This PDF file contains the front matter associated with SPIE Proceedings Volume 6694, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

I have proposed a model, in which adenosine triphospate (ATP) plays a key role in prebiological evolution. Life is a phenomenon of evolving ordering. It can be shown that a system of conjugated irreversible reactions supplied by energy and dwelling near a steady state, is charged to produce ordering. ATP has properties which are the most appropriate to be involved in such a system. Primary synthesis of ATP demands strong reduced conditions. I show here that such conditions may exist on the early Earth.

Assuming an extra-terrestrial formation of life's molecular building blocks such as amino-acids, a possible abiotic explanation for the selection of the L enantiomers could be the exposure to an asymmetric bias such as far UV Circularly Polarized Light (CPL), during their journey towards Earth, inducing some enantiomeric excess (e.e) that could then be amplified on Earth via suitable autocatalytic mechanisms. Synchrotron Radiation (SR), with its intense flux and broad tunability, is a unique tool which mimics such an interstellar far UV CPL. We have recently employed it to study : (1) The irradiation of solid films of the amino acid D,L-leucine, i.e. under relevant astrophysical conditions. Starting from racemic D,L-leucine irradiated with CPL SR beam at 6.8 eV (182 nm), we have been able to induce by enantioselective photolysis an e.e. of 2.6 %, as measured by chiral-sensitive CG-MS analysis, in accordance with the CD spectrum recorded on the same type of sample. (2) CPL-induced gas phase photoionization of chiral molecules. By measuring the angular distribution of photoelectrons ejected from pure enantiomers, we observed a strong anisotropy (up to 16 %) in the forward/backward direction with respect to the light propagation axis. Because of momentum conservation, such an effect is accompanied by an asymmetric recoil of the corresponding ions that could lead to a high e.e. Future prospects on the new VUV SR beamline DESIRS at SOLEIL are presented.

Frank Tipler, in The Physics of Immortality, wrote about how to spread a form of traveling artificial life throughout the known, expanding universe, prior to collapse. The key is to make the ALife self-reproducing, permitting exponential growth, like life itself, but faster. We ask whether microbial extremophiles could have originated in a single location at an early phase of a big bang universe, and spread throughout the cosmos, as is commonly assumed in discussions of the panspermia hypothesis? Since the universe was much smaller when the first condensed matter appeared, this hypothesis merits consideration. In comparing particle horizons with biohorizons, we find that the answer is no: at our earliest estimated time for the origin of life, 500x10⁶ years after the big bang, if life started everywhere it could, there would have had to have been at least 50,000 origins of life. In the course of our rough calculations, we introduce the concepts of the generations of life (from microorganisms to consciousness), the Biocosmological Principle that life is spread throughout the universe, life as a wave in an active medium, and the speed of life, i.e., the speed of ejecta from galaxies and lesser bodies on which life could be transported.

We have found that alcohols catalyze a rapid polymerization of silicic acid to silica gel upon the addition of alcohols. Like amino acids, alcohols could be preserved in the silica gel by two mechanisms. In the first mechanism, the alcohols become entombed in the silica gel. In this case, only Si-O-Si bonds would be observed in the infrared (IR) spectra. In the second mechanism, the alcohols make chemical bonds with the silicic acid, to create organo-silicates. In this case, Si-O-C bonds would be observed in the IR. We have found that steric hindrance plays a major role in the volume of an alcohol required. Amino alcohols are more effective in creating a viscous gel than the alcohols, and appeared to form covalent Si-O-C bonds in some cases. Characteristic shifts in the Si-O-Si bands of over 50 cm^-1 towards lower IR frequencies can be observed in the alcohol gels. The hydrolysis of known organo-silicates has led to the identification of the Si-O-C band in the region of 1225-1150 cm^-1, and the Si-O-Si band in the region of 1125-1000 cm^-1. Alcohols play an important role in many biological pathways, and could serve as biosignatures in extreme environments including meteorites and other planets.

This article intends to continue our previous work on the symbiogenic approach to chemical and biological evolution. We believe that cooperative and synergistic processes were responsible, using terrestrial and extraterrestrial materials, for the creation of a large prebiotic pool, closely related to geochemical contexts, and intense interactions within. Probably, a series of synergistic and cooperative effects produced a wide source of creativity, and functional advantages that pushed the emergence of complex and functionally integrated biological systems, through the evolution of self-organization and auto-catalysis. It was only after this biochemical evolution of structures, which produced the informational capabilities necessary for self-replication, that the Darwinian mechanisms could arise. This way of perceiving the emergence of life follows the proposals regarding life's initial evolution in which the progenote proposed consisted in an open community of very diverse primitive cellular entities with intense symbiotic associations, antagonisms, and competition, and with a rapid and reticulate pattern of evolution. We believe this symbiogenic approach should be considered in the understanding of chemical and biological evolution. This discussion contributes to the development of astrobiological knowledge, since it gives other perspectives about life's appearance and development on Earth and elsewhere.

During the past decade, Environmental and Field Emission Scanning Electron Microscopes have been used at the NASA/Marshall Space Flight Center to investigate freshly fractured interior surfaces of a large number of different types of meteorites. Large, complex, microfossils with clearly recognizable biological affinities have been found embedded in several carbonaceous meteorites. Similar forms were notably absent in all stony and nickel-iron meteorites investigated. The forms encountered are consistent in size and morphology with morphotypes of known genera of Cyanobacteria and microorganisms that are typically encountered in associated benthic prokaryotic mats. Even though many coccoidal and isodiametric filamentous cyanobacteria have a strong morphological convergence with some other spherical and filamentous bacteria and algae, many genera of heteropolar cyanobacteria have distinctive apical and basal regions and cellular differentiation that makes it possible to unambiguously recognize the forms based entirely upon cellular dimensions, filament size and distinctive morphological characteristics. For almost two centuries, these morphological characteristics have historically provided the basis for the systematics and taxonomy of cyanobacteria. This paper presents ESEM and FESEM images of embedded filaments and thick mats found in-situ in the Murchison CM2 and Orgueil CI1 carbonaceous meteorites. Comparative images are also provided for known genera and species of cyanobacteria and other microbial extremophiles. Energy Dispersive X-ray Spectroscopy (EDS) indicates that the meteorite filaments typically exhibit dramatic chemical differentiation with distinctive difference between the possible microfossil and the meteorite matrix in the immediate proximity. Chemical differentiation is also observed within these microstructures with many of the permineralized filaments enveloped within electron transparent carbonaceous sheaths. Elemental distributions of these embedded filaments are not consistent with recent cyanobacteria or other living or preserved microbial extremophiles that have been investigated during this research. The meteorite filaments often have a nitrogen content below the sensitivity level of the EDS detector. Carbon, Sulfur, Iron or Silicon is often highly enriched and hence anomalous C/N and C/S ratios when compared with modern cyanobacteria. The meteorite forms that are unambiguously recognizable as biological filaments are interpreted as indigenous microfossils analogous to several known genera of modern cyanobacteria and associated trichomic filamentous prokaryotes.

