms and a firm believer that living microorganisms locked in ice have a chance of remaining viable for long periods in outer space. The debate over whether the Antarctic Allan Hills meteorites brought life from Mars (or were contaminated by life on Earth) is the best known case. Hoover said that other evidence abounds, including asteroids striking the Earth or Mars and blasting materials into space, the survival of streptococcus bacteria on the Surveyor 3 moon lander, and the survival of microorganisms inside Antarctic ice. The possibilities expanded this week when NASA released new images and data that Europa, one of Jupiter's larger moons, slush and perhaps liquid water near the surface. That raises the intriguing possibility that Europa may harbor life. Discoveries on the Earth over the last few years show that life thrives or can be preserved in a range of "hostile" conditions, from volcanic vents deep in ocean trenches, to ice more than 400,000 years old, to Siberian permafrost more than 5 million years old. This week, Hoover and Dr. S. S. Abyzov of Russia's Institute of Microbiology of the Russian Academy of Sciences in Moscow are examining ancient ice drilled at Russia's Vostok (East) Station about 1,000 km (1,600 mi) from the South Pole. Eventually, they hope to examine water taken from inside a lake--liquid, not ice-- discovered under Vostok Station in 1996. The first samples being examined are from 386 meters (1,266 ft) down; the deepest in this set is from 1,249 meters (4,097 ft). Samples from as deep as 3,610 meters (11,840 ft) are on their way from Vostok to the Institute of Microbiology. Abyzov says that portions will be brought to Marshall [Spaceflight Center] later this year. Russian scientists have been drilling at Vostok since 1974. In 1996, seismic and other tools revealed the lake's presence in 1996. Lake Vostok is overlaid by about 3,710 meters (12,169 ft) of ice and may be 500,000 to 1 million years old. Since the discovery, drilling has gone slowly while procedures are worked out to keep it pristine. No one has seen or sampled the lake-- the deepest ice sample is from 100 meters (328 feet) above the liquid surface--nor is anyone sure why it is liquid, hence the scientific curiosity. While Lake Vostok holds clues about life on Earth, it also is a good model for conditions on Europa. The lake is about 48 by 224 km (30 by 140 mi) in size--about the size of Lake Ontario-- and 484 meters (1,600 ft) deep. Recent data indicate that it has about 50 meters (165 ft) of sediment at the bottom. "Recent research [shows] that extremely severe conditions of cosmic environments do not exclude the possibility that microorganisms may exist in anabiotic states at high altitudes in interplanetary space," Abyzov wrote in a recent paper. The only way to resolve the question is to use the Antarctic as a model for conditions in comets, the Martian ice caps, and other icy moons orbiting Jupiter and Saturn. At Vostok station in 1975, Abyzov discovered bacteria, fungi, diatoms, and other microorganisms which were blown to Antarctica by winds from lower latitudes. The numbers of the organisms at different depths, and thus different ages of the ice, change with major climate changes on the Earth. Thus, the ice also serves as a time capsule, preserving specimens of life as far back as 500,000 years. This offers the potential for studying how genetic material changes over the centuries. Abyzov brought his samples to Marshall to use the Environmental Scanning Electron Microscope, or ESEM, a relatively new tool that Marshall uses to analyze how materials fail and break. It was originally designed to analyze biological specimens in their natural environment, without coating them in gold to make them reflective. And that's ideal for observing whatever is in the ice. It also uses an X-ray scan to analyze the elements in a target, an important step in determining whether an object is organic. The ice specimens will be analyzed at Marshall over the next week, then Abyzov will go to the Jet Propulsion Laboratory to work with another colleague with different analytical tools. Check back in a few days for a follow-up story on what the ESEM finds. Abyzov describes his research in a chapter of Antarctic Microbiology (E. Imre Friedmann, ed., ISBN 0-471-50776-8, New York, Wiley, 1993, 644 pp). In the book, international authorities present expert and comprehensive papers concerning the diversity of such Antarctic microorganisms as prokaryotes, fungi, algae and protozoa and their freshwater, marine and terrestrial environments. In fact, the entire ecosystem of the Antarctic continent and its surrounding seas is based primarily on microorganis's. Coverage