MARSBUGS: The Electronic Astrobiology Newsletter Volume 6, Number 17, 18 June 1999. Editors: Dr. David J. Thomas, Biology and Chemistry Division, Lyon College, Batesville, AR 72503-2317, USA. Marsbugs@aol.com or dthomas@lyon.edu Dr. Julian A. Hiscox, School of Animal and Microbial Sciences, University of Reading, Reading, RG6 6AJ, United Kingdom. J.A.Hiscox@reading.ac.uk Marsbugs is published on a weekly to 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) A RETURN TO UTOPIA? By Julian A. Hiscox, Howell G. M. Edwards, David Wynn-Williams 2) UNEARTHING CLUES TO MARTIAN FOSSILS: THE HUNT FOR SIGNS OF ANCIENT LIFE ON MARS LEADS SCIENTISTS TO MONO LAKE, CA By Tony Philips 3) EUROPE IS GOING TO MARS From ESA Science News 4) NEW MARS GLOBAL SURVEYOR IMAGES By Ron Baalke 5) GALILEO EUROPA MISSION STATUS JPL release 6) THIS WEEK ON GALILEO JPL release 7) JPL'S NEW MARS ROVER TO BE REMOTELY CONTROLLED BY L.A. STUDENTS JPL release ------------------------------------------------------------------ A RETURN TO UTOPIA? By Julian A. Hiscox1*, Howell G. M. Edwards2, David Wynn-Williams3 11 June 1999 1School of Animal and Microbial Sciences, University of Reading. 2Chemical and Forensic Sciences, University of Bradford. 3British Antarctic Survey *To whom correspondence should be addressed: j.a.hiscox@reading.ac.uk The search for life in the solar system is a long and complex process. Over twenty years have passed since our last direct search for extraterrestrial life. The planet of choice was Mars and the reasons for looking for life were based upon centuries of speculation and a little scientific data about the planet. Two identical spacecraft, called Viking, were sent to Mars, each was composed of an orbiter and lander. One of the functions of the landers was to look for microbial life at two separate locations on the surface. The three Viking Lander experiments and the gas chromatograph-mass spectrometer (GCMS) pretty much demonstrated that no terrestrial type life was found adjacent to the Viking Landers and by inference the rest of the planet's surface. At the time there was wide spread disappointment with the result and many scientists pretty much rapped up the life on other worlds debate. This feeling was perhaps best summed up by the former chief of the bioscience section of the Mariner and Viking missions at the Jet Propulsion Laboratory, Norman H. Horowitz. In his book, To Utopia and Back, he wrote "The failure to find life on Mars was a disappointment, but it was also a revelation. Since Mars offered by the most promising habitat for extraterrestrial life in the solar system. It is now almost certain that the Earth is the only life-bearing planet in our region of the galaxy". Yet for the past few years planetary scientists are again a buzz about the possibility of finding both extinct and possibly living (extant life) on Mars, and another more outlandish body of the solar system, Europa, one of Jupiter's satellites. Why is this so? Since the Viking biology experiments were conceived in the 1960s we have a far better understanding of life on Earth, both at the physical and molecular level. This guides us as to where we can feasibly speculate that life might reside on other planets (and moons). Life scientists used to think that life was confined with fairly narrow parameters, yet the versatility of microbial life illustrates that evolution has little boundaries. Any habitat suitable for the growth of higher organisms will also permit microbial growth, but in addition, there are many habitats unfavorable to higher organisms where microorganisms exist and even flourish. Microbes can live in the deserts of Antarctica-- the coldest driest places on Earth, to hot springs--the hottest, wettest places on Earth. Recently terrestrial organisms have been discovered living within the Columbia River basalt in the Pacific northwest and elsewhere. Other locations include places as deep as three kilometers below the surface. These locales provide a model for the possibility of organisms living deep below the martian surface protected from the harsh ultra-violet radiation that bathes the surface and the extremely cold temperatures. These organisms survive by metabolizing hydrogen that has been produced by chemical interactions between pore water and the basalt, they are thought to be completely independent of any input chemical energy from the surface, and are thus completely divorced from the Sun. Planetary habitability Scientists have recognized that there is a close coupling between life and geological and possible atmospheric conditions. Logically one of the key criteria identified was the stability of liquid water over geologically significant periods of time. Liquid water is a fundamental requirement for life. Not only because reactions occur in solution, but also it plays a fundamental role in life's chemistry. The other most important molecules are carbon, nitrogen, sulfur and phosphorus. Together with the elements in water (hydrogen and oxygen), they form the CHNOPS elements. Two bodies that may satisfy these criteria in the solar system are ancient Mars and present day Europa. Because of the Viking landers, Mars Pathfinder and analysis of the thirteen meteorites from Mars we are pretty certain that CHNOPS elements are or were present on Mars. Analysis of images taken from orbit, by Mariner 9, Viking Orbiters 1 and 2, and Mars Surveyor provide almost definitive evidence that liquid water once flowed freely on the martian surface. So much so, that some scientists speculate that the northern martian plains may once have been covered with an ocean. If liquid water was stable on Mars, then this implies that the climate was warmer and wetter, i.e. a thicker carbon dioxide atmosphere. Both Voyager 2 and more recently Galileo have returned abundant images which indicate that Europa has a liquid water interior surrounded by an icy coat. However, no detailed analysis has been conducted for the CHNOPS elements. Given that Mars was once flowing in water why didn't Viking find any traces of martian life? The answer is probably simple; it was the wrong place and looked for the wrong type of microorganisms. In looking for life there are many routes to take and no one route is likely to provide a definitive answer. Imagine trying to look for life on the Earth. You could hit the jackpot and land on