No principal differences have been found between microfossils described from Cambrian and Phanerozoic and the 2000 Ma phosphorites. Numerous samples revealed diverse microbial microstructures interpreted as cyanobacterial mats consisting of filamentous (1-3 μm in diameter, 20 μm in length), coccoidal (0.8-1.0 μm) and ellipsoidal or rod-shaped microfossils (0.8 μm in diameter, around 2 μm in length) which morphologically resemble modern Microcoleus and Siphonophycus, Thiocapsa, and Rhabdoderma, respectively, reported from alkaline or saline environments. The sequence of the early Palaeoproterozoic events which point to a significant oxidation of the hydrosphere, including the formation of phosphorites and changes in the phosphorous cycle, mimics the sequence which was repeated at the Neoproterozoic-Cambrian transition, implying that oxidation of the terrestrial atmosphere-hydrosphere system experienced an irregular cyclic development.

We show that radiogenic heating in primordial comets of radii in excess of ~10km could produce liquid water cores persisting for hundreds of thousands to millions of years. Supposing comets were seeded with even the smallest numbers of viable microbes at the time of their formation from pre-solar material, there is ample time for exponential amplification within the liquid interiors before refreezing occurs. Freeze-dried biological material is returned to interplanetary and interstellar space during cometary activity as the outer layers of comets are stripped away via sublimation. Modelling of the post-impact 8-12μm spectra of Tempel 1 gives a strong indication of mixtures of clays and organics in comparable quantity, clays in turn providing evidence of a liquid water history of the comet. The totality of comets in a galaxy or a cluster of galaxies, seems to provide a far more promising setting for an origin of life than any setting thus far proposed in relation to the primitive Earth. Once life has originated in a comet mechanisms of interstellar panspermia that have recently been identified will disperse throughout the Galaxy within a few billion years. Keywords: Comets, liquid water, clay, organics, origin of life, panspermia

Secular changes in the stable sulfur isotope composition of seawater sulfate on Earth range from approximately 25 to 30 per mil (CDT). Minimal fractionation has been observed for the direct assimilation of seawater sulfate by plants into the two sulfur containing protein amino acids, methionine and cysteine. Similarly, sulfur isotope fractionation appears to be minimal with increasing trophic level. Thus, in theory, secular changes in the stable sulfur isotope composition of sulfur containing amino acids in ancient marine organisms should mimic that of seawater sulfate. The presence of sulfur containing amino acids elsewhere in the solar system and a comparison of their respective stable sulfur isotope values to those of sulfate containing minerals of similar ages may provide an alternative approach for determining the occurrence of past extraterrestrial life.

This research documents the analysis and interpretation of selected Carbonaceous Chondrites (CC) including Murchison, Allende, NWA 3003, Dhofar 735, Orgueil, Tagish Lake and Vigarano using organic petrology, scanning electron microscopy, and petroleum geochemistry. The kerogen microstructures and bitumen within CCs closely resemble remnant 2.5 Ga terrestrial microbial-like structures and their biodegraded components and solid bitumen. In both instances, organoclasts are associated with framboidal iron sulfides or oxides and clay-like minerals. The organic-rich kerogens within three CCs (especially Murchison) might have served as petroleum source rocks for the early generation of hydrocarbons. The maturity varies between 0.7% (Orgueil) and 1.24% (Murchison), to 5.1 % Ro (Vigarano) with predicted maturation temperatures of 100° to 475°C. Geochemical analysis of selected CCs (Murchison, Orgueil, and Tagish Lake) reveal the organic richness and the presence of low molecular weight n-alkanes (C₁₀ to C₂₀), complex cyclo-and isoalkanes, nonhydrocarbons, elemental sulfur with abundant aromatic compounds, most of them similar to bacterial and algal derived petroleum products. Apart from the concept of panspermia, the data highlights that three CCs sustained a formation temperature (<200°C) capable of supporting bacterial growth in a cooler early Solar System environment. In effect, the information encoded within these extraterrestrial sediments represents a cosmic analogue to terrestrial geopolymers and bitumen that may include some crude oil biomarkers. Therefore, the authors propose a model of a "universal unconventional petroleum system", which implies a prospect of oil and gas within the Martian environment and elsewhere within the Solar System.

The ability to distinguish possible microfossils from recent biological contaminants is of great importance to Astrobiology. In this paper we discuss the application of the ratios of life critical biogenic elements (C/O; C/N; and C/S) as determined by Energy Dispersive X-ray Spectroscopy (EDS) to this problem. Biogenic element ratios are provided for a wide variety of living cyanobacteria and other microbial extremophiles, preserved herbarium materials, and ancient biota from the Antarctic Ice Cores and Siberian and Alaskan Permafrost for comparison with macrofossils and microfossils in ancient terrestrial rocks and carbonaceous meteorites.

The NASA Stardust mission to comet 81P/Wild-2 returned to Earth in January 2006 carrying captured cometary dust grains. Analysis of these grains is permitting an extensive study of cometary composition to be carried out. This includes identifying both the mineral and organic content of the captured material. Based on this, the picture emerges of a comet whose component materials have a diverse origin and which has not undergone any extensive aqueous alteration, has a nitrogen rich organic history, may contain amines and at least 1 amino acid and has organics which in some respects resemble interplanetary dust particles and meteorites, in others resemble one and not the other, and in yet others are distinct from both. In terms of astrobiology, comets as a source of organic materials for the inner Solar System clearly have a role to play, but this cannot be fully assessed based on the history of just one comet nucleus. Nevertheless, the positive identification of a range of organic materials in this comet significantly moves forward the discussion of organic materials and comets.

