Indigenous reduced carbon has been observed in the Martian meteorite Nakhla. For the first time we have analyzed the in situ carbon by a suite of micro-analytical techniques in order to identify and characterize the reduced carbonaceous matter. Optical analysis of the Nakhla petrographic thin-section revealed the existence of a dark brown/red vein-filling material appearing as a series of bifurcating intrusions into a fine (<300 nm width) crack / fissure system within an olivine/augite groundmass. Micro-analytical analyses utilizing Focus Ion Beam (FIB) extraction techniques, FESEM/EDX, STEM/EDX, NanoSIMS Ion Microprobe, Laser Raman Spectroscopy, Stepped-Combustion Isotopic Mass Spectrometry have been utilized. The structure of the carbonaceous phase in Nakhla indicates it could not have been introduced allochthonously in its current physical form. The close association to a region of secondary mineralization (i.e., iddingsite) implies, although certainly does not confirm, a connection with the period of Martian aqueous alteration experienced by the rock. This carbonaceous material has similarities to macromolecular carbonaceous matter and yet possesses a complex structural and textural morphology that is not observed in carbonaceous or ordinary chondrite meteoritic kerogen. One of the possible origins for the carbonaceous matter is from biogenic processes operating on Mars.

The Orgueil CI1 meteorite, which fell in southern France on the evening of May 14, 1864, has been one of the most extensively studied of all known carbonaceous meteorites. Environmental and Field Emission Scanning Electron Microscopy (ESEM and FESEM) studies of freshly fractured interior surfaces of the Orgueil meteorite have resulted in the detection of the fossilized remains of a large and diverse population of filamentous prokaryotic microorganisms. The taphonomy and the modes of the preservation of these remains are diverse. Some of the remains exhibit carbonization of a hollow sheath and in other cases the remains are permineralized with watersoluble evaporite minerals, such as magnesium sulfate or ammonium salts. Images and EDS spectral data are provided documenting a variety of Orgueil microstructures: abiotic evaporite minerals; pre-solar grains; framboids, ovoids and fluorine-rich filaments of indeterminate biogenicity. These results provide information regarding the size, size range, morphologies and chemical compositions of abiotic microstructures found in native cryptohalite and crystalline and fibrous epsomites from Poison Lake, Washington, USA and Catalayud, Zaragoza, Aragon, Spain. High resolution ESEM and FESEM secondary and backscattered electron Images and Energy Dispersive X-ray Spectroscopy (EDS) data will also be presented of recognizable filamentous cyanobacteria and other prokaryotic microfossils. Many of the microfossils found embedded in the meteorite rock matrix are consistent in size and microstructure with known genera and species of filamentous cyanobacteria. Many of these forms can be recognized as morphotypes of cyanobacteria belonging to the Order Oscillatoriaceae. These large, complex microstructures are clearly distinguishable from the abiotic minerals examined - cryptohalite and fibrous epsomites. Many of the well-preserved filamentous forms in the Orgueil meteorite are embedded in the rock matrix and exhibit identifiable biological characteristics and EDS elemental compositions that clearly differentiate them from abiotic microstructures. They exhibit branched and unbranched filaments; uniseriate and multiseriate ensheathed trichomes with specialized cells and structures for reproduction (e.g. hormogonia and akinetes) and nitrogen fixation (heterocysts). The meteorite forms also show evidence of motility (emergent hormogonia and hollow, coiled empty sheaths) and they are often found in mats, consortia and microbial assemblages that are consistent with the known associations and ecologies of modern genera and species of cyanobacteria. Smaller filaments, consistent with the phototrophic filamentous prokaryotes typically present in anoxic layers associated with modern cyanobacterial mats, have also been found in the Orgueil meteorite.

Three quarters of Earth's near surface rock is volcanic and virtually all of it has persistent or intermittent exposure to water. Hydration of the primary igneous silicate minerals (feldspar, pyroxene, olivine, and amorphous glass) and chemical exchange between these minerals and water produces secondary phyllosilicate minerals. The mineral-water interface is energy rich and supports diverse microbial communities that take up residence along cooling cracks and fractures. Microbes bore into minerals and leave trace fossils and organic evidence of their presence. The Martian surface is also dominated by volcanic rocks and some of these have been exposed to water long enough for phyllosilicates to form. These phyllosilicates are found in some Martian meteorites and a widespread distribution of phyllosilicates is indicated by reflected infrared light from some areas of Mars. As microbial trace fossils have been preserved for billions of years on Earth, if life ever existed at water-rock interfaces on Mars, then evidence of this life will have been preserved in the rocks. Areas of Mars that are likely to contain rocks that once were in contact with water can be located with orbital imagery. A rover on the Martian surface can locate outcrops likely to contain evidence of water-rock interaction based on the geological context and outcrop morphology. Examination of prepared surfaces of outcrops with a microscopic imager could reveal microbial trace fossils. Chemical analysis of the same surfaces prepared for microscopic imaging could reveal complex organic compounds. Here we report on a strategy for evaluating landing sites on Mars for their potential for containing evidence of microbial activity in volcanic rocks.