a cornfield in the middle of Nebraska--pretty obvious signs of life. You could land in the middle of Yankee Stadium, you could land in the sea, or you could end in the middle of a volcano, and so on. Each one of these samplings would give you an increasingly better idea of life on Earth. Therefore, perhaps the best approach when looking for life would be to send a number of probes to different locations or to sample different material. Given that the martian surface is an extremely hostile place for life then one place to look for living martian organisms would be below the surface, perhaps deep underground where liquid water may still be in abundance. Based upon hydrological models that take into account global martian topography, Martyn Fogg predicts the existence of artesian basins on Mars where pressurized groundwater may exist at comparatively shallow depths. Fogg suggests that it is possible that such basins are extensive and could involve Hellas and much of the northern plains. The implication of this is that the liquid water resource on Mars might be easier to probe and exploit than commonly assumed. Mike Carr, of the United States Geological Survey, argues that the geothermal gradient is such that Mars is likely to have liquid water near the equator at depths as shallow as about two kilometers. The presence of water is suggested by large flood channels that appear to have been caused by the occasional sudden release of large quantities of liquid water from deep below the surface. From studying different types of microbes on Earth and in different habitats we can paint a picture of what and where life might be found on Mars and also Europa. When we think of existence of microbes in nature we must learn to think small. Because microorganisms are usually invisible, their physical existence in an environment is often unsuspected - especially on other planets. In many cases it is not the microorganisms themselves that we observe in a natural environment, but instead, like the Viking landers, we look for chemical evidence of their existence. Several procedures are available for looking for microbial activity. One of the most widely used is measurement of respiration, as either oxygen uptake or carbon dioxide production. A sample of soil or water is incubated in a closed chamber under simulated natural conditions and a change in one of these gases is measured. Although adequate, this method is not very sensitive. A similar principal was used by the Viking landers--but with far more sensitivity. The Viking approach For the measurement of specific microbial processes in the environment, radioisotopes are very useful. They provide extremely sensitive and highly specific means of measuring chemical processes. Which is one of the reasons why they were chosen for the Viking lander experiments. For example, if photosynthesis is to be measured, the light-dependent uptake of radioactive carbon dioxide (14CO2) into cells can be measured. Methanogenesis in natural environments can be studied by measuring the conversion of 14CO2 to 14CH4 (methane). Heterotrophic activity can be measured by following incorporation of 14C-organic compounds (for example, the uptake of 14C-glucose or 14C-amino acids). If sulfate reduction is of interest, the rate of conversion of 35SO4- to H235S can be assessed. When considering radioactive tracers for Mars and especially Europa, consideration has to be given to mission duration. Given current transit times between Earth and Mars and Europa, any experiments involving 35S would probably impractical. 35S is a very short-lived isotope (approximately 56 days), versus over nine years for 14C. As with the Viking lander experiments, there is always the possibility that some transformation of a labeled compound might be due to a strictly chemical or physical process, rather than microbial process, it is essential when using isotopes to employ proper controls. The key control necessary, of course is the killed cell control. It is absolutely essential to show that the transformation being measured in nature is prevented by microbial agents or heat treatments that are known to block microbial action or kill the organisms. For Mars, it would be prudent to heat treat samples at least above 113°C--the upper limit for microbial life on this planet. Alternative methods for sterilization could include chemical treatment, such as four percent formalin--however this may interact with the chemistry of the regolith sample. Perhaps a better alternative would be exposure of the sample to a lethal level of radiation. Such a source of radioactivity--say cobalt--could be easily carried on a lander. Viking labeled release mk2. Gil Levin, the main proponent that life might still be present at the martian surface, and that the Viking experiments showed a positive sign for life, has proposed what he describes as an unambiguous martian life detection experiment. The instrument to conduct this experiment is based on the Viking labeled release (LR) experiment. Levin's rationale is that all known life forms make and utilize L-amino acids and D-carbohydrates preferentially over the respective stereoisomers. On the other hand, no natural chemical reactions can distinguish between stereoisomers. Therefore, any strong response by an unknown agent to one isomer of an administered compound over its stereoisomer constitutes indisputable proof that the agent producing the reagent is biological. Levin suggests that a modified LR instrument could administer L- and D-isomers of amino acids and carbohydrates to discrete portions of the same soil sample. If one isomer was preferentially depleted compared to that of the other isomer, then he suggests this would be proof of life. Assuming a positive response, Levin goes further and suggests that if the stereo- specificity differs from terrestrial life that this would hint an independent origin of life. The same stereo-specificity between "martian" life and terrestrial life would give no indication either way, as presumably there is a fifty-fifty chance that life could use the D- or L-forms of biological material. Whilst in principle an excellent idea, the assumption is made that martian organisms will use either the D- or L - forms of amino acids and carbohydrates. One could imagine a scenario by which martian organisms could utilize both types of