Recent observations of cyanobacterial fossils on carbonaceous chondrites have conclusively established the presence of fossil organisms on extraterrestrial bodies widely presumed to be comets. Likewise, the data from four cometary flyby (and one impact) missions and the exploration of a peculiar S-type asteroid, show evidence of liquid water in the past or present. In addition, sand grains returned from the tail of comet P/Wild-2 demonstrate that comets accrete inner Solar System material. So it is a short step to propose the separate and independent existence of a cometary biosphere, the ecosystem of organisms that exploit the niche of an extraterrestrial environment. This paper attempts to lay the framework for such a hypothetical ecosystem, and establish criteria for its continued existence and spread.

I review three types of related cometary phenomena, which, in the order listed, are increasingly important in studies of cometary evolution: dust jet-like morphological features in comet heads; outbursts; and nucleus fragmentation. Gas-driven collimated jets consisting predominantly of microscopic dust particles are a standard mode of comet activity, as has amply been documented by numerous ground-based observations and even more convincingly by closeup images taken with the cameras aboard the space missions that flew by four periodic comets between 1986 and 2005. Gas expanding from discrete emission sources on or below the nucleus surface drags dust with it into the atmosphere in quantities that vary with time. Briefly occurring sudden great enhancements of activity are known as outbursts. Dust ejecta in most outbursts do not include larger objects than boulder-sized ones, thus limiting the total mass delivered in such episodes. At times, however, outbursts accompany a nucleus fragmentation event, which signals a major episode. Fragmentation events have a tendency to recur, their products offering a complex hierarchy of large fragments. A rapid sequence of fragmentation events may end up with a sudden, complete disintegration of a significant fraction of the original comet or, more rarely, the entire comet. Indications are that cascading fragmentation is the most efficient process of comet aging and ultimate demise.

Biologists tacitly assume that all life on Earth descended from a common origin. This assumption is based on biochemical similarities and gene sequencing, which enables organisms to be positioned on a common tree of life. However, most terrestrial organisms are microbes, and it is impossible to deduce their biochemical nature from morphology alone. The vast majority of microbes remain unclassified, leaving open the possibility that some of them might be an alternative form of life, arising either from an independent origin, or representing a hitherto overlooked very ancient branch of the known tree. Thus there may exist an extinct, or even extant, shadow biosphere. I discuss various research proposals for locating and identifying "alien" organisms on Earth, both ecologically separate and ecologically integrated.

After only three years of close observation from the Cassini-Huygens mission, Titan appears more and more as one of the key planetary bodies in the solar system for astrobiological studies. Titans does not look any more like a frozen primitive Earth, but like an evolving planet, geologically active, with cryovolcanism, eolian erosion, clouds and precipitations, and a methane cycle very similar to the water cycle on Earth. The new data also show a very complex organic chemistry in the highest atmospheric zones of the satellite, with the formation in the ionosphere of high molecular weight organics feeding the lower zones, down to the surface. In spite of the low surface temperature, these organics are probably evolving once in contact with water ice and form organic molecules of biological interest. This may explain the reflectance spectrum of Titan' surface observed by the DIRS instrument on Huygens. Thus, contrary to what was expected, the organic chemistry on Titan seems mainly concentrated in the ionosphere, in the aerosols and on the surface. These astrobiological aspects of Titan are presented and discussed on the basis of the already available Cassini-Huygens data, as well as the needed post Cassini exploration.

Few, if any, major scientific quests have taken such frequent, diametrically opposed changes in prospect and direction as has the search for life on Mars. The erratic courses and their supporting rationales are traced: from Percival Lowell's astonishing pronouncement of intelligent beings on the red planet; to their denouement by Mariner 4; to the strong contraindications of any form of Martian life relayed by Mariners 6 and 7; to the discovery of a different, perhaps once-habitable, Mars revealed by the detailed orbital images, including the first evidence of ancient rivers, taken by Mariner 9; to the still-controversial claim of the detection of microbial life by the 1976 Viking Missions; to NASA's subsequent prohibition against any Mars life detection experiments; to the recently emerged consensus, propelled by findings of Pathfinder, the Mars Exploratory Rovers and the continuing discoveries of life in extreme environments on Earth, that past or extant life on Mars is likely. Against this background, the future Mars missions' experiments bearing on the life issue are reviewed. The case is made that none of these experiments, as currently planned, still subject to the prohibition against direct life detection experiments, can resolve this paramount and fundamental question that bears so heavily on the origin and distribution of life, and our place in the universe.

The conditions on Mars imply an evolutionary advantage for organisms employing a mixture of H₂O₂ and H₂O in their intracellular fluid: the H₂O₂-H₂O eutectic freezes at -56.5°C, is hygroscopic and a source of oxygen. Contrary to common belief, H₂O₂ is used for a variety of purposes in terrestrial biochemistry. The Viking Lander Biology Experiments have often been interpreted as the result of inorganic oxidants in the Martian soil. Here, we interpret the Viking findings as the result of the reactions of H₂O₂-H₂O based life. Several hitherto puzzling findings are explained by the H₂O₂-H₂O hypothesis. The lack of detected organics is the result of autooxidation of the organisms as these were gradually heated. Supportive observations were made in the PR and LR experiments. Our interpretation is that the addition of water vapor at a relatively high temperature could only be withstood by the organisms for a short time, as they perished due to hyperhydration. The evolution of oxygen in the GEx experiment is explained by the high oxidative content of the organisms as they perished in this experiment. The PR experimental conditions were most Mars-like and carbon assimilation could be detected but no growth. Particularly, the GEx experiment allows the calculation of biomass in the Martian soil based on measured evolution of reaction products. Further properties of the suggested organisms such as metabolic reactions and by-products may be detected by future Mars missions.