Ancient Archaean and Proterozoic rocks are model objects for the investigation of rocks comprising astromaterials. Three types of fossil microorganisms found in Archaean rocks of Karelia are determined: 1. forms found in situ, in other words microorganisms of the same-age as the rock matrix, that is valid Archaean fossils, 2. endolithic fossil microorganisms, that is to say forms inhabited early formed rocks, and 3. younger than Archaean-Proterozoic mineralised microorganisms, that is later contamination. The structures belong (from our point of view) to the first type, or genuine Archaean forms were mainly under our examination. Practical investigation of ancient microorganisms from Greenstone-Belt of Northern Karelia turns to be very perspective. It shows that even in such ancient period as the Archaean an ancient diverse world existed. Moreover probably such relatively highly organised forms as cyanobacteria and perhaps eukaryotic forms existed in Archaean world.

Instrument development for in situ extraterrestrial life detection focuses primarily on the ability to distinguish between biological and non-biological material, mostly through chemical analysis for potential biosignatures (e.g., biogenic minerals, enantiomeric excesses). In constrast, biochemical analysis techniques commonly applied to Earth life focus primarily on the exploration of cellular and molecular processes, not on the classification of a given system as biological or non-biological. This focus has developed because of the relatively large functional gap between life and non-life on Earth today. Life on Earth is very diverse from an environmental and physiological point of view, but is highly conserved from a molecular point of view. Biochemical analysis techniques take advantage of this similarity of all terrestrial life at the molecular level, particularly through the use of biologically-derived reagents (e.g., DNA polymerases, antibodies), to enable analytical methods with enormous sensitivity and selectivity. These capabilities encourage consideration of such reagents and methods for use in extraterrestrial life detection instruments. The utility of this approach depends in large part on the (unknown at this time) degree of molecular compositional differences between extraterrestrial and terrestrial life. The greater these differences, the less useful laboratory biochemical techniques will be without significant modification. Biochemistry and molecular biology methods may need to be "de-focused" in order to produce instruments capable of unambiguously detecting a sufficiently wide range of extraterrestrial biochemical systems. Modern biotechnology tools may make that possible in some cases.

Analysis of spectral and imaging data from meteoritic samples and sample return missions would benefit significantly from a systematic, quantitative statistical classification methodology and a common set of standards for data collection [McDonald and Storrie-Lombardi, 2006]. Stochastic artificial neural networks can be trained using elemental abundance distributions for the detection of macroscopic fossils [Storrie-Lombardi and Hoover, 2004] and extant microbial life [Storrie-Lombardi and Hoover, 2005]. These non-linear algorithms are particularly attractive since they can produce a Bayesian estimate of the classification accuracy of either human experts or automated, unsupervised classification algorithms. In sub-ocean and surface basalts on earth the networks can distinguish regions of biotic and abiotic alteration of basalt glass from unaltered samples using only elemental abundances as inputs [Storrie-Lombardi and Fisk, 2004b]. Recently, evidence has been presented documenting the presence of morphologic signatures in the Mars meteorite Nakhla [Fisk et al., 2004; Fisk et al., 2006] previously noted in regions of biotic alteration in sub-ocean and surface terrestrial basalts [Fisk et al., 2003; Furnes et al., 2004]. The tunneling alterations are not conclusive evidence of biotic alteration of Nakhla on Mars. However, the meteorite is well known to have experienced aqueous alteration prior to arrival on earth and is rich in carbon [Gibson et al., 2006; McKay et al., 2006]. We here present an initial application of our probabilistic classification strategy to assess elemental abundance distributions from multiple target regions in Nakhla and lunar dust samples collected by Apollo 17 astronauts. We present scanning electron microscope images and elemental abundance point distributions (C, N, O, Na2O, MgO, Al2O3, SiO2, P2O5, S, Cl, K2O, CaO, and FeO) for a series of target regions. We discuss our observations in the context of data previously presented in these meetings for extant cyanobacteria, fossil trilobites, Orgueil meteorite, and terrestrial basalt targets. These data are being added to a database that will made available to the biogeology and astrobiology communities as part of an ongoing effort to provide a quantitative probabilistic methodology for analysis of putative elemental abundance geobiological signatures.