compounds. Such a metabolic pathway may have evolved because presumably such material would have been scarce on Mars once surface became deleterious for life. Therefore if the D- and L- forms were equally depleted then this could be due to either a feature of the martian surface chemistry (as probably happened with the Viking biology experiments), or life. Since technology has advanced since the Viking Lander instruments, which were developed in the sixties and early seventies, the modified LR instrument could be simplified and miniaturized compared to the original. Levin proposes that this new instrument could be deployed on the planetary surface and, or placed in penetrators to sample at depth. Prepare the electrodes... A number of microbial ecologists on the Earth are making use of small glass electrodes to study microbes. These electrodes are commonly referred to as microelectrodes and are used to measure the activity of microorganisms in nature. Although limited to measurements of those chemical species that can be detected with an electrode, and also a microenvironment with liquid water, several types of electrodes have found use in field studies. The three most commonly used microelectrodes are those that measure oxygen, sulfide and pH. As the name implies microelectrodes are very small, and the tip of an electrode ranges in diameter from 5 to 100 µm. The electrodes are carefully inserted into the material to be studied using a micro-manipulator--a device that allows for precise movement of the electrode through distances of a millimeter or less. Microelectrodes have been used extensively in the study of chemical transformations and photosynthesis in microbial mats. Microelectrodes allow the investigator to make sequential measurements of a particular chemical parameter at extremely fine intervals while passing through the mat. They can be immersed through a microbial mat in 200-300 µm increments, and have proven to be the only method of measuring the extremely sharp gradients of chemical such as oxygen and sulfide that occur in these ecosystems. Microelectrodes do have their limitations. A key one is their fragility. Also, they are not practical tools for the study of solid habitats such as dry soil. So they could not be used on the surface of Mars, but could presumably be used in polar regions, or in the subsurface environment where liquid water might be stable. Or Europa! The softly, softly approach Many of the experiments for looking for subsurface life on Mars and Europa would necessarily involve the destruction of the material that the putative life was contained in, and perhaps more importantly, any martian organisms would also be destroyed. This seems a shame given that if live was present it may presumably be very scarce! One approach that would be non-destructive is being developed by Howell Edwards at the University of Bradford and David Wynn-Williams of the British Antarctic Survey, and their exobiology research student, Emma Newton. Their idea (and others) is to use what is called a Raman spectroscope. This instrument shines a laser beam at a sample and then measures the light that is scattered. Depending on the properties of the sample, the amount and type of light scattered varies. The Raman spectrum of a given compound consists of a unique fingerprint of all its atoms, groups and their interactive effect. Characteristic peaks from this spectrum can be used to identify a target compound amongst other in a mixed sample. In addition, this technique can distinguish material of both biological and non-biological (geological) in origin. The focused laser beam allows analysis of discrete biological layers within mineral substrata. Short wavelength lasers can be used to analyze biomolecules and inorganic materials of the mineral habitat (rock or soil). However, pigments of the photosynthetic microbes that use sunlight to drive surface communities fluoresce under short-wave light. So to analyze organisms such as the cyanobacteria which were amongst the earliest colonists of the surface of the Earth over 3.5 billion years ago, they use an infra-red laser which gives a Raman spectrum without interference from fluorescence. As cyanobacteria may have evolved on Mars during the "warm wet" period at the same geological time as on Earth, this approach could be used to detect their fossil biomolecules in martian sediments. Using an infrared Raman spectrometer in the laboratory, Edwards and Wynn-Williams have examined translucent sandstone samples containing cryptoendolithic microorganisms from the Antarctic dry valleys. Endolithic communities, up to 8 mm inside the fabric of the rock, might have been the final survivors on Mars as the surface water either froze into permafrost or was lost from the surface altogether. This Antarctic habitat provides one of the best models for life on ancient Mars. The "biological signatures", so called bio-markers, left behind by extinct martian endolithic microorganisms could be could be compared with an Antarctic database of the "fingerprints" of similar biomolecules for interpreting future exobiological surveys of the martian surface. At the moment laboratory-based infrared Raman spectrometers weigh several tens of kilograms and require high levels of power consumption. If they are going to be incorporated onto Mars landers, in today's times of faster, better, cheaper then their weight and power consumption are going to have to be reduced. In addition these instruments are very delicate and the shock of a "hard" landing on Mars would be detrimental, as well as a fluctuation in temperature of up to 150oC. Howell Edwards suggests improvements can be made such as special CCD detectors, fiber optics, solid state diode lasers and holographic filters. With compromises using slightly shorter wavelengths, we foresee that the mass of a Mars instrument suitable for cyanobacterial studies could be reduced to about 1 kg, like the short-wavelength systems already aboard NASA Mars missions. To take a laboratory to Mars or Europa or to bring Mars to Earth? The investigation of samples from the SNC meteorites has shown how both unambiguous and ambiguous laboratory analyses can be. Because of project Viking we know the precise composition of the martian atmosphere and coupled with Mars Pathfinder a fair idea of the mineralogical composition of the martian