The Viking mission was the only mission to date that conducted life detection experiments. It revealed ambiguous and still controversial results. New findings and hypotheses urge a re-evaluation of the Viking results and a re-evaluation of the evidence for the possible presence of life on Mars in general. Recent findings of abundant water ice on Mars, the presence of liquid contemporary water on the Martian surface, and the detection of methane in the Martian atmosphere further support this possibility. Current missions to be launched focus on habitability considerations (e.g., NASA Phoenix, NASA Mars Science Laboratory), but shy away from directly testing for life on Mars, with the potential exception of the ESA ExoMars mission. If these currently planned missions collect positive evidence toward habitability and the possible existence of extraterrestrial (microbial) life on Mars, it would be timely to propose a new mission to Mars with a strong life detection component. We propose such a mission called BOLD: Biological Oxidant and Life Detection Mission. The BOLD mission objective would be to quantify the amount of hydrogen peroxide existing in the Martian soil and to test for processes typically associated with life. Six landing packages are projected to land on Mars that include a limited power supply, a set of oxidant and life detection experiments, and a transmitter, which is able to transmit information via an existing Mars orbiter back to Earth.

After a picture-perfect launch to Mars on August 4, 2007, the Phoenix mission will land near 70° N on the northern lowlands on May 25, 2008 and perform an in situ investigation of the ice layer discovered by the Mars Odyssey scientists in 2002. Mars undergoes climate change through obliquity and orbital variations on time periods of 50,000 years. By analyzing the minerals, aqueous chemistry, and grain shapes of the soil associated with the ice, Phoenix will determine whether the ice has ever melted and modified the soil properties. Since water is a necessary substance for life on Earth, a major question for the mission is whether the northern plains represent a habitable zone on Mars. Besides water. the Phoenix team will assess the organic content of the soil and ice as well as the abundances of biologically active elements. Finally, the transport of water through soils and atmosphere is measured using a Canadian meteorological station supplemented by probes to evaluate soil conductivity.

The diatoms (Division Bacillariophyta) are aquatic, pigmented single-celled photosynthetic eukaryotes. They are a major component of the food chain in marine, estuarine and freshwater ecosystems. These diploid organisms have the ability to take dissolved silica out of the water column, and use it to create their cell walls. The taxonomy and classification system for the group is based to a large part on cell wall symmetry, as well as the number, type, position and organization of the many perforations in the glass. As a group, diatoms are found in almost every water type of water body around the globe, including a wide range of extreme environments. Individual species, however, have limited distributions and ecological requirements. Preservation of the glass cell walls in sedimentary basins has left nearly a 120 million year record. Species-related distributions, and well-preserved record make diatoms an excellent tool for environmental reconstruction and monitoring. New research on diatoms includes applications to conservation biology, astrobiology, nanotechnology, and biofuels.

Culturable bacteria have recently been found in the stratosphere (at heights up to 41km). How do such bacteria cross the tropopause to reach such heights? Although possible mechanisms are suggested here, such transfer remains difficult to explain. It is however, likely to more easily achieved by sub-micron bacteria. Such small forms have been found in terrestrial environments and have the potential to seed the stratosphere. Large, ten micron clumps of bacteria have also been found in the stratosphere and it is suggested that these are incoming to Earth from space. Finally, the possibility will be discussed that the presence of bacteria in the stratosphere has led to an increase in the rate of evolution.

Early life on Earth had to cope with harsh conditions, including full spectrum solar UV. Since DNA absorbs in the highly energetic UV-C and VUV, solar irradiation was likely an obstacle to the expansion of life on Earth, until biological mechanisms evolved to cope with UV liability (including the biosynthesis of UV screens) and ozone (derived from oxygen produced by photosynthesis) accumulated in the stratosphere. In an effort to better understand the UV liability of DNA, we used synchrotron light to measure VUV-UV absorption spectra (125-340 nm) for DNA and its components (oligonucleotides and mononucleotides). We also measured VUV-UV absorption spectra for potential and known UV screens, including amino acids, proteins, amines (including polyamines), scytonemin, mycosporine-like amino acids, β- carotene, melanin and flavonoids. Among these, flavonoids seem remarkably suited to protecting DNA in the VUV-UV. Flavonoids accumulate in seed coats, where they confer resistance to monochromatic UV (254 nm) and polychromatic UV (200-400 nm). We discuss these findings in relation to the origin and evolution of life and its potential dispersal through space.

The worldwide effort to grow nanotechnology, rather than use lithography, focuses on diatoms, single cell eukaryotic algae with ornate silica shells, which can be replaced by oxides and ceramics, or reduced to elemental silicon, to create complex nanostructures with compositions of industrial and electronics importance. Diatoms produce an enormous variety of structures, some of which are microtubule dependent and perhaps sensitive to microgravity. The NASA Single Loop for Cell Culture (SLCC) for culturing and observing microorganisms permits inexpensive, low labor in-space experiments. We propose to send up to the International Space Station diatom cultures of the three diatom species whose genomes are currently being sequenced, plus the giant diatoms of Antarctica (up to 6 mm length for a single cell) and the unique colonial diatom, Bacillaria paradoxa. Bacillaria cells move against each other in partial synchrony, like a sliding deck of cards, by a microfluidics mechanism. Will normal diatoms have aberrant patterns, shapes or motility compared to ground controls? The generation time is typically one day, so that many generations may be examined from one flight. Rapid, directed evolution may be possible running the SLCC as a compustat. The shell shapes and patterns are preserved in hard silica, so that the progress of normal and aberrant morphogenesis may be followed by drying samples on a moving filter paper "diatom tape recorder". With a biodiversity of 100,000 distinct species, diatom nanotechnology may offer a compact and portable nanotechnology toolkit for space exploration anywhere.

Microorganisms occupy almost every habitable niche on Earth. Some of them may use inorganic or organic substances rather than light as energy sources. We refer to this group as chemotrophs in order to distinguish them from those organisms that use light as an energy source (phototrophs). Both chemotrophs and phototrophs are abundant in environments where one or more physical, or chemical parameters show values far from the lower or upper limits known for life. These ambient habitats are referred to as normal environments. When microorganisms succeed in adapting themselves to harsh niches they are referred to collectively as extremophiles (Seckbach 2004, 2006). We review arguments that militate in favor of microorganisms that in the past and present may have occupied other niches in the Solar System. Among the extremophiles we find representatives of the three domains of life (Bacteria, Archaea, and Eukarya). Some of the possible candidates for life in the Solar System are the extremophiles including chemotrophs, especially sulfur-reducing bacteria (SRB). Another example of chemotrophs are the methanogens. Those microbes are capable of producing methane as a metabolic byproduct of the reduction of carbon dioxide, a process that is called methanogenesis. Searching for new forms of life (within the extraterrestrial regions) is the object of planning within the Cosmic Vision Program of ESA, in collaboration with NASA, and other space agencies. Indeed, sulfur traces on Jupiter's moon Europa detected by the Galileo mission have been conjectured to be endogenic, most likely of cryovolcanic origin, due to their non-uniform distribution in patches. The Galileo space probe first detected the sulfur compounds, as well as revealing that this moon almost certainly has a volcanically heated and potentially habitable ocean hiding beneath Europa surface layer of icy water. In this paper we restrict our attention to possible biomarkers that could signal on Europa the presence extremophiles in general and chemotrophs, especially the presence of sulfur reducers.