Surface and atmospheric conditions make it unlikely that life as we know it presently exists elsewhere in our solar system. However, this does not preclude the possibility of ancient, extraterrestrial life, which could have originated from Earth or have been introduced to Earth. Since the oldest known sediments on Earth contain evidence for life, it is not possible to determine what the Earth's chemical composition was like prior to life's origin. This evidence can only be sought from meteorites and planetary materials that were formed during the early stages of solar system formation approximately 4.5 to 4.0 GΑa. Criteria are presented that can be used to determine if amino acids in these ancient materials are evidence of ancient life or if they were formed by non-biological processes.

The holy grail of astrobiology is the discovery of a second sample of life that has emerged de novo, independently of life on Earth (as opposed to extraterrestrial life that shares a common origin with terrestrial life via a panspermia process). It would then be possible to separate aspects of biology that are lawlike and expected from those that are accidental and contingent, and thus to address the question of whether the laws of nature are intrinsically bio-friendly. The popular assumption that life is an almost inevitable product of physics and chemistry, and therefore widespread in the universe, is known as biological determinism. It remains an open question whether biological determinism is correct, as there is little direct evidence in its favour from fundamental physics. Homochirality is a deep property of known life, and provides an important test case for the competing ideas of contingency versus lawfulness - or chance versus necessity. Conceivably, a chiral signature is imprinted on life by fundamental physics via parity-violating mixing of the weak and electromagnetic interactions. If so, homochirality would be universal and lawlike. On the other hand, it may be the result of chance: a random molecular accident during the pre-biotic phase. If the latter explanation is correct, one could expect that a second sample of life may have opposite chiral signature even if it resembled known life in its basic biochemistry. There is thus a curious obverse relationship between chirality and biogenesis in relation to biological determinism. If the chiral signature of life is the product of chance, we may hope to discover "mirror life" (i.e. organisms with opposite chiral signature) as evidence of a second genesis, and the latter would establish that life's emergence from non-life is quasi-deterministic. On the other hand, if the chiral signature is determined by fundamental physics, then it may be much harder to establish an independent origin for extraterrestrial life with biochemical make-up resembling that of known life. Whilst the experimental search for a second sample of life - possibly by detecting a chiral "anomaly" - continues, some theoretical investigations may be pursued to narrow down the options. Chiral determinism would be an intrinsically quantum process. There are hints that quantum mechanics plays a key role in biology, but the claim remains contentious. Here I review some of the evidence for quantum aspects of biology. I also summarize some proposals for testing biological determinism by seeking evidence for a multiple genesis events on Earth, and for identifying extant "alien microbes" - micro-organisms descended from an independent origin from familiar life.

The fact that organotrophic organisms on Earth use L-amino acids and D-sugars as an energy source is recognized as one of the universal features of life. The chirality of organic molecules with asymmetric location of group-radicals was described a relatively long time ago. Louis Pasteur observed that abiotic (chemical) processes produced mixtures with equal numbers (racemic) of the two forms but that living organisms possessed a molecular asymmetry that included only one of the enantiomers (homochirality). He speculated that the origin of the asymmetry of chiral biomolecules might hold the key to the nature of life. All of the amino acids in proteins (except for Glycine which is symmetrical) exhibit the same absolute steric configuration as L-glyceraldehyde. D-amino acids are never found in proteins, although they do exist in nature and are often found in polypeptide antibiotics. Constitutional sugars of cells, opposite to the amino acids, are the D-enantiomers, and the appearance of L-sugars in Nature is extremely rare. Notwithstanding this fact, the metabolism of some bacteria does have the capability to use amino acids and sugars with alternative chirality. This property may be caused by the function of specific enzymes belonging to the class of isomerases (racemases, epimerases, isomerases, tautomerases). In our laboratory, we have investigated several anaerobic bacterial strains, and have found that some of these bacteria are capable of using D-amino acids and L-sugars. Strain BK1 is capable of growth on D-arginine, but its growth characteristics on L-arginine are approximately twice as high. Another alkaliphilic strain SCA^T (= ATCC BAA-1084^T = JCM 12857^T = DSM 17722^T = CIP 107910^T) was found to be capable of growth on L-ribose and L-arabinose. It is interesting that this strain was incapable of growth on D-arabinose, which suggests the involvement of some alternative mechanism of enzyme activity. In this paper, we describe the preliminary results of these microbiological studies and discuss some possible implications.

