This PDF file contains the front matter associated with SPIE Proceedings Volume 7819, including the Title Page, Copyright information, Table of Contents, introduction (if any), and the Conference Committee listing.

The 1959 Nature article by Giuseppe Cocconi and Phil Morrison¹ provided the theoretical underpinnings for SETI, accompanied in 1960 by Project Ozma², the first radio search for signals by Frank Drake at the National Radio Astronomy Observatory (NRAO). Well over 100 search programs have been conducted since that time, primarily at radio and optical wavelengths, (see www.seti.org/searcharchives) without any successful signal detection. Some have suggested that this means humans are alone in the cosmos. But that is far too strong a conclusion to draw from far too small an observational sampling. Instead of concluding that intelligent life on Earth is unique, it is more appropriate to note that in 50 years our ability to search for electromagnetic signals has improved by at least 14 orders of magnitude and that these improvements are still occurring at an exponential rate. At the SETI Institute we are in the process of reinventing the way we search in order to fully utilize these technological enhancements. We are now building the setiQuest community and we intend to get the world involved in making our searches better. We need to find ways to harness the intelligence of all Earthlings in order to better seek out extraterrestrial intelligence. If we do it right, we just might succeed, and we might also change how we see ourselves, and make our own world a better place.

Homochirality of the biomolecules (D-sugars of DNA and RNA and L-amino acids of proteins) is a fundamental property of all life on Earth. Abiotic mechanisms yield racemic mixtures (D/L=1) of chiral molecules and after the death of an organism, the enantiopure chiral biomolecules slowly racemize. Several independent investigators have now established that the amino acids present in CI1 and CM2 carbonaceous meteorites have a moderate to strong excess of the L-enantiomer. Stable isotope data have established that these amino acids are both indigenous and extraterrestrial. Carbonaceous meteorites also contain many other strong chemical biomarkers including purines and pyrimidines (nitrogen heterocycles of nucleic acids); pristine and phytane (components of the chlorophyll pigment) and morphological biomarkers (microfossils of filamentous cyanobacteria). Energy dispersive X-ray Spectroscopy (EDS) analysis reveals that nitrogen is below the detectability level in most of the meteorite filaments as well as in Cambrian Trilobites and filaments of 2.7 Gya Archaean cyanobacteria from Karelia. The deficiency of nitrogen in the filaments and the total absence of sugars, of twelve of the life-critical protein amino acids, and two of the nucleobases of DNA and RNA provide clear and convincing evidence that these filaments are not modern biological contaminants. This paper reviews the chiral, chemical biomarkers morphological biomarkers and microfossils in carbonaceous meteorites. This paper reviews chiral and morphological biomarkers and discusses the missing nitrogen, sugars, protein amino acids, and nucleobases as "bio-discriminators" that exclude modern biological contaminants as a possible explanation for the permineralized cyanobacterial filaments found in the meteorites.

The amplification of L-enantiomers of amino acids from racemates was likely a precondition for the origin of life on Earth. Engel and Nagy¹ first reported that seven protein amino acids in the Murchison meteorite exhibited a significant L-enantiomer excess, leading to speculation that meteorite bombardment during the earliest stages of Earth history provided these essential building blocks for the development of life. Stable isotope signatures of amino acids extracted from the Murchison meteorite confirmed the extraterrestrial origin and stereochemistry of these compounds^2,3. However, until recently, plausible explanations for the observed magnitude of the L-enantiomer excess in Murchison have been lacking. Alternative methods for the asymmetric amplification of L-amino acids have recently been reported^e.g.4,5 that are consistent with that observed in the Murchison meteorite. A model is presented for the synthesis and subsequent alteration of amino acids on the parent body of the Murchison meteorite that is consistent with the stereochemistry presently observed.