ranges from marine sediments and sea ice to exobiological implications and environmental concerns. [More information and images concerning Vostok station may be found at http://science.msfc.nasa.gov/newhome/headlines/ ast04mar98_1.htm#anchor647575] ------------------------------------------------------------------ PALEOCLIMATOLOGY--DECIPHERING MYSTERIES OF PAST CLIMATE FROM ANTARCTIC ICE CORES from the American Geophysical Union [Earth in Space, Vol. 8, No. 3, November 1995, p. 9. (c)1995 American Geophysical Union. Permission is hereby granted to journalists to use this material so long as credit is given, and to teachers to use this material in classrooms.] The history of the world's climate is recorded in the layers of sediment that accumulated over thousands of years in ice and rock. Paleoclimatologists are studying sediment encapsulated in deep Antarctic ice to answer a few perplexing questions about the conditions that prevailed during the ice ages. by Vostok Project Members: S. S. Abysov, M. Angelis, N. I. Barkov, J. M. Barnola, M. Bender, J. Chappellaz, V. K. Chistiakov, P. Duval, C. Genthon, J. Jouzel, V. M. Kotlyakov, B. B. Kudriashov, V. Y. Lipenkov, M. Legrand, C. Lorius, B. Malaize, P. Martinerie, V. I. Nikolayev, J. R. Petit, D. Raynaud, G. Raisbeck, C. Ritz, A. N. Salamatin, E. Saltzman, T. Sowers, M. Stievenard, R. N. Vostretsov, M. Wahlen, C. Waelbroeck, F. Yiou, P. Yiou Ice cores drilled at Vostok Station, Antarctica, 10 years ago by Russia, France, and the United States are providing a wealth of information about past climate and environmental changes over more than a full glacial-interglacial cycle. The ice cores show that East Antarctica was colder and drier during glacial periods than during the Holocene and that atmospheric circulation was more vigorous during glacial times. The ice cores also support evidence from studies that use deep-sea sediment to reconstruct changes in past sea level and oceanic temperature. These studies link Pleistocene climate change with the position of the Earth on its orbit and tie carbon dioxide and methane concentrations to temperature. Vostok research station has operated year-round for more than 37 years. In the 1970's, researchers from the Soviet Union drilled a set of holes 500-952 m deep in the ice. These holes have been used to study the oxygen isotope composition of the ice, which showed that ice of the last glacial period was present below about 400 m depth. Then three more holes were drilled: in 1984, Hole 3G reached a final depth of 2202 m; in 1990, Hole 4G reached a final depth of 2546; and in 1993 Hole 5G reached a depth of 2755 m. The station was temporarily closed in January 1994, but it reopened last November and drilling continued during the winter of 1995. The core, the longest ever drilled, has now reached 3100 m. It is 50 m longer than the core from Greenland that previously held the record. Ice cores provide continuous information on key properties of paleoclimate including local temperature and precipitation rate, humidity, and wind speed. Ice cores also record changes in atmospheric composition. They can be used to measure trace gas concentrations, chemical impurities of terrestrial and marine origin, other trace compounds or isotopes, cosmogenic isotopes, extraterrestrial material, and aerosols of volcanic and anthropogenic origin. Ice cores from Vostok, Antarctica, were the first to cover a full glacial-interglacial cycle. And, despite recent drillings in central Greenland, they still carry the distinction of being the only ice cores that scientists are certain have remained undisturbed for the last interglacial and the penultimate glacial periods. Interpreting Paleoclimate From Ice Cores Two elements--deuterium and oxygen 18--are important because they can be used to reconstruct past temperature changes in polar regions. In Antarctica, a cooling of 1°C results in a decrease of 9 per mil deuterium. An accurate chronology is essential for interpreting ice core paleoclimate data. At Vostok, accumulation is too low for recognizable annual signals to form, so we developed a chronology combining an ice flow model and an accumulation model that accounts for the fact that accumulation was lower during colder periods and vice versa. Because the accumulation rate is governed by saturation water vapor pressure, past accumulation may be estimated from the temperature record. Accumulation rates inferred in this way are supported by measurements of beryllium 10 (10Be), an isotope produced by the interaction of cosmic rays and the upper atmosphere, can be used to determine past snow accumulation in Vostok ice. Deposition of this cosmogenic isotope