regolith. Using this data we can with a great degree of confidence (99.99%) state that the SNC meteorites are martian in origin. However, as Malcolm Walter pointed out because ALH84001 is a rock out of context we have no precise idea of the history of the rock. If we are talking about looking for microfossils we know that we should be looking in areas where liquid water was present--i.e. sedimentary regions. Whilst measurements of the martian surface from landers and rovers are fantastic, one of the holy grails of robotic exploration must surely be a sample return mission. As Mike Carr suggests in his book "Water on Mars", Experience with the Moon emphasizes the enormous power of returned samples when placed in the context of global data... having lunar samples in hand allowed the complete analytic and intellectual capacity of the science community to focus on the Moon's evolution. The current science-craft in orbit around Mars at the moment should be able to point us to regions of biological interest. These include hydrothermal deposits, ancient sediments deposited by water, and lacustrine sediments. Although photosynthetic systems are energetically the most efficient way of obtaining energy for metabolism, there are anaerobic (oxygen-free) microbial systems, which can obtain energy from chemical transformations of iron, sulfur or even hydrogen. The "chemolithotrophic" organisms that can do this do not require sunlight and can therefore evolve in the dark, geothermally warmed ground-water of the deep subsurface of Earth and possibly Mars. We have found them on Earth living kilometers below the surface. Beneath the land, they are known to grow under high pressures at temperatures above 76°C, whilst in the "black smokers" of mid- oceanic ridges the record growth temperature is now 113°C for a bacterium called Pyrolobus. These anaerobic bacteria could be alive on Mars right now, perhaps two kilometers beneath the surface, unfortunately out of the reach of current lander technology. Another potential chemolithotrophic microbial community supported by anaerobic geothermal conditions may exist beneath the ice-crust of Jupiter's moon, Europa. Its eccentric orbit results in tidal friction, which warms up its core and may create "black smokers" in the potential sub-ice ocean. Europa being further away than Mars makes sample return missions even more complex. Probably the best bet with Europa will be to send a number of sophisticated robots that are able to explore the Europan ocean. Currently planetary scientists are evaluating such techniques in Antarctica. An underground lake the size of lake Ontario has been discovered 4.2 km beneath the central Antarctic ice sheet. The lake, called Vostok, has been isolated from the rest of the planet for over a million years. Scientists and engineers are developing an instrument called a Cryobot, which can melt ice, and a "Hydrobot" submersible which will not only image the underside of the ice and sediments but will also look for potentially life-supporting "hot spots", analogous to those predicted for Europa. Summary As our knowledge of the survival limits of microbial life on Earth broadens with the discovery of organisms in increasingly "hostile" habitats, so we must broaden our view of the likelihood of finding evidence of former, or even current, life on Mars and or Europa. The challenge will be finding sites where their biomolecules are preserved for comparison with our increasing Earthly database of microbial "fingerprints". ------------------------------------------------------------------ UNEARTHING CLUES TO MARTIAN FOSSILS: THE HUNT FOR SIGNS OF ANCIENT LIFE ON MARS LEADS SCIENTISTS TO MONO LAKE, CA By Tony Philips From NASA Space Science News 11 June 1999 If, while innocently enjoying this article, you were unexpectedly transported to the surface of Mars, three things would happen before you could finish reading. First you would die either from asphyxiation or hypothermia. Mars' carbon dioxide atmosphere is 100 times less dense than Earth's and the average surface temperature is -60°C. The exact cause of death would depend on the season, the time of day (martian temperatures fluctuate as much as 100° from dawn to dusk), and the latitude of your surprise landing site. Next you would begin to dry out. There is no liquid water on the surface of Mars and little, if any water vapor in the atmosphere. Your lifeless body would become desiccated like an Egyptian mummy. Finally, not that it would matter terribly, you would contract a very nasty sunburn. The red planet's rarefied atmosphere does a poor job blocking UV rays from the sun (there is no protective ozone layer in the atmosphere). Radiation levels are so intense that they probably sterilize the uppermost layers of Martian soil. The next time you visit Mars, take a space suit. Undoubtedly present-day Mars is not a congenial place for life as we know it, but it may have been friendlier in the distant past. There is growing evidence to support a view of ancient Mars as a remarkably Earth-like planet. Between three and four billion years ago liquid water flowed in channels and collected in lakes and ponds all over the red planet. There may have even been an ocean. The surface temperature was a balmy 0°C or above to allow liquid water. To allow that to happen, the atmosphere must have been a lot denser than it is today. A dynamic molten core gave rise to a global magnetic field that protected Mars from the ravages of the solar wind and powered tectonic activity in the martian crust. Hot springs were likely commonplace. Billowing volcanoes resupplied a dense martian atmosphere with greenhouse gases needed to sustain a warm and wet climate. The reality of this picture is somewhat controversial, but if it is true, it seems likely to many scientists that early Mars could have teemed with simple forms of life. "Microbial communities developed on early Earth in less than a billion years, so it's plausible that simple organisms also developed on an early wet and SCIENCE NEWS warm Mars," says Dr Jack Farmer, a geobiologist at Arizona State University. "Current conditions on the martian surface are hostile to life, but there might be a fossil record of ancient microorganisms if we look in the right places." Farmer (formerly of NASA/Ames) along with his collaborators at ASU, is a pioneer in the new