The petroleum hydrocarbons (oil like components and gas) and kerogen macromolecule are abundant within the extraterrestrial atmospheric particles, as reservoir of lakes and oceans or in hydrate forms, and within various carbonaceous chondrites (from asteroid belts, comets, and planets/moons), and as solid residue within the planets or moons within and outside our Solar System. Some of the important occurrences of petroleum hydrocarbons are: (a) the cup-like craters and large lakes, in the atmosphere within two moons of Saturn (Hyperion and Titan), and possibly also in Saturn's rings; (b) solid organic complexes with aromatic and aliphatic units within Iapetus and many bodies in the outer Solar System; (c) abundance of water, methane, gas hydrates within Mars; (d) remnant of nannofossils, kerogen-like geopolymers, and oil-like components within most of the CM, C1, and C2 carbonaceous chondrites. These discoveries clearly rekindled the very old debate over the biogenic or abiogenic origin on the genesis of these hydrocarbons. Several theories are prevalent for the abiogenic origin of petroleum: formation of gas by mantle decompression and thermal tsunami; various deep polymerization processes in the upper mantle gases through inorganic processes; gases evolved from a hot deep biosphere in the mantle, migration through deep-seated faults, and eventual polymerization of gases to heavier hydrocarbons. Most prevalent ideas of the origin of petroleum pool within various stratigraphic intervals in the terrestrial environment are overwhelmingly connected to the thermal degradation of macromolecular kerogen of biological entities. The current publication illustrated both these views on the genesis of petroleum hydrocarbons within carbonaceous chondrites that could be derived from other planets or moons within our Solar System and the asteroid belts and beyond.

The search for life elsewhere in the solar system has focused on experiments to detect extant life and on the detection of ancient remnants of life from times in the distant past when planetary bodies may have had more hospitable climates for the proliferation of life as we know it. With respect to the latter, compounds that are ubiquitous to life on Earth (e.g. amino acids) are logical targets when attempting to assess the possible occurrence of ancient extraterrestrial life. However, subsequent to death, the distribution and stereochemistry of amino acids change with the passage of time, and these changes may vary depending on environments of preservation. Amino acid distributions and stereochemistry for microorganisms in desert and arctic environments are presented and compared to those derived from older rocks and sediments that they are associated with. Criteria are suggested for the assessment of ancient, extraterrestrial life based on these distributions.

Different methods for the investigation of ancient microfossils - in macerates, in thin sections and in fresh chips in scanning electronic microscope - are discussed. The overwhelming advantage of the Scanning Electron Microscopy method is shown.

Complexes of fossilized microorganisms were identified and studied in the rocks of the Lower Paleoproterozoic Suisarian Formation representing the stratotype of the Ludicovian Supergroup, Karelian complex of Central Karelia. The fossil microorganisms from different zones of pillow lavas were compared.

Most chemical reactions on asteroids, from which meteors and meteorites originate, are hypothesized to occur primarily in the solid mixtures. Some secondary chemical reactions may have occurred during the periods of the aqueous alteration of the asteroids. A myriad of organic compounds have been isolated from the meteorites, but the chemical pathways by which they were formed are only partially elucidated. In this paper we propose that many meteoritic organic compounds were formed in the solventless and solid-state reactions, which were only recently explored in the conjunction with the green chemistry (environmentally friendly). A typical solventless approach exploits the phenomenon of the mixed melting points. As the solid materials are mixed together, the melting point of the mixture becomes lower than the melting points of its individual components. In some cases the entire mixture may melt upon mixing. The reactions would then occur in a viscous melted state. In the traditional solid-state reactions the solids are mixed together, which allows for the intimate contact of the reactants, but the reaction occurs without melting. Numerous examples of the known solventless and solid-state reactions which are particularly relevant to the meteoritic chemistry are described.