Compared to prevalent alkaline to neutral hypersaline environments, acidic hypersaline environments have been scarcely studied. However, they hold interest to many researchers in that these environments have similar geological and geochemical characteristics as those found in lithified strata on Mars. Fieldwork indicated that Lake Brown, located in Western Australia, possessed pH values of 3.1-4.5 and salinity between 13.0-23.0%. Water column, groundwater, and sediment samples were collected from the lake during the austral winter of 2005. These samples were analyzed with both traditional culture and molecular methods. Modified growth media and minimal media were designed to match the composition (Cl, Na, Mg, SO4, K, Ca, and Br) of Lake Brown surface and ground waters for the enrichment of microorganisms. One of the isolates obtained, Brown 1, can grow in media that possesses pH values of 3-7 with optimal growth at pH 4, salinity that ranged from 5% to saturation with optimal growth at 5% and could grow under temperatures that ranged from 20°C to 65°C with optimal grow occurring at 37°C. The isolate's optimum growth conditions are similar to those found in Lake Brown. The isolate is a Gram-negative rod that forms yellow colonies on 17% Phytogel. Its 16S rRNA gene can be amplified with bacterial primers but not with archaeal primers. Its 16S rRNA gene sequence suggests that the isolate is a gamma proteobacterium. Studies on organisms isolated from environments such as Lake Brown, an acid hypersaline lake, can provide an opportunity to both expand our knowledge of terrestrial extremophiles and gain insight on the possible forms of life that might have existed on Mars.

Soap Lake is a hypersaline, alkaline lake in Central Washington State (USA). For the past five years the lake has been the site of an NSF Microbial Observatory project devoted to identifying critical geochemical and microbial characteristics of the monimolimnion sediment and water column, and has demonstrated rich multispecies communities occupy all areas of the lake. Soap Lake and similar soda lakes are subject to repeated transient periods of extreme evaporation characterized by significant repetitive alterations in salinity, pH, and total water volume, yet maintain high genetic and metabolic diversity. It has been argued that this repetitive cycle for salinity, alkalinity, and sulfur concentration has been a major driver for prokaryote evolution and diversity. The rapidity of wet-dry cycling places special demands on genome evolution, requirements that are beyond the relatively conservative eukaryotic evolutionary strategy of serial alteration of existing gene sequences in a relatively stable genome. Although HGT is most likely responsible for adding a significant amount of noise to the genetic record, analysis of HGT activity can also provide us with a much-needed probe for exploration of prokaryotic genome evolution and the origin of diversity. Packaging of genetic information within the protective protein capsid of a bacteriophage would seem preferable to exposing naked DNA to the highly alkaline conditions in the lake. In this study, we present preliminary data demonstrating the presence of a diverse group of phage integrases in Soap Lake. Integrase is the viral enzyme responsible for the insertion of phage DNA into the bacterial host's chromosome. The presence of the integrase sequence in bacterial chromosomes is evidence of lysogeny, and the diversity of integrase sequences reported here suggests a wide variety of temperate phage exist in this system, and are especially active in transition zones.

The High-Lakes Project is funded by the NAI and explores the highest perennial volcanic lakes on Earth in the Bolivian and Chilean Andes, including several lakes ~6,000 m elevation. These lakes represent an opportunity to study the evolution of microbial organisms in relatively shallow waters not providing substantial protection against UV radiation. Aguas Calientes (5,870 m) was investigated (November 2006) and samples of water and sediment collected at 1, 3, 5, and 10 cm depth. An Eldonet UV dosimeter positioned on the shore records UV radiation and temperature, and is logging data year round. A UV SolarLight sensor allowed acquisition of point measurements in all channels at the time of the sampling. UVA, UVB, and PAR peaks between 11:00 am and 1:00 pm reached 7.7 mW/cm², 48.5 μW/cm², and 511 W/m², respectively. The chemical composition of the water sample was analyzed. DNA was extracted and DGGE analyses with bacterial and archaeal 16S fragments were performed to describe microbial diversity. Antibiotic resistances were established previously in similar environments in Argentine Andean wetlands. In order to determine these resistances in our samples, they were inoculated onto LB and R2A media and onto R2A medium containing either chloramphenicol, ampicillin or tetracycline. Bacterial was higher than archeal cell number determined by RT-PCR in all the samples, reaching maximum total values of 5x10⁵ cell mL-1. DGGE results from these samples and Licancabur summit lake (5,916 m) samples were also compared. Eight antibiotic-resistant Gram negative strains have been isolated with distinct resistance patterns.

The impact of individual extremes on life, such as UV radiation (UVR), temperatures, and salinity is well documented. However, their combined effect in nature is not well-understood while it is a fundamental issue controlling the evolution of habitat sustainability within individual bodies of water. Environmental variables combine in the Bolivian Altiplano to produce some of the highest, least explored and most poorly understood lakes on Earth. Their physical environment of thin atmosphere, high ultraviolet radiation, high daily temperature amplitude, ice, sulfur-rich volcanism, and hydrothermal springs, combined with the changing climate in the Andes and the rapid loss of aqueous habitat provide parallels to ancient Martian lakes at the Noachian/Hesperian transition 3.7-3.5 Ga ago. Documenting this analogy is one of the focuses of the High-Lakes Project (HLP). The geophysical data we collected on three of them located up to 5,916 m elevation suggests that a combination of extreme factors does not necessarily translate into a harsher environment for life. Large and diverse ecosystems adapt to UVR reaching 200%-216% that of sea level in bodies of water sometimes no deeper than 50 cm, massive seasonal freeze-over, and unpredictable daily evolution of UVR and temperature. The HLP project has undertaken the first complete geophysical and biological characterization of these lakes and documents how habitability is sustained and prolonged in declining lakes despite a highly dynamical environment. The same process may have helped life transition through climate crises over time on both Earth and Mars.