is assumed to be constant. The chronology of the ice at Vostok has been established down to 2546 m, which is dated at 220,000 years before present. The combined deuterium record from the 3G and 4G cores shows the last two glacial-interglacial transitions with atmospheric temperature changes of about 6°C. The last ice age is characterized by three minima separated by slightly warmer episodes called interstadials. The penultimate glacial is characterized by the same sequence of interstadial events and taken as a whole the last two glacial periods appear very similar. The chronology of the Vostok ice core is also supported by a glaciological model. Southern Ocean temperature variations correlate with those at Vostok. Also, because photosynthesis transmits seawater variations to atmospheric O2, the variations in 18O of O2 in air trapped in the Vostok ice roughly coincide with variations in 18O of seawater reflected in the isotopic content of the forams in deep-sea sediments. There is also a correlation between the Vostok dust concentration and the record of mass accumulation rate in a core taken from the Indian Ocean. Beyond their use as dating tools, ice cores convey specific geochemical information. Variations in 10Be concentrations are caused by factors other than accumulation changes. The existence of peaks in 10Be around 35 and 60 kyr B.P. have been attributed to increased production of 10Be. The 18O of O2 record also contains information about fractionation by biogeochemical and hydrologic processes. Similarities between Vostok and Southern Ocean temperatures indicate that the Vostok record is representative of a large geographical area, while agreement with the 18O of deep- sea core suggests that the broad features of this record are somewhat global. Changes in terrestrial aerosols hold the key to past climate. More dust was present in glacial periods than during interglacials; this suggests that glacial periods were characterized by extensive deserts, intense surface winds in the desert source regions, and more efficient transport along the imaginary circular path that runs perpendicular to the equator through the poles. This idea of stronger circulation during glacial periods is reinforced by the fact that glacial values of marine aerosols are much higher than interglacial levels. Another important aspect of change in the past atmosphere's aerosol load is a secondary aerosol composed of nonseasalt sulfate and methanesulfonic acid (MSA), an oxidation product emitted by marine organisMs. Although studies based on MSA measurements show that the link between climate and biogenic marine activity could be more complex than initially thought, both nonseasalt sulfate and MSA records indicate that the ocean-atmosphere sulfur cycle is extremely sensitive to climate change. Sulfate aerosols affect climate by "thickening" the atmosphere. Air Sampling Air initially enclosed in Vostok ice provides our only record of variations in the atmospheric concentrations of CO2 and CH4 over a complete glacial-interglacial cycle. For both greenhouse gases, concentrations are higher during interglacial periods than during full glacial periods. Since preindustrial times, levels of CO2 and CH4 have increased sharply. A close correlation between these gas concentrations and the Vostok isotopic temperature has been confirmed by extending the record over part of the previous cycle. However, at the end of the last interglacial, the CO2 decrease significantly lags Antarctic cooling, while CO2 and Antarctic temperatures increase during the warmings of the glacial- interglacial transitions. Interestingly, at least during certain deglaciation periods, the trace gas increase precedes the onset of most melting of the northern ice sheets by several thousand years. From a climatic viewpoint, CO2 and CH4 have played an important role. Together with the growth and decay of the Northern Hemisphere ice sheets, these greenhouse gases have amplified the initial orbital forcing, and they account for about half of the glacial-interglacial climate changes. This supports the idea that significant greenhouse warming will occur in the next century. Ice sheet modeling is used to date ice cores and study long-term interaction between climate and the dynamics of large ice sheets. Information gained from studies of ice texture and fabric, ice rheology, and ice densification is crucial to this objective. Models predict that the ice sheet over Vostok will thin during cold periods. In agreement, the long-term trends of total air content in the ice show that during colder periods air pressure was higher. This supports the idea that elevation of the ice sheet was lower. Other