The role of the observer in the scientific process has been studied in various contexts, including philosophical. It is notorious that the experiments are theory-loaded, that the observers pick and choose what they consider important based on their scientific and cultural backgrounds, and that the same phenomenon may be studied by different observers from different angles. In this paper we critically review various authors' views of the role of the observer in the scientific process, as they apply to astrobiology. Astrobiology is especially vulnerable to the role of the observer, since it is an interdisciplinary science. Thus, the backgrounds of the observers in the astrobiology field are even more heterogeneous than in the other sciences. The definition of life is also heavily influenced by the observer of life who injects his/her own prejudices in the process of observing and defining life. Such prejudices are often dictated by the state of science, instrumentation, and the science politics at the time, as well as the educational, scientific, cultural and other background of the observer.

Robust, tunable Surface enhanced Raman spectroscopy (SERS) substrates were created using the Langmuir-Blodgett technique. Initial studies of Langmuir-Blodgettry were done with arachidic acid to optimize monolayer deposition parameters. Hydrophilic and hydrophobic glass substrates were prepared and coated with arachidic acid. SERS monolayer substrates were then made from Ag nanostructures. Deposition of Ag nanoparticles using the Langmuir Blodgett technique resulted in clusters of Ag monolayers. The films were capable of SERS for Rhodamine 6G (R6G) and a range of biomolecules. Raman imaging of these films revealed the overall distribution of the SERS effect. In comparison of the enhancement performances, Ag nanowires were also deposited on glass substrates using Langmuir Blodgettry. The resulting substrate consisted of oriented bundles of Ag nanowires. SERS of R6G was observed on these bundles when the polarization of light was longitudinal to the wire axis. Raman imaging showed the distribution of hotspots on the nanowire bundles.

We explore the conditions prevailing in primordial planets in the framework of the HGD cosmologies as discussed by Gibson and Schild. The initial stages of condensation of planet-mass gas clouds is set at 300,000 yr (0.3My) following the onset of plasma instabilities when ambient temperatures were >1000K. Eventual collapse of the cloud into a solid structure, dominated by water-ice and organics takes place against the background of an expanding universe with declining ambient temperatures. Isothermal free fall collapse occurs initially via quasi equilibrium polytropes until opacity sets in due to molecule and dust formation. The contracting cooling cloud is a venue for molecule formation and the sequential condensation of solid particles, starting from mineral grains at high temperatures to ice particles at lower temperatures, Water-ice becomes thermodynamically stable between 7 and 15 My after the initial onset of collapse, and contraction to form a solid icy core begins shortly thereafter. The icy planet core, which includes a fraction of radioactive nuclides, ²⁶Al and ⁶⁰Fe, melts through interior heating. We show, using heat conduction calculations, that the interior domains remain liquid for tens of My for 300km and 1000km objects, but not for 30 or 50km objects. Initially planets are separated by relatively short distances, measured in tens to hundreds of AU, because of the high density of the early universe. Thus exchanges of materials, organic molecules and evolving templates could readily occur providing optimal conditions for an initial origin of life. The condensation of solid molecular hydrogen as an extended outer crust takes place much later in the collapse history of the protoplanet. When the object has shrunk to several times the radius of Jupiter, the hydrogen partial pressure exceeds the saturation vapour pressure of solid hydrogen at the ambient temperature and condensation occurs.

Understanding the Earth spectral bio-signatures provides an important reference datum for accurate de-convolution of collapsed spectral signals from potential earth-like planets of other star systems. This study presents a new ray tracing computation method including an improved 3D optical earth model constructed with the coastal line and vegetation distribution data from the Global Ecological Zone (GEZ) map. Using non-Lambertian bidirectional scattering distribution function (BSDF) models, the input earth surface model is characterized with three different scattering properties and their annual variations depending on monthly changes in vegetation distribution, sea ice coverage and illumination angle. The input atmosphere model consists of one layer with Rayleigh scattering model from the sea level to 100 km in altitude and its radiative transfer characteristics is computed for four seasons using the SMART codes. The ocean scattering model is a combination of sun-glint scattering and Lambertian scattering models. The land surface scattering is defined with the semi empirical parametric kernel method used for MODIS and POLDER missions. These three component models were integrated into the final Earth model that was then incorporated into the in-house built integrated ray tracing (IRT) model capable of computing both spectral imaging and radiative transfer performance of a hypothetical space instrument as it observes the Earth from its designated orbit. The IRT model simulation inputs include variation in earth orientation, illuminated phases, and seasonal sea ice and vegetation distribution. The trial simulation runs result in the annual variations in phase dependent disk averaged spectra (DAS) and its associated bio-signatures such as NDVI. The full computational details are presented together with the resulting annual variation in DAS and its associated bio-signatures.