We have performed the Maillard reaction of a series of meteoritic amino acids with sugar ribose under simulated prebiotic conditions, in the solid state at 65°C and at the room temperature. Many meteoritic amino acids are highly reactive with ribose, even at the room temperature. We have isolated high molecular weight products that are insoluble in water, and have studied their structure by the IR (infrared) and solid-state C-13 NMR (nuclear magnetic resonance) spectroscopic methods. The functional groups and their distribution were similar among these products, and were comparable to the previously isolated insoluble organic materials from the Maillard reaction of the common amino acids with ribose. In addition, there were some similarities with the insoluble organic material that is found on Murchison. Our results suggest that the Maillard products may contribute to the composition of the part of the insoluble organic material that is found on Murchison. We have also studied the reaction of sodium silicate solution with the Maillard mixtures, to elucidate the process by which the organic compounds are preserved under prebiotic conditions.

July 30, 2006 was the 30^th anniversary of the Viking Mission's first Labeled Release (LR) life detection experiment on Mars. The strong response, together with supporting results from eight additional LR tests of Martian soil, established the presence of an active agent that was inhibited by heating. The data satisfied the pre-mission criteria for the detection of living microorganisms. However, the scientific community reacted cautiously, generally concluding that the activity in the soil was caused by chemistry or physics. Over the last three decades, investigation of Mars has greatly increased. Soil, rock and atmospheric analyses have been made. Multi-spectral observations have been made from Mars and Earth orbits and from Earth-based telescopes. Knowledge of extreme habitats and bizarre life forms that populate them on Earth has increased dramatically. However, this vast amount of new astrobiological information has yet to be integrated into an objective scientific evaluation of the LR results and the possibilities for life on Mars. Indeed, in part upon misinterpretations of the new findings, myths have been embedded into the scientific literature of Mars. Based on these myths as key ingredients, a false "standard model" of Martian life potential has been developed. It has been accepted by much of the astrobiological community, and, through its endorsement, the world at large. This paper attempts to bring the supportable facts together in calling for a revision of the current consensus regarding life on Mars. It recommends actions to facilitate the paradigm change.

A primary goal of the astrobiology program is the search for fossil records. The astrobiology exploration strategy calls for the location and return of samples indicative of environments conducive to life, and that best capture and preserve biomarkers. Successfully returning samples from environments conducive to life requires two primary capabilities: (1) in situ mapping of the mineralogy in order to determine whether the desired minerals are present; and (2) nondestructive screening of samples for additional in-situ testing and/or selection for return to laboratories for more in-depth examination. Two of the most powerful identification techniques are micro-imaging and visible/infrared spectroscopy. The design and test results are presented from a compact rugged instrument that combines micro-imaging and spectroscopic capability to provide in-situ analysis, mapping, and sample screening capabilities. Accurate reflectance spectra should be a measure of reflectance as a function of wavelength only. Other compact multispectral microimagers use separate LEDs (light-emitting diodes) for each wavelength and therefore vary the angles of illumination when changing wavelengths. When observing a specularly-reflecting sample, this produces grossly inaccurate spectra due to the variation in the angle of illumination. An advanced design and test results are presented for a multispectral microimager which demonstrates two key advances relative to previous LED-based microimagers: (i) acquisition of actual reflectance spectra in which the flux is a function of wavelength only, rather than a function of both wavelength and illumination geometry; and (ii) increase in the number of spectral bands to eight bands covering a spectral range of 468 to 975 nm.

The Mars Exploration Rovers (MER) Sojourner in 1997, and Spirit and Opportunity in 2004, provide an example of how the selection of rover size impacts the nature of their respective mission objectives and capabilities. Smaller rovers tend to be more nimble and can more closely explore a complex environment, but at a cost of reduced capability. Larger rovers have enhanced capabilities, but at a cost of being somewhat ponderous, especially in complex environments. A hierarchical roving concept attempts to optimize the best of these extremes by carrying a hierarchy of smaller specialized rovers within a larger one. The larger carrier rover acts as a communications relay and power recharge source for the smaller rovers and transports them collectively to a deployment site. After having been deployed and executing their respective missions, the smaller rovers are recovered by the carrier rover and then transported to the next site. Additional benefits of this approach include redundancy, spatially distributed capability, greater situational awareness, and the opportunity for self-rescue. Design and construction experience with a carrier rover containing three smaller specialized rovers is discussed, as are the design tradeoffs.