scientific discipline called exopaleontology--the search for signs of primeval life on other planets. "Mars may harbor the best preserved rocks in the solar system," he continued. "For example, the Allan Hills meteorite [an ancient potato-sized rock from Mars that crashed into Antarctica 13,000 years ago] is nearly 4.6 billion years old. The fossil record on Mars might go all the way back to the earliest history of the planet." Farmer says he wouldn't mind visiting Mars to prospect for fossils in person, but an unmanned probe is likely to be the first exopaleontologist on the red planet. Where should a Mars lander set down to seek out the elusive fossil record? The answer to that question may be found here on Earth in an otherworldly place called Mono Lake. Mono Lake "Mono Lake lies in a lifeless, hideous desert... This solemn, silent, sailless sea--this lonely tenant of the loneliest spot on earth--is little graced with the picturesque." -Mark Twain, Roughing It, 1875 Mono Lake in California is nearly 700,000 years old, making it one of the oldest lakes in North America. Throughout its long existence, salts and minerals have washed into the lake from Eastern Sierra streams, but there is no outlet. Fresh water evaporating leaves behind salts and minerals so that now Mono Lake is about 21/2 times as salty and 80 times as alkaline as the ocean. Swimmers in the lake find that they literally cannot sink (dissolved carbonates, chlorides and sulfates make floating easy) but their skin does tend to bleach and burn in the alkaline water. Although Mono Lake is an extreme environment for life, it hosts a thriving ecosystem. There are no fish, but the lake supports trillions of brine shrimp (which feed vast numbers of nesting and migrating birds) and a bizarre variety of scuba-diving alkaline flies. It is also brimming with microorganisms such as diatoms, cyanobacteria and filamentous algae. "The geology of the Mono Basin reminds me of many old martian lake beds," says Farmer. "Take Gusev Crater for example. It's a basin on Mars formed by an impact more than 3.5 billion years ago. Water flowed in through channels in a huge canyon called Ma'adim Vallis, but there was no outlet. It was an evaporative lake site." There is almost certainly no life in places like Gusev Crater today. All the ancient ponds and lakes on Mars are now bone dry and scorched by solar UV radiation. Nevertheless, there could be fossils of life forms that thrived billions of years ago, and a curious geological feature of Mono Lake may be telling us where and how to look for them. At first glance the most striking aspect of Mono Lake are the weird mineral spires called tufa, a type of freshwater limestone. They are formed when calcium-rich spring water bubbles up through the alkaline lake, which is rich in bicarbonate. The calcium and bicarbonate combine, precipitating out as limestone. Tufa towers only grow while underwater, but at Mono Lake they can be seen towering as much as 12 feet above the surface. That's because the lake level has been lowered in recent years to supply water to Los Angeles, 360 miles to the south. "Whenever you have minerals that precipitate rapidly as they do around the springs in Mono Lake, microorganisms become entombed," says Farmer. "The fossils of soft-bodied microbes formed by this process could be preserved for billions of years." Farmer has spent many years studying the tufa at Mono Lake as an analog of carbonate deposits that might one day be discovered on Mars. "There are lots of microfossils here and there in the tufa, formed where the rapid precipitation of carbonates captured microorganisms," continued Farmer. "I've seen larval casings of alkaline flies and cyanobacteria fossils, also things that look like algae (simple multicellular plants). I haven't yet found any fossils of brine shrimp, but I'm still looking." "In thin sections of tufa I've also found clumps of decayed organic material called kerogen, which may contain chemofossil signatures. Chemofossils are the chemicals produced by the breakdown of cell walls. For example, Mono Lake diatoms have a hard shell with an organic coating that protects them from the alkaline water. When they die, the coating dissolves and so does the diatom. All that's left of this organic material is trace chemicals. It is possible to relate such products to specific organisms like diatoms or algae, but its not always easy. You have to become a Sherlock Holmes and piece together what the community must have been like from clues (both chemical and fossil) that are preserved." "In evaporative basins, there's a lot of variation in chemistry from basin to basin, and throughout the history of the lake," Farmer continued. "What's beautiful about Mono Lake is that we have an active system of tufa-formation and mineral precipitation. Other paleo-lake basins in Western North America are now dry because the climate has changed and evaporation now dominates inflow." In search of Mono Lake--on Mars? Finding microfossils on Mars won't be easy, even if life once existed there. After all Mars is a big planet and fossils are not likely to be found just anywhere. No one knows for sure, but Farmer and collaborators think that a good starting point might be evaporative basins with carbonate deposits where microbial fossils could be entombed, in other words, places that were once like Mono Lake. The chemical mixture in an evaporative basin depends on what kinds of rocks are in the vicinity. When water flows into a lake, it flows over rocks and dissolves minerals and ions such as sodium, chloride ions, potassium, and calcium--all the salts commonly found in the Western Salt Lakes. In an evaporative basin the salts and minerals become concentrated, and the lake naturally becomes alkaline with pH >9. The detailed chemical balance depends on the details of the terrain. This general picture is true on both Mars and Earth. "Compared to Earth, Mars has a much different set of source rocks," explains Farmer. "On Mars the crust is more like the ocean floor on Earth, featuring basalts, iron, magnesium, and silicate-poor rocks. Rocks in the Mono Basin are enriched in silica, sodium and potassium. Because water was less abundant, it took longer to build up briny water on Mars through evaporation. But the waters there would be richer in calcium, magnesium, and iron. In spite of