The recent discoveries of evidence for liquid saline water^1,2,3,4 and methane⁵ on Mars have excited the science community by reviving the possibility of extant microbial life in this nearby planet. Here we report recently discovered photometric and spectral evidence that liquid saline water exists on Mars⁴. We show that this finding indicates that deliquescence occurs seasonally on some areas of Mars' polar region⁴. These discoveries support the hypothesis that liquid saline water is ubiquitous in the shallow Martian subsurface. This has important implications for the search for extraterrestrial life because a diverse array of terrestrial microorganisms thrives in highly saline water or brines^6,7. We conclude this article by describing in situ and remote sensing instruments for detecting brines in the Martian subsurface and studying their relationship with sources and sinks of trace gases.

The basis for chiral biomarkers that have been increasingly proposed to obtain evidence for life is reviewed. Specific problems in accepting them and other biomarkers as proof of life are cited. A new chiral method is offered to overcome these difficulties, a method that can make an unambiguous determination of extant microbial life.

We present a likelihood estimate that methane was a significant component of the gas detected by the Labeled Release (LR) experiment in the Viking Mission to Mars of 1976. In comparison with terrestrial methanogen production of methane we estimate the size of the putative microbe population necessary to produce the LR gas, had it been primarily methane. We extrapolate that figure to estimate the number of methanogens necessary to produce the methane content of the Martian atmosphere. Next, we estimate the amount of Martian soil and the amount of water needed for that global population of microbes. Finally, assuming a globally distributed population of such microbes, we estimate the likely sub-surface depth at which such methanogens could be detected.

The circumpolar region of Mars was surveyed for possible habitats in the area of seasonal ice cap. Dark Dune Spots were found to be good candidates as they are covered by water ice there without carbon-dioxide ice, and show flow-like features in springtime. Based on theoretical calculations interfacial water or bulk brine may be present there that decomposes the aggressive oxidants. Temperature values in springtime around noon could be favorable for metabolism of known extremophyles on Earth, and water uptake may be possible at nighttime. During the warm daytime period the water loss could be lowered by densely packed grain structure of the soil, hygroscopic salts, and polysaccharide-like materials, as it was observed in the samples of cryptobiotic crust from hot and cold deserts on Earth. This work outlines the basic elements of these possible circumpolar microhabitats.

The detection of extraterrestrial life in-situ assumes that a positive indication is the result of an indigenous life form, and not the result of forward contamination from Earth. Atmospheric discharge cold plasma jets have proven effective in the decontamination of a wide range of microorganisms, including Deinococcus radiodurans, through multiple modes of action, yet the effect is relatively gentle on surfaces being decontaminated. An individual plasma jet may have a beam diameter of only a few millimeters, requiring extensive decontamination time for a given surface area. Techniques are discussed for assembling large area multi-jet arrays, and their mechanisms of decontamination. Application to back contamination in sample return missions is also considered.

We have shown that the red cells found in the Red Rain (which fell on Kerala, India, in 2001) survive and grow after incubation for periods of up to two hours at 121°C . Under these conditions daughter cells appear within the original mother cells and the number of cells in the samples increases with length of exposure to 121°C. No such increase in cells occurs at room temperature, suggesting that the increase in daughter cells is brought about by exposure of the Red Rain cells to high temperatures. This is an independent confirmation of results reported earlier by two of the present authors, claiming that the cells can replicate under high pressure at temperatures upto 300°C. The flourescence behaviour of the red cells is shown to be in remarkable correspondence with the extended red emission observed in the Red Rectagle planetary nebula and other galactic and extragalactic dust clouds, suggesting, though not proving an extraterrestrial origin.

Extremophiles are microorganisms that have adapted to severe conditions that were once considered devoid of life. The extreme settings in which these organisms flourish on Earth resemble many extraterrestrial environments. Identification and classification of extremophiles in situ (without the requirement for excessive handling and processing) can provide a basis for designing remotely operated instruments for extraterrestrial life exploration. An important consideration when designing such experiments is to prevent contamination of the environments. We are developing a reference spectral database of autofluorescence from microbial extremophiles using long-UV excitation (408 nm). Aromatic compounds are essential components of living systems, and biological molecules such as aromatic amino acids, nucleotides, porphyrins and vitamins can also exhibit fluorescence under long-UV excitation conditions. Autofluorescence spectra were obtained from a light microscope that additionally allowed observations of microbial geometry and motility. It was observed that all extremophiles studied displayed an autofluorescence peak at around 470 nm, followed by a long decay that was species specific. The autofluorescence database can potentially be used as a reference to identify and classify past or present microbial life in our solar system.

Our previous study of chirality led to interesting findings for some anaerobic extremophiles: the ability to metabolize substrates with alternate chirality enantiomers of amino acids and sugars. We have subsequently found that not just separate microbial species or strains but entire microbial communities have this ability. The functional division within a microbial community on proteo- and sugarlytic links was also reflected in a microbial diet with L-sugars and D-amino acids. Several questions are addressed in this paper. Why and when was this feature developed in a microbial world? Was it a secondary de novo adaptation in a bacterial world? Or is this a piece of genetic information that has been left in modern genomes as an atavism? Is it limited exclusively to prokaryotes, or does this ability also occur in eukaryotes? In this article, we have used a broader approach to study this phenomenon using anaerobic extremophilic strains from our laboratory collection. A series of experiments were performed on physiologically different groups of extremophilic anaerobes (pure and enrichment cultures). The following characteristics were studied: 1) the ability to grow on alternate chirality enantiomers - L-sugars and D- amino acids; 2) Growthinhibitory effect of alternate chirality enantiomers; 3) Stickland reaction with alternate chirality amino acids. The results of this research are presented in this paper.

To prevent forward contamination and maintain the scientific integrity of future life detection missions, it is important to characterize and attempt to eliminate terrestrial microorganisms associated with exploratory spacecraft and landing vehicles. Among the organisms isolated from spacecraft-associated habitats, spores of Bacillus pumilus SAFR-032 exhibited unusually high resistance to decontamination techniques such as UVradiation and peroxide treatment. Subsequently, Bacillus pumilus SAFR-032 was flown to the International Space Station (ISS) and exposed to a variety of space conditions using the European Technology Exposure Platform and Experiment Facility (EuTEF). After 18 months exposure in the EuTEF facility under dark space conditions, SAFR-032 spores showed 10 to 40% survivability, whereas a survival rate of 85 to 100% was observed when these spores were kept aboard the ISS under dark simulated-Mars atmospheric conditions. In contrast, when UV (>110nm) was exerted on SAFR-032 spores for the same time period and conditions using the EuTEF, a ~7-log reduction in viability was noticed. However, the UV exposure still did not inactivate all the spores as 19 CFUs were later isolated via cultivation. A parallel experiment was conducted on Earth with identical samples but under simulated conditions. Spores exposed to ground simulations showed less of a reduction in viability when compared with the "real space" exposed spores (~3-log reduction in viability for Mars UV, and ~4-log reduction in viability for Space UV). The data generated is important to assess the probability and mechanisms of microbial survival, microbial contaminants of risk for forward contamination, in situ life detection, and to safeguard the integrity of sample return missions.

The red rain microbes, which caused red rain phenomenon in Kerala, India, exhibit many characteristics much different from conventional microorganisms. Previous study indicates that these microbes are possibly of extraterrestrial origin. Their ability to multiply at extreme high temperature of 300°C and the