Recent missions to Mars raise the possibility of surface sedimentary sequences that may contain the organic remains of past or present Martian biota. Irrespective of the mechanism of any biological processes on Mars, it seems reasonable to presume that they will involve the transfer and reaction of carbon-bearing molecules. In this case, following the example of terrestrial life forms such as plants and bacteria, it is almost certain that these processes will be accompanied by changes in ¹²C/¹³C ratios (which are themselves the result of kinetic isotope effects imparted during the embedded chemical/physical processes). Thus, just as carbon in biological organic matter on Earth is enriched in the lighter carbon isotope relative to mantle (juvenile) carbon, the logical consequence of Martian life is a stable carbon isotopic gradient from the top of the mantle to the surface sedimentary rocks. Stepped combustion-isotope ratio mass spectrometry is a proven technique for measuring the isotopic composition of ambient carbon trapped in crystals during magma solidification. Data from SNC meteorites extracted from different depths on Mars are not inconsistent with a biologically-produced carbon isotope gradient in the Martian crust and provide directions for future research and exploration.

Despite numerous attempts, we still do not have a satisfactory definition of life. It is generally accepted that one of the essential features of life is the ability of an organism to reproduce. This implies that mules, workers ants, and other sterile individuals are not alive. To correct this apparent problem, we suggest that life should be defined in two ways. In the first way life is defined as a phenomenon, for which the reproduction of some, but not all individuals is essential. In the second way, life is defined as a set of characteristics of an individual organism, among which the reproduction is not essential. We explore Aristotle's classifications of things that exist, in which he placed individual living beings as primary substances, above their species and genera, which are secondary substances. Definition of life as a phenomenon needs to link life to its origins. Life presumably emerged from abiotic matter via chemical evolution. We have examined Aristotle's concept of change in which potentiality goes to actuality, and its variant, Kauffman's concept of adjacent possible, for their possible application in the prebiotic chemical evolution. We have found that these principles are somewhat useful in the back engineering process, but that they have very little predictive value.

Since the first Voyager data, Titan, the largest satellite of Saturn and only satellite in the solar system having a dense atmosphere, became one of the key planetary bodies for astrobiological studies, due to: i) its many analogies with planet Earth, in spite of much lower temperatures, ii) the already well observed presence of an active organic chemistry, involving several of the key compounds of prebiotic chemistry, in the gas phase but also assumed to occur in the solid phase through the haze particles. And the potential development of a prebiotic chemistry in liquid water, with a possible water ocean in its internal structure, and the possible episodic formation of small liquid water bodies for short but not negligible time duration at the surface (from the melting of surface water ice by impact), iii) the resulting possibility that life may have emerged on or in Titan and may have been able to adapt and to persist. These aspects are examined with some of the associated questions on the basis of the already available Cassini-Huygens data.

During the past few decades, the delivery of water, organics, and prebiotic chemicals to the Biosphere of Earth during the Hadean (4.5-3.8 Ga) period of heavy bombardment by comets and asteroids has become more widely accepted. Comets are still largely regarded as frigid, pristine bodies of protosolar nebula material that are devoid of liquid water and therefore unsuitable for life. Complex organic compounds have been observed in comets and on the water-rich asteroid 1998 KY26 and near IR observations have indicated the presence of crystalline water ice and ammonia hydrate on the large Kuiper Belt object (50000) Quaoar that has resurfacing suggesting cryovolcanic outgassing. Spacecraft observations of the chemical compositions and characteristics of the nuclei of several comets (Halley, Borrelly, Wild 2, and Tempel 1) have shown that comets contain complex organic chemicals; that water is the predominant volatile; and that extremely high temperatures (~350-400 K) can be reached on the surface of the very black (albedo~0.03) nuclei of comets when they approach the Sun. Impact craters and pinnacles observed on comet Wild 2 suggest a thick crust. Episodic outbursts and jets from the nuclei of several comets indicate that localized regimes of liquid water and water vapor can periodically exist beneath the comet crust. The Deep Impact mission found the temperature of the nucleus of comet Tempel 1 at 1.5 AU varied from a minimum of 280 ±8 K the 330K (57 °C) on the sunlit side. In this paper it is argued that that pools and films of liquid water exist (within a wide range of temperatures) in cavities and voids just beneath the hot, black crust. The possibility of liquid water existing over a wide range of temperatures significantly enhances the possibility that comets might contain niches suitable for the growth of microbial communities and ecosystems. These regimes would be ideal for the growth of psychrophilic, mesophilic, and thermophilic photoautotrophs and chemolithotrophs such as the motile filamentous cyanobacteria (e.g., Calothrix, Oscillatoria, Phormidium, and Spirulina) that grow in geothermal springs and geysers of Earth at temperatures ranging from 320K to 345K and are also found growing in cold polar desert soils. The mineralized remains of morphotypes of all of these cyanobacteria have also been found in the Orgueil CI1 and the Murchison CN2 carbonaceous meteorites that may derive from cometary parent bodies. Observational results that support the hypothesis that liquid water can in active regions just beneath the surface of comets and that comets, carbonaceous meteorites, and asteroids may have played a significant role in the origin and evolution of the Biosphere and in the distribution of microbial life throughout the Solar System.s