these chemical differences, the basic picture is still the same: rapid precipitation of minerals would have been an important process in these ancient martian basins, and if microorganisms were there, their fossils would have been entombed." Phil Christensen, one of Farmer's collaborators, is using the Thermal Emission Spectrograph (TES) on Mars Global Surveyor to search out places on Mars with tufa-like carbonate formations in evaporated lake beds. Carbonates have specific kinds of absorption features in mid-infrared spectra that should be easy to identify. Unfortunately, the resolution of the TES is only 3 km/pixel, which would make smaller carbonate deposits like those at Mono Lake difficult to detect. In March 2001 an Arizona State University instrument called THEMIS (Thermal Emission Imaging System) is scheduled for launch on NASA's Mars Surveyor 2001 orbiter. With a spatial resolution of 100m per pixel, the ASU spectrometer could easily detect the signature of carbonate deposits at the scale of the Mono Lake tufas. "I'm optimistic," concludes Farmer. "Eventually I believe we're going to find carbonate deposits on Mars--places that remind us of Mono Lake--and when we do we'll have strong arguments for a landing site for exobiology. It's just a matter of time." Appendix: Where did all the water go? There may have once been ponds and lakes on Mars, but they're dry now. Physical conditions on the surface of Mars, namely low atmospheric pressure and low temperature, conspire to make liquid water unstable. The average atmospheric pressure on Mars is only about six millibars compared to the Earth's average pressure of 1013 millibars. The average surface temperature on Mars is about -60°C compared to the Earth's 15°C. At certain locations and times on Mars, when the air pressure is high enough and the temperature is above freezing (greater than 0°C), liquid water is theoretically possible; but the rate of evaporation would be so great that liquid water (if it were present) would rapidly vaporize. Nevertheless, there is widespread evidence of dried-up valleys and channels thought to have been eroded by liquid water. Many martian outflow channels strongly resemble flood channels on Earth, like those in eastern Washington in the USA. On Mars they may have formed when groundwater or subsurface slush was catastrophically brought to the surface, perhaps triggered by large impacts or "marsquakes". On the other hand, geological studies of the valley networks suggest that these must have been gradually eroded by running water: some show morphology suggesting formation by groundwater sapping (i.e. when a river is fed by a spring and the valley grows by headward erosion); others seem to have been produced by precipitation runoff. The valley networks are almost completely (but not quite) restricted to ancient upper highlands, dated as 3.5 to 4.0 billion years old from the quantity of impact craters, so it is postulated that environmental conditions on Mars must have been conducive to liquid water at this time. Right: High resolution Mars Global Surveyor images were combined [Image] with Viking Orbiter color data to produce this stunning, detailed view of a Martian canyon's edge. The area pictured is about 6 miles wide and represents a tiny part of the northern edge of the canyon Valles Marineris, whose total length is about 2,500 miles. Details 20 to 30 feet across can be seen in the high- resolution data. What processes caused the well-defined layers in the steep canyon walls? In the Grand Canyon on planet Earth, sedimentary processes have resulted in spectacular rock layers. But volcanoes created similar layers of rock in canyons of the Hawaiian Islands. Regardless of the origin of layering on Mars, its extent suggests that early Mars was geologically active and complex. The upper limit on the present amount of water on the martian surface is 800,000 to 1.2 million cubic miles (3.2 to 4.7 million cubic kilometers), or about 1.5 times the amount of ice covering Greenland. If both caps are composed completely of water, the combined volumes are equivalent to a global layer 66 to 100 feet (22 to 33 meters) deep, about one-third the minimum volume of a proposed ancient ocean on Mars. [For more information on this story, see http://science.nasa.gov/newhome/headlines/ast11jun99_1.htm] ------------------------------------------------------------------ EUROPE IS GOING TO MARS From ESA Science News (http://sci.esa.int) 11 June 1999 The European Space Agency's Mars Express mission has won unanimous approval. It will be the first mission Europe has sent to the red planet. The Agency's Science Programme Committee (SPC) approved Mars Express after ESA's Council, meeting at ministerial level in Brussels on 11 and 12 May, had agreed the level of the science budget for the next 4 years, just enough to make the mission affordable. "Mars Express is a mission of opportunity and we felt we just had to jump in and do it. We are convinced it will produce first-rate science", says Hans Balsiger, SPC chairman. As well as being a first for Europe in Mars exploration, Mars Express will pioneer new, cheaper ways of doing space science missions. "With a total cost of just 150 million euros, Mars Express will be the cheapest Mars mission ever undertaken", says Roger Bonnet, ESA's Director of Science. Mars Express will be launched in June 2003. When it arrives at the red planet six months later, it will begin to search for water and life. Seven instruments, provided by space research institutes throughout Europe, will make observations from the main spacecraft as it orbits the planet. Just before the spacecraft arrives, it will release a small lander, provided by research institutes in the UK, that will journey on to the surface to look for signs of life. The lander is called Beagle 2 after the ship in which Charles Darwin sailed round the world in search of evidence supporting his theory of evolution. But just as Darwin had to raise the money for his trip, so the search is on for public and private finance for Beagle 2. "Beagle 2 is an extremely important element of the mission", says Bonnet. Europe's space scientists have envisaged a mission to Mars for over fifteen years. But limited funding has prevented previous proposals from going ahead. The positioning of the planets in 2003, however, offers a particularly