Recent developments in nanopore analysis of macromolecules and liquid-core optical waveguides have the potential to allow fabrication of fully planar optofluidic labs-on-a-chip. Nanopores are able to detect single molecules of biopolymers such as DNA and proteins, and liquid-core antiresonant reflecting optical (ARROW) waveguides also have this capability. We are developing an instrument that combines the strengths of both approaches which we believe will lead to a high-performance, low-cost instrument suitable for life detection on planetary surfaces such as Mars and Europa.

Last year at this meeting we described a computer application (Brown and Storrie-Lombardi, 2006), the Mars Reconnaissance PRISM or MR PRISM, designed to analyze hyperspectral data collected by the Compact Imaging Spectrometer for Mars (CRISM). The application links the spectral, imaging and mapping perspectives on the CRISM dataset by presenting the user with three different ways to analyze the data. At this time last year, CRISM was still in calibration mode and we presented data from ESA's OMEGA instrument to demonstrate the functionality of MR CRISM. A primary goal in developing this application is to make the latest algorithms for detection of spectrally interesting targets available to the Planetary Science community without cost to the individual investigator and with a minimal learning barrier. This would enable the community to look for Mars surface targets such as ices, hydrothermal minerals, sulfate minerals and hydrous minerals and map the extent of these deposits. The CRISM team has now provided significant data sets to our community. We have used one such data set to conduct a study on an exposed water ice mound. We review here our results on observations made of a ~36km diameter crater, recently named Louth, in the north polar region of Mars (at 70°N, 103.2°E). High-resolution imagery from the instruments on the Mars Reconnaissance Orbiter spacecraft were used to map a 15km diameter water ice deposit in the center of the crater. The water ice mound has surface features that include roughened ice textures and layering similar to that found in the North Polar Layered Deposits. We describe the data analysis process including detection and mapping of hydroxyl mineral signatures using the MR PRISM software suite. MR PRISM is currently in the prototyping stage. Future additions planned include a Bayesian analysis engine, the capacity to handle atmospheric correction routines provided by the CRISM team, the ability to display MOC, THEMIS and HiRISE data and eventually the ability to run on a distributed network to speed up processing of large image cubes. When the software is released to the general community, we hope its embedded scripting language, 'Groovy', will make it the 'front end' for many more sophisticated algorithms from all branches of Mars research.

We developed a high resolution light imaging system. Diffraction gratings with 100 nm width lines as well as less than 100 nm size features of different-shaped objects are clearly visible on a calibrated microscope test slide (Vainrub et al., Optics Letters, 2006, 31, 2855). The two-point resolution increase results from a known narrowing of the central diffraction peak for the annular aperture. Better visibility and advanced contrast of the smallest features in the image are due to enhancement of high spatial frequencies in the optical transfer function. The imaging system is portable, low energy, and battery operated. It has been adapted to use in both transmitting and reflecting light. It is particularly applicable for motile nanoform systems where structure and functions can be depicted in real time. We have isolated micrometer and submicrometer particles, termed proteons, from human and animal blood. Proteons form by reversible seeded aggregation of proteins around proteon nucleating centers (PNCs). PNCs are comprised of 1-2nm metallic nanoclusters containing 40-300 atoms. Proteons are capable of spontaneous assembling into higher nanoform systems assuming structure of complicated topology. The arrangement of complex proteon system mimics the structure of a small biological cell. It has structures that imitate membrane and nucleolus or nuclei. Some of these nanoforms are motile. They interact and divide. Complex nanoform systems can spontaneously reduce to simple proteons. The physical properties of these nanoforms could shed some light on the properties of early life forms or forms at extreme conditions.

To settle an optimal analytical strategy of the search for life traces, it is decisive to start their study in the preliminary examination stages of the extraterrestrial Returned Samples, once they are still stored in their original container. The relevance of the application of on-going synchrotron micro-X-ray fluorescence (XRF) methodological developments performed at the ID21/ID22 beamlines of the ESRF is critically examined in this paper. XRF computed tomography (CT) at ID22 is in general a precious tool allowing a non-invasive and non-destructive determination of the three-dimensional mineralogy with micrometer resolution of sub-millimeter silicate grains. A combination of absorption and Compton tomographies is a more promising method to image bulk views of the organic matter distribution. XRF-scanning X-ray microscopy (SXM) at ID21 is in general not adapted for studying samples across a container. However, it appears to be a unique tool to draw up a list of the sub-surface sites where tiny amounts of organic matter are present. Adaptation of the SXM chamber to the quarantine criteria stipulated by the spatial agencies is a way to permit such analyses in the preliminary examination stages.

Great Salt Lake (GSL) is home to halophiles, salt-tolerant Bacteria and Archaea, which live at 2-5M NaCl. In addition to salt tolerance, GSL halophiles exhibit resistance to both ultraviolet (UV) irradiation and desiccation. First, to understand desiccation resistance, we sought to determine the diversity of GSL halophiles capable of surviving desiccation in either recently formed GSL halite crystals or GSL Artemia (brine shrimp) cysts. From these desiccated environments, surviving microorganisms were cultured and isolated, and genomic DNA was extracted from the individual species for identification by 16S rRNA gene homology. From the surface-sterilized cysts we also extracted DNA of the whole microbial population for non-cultivation techniques. We amplified the archaeal or bacterial 16S rRNA gene from all genomic DNA, cloned the cyst population amplicons, and sequenced. These sequences were compared to gene databases for determination of closest matched species. Interestingly, the isolates from the crystal dissolution are distinct from those previously isolated from GSL brine. The cyst population results reveal species not found in crystals or brine, and may indicate microorganisms that live as endosymbionts of this hypersaline arthropod. Second, we explored UV resistance in a GSL haloarchaea species, "H. salsolis." This strain resists UV irradiation an order of magnitude better than control species, all of which have intact repair systems. To test the hypothesis that halophiles have a photoprotection system, which prevents DNA damage from occurring, we designed an immunoassay to detect thymine dimers following UV irradiation. "H. salsolis" showed remarkable resistance to dimer formation. Evidence for both UV and desiccation resistance in these salt-tolerant GSL halophiles makes them well-suited as models for Astrobiological studies in pursuit of questions about life beyond earth.