Moons of giant planets may represent an alternative to the classical picture of habitable worlds. Within our own solar system Europa has long served as an intriguing candidate for a subsurface liquid water ocean. Sustained by tidal heating, such an ocean can exist well beyond the range at which stellar heating could raise surface temperatures to similar levels. For exoplanets, with their extraordinarily diverse orbital architectures, the same situation may arise, along with a host of other possibilities - including those where a combination of tidal and stellar heating results in water rich moons experiencing temperate surface conditions. The next generation of space-based planet finders and ground based large telescopes should begin to probe the population of moons around exoplanets - thereby opening up a new avenue in the search for life. We discuss some of these possibilities by investigating the dynamical constraints on moon systems of giant planets and by studying the characteristics of a set of 74 known extrasolar giant planets located beyond 0.6 AU from their parent stars - where moons should be long-lived with respect to removal by stellar tides. By estimating the stellar insolation that moons would experience for these exoplanet systems, and the implications for sublimation loss of volatiles, we find that between 15 and 27% of all known exoplanets may be capable of harboring small, icy, moons. In addition, by applying a simplified energy balance model, we find that some 22-28% of all known exoplanets could potentially harbor moons which, if large, could experience temperate surface conditions due to a combination of tidal and stellar heating. Large moons (0.1M_⊕), at orbital radii commensurate with those of the Galilean satellites, could maintain temperate, or habitable, surface conditions during episodes of tidal heat dissipation ranging from that seen on Europa to 10-100 times greater. We discuss the implications of these findings in the context of habitability.

Three recent in situ spacecraft missions have explored comets or asteroids, producing data in conflict with the standard comet paradigm, the Whipple Dirty Snowball Model (DSM). We have developed an alternative Wet Comet Model (WCM) which proposes that comets undergo an irreversible phase change to a wet comet when they enter within Mars orbit. The WCM may explain some of the observational discrepancies seen by Deep Impact, Stardust and Hayabusa. In particular, it accurately predicted Deep Impact observation of organics, biominerals, and meltwater temperatures. Predictions concerning Stardust's returned cometary dust particles have yet to be falsified, but if comets are largely composed of the silicates seen by Stardust, there may be a cometary explanation for Itokawa's low density rubble-pile observed by Hayabusa.

Soap Lake is a haloalkaline lake located in central Washington. This lake is a remnant of the Missoula flood events that created the landscape of western Montana, the southeastern portion of Washington state, and much of Oregon. It is 15,000 - 20,000 years old, and has maintained a stable meromixis for the last 10,000 years. This carbonate lake is characterized by a brackish mixolimnion, and a monimolimnion with a salinity of ~14%. The pH of both layers of the lake is approximately 10. Both layers also have a high concentration of dissolved sulfate, with the mineral mirabilite (Na₂SO₄•10H₂O) found in the monimolimnion sediments. Sulfide concentrations in the monimolimnion exceed 100 mM. As part of the mission of the NSF Soap Lake Microbial Observatory, microorganisms involved in the sulfur cycle in this lake were studied in terms of their diversity and function. High rates of sulfate reduction were measured in both layers of the lake, with new species of sulfate-reducing bacteria seen in both areas. A particularly novel psychrophilic sulfur oxidizer was isolated from the monimolimnion. This organism has the ability to induce the formation of mirabilite, which was assumed to be an abiotically deposited evaporite mineral. This is the first evidence for a biogenic origin of this mineral. This leads to the possibility that related sulfate minerals, such as those reported on the Mars surface, may have a biogenic origin.