favorable passage to the red planet--an opportunity not to be missed. Mars Express will be joined by an international flotilla of spacecraft that will also be using this opportunity to work together on scientific questions and pave the way for future exploration. ESA is now able to afford Mars Express because it will be built more quickly and cheaply than any other comparable mission. It will be the first of the Agency's new flexible missions, based on maximum reuse of technology off-the-shelf and from other missions (the Rosetta cometary mission in this case). Mars Express will explore the extent to which innovative working practices, now made possible by the maturity of Europe's space industry, can cut mission costs and the time from concept to launch: a new kind of relationship with industrial partners is starting. "We are adopting a new approach to management by delegating to Matra Marconi Space (the prime contractor) responsibility for the whole project. This means we can reduce the ESA's management costs," says Bonnet. Despite the knockdown price, however, the future of Mars Express has hung in the balance because of the steady erosion of ESA's space science budget since 1995. Last November, the SPC said the mission could go ahead only if it could be afforded without affecting missions already approved, especially the FIRST infra- red observatory and the Planck mission to measure the cosmic microwave background. On 19/20 May, the SPC, which has the ultimate decision over the Agency's science missions, agreed that the level of resources allowed was just sufficient to allow Mars Express to go ahead. "To do such an ambitious mission for so little money is a challenge and we have decided to meet", says Balsiger. For more information, please contact ESA Public Relations Division Phone: +33(0)1.53.69.7155, Fax: +33(0)1.53.69.7690 Useful links for this story Mars Express mission overview http://www.estec.esa.nl/spdwww/mars/html/moreabout.html Close encounter with Mars http://sci.esa.int/missions/newsitem.cfm?TypeID=22&ContentID=4650 ------------------------------------------------------------------ NEW MARS GLOBAL SURVEYOR IMAGES By Ron Baalke 10 June 1999 The following new images taken by the Mars Global Surveyor spacecraft are now available. North Nilosyrtis Mensae Regional View of the Tharsis Volcanoes 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 North Nilosyrtis Mensae MGS MOC Release No. MOC2-133, 10 June 1999 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image was obtained during the first week of June 1999. It shows a portion of the Nilosyrtis Mensae region, located north of Syrtis Major and southwest of Utopia Planitia. This region is part of a planet-wide transition zone that separates the high, cratered terrain of the southern two thirds of Mars from the low, relatively uncratered northern plains. Old remnants of the cratered highlands are common in this transition zone, and they are usually in the form of mesas and buttes. The MOC image shows several low, flat-topped mesas. Although flat at large scale, their surfaces are quite rough and bumpy at smaller scales. Many of these bumps might be boulders, but the resolution of this particular image (4.5 meters--15 feet--per pixel) is not high enough to be certain. The lowlands surrounding the mesas are cracked and pitted--especially the darker surfaces on the right side of the image. The cause of the pitting is not known and can only be speculated upon (because the material removed from each pit is now gone). Possible origins for the pits include removal of dust or sand by wind and/or sublimation of ice from the near subsurface. The picture covers an area 3 kilometers (1.9 miles) wide and is illuminated from the left. Mars Global Surveyor Mars Orbiter Camera Regional View of the Tharsis Volcanoes MGS MOC Release No. MOC2-134, 10 June 1999 The volcanoes of the Tharsis region are highlighted by this color image mosaic obtained on a single martian afternoon by the Mars Orbiter Camera (MOC) onboard the Mars Global Surveyor (MGS) spacecraft. Olympus Mons dominates the upper left corner--it is one of the largest known volcanoes and is nearly 550 km (340 miles) wide. The grayscale image on the right shows the name of each volcano in the scene. The white or bluish-white features are clouds. Clouds are common over the larger Tharsis volcanoes in mid-afternoon. The four largest volcanoes are more than 15 km (9 miles) high. Viewed from Earth by telescope before any spacecraft had visited the planet, astronomers often described a "W-shaped" white cloud over the Tharsis region. This "W" was actually the result of seeing the combined effects of bright clouds hanging over the Ascraeus, Pavonis, Arsia, and Olympus volcanoes. The clouds result when warm air containing water vapor rises up the slopes of each volcano, cools at the higher altitude, and causes the water vapor to freeze and form a cloud of ice crystals. Pavonis Mons lies on the martian equator, north is up, and sunlight is illuminating the scene from the left. The picture is a mosaic of red and blue filter images taken on three consecutive orbits. The slightly blurred appearance of the left side of Arsia Mons results from distortion toward the edges of the images used to make the mosaic. To remove the blur, an image obtained on another day would be added to the mosaic--however, this image would not match well because the cloud patterns will have changed by the next day. Mosaics such as the one shown here are used to monitor changes in martian weather and to plan future observations. ------------------------------------------------------------------ GALILEO EUROPA MISSION STATUS JPL release 14 June 1999 Various scientific discoveries by NASA's Galileo spacecraft have been reported recently. In one discovery, a cloud of microscopic dust grains surrounding Jupiter's large moon Ganymede has been found by Galileo's dust detector system. Scientists believe this dust cloud is created when interplanetary meteoroids slam into Ganymede's surface. The findings are featured in last week's edition of the journal Nature. Scientists are also poring over intriguing findings about surface temperatures on Jupiter's moon Europa gathered by Galileo's photopolarimeter-radiometer, which measures temperature and other traits of Jupiter's atmosphere, clouds and moons. The information, published