An analysis is carried out of the survival fraction of micro-organisms exposed to extreme shock pressures. A variety of data sources are used in this analysis. The key findings are that survival depends on the behaviour of the cell wall. Below a critical shock pressure there is a relatively slow fall in survival fraction as shock pressures increase. Above the critical threshold survival starts to fall rapidly as shock pressure increases further. The critical shock pressures found here are in the range 2.4 to 20 GPa, and vary not only from organism to organism, but also depend on the growth stage of given organisms, with starved (i.e., no growth) states favoured for survival. At the shock pressures typical of those involved in interplanetary transfer of rocky materials, the survival fractions are found to be small but finite. This lends credence to the idea of Panspermia, i.e. life may naturally migrate through space. Thus for example, Martian meteorites should not a prior be considered as sterile due to the shock processes they have undergone, but their lack of viable micro-organisms either reflects no such life being present at the source at the time of departure or the influence of other hazardous processes such as radiation in space or heating of surfaces during entry into a planetary atmosphere.

The radiation resistance-repair genes in Deinococcus radiodurans (DR) and E-coli were analyzed in terms of the A, T, C, G nucleotide fluctuations. The studied genes were Rec-A, Rec-Q, and the unique DR PprA gene. In an ATCG sequence, each base was assigned a number equal to its atomic number. The resulting numerical sequence was the basis of the statistical analysis. Fractal analysis using the Higuchi method gave a fractal dimension increase of the Deinococcus radiodurans genes as compared to E-coli, which is comparable to the enhancement observed in the human HAR1 region (HAR1F gene) over that of the chimpanzee. Near neighbor fluctuation was also studied via the Black-Scholes model where the increment sequence was treated as a random walk series. The Deinococcus radiodurans radiation gene standard deviations were consistently higher than that of the E-coli deviations, and agree with the fractal analysis results. The sequence stacking interaction was studied using the published nucleotide-pair melting free energy values and Deinococcus radiodurans radiation genes were shown to possess larger negative free energies. The high sensitivity of the fractal dimension as a biomarker was tested with correlation analysis of the gamma ray dose versus fractal dimension, and the R square values were found to be above 0.9 (N=5). When compared with other nucleotide sequences such as the rRNA sequences, HAR1 and its chimpanzee counterpart, the higher fluctuation (correlated randomness) and larger negative free energy of a DR radiation gene suggested that a radiation resistance-repair sequence exhibited higher complexity. As the HAR1 nucleotide sequence complexity and its transcription activity of co-expressing cortex protein reelin supported a positive selection event in humans, a similar inference of positive selection of coding genes could be drawn for Deinococcus radiodurans when compared to E-coli. The origin of such a positive selection would be consistent with that of a Martian environment.

The surface of Mars is exposed to higher levels of solar and galactic cosmic ray irradiation than Earth due to its very weak magnetic field. Thus, microorganisms that could possibly survive in the shallow subsurface of Mars would likely be radiotolerant. To better understand microorganisms that might reside in this environment of Mars, a number of isolates were obtained from the area around a gamma-radiation source, ¹³⁷Cs, located on the UMR campus. Radiation sensitivity assays were performed on the isolates as well as on the common bacterium, E. coli. All the organisms tested were able to withstand exposures up to 20 Gy. The E. coli control did not survive exposures of 200 Gy, while the isolate designated 1B-1 could. Another isolate, Cont-1, also withstood this exposure. Each of the isolates produced white growth on solid medium and their cells are rod-shaped. The study of these isolates and similar organisms could enhance our knowledge of these unique extremophilic bacteria and might provide insight into the microorganisms that could be present in the shallow subsurface of Mars.

Chirality is an excellent indicator of life, but naturally occurring terrestrial and extra-terrestrial samples nearly always exhibit massive depolarizing light scattering (DLS). This problem bears a striking resemblance to that of developing a chirality-based non-invasive glucose monitor for diabetics. Both applications require a lightweight, compact, efficient, and robust polarimeter that can operate despite significant DLS. So for astrobiological applications, we developed a polarimeter that was inspired from a polarimetry technique previously investigated for non-invasive in-vivo glucose-sensing. Our polarimeter involves continuously rotating the plane of linear polarization of a laser beam to probe a sample with DLS, and analyzing its transmission with a fixed analyzer to obtain a sinusoidal voltage signal. We lock-in detect this signal using a reference signal from an analogous set up without any sample. With milk as a scatterer, we find that this polarimeter detects chirality in the presence of three orders of magnitude more DLS than conventional polarimeters. It can accurately measure 0.1° of polarization rotation in the presence of 15% milk.

Often, micromorphologies, interpreted as microfossils, provide the first clues to exciting and potentially controversial discoveries related to the early origins of life on the Earth, as well as the potential for life on other planets. It has been said, however, that exceptional claims require exceptional proof, and micromorphological evidence alone may have several possible interpretations, both biotic and abiotic. Garcia-Ruiz, et al. (2003) have shown how silica-coated carbonate crystals in a chert-like matrix can self-assemble inorganically into long folded or braided filaments that closely resemble cyanobacteria fossils thought to be 3.5 billion years old. Recent advances in the field of Materials Science provide numerous other examples ofmicromorphologies that, due to their complexity and structure, might be misinterpreted as microfossils despite their clearly abiotic origin. Several examples will be discussed. While the chemistries ofthese abiotic micromorphologies could be considered rather exotic and therefore discounted, the same fossilization process that operates on biotic microorganisms could operate here as well.

The label "soil" is used in a great variety of significations but seldom to indicate what is meant by it as a thorough concept in soil science/pedology. This is particularly true when used by scientists not acquainted with soil science even on Earth. Hence, the label "soil" very often stands for features occurring in surficial deposits of planets (as the Earth itself) not really dealing with soil development. Soil development is a complex result/product from major natural factors as water/precipitation, geomorphology/edaphic position, sediment /surficial deposits and by and large climate. All these factors are reflected in a "soil-type" of the earthly soil-classification-system. In reverse "soils" reflect pedologic/climatic conditions of the past possibly pointing at the presence of water and vegetation in a given landscape. As soils are thus intrinsically related to life on planets as on Earth the label soil in searching for Life on Mars should be used properly. Phyllosilicates and red clays (even in traces) recently discovered by many scientists on the Red Planet may indicate the presence of thorough soils on Mars. The term "regolith" for the Martian soil should then be avoided.