The salinity and sulfate concentrations of microbial mats collected from hypersaline salterns were mainipulated to examine the effects of low sulfate concentrations and lowered salinity on carbon metabolism. As sulfate was slowly removed from the mats, methane production and flux increased, with highest fluxes and concentration in mats at lowered salinity (35 ppt) and low sulfate concentrations. The δ¹³C values of bulk particulate organic carbon (POC) ranged from about -10 to -12 &perthou;, similar to what had been observed previously for these cyanobacterial mats. In mats with higher sulfate concentrations, pore water profiles of dissolved inorganic carbon (DIC) δ¹³C values decreased with depth. However, in the mats with lowered sulfate, the DIC δ¹³C values increased substantially, from about -1 &perthou; in the overlying water to +12 &perthou; by 20 mm depth. Although the increase in DIC δ¹³C values is consistent with biogenic methanogenesis, the measured methane concentrations in these mats were not great enough to be the sole cause of the increase. These positive isotopic values, as well as the higher acetate concentrations observed in the low-sulfate mats, are also consistent with the occurrence of acetogenesis.

Evolution is usually taught as the result of mutations and genetic recombinations combined with natural selection, but most living forms have symbiotic relationships with microorganisms, and in this sense symbiogenesis seems to play a very important role in the origin and life evolution. Symbiosis is an important support for the acquisition of new genomes and new metabolic capacities, which drives living forms' evolution. In this sense, the evolutionary changes can be explained by an integrated cooperation between organisms, in which symbiosis acts, not as an exception, but rather as the rule in nature. Beginning with the eukaryotic cell formation, symbiogenesis appears to be the main evolutionary mechanism in the establishment and maintenance of biomes, as well as the foundation of biodiversity, based on rather suddenly evolutionary novelty, which challenges the Darwinian gradualism. These principles can be applied to the life on Earth and beyond.

Stromatolites offer a unique window into 3.5 billion years of evolution of the microbial communities that built them within the context of an evolving Earth. Our interest is not in the microbial life or their external matrix as independent entities, but the appearance and evolution of complexity itself within this biogeological system. We adopt the canonical definition of complexity as the emergence and detection of previously unseen properties (structures, functions, information), and we propose that the defining emergent property of stromatolites apparent to the human expert eye is the lamination. To develop a quantitative complexity metric for stromatolites, we must ask what makes it possible for the human brain to perceive lamination? Our visual system operates optimally as a difference machine rapidly identifying variations in signal intensity and redundancy in neighboring regions. In stromatolites, such differences are detected by first scanning parallel to the growth surface and then placing layers in context by scanning orthogonal to that surface. We propose that the fundamental metric for stromatolite complexity resides in the laminae themselves and that easily measured differences in luminance, variability, and redundancy between alternating laminae is an emergent feature of stromatolite complexity. The metrics calculated for laminae in photomicrographs revealed significant differences between putative biotic/abiotic laminae. The statistical indices calculated can contribute to stromatolite recognition, description, and classification. The indices are easily calculated in the laboratory or in the field on personal computers. We propose that such statistical information metrics be included as a standard component in the description of extant and fossil stromatolites.

A common class of organic compound in low petrographic type meteorites is the sulfur-containing thiophenes. The presence of this compound class in organic-rich meteorites which have experienced substantial levels of aqueous alteration is relatively unexplored. Early reports of these compounds attributed them to artefacts brought about by reactions between elemental sulfur and organic matter during high temperature extraction and analysis steps. Subsequent investigations confirmed their indigeneity, yet their environment of formation remained unconstrained. Here we present data which suggests that thiophenes are parent body alteration products that reflect the role of liquid water on asteroids in the early solar system.

Making science was and always will be a continuous challenge; however teaching science is a step forth. A good example is astrobiology. Defined as the scientific study of biological processes on Earth and beyond, it connects research in chemistry, physics, biology, geology, astronomy and planetary sciences. This interconnected scientific network allows us to visualize a new approach of the life's nature and its origins and development on Earth and elsewhere in the universe. With these goals, we wish to look within the nature of life, observing a new paradigm in the construction of the scientific knowledge. Teaching astrobiology is not an easy task. There are several constrains, such as treating and integrating diverse areas of knowledge and teaching a science that embraces so many questions presently unanswered and on which students have so many doubts and wrong pre-instructional beliefs. Another obstacle is the rapidly spreading of Intelligent Design, the new incarnation of creationism, which considers astrobiology as a danger for its policies, dogmas and philosophy. However, the principal barrier for teaching astrobiology is, without doubt, the difficulty to integrate this science in the curricular domain.