in the journal Science, reveals that while Europa's daytime temperatures are as expected, its nighttime temperatures are puzzling. At night, it appears the temperatures vary considerably from place to place, in patterns not related to geology or reflectivity of the surface. Spacecraft engineers are trying to find out why one of the two channels on the photopolarimeter-radiometer showed little or no signal during the recent flyby of Jupiter's pockmarked moon, Callisto. The affected channel is used to measure temperatures of Jupiter and its moons. Also in the most recent batch of data played back by Galileo is an observation of Europa, taken while the icy moon was in Jupiter's shadow. The observation was made by Galileo's near infrared mapping spectrometer. There are also pictures of cratered terrain that will help scientists calculate the age of Callisto's surface and other observations of the young Bran crater, which offers a good view of Callisto's crust. The tape recorder playback will be paused twice this week. On Tuesday, it will pause for a standard gyroscope performance test and for a turn to keep the spacecraft antenna pointed toward Earth. On Saturday, standard maintenance on Galileo's propulsion system will be performed. Galileo's next destination is another flyby of Callisto on June 29 at 11:47 p.m. Pacific Daylight Time. The spacecraft has been orbiting Jupiter and its moons for 31/2 years. Right now, the spacecraft is more than halfway through a two-year extended Galileo Europa Mission, a follow-on to the primary mission that ended in December 1997. JPL manages the mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology, Pasadena, CA. ------------------------------------------------------------------ THIS WEEK ON GALILEO JPL release 14-20 June 1999 Playback of images and other science data is Galileo's primary activity this week. The data were acquired by Galileo's instruments and stored on the spacecraft's onboard tape recorder during an encounter with Jupiter and its moon Callisto in early May. Playback is interrupted twice this week. On Tuesday, it is paused for a turn that will keep the spacecraft's antenna pointed toward Earth and for a standard gyroscope performance test. On Saturday, playback is interrupted to perform standard maintenance on the spacecraft's propulsion systems. This week's playback is part of the second pass through the data stored on the spacecraft's tape recorder. This second opportunity allows the replay of data lost in transmission to Earth, reprocessing of data using different parameters, or return of additional new data. All data played back this week are from observations made by the solid-state imaging camera and near- infrared mapping spectrometer. The solid-state imaging camera returns the bulk of this week's data. In several observations of Jupiter's atmosphere, the camera returns images showing the evolution of atmospheric waves along the equator, cloud motions in Jupiter's north and south equatorial belts, and in a high-speed jet in the northern hemisphere. The camera also returns an observation of Jupiter's aurora that will allow scientists to measure its vertical structure at high resolution. The camera returns one observation of Ganymede this week. The observation fills a gap in data obtained in previous orbits designed to provide a global description of the size and shape of Ganymede. The imaging camera then moves on to return three observations of Callisto. The first captures a dark feature that could provide evidence of ancient volcanism. The second observation contains dark terrain that was imaged through seven different color filters, and the third contains images designed to be used to gather statistics on the size distribution of craters on Callisto's surface. These crater statistics will enable scientists to estimate the age of Callisto's surface and understand crater distribution in different regions of the surface. The near-infrared mapping spectrometer returns one observation this week. The observation contains measurements that will allow scientists to determine the chemical composition in a region of Callisto's surface. For more information on the Galileo spacecraft and its mission to Jupiter, please visit the Galileo home page at http://www.jpl.nasa.gov/galileo ------------------------------------------------------------------ JPL'S NEW MARS ROVER TO BE REMOTELY CONTROLLED BY L.A. STUDENTS JPL release 15 June 1999 The Los Angeles-area high school students who participated in the recent Mojave Desert "test-drive" of JPL's newest Mars rover will be demonstrating how they do it this Thursday as part of the county's "Report Card to the Community" about student access to technology. The event, sponsored by the Los Angeles County Office of Education, takes place Thursday, June 17 at the Dorothy Chandler Pavilion, 135 North Grand Avenue, Los Angeles, CA. The students will be driving the rover from 7:30 AM until 9 AM. After that, they will be available for interviews until the close of the event at 12:30 PM. The students from Belmont and Marshall High Schools will be remotely controlling the Field Integrated Design and Operations (FIDO) rover from their demo area in the balcony of the Dorothy Chandler Pavilion. FIDO will be in the Mars Yard at NASA's Jet Propulsion Laboratory in Pasadena, where it will receive the students' commands and follow their directions. FIDO is designed to test the advanced technology of the Athena flight rover and science payload that will be launched as part of NASA's Mars Sample Return missions in 2003 and 2005. These are the same students who worked with scientists and engineers in April during the first-ever student test drive of a NASA/JPL rover in the Mojave Desert. In addition to the Los Angeles students, students from schools in Phoenix, Ithaca, NY, and St. Louis make up a consortium called LAPIS, which stands for the initials of their hometowns. Together the four schools formed an integrated mission team and were responsible for planning, conducting and archiving the two-day desert mission using FIDO. The FIDO rover development and the Mars Sample Return 2003/2005 missions are managed by NASA's Jet Propulsion Laboratory for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA. ------------------------------------------------------------------ End Marsbugs Vol. 6, No. 17.