studies confirm that microorganisms-- including species that have disappeared elsewhere--could survive in the deep Antarctic ice for many thousands of years following anabiosis. Sample Analysis: Preliminary Results In France and the United States, analysis of samples of the last 200 m of core 5G are nearly complete and exciting results have emerged. The bottom part of the core (2755 m) corresponds to an age of 240 kyr B.P., reaching back to the penultimate interglacial period. The warmest part of this penultimate interglacial was likely as warm as today in Antarctica. One of the most remarkable result derived from this new record is the striking similarity of the last two climatic cycles, which is not documented in any other paleorecord. GLOSSARY Chronology- Arranging events in their proper sequence. Cosmogenic Isotope- An isotope that can be used to study the age and origin of the Earth. Forams- A family of aquatic microorganisms that are important as age indicators, as rock-building agents, and in seafloor deposits. Fractionation- The separation of chemical elements in nature. Ice Age- A time of extensive glacial activity also called a glacial epoch (see definition for Pleistocene). Ice Sheet Modeling- Ice sheet models incorporate ice-flow laws that account for the mechanical and thermodynamical properties of the ice. Interstadial- Warmer substage of a glacial stage, marked by a temporary retreat of the ice. Isotope- A particular atom of an element that has the same number of electrons and protons as the other atoms of the element, but a different number of neutrons. The temperature at which an oxygen- bearing geologic material formed can be determined by studying the oxygen isotope it contains. Minima- Time or position of the greatest retreat of a glacier. Pleistocene- The "Great Ice Age," during which glaciers and ice sheets covered the land masses 4 times over 2 million years ago. These massive ice advances were separated by longer warm interglacial periods. ------------------------------------------------------------------ CASSINI MISSION STATUS JPL release 3 March, 1998 The Cassini spacecraft successfully performed the second scheduled trajectory adjustment of its mission last week, fine- tuning its flight path in preparation for its flyby of Venus on April 26. The trajectory adjustment needed was so minor that the maneuver was performed using Cassini's small hydrazine thrusters instead of the spacecraft's large main engine. Engineering data recorded during the thruster firing confirmed that the maneuver went as planned, with all spacecraft and ground components performing perfectly. A final trajectory adjustment prior to the Venus flyby is scheduled in early April. Cassini remains in excellent health, flying at a speed relative to the Sun of approximately 137,000 kilometers per hour (about 85,000 miles per hour). It is slowly gaining speed as it feels the tug of gravity from Venus. The spacecraft will gain a significant boost in speed when it swings around Venus next month. Cassini has traveled approximately 362 million kilometers (about 224 million miles) since launch on October 15, 1997. ------------------------------------------------------------------ STARDUST STATUS REPORT by Ken Atkins 27 February, 1998 STARDUST Assembly, Test and Launch Operations (ATLO) made good progress this week with telecom interface tests nearing completion today. A solution was developed for the data transfer problems discovered in the Cometary and Interstellar Dust Analyzer (CIDA) interface testing last month. Plans show the upgraded electronic simulator box arriving from Germany next week to support validating and testing the fix. New ATLO flow plans allowed the CIDA team two weeks of schedule relief for their flight unit delivery. The flight Sample Return Capsule (SRC) canister bake-out was completed to provide the required clean environment for aerogel collector tray installation. The SRC avionics completed 100 hours burn in and the certification was completed to permit flight installation. Fault Protection workshop #3 was held this week in order to concentrate on Fault Protection test planning and execution. Results were very good, indicating a thorough test program for the fault protection software. The flight solar arrays completed functional lighting tests and acoustic test. The first chip containing public names, letters and pictures has been installed on the SRC avionics deck. For more information on the STARDUST mission--the first ever comet sample return mission--please visit the STARDUST home page: http://stardust.jpl.nasa.gov/ ------------------------------------------------------------------ End Marsbugs Vol. 5, No. 5