The microflora of the cryosphere of planet Earth provides the best analogs for life forms that might be found in the permafrost or polar ice caps of Mars, near the surface of the cometary nuclei, or in the liquid water beneath the ice crusts of icy moons of Jupiter and Saturn. For astrobiology the focus on the study alkaliphilic microorganisms was enhanced by the findings of abundant carbonates and carbonate globules rimmed with possibly biogenic magnetites in association with the putative microfossils in the ALH84001 meteorite. Although the ALH84001 "nanofossils" were too small and simple to be unambiguously recognized as biogenic, they stimulated Astrobiology research and studies of microbial extremophiles and biomarkers in ancient rocks and meteorites. Recent studies of CI and CM carbonaceous meteorites have resulted in the detection of the well-preserved mineralized remains of coccoidal and filamentous microorganisms in cyanobacterial mats. Energy Dispersive X-ray Analysis has shown anomalous biogenic element ratios clearly indicating they are not recent biological contaminants. This paper reviews microbial extremophiles in context of their significance to Astrobiology and the evolution of life. Extremophilic microorganisms on Earth are models for life that might endure high radiation environments in the ice near the surface of comets or on the icy moons of Jupiter and Saturn and in the seafloor deep beneath the icy crusts of Europa and Enceladus.

We present design, integration and test results for a field Raman spectrometer science payload, integrated into the Mars Analog Research and Technology (MARTE) drilling platform. During the drilling operation, the subsurface Raman spectroscopy inspection system has obtained signatures of organic and mineral compositions. We also performed ground truth studies using both this field unit and a laboratory micro Raman spectrometer equipped with multiple laser excitation wavelengths on series of field samples including Mojave rocks, Laguna Verde salty sediment and Rio Tinto topsoil. We have evaluated laser excitation conditions and optical probe designs for further improvement. We have demonstrated promising potential for Raman spectroscopy as a non-destructive in situ, high throughput, subsurface detection technique, as well as a desirable active remote sensing tool for future planetary and space missions.

Rapid adaptation to acute environmental change demands co-evolution of indigenous viral populations and their hosts. Horizontal gene transfer (HGT) is a highly efficient adaptive mechanism, but a difficult phenomena to dectect. The mosaic nature of bacteriophage genomes resulting from HGT has generally been explored using phylogenetic analysis of coding regions. Focusing on the proteome certainly provides one window into the origin and evolution of genome information storage. However, the original fitness function for a nucleotide polymer would arise from a more primal survival imperative predating the appearance of a coding function. Multivariate analysis of a genome information storage metric (lossless compression), nucleotide distributions, and distributions of the three major physiochemical characteristics of the polymer (triple:double bonding [G+C], purine:pyrimidine [G+A], and keto:amine [G+T] fractions) produces a metric to detect and characterize mosaicism in both coding and non-coding regions of a genome. We discuss possibilities and limitations of using these techniques to investigate HGT and the origins and evolution of genome complexity. Analysis of available virus (n= 2374) and bacteriophage genomes (n=417) indicates these probes can perform whole-genome taxonomy tasks or sliding window searches for evidence of HGT in a single genome. HGT responses may serve as a canary or bell-weather for global environmental change. We discuss one area of application of considerable interest to our institute: the response of cyanophage and their cyanobacteria hosts to variations in ultraviolet solar flux in geographically isolated Antarctic lakes.

In this paper we discuss the astrobiological importance of various viruses, nanobacteria, Archaea and bacteria. Viruses and nanobacteria challenge the current definitions of life, but we consider them here as life forms. Nanobacteria have interesting mode of fossilization and have a potential for creating biosignatures. Archaea and some bacteria make unique lipid-related compounds that can be used as biosignatures. We focus on the organisms and life forms that seem to be well suited for the life on Mars or other extraterrestrial environments that are harsh. Many of these organisms and life forms share their genetic material freely with other organisms and species. Such an altruistic approach may have been typical for the early life on Earth.

The Maillard reaction occurs when sugars and amino acids are mixed together in the solid state or in the aqueous solution. Since both amino acids and sugar-like compounds are found on meteorites, we hypothesized that they would also undergo the Maillard reaction. Our recent work supports this idea. We have shown previously that the water-insoluble Maillard products have substantial similarities with the insoluble organic materials from the meteorites. The Maillard organic materials are also part of the desert varnish on Earth, which is a dark, shiny, hard rock coating that contains iron and manganese and is glazed in silicate. Rocks that are similar in appearance to the desert varnish have been observed on the Martian surface. They may also contain the organic materials. We have undertaken study of the interactions between the Maillard products, iron and other metals, and silicates, to elucidate the role of the Maillard products in the chemistry of desert varnish and meteorites. Specifically, we have synthesized a series of the Maillard-metal complexes, and have tested their reactivity towards silicates. We have studied the properties of these Maillard-metal-silicate products by the IR spectroscopy. The astrobiological potential of the Maillard-metal complexes is assessed.

In the soft reduced sediments of the continental shelf, below the oxygen minimum zone (OMZ) of the eastern South Pacific (ESP), peculiar microbial communities have been disclosed which include a variety of large prokaryotes, protists and small metazoans. Dominant among the prokaryotes are large multi-cellular filamentous bacteria which, according to their size range, are roughly divided into megabacteria and macrobacteria. The former group is made up of a few species of Gamma Proteobacteria of the genera Thioploca and Beggiatoa and the second group includes a diversity of phenotypes. Protists include ciliates, flagellates, and foraminifers and the metazoans are mostly nematodes and small polychaetes. A significant similarity has been found in the exploitation of the area/volume relationship among these large bacteria and their fossil analog forms as described from pre-Cambrian rocks. For the same reason, the latter have mostly been referred to as algae or cyanobacteria in the literature. The presence of these seemingly ancient bacteria in the sediments of the oxygen minimum zones of the ESP, one of the most productive but also ecologically most inefficient marine ecosystems of the world, suggests that such setting must have prevailed throughout the geological history of the planet allowing for their survival and further that it might be considered an analog of Proterozoic ocean conditions. These non-cyanobacterial communities offer an alternative hypothesis to students of the evolution of life on Earth and may be of special interest to astrobiologists looking for life or traces of life in terrestrial or extraterrestrial environments since these do not necessarily imply a photosynthesis-based metabolism.