Mode of preservation of organic materials on early Earth, Mars or other extraterrestrial objects, and during the space transport on objects such as meteors, is one of the NASA's interests. This is especially true for the bio-organic materials, which could indicate life, past or present. Finding of such materials preserved in some ancient rocks, for example, could be interpreted as a biosignature. We have developed an experimental model for silicification, in which we have synthesized silica gels by reacting sodium silicate solution with various amino acids and with their mixtures with sugars, so-called Maillard mixtures. Our results indicate that these organic materials cause rapid and massive polymerization of silica. Such process may encrust organics or small organisms and thus preserve them. We have studied the gels we synthesized by the infrared (IR) spectroscopic method, and have detected small amount of the organic material in the silica gel. The gels were distinct in each case and have aged differently. In some cases, gel-sol-gel transformations were observed, which may be important for transport of both gels and the organics under prebiotic conditions. The gels obtained from the Maillard mixtures differ from those from the amino acids. Deuteration of the gels was performed in an attempt to resolve the bands in the Si-O-Si and Si-O-C region.

We describe a computer application designed to analyze hyperspectral data collected by the Compact Infrared Spectrometer for Mars (CRISM). The application links the spectral, imaging and mapping perspectives on the eventual CRISM dataset by presenting the user with three different ways to analyze the data. One of the goals when developing this instrument is to build in the latest algorithms for detection of spectrally compelling targets on the surface of the Red Planet, so they may be available to the Planetary Science community without cost and with a minimal learning barrier to cross. This will allow the Astrobiology community to look for targets of interest such as hydrothermal minerals, sulfate minerals and hydrous minerals and be able to map the extent of these minerals using the most up-to-date and effective algorithms. The application is programmed in Java and will be made available for Windows, Mac and Linux platforms. Users will be able to embed Groovy scripts into the program in order to extend its functionality. The first collection of CRISM data will occur in September of 2006 and this data will be made publicly available six months later via the Planetary Datasystem (PDS). Potential users in the community should therefore look forward to a release date mid-2007. Although exploration of the CRISM data set is the motivating force for developing these software tools, the ease of writing additional Groovy scripts to access other data sets makes the tools useful for mineral exploration, crop management, and characterization of extreme environments here on Earth or other terrestrial planets. The system can be easily implemented for use by high school, college, and graduate level students.

The capabilities of the KMC-2 beamline at BESSY for spatially resolved x-ray measurements with micro- and nanometer resolution are reviewed. An application of micro- X-ray fluorescence analysis (μXRFA), micro-extended X-ray absorption fine structure (μEXAFS), micro-X-ray absorption near-edge structure (μXANES) as well as standing wave technique (SWT) as a powerful method for the organic and non-organic samples characterization with synchrotron radiation is discussed. Mono and poly-capillary optical systems were used for characterization of organic and non-organic samples, by means of μXRFA mapping and μEXAFS and μXANES. The results of depth resolved tungsten XAFS measurements in a Si/W/Si trilayer embedded in a Au waveguide structure are presented. A depth resolution on the order of 1nm has been achieved.

Focal-plane speckles set important sensitivity limits on ground- or space-based imagers and coronagraphs that may be used to search for faint companions, perhaps ultimately including exoplanets, around stars. As speckles vary with atmospheric fluctuations or with drifting beamtrain aberrations, they contribute speckle noise proportional to their full amplitude. Schemes to suppress speckles are thus of great interest. At high adaptive correction, speckles organize into species, represented by algebraic terms in the expansion of the phase exponential, that have distinct spatial symmetry, even or odd, under spatial inversion. Filtering speckle patterns by symmetry may eliminate a disproportionate fraction of the speckle noise while blocking (only) half of the image signal from the off-axis companion being sought. The fraction of speckle power and hence of speckle noise in each term will vary with degree of correction, and so also will the net symmetry in the speckle pattern. Systematic numerical investigations are presented of the net symmetry of noise variance as a function of adaptive correction, i.e., Strehl ratio S, and deformable mirror actuator density D/a, where a is the deformable mirror actuator spacing referred to the pupil of diameter D, which controls the characteristic transverse spatial frequency of the wavefront. The degree of speckle symmetry is found to be substantial even at current relatively modest ground-based corrections (S=0.6, D/a=16 in the near-infrared). With parameters representative of "extreme" adaptive optics of the near future (S=0.99, D/a=100), the antisymmetric noise variance fraction is 0.99967 averaged over two Airy rings in the inner halo, so simple image processing (symmetry filtering) can improve the net speckle-noise-limited companion-detection SNR by a factor of about 28. Analogous processing can enhance SNR in coronagraphic searches, where speckle patterns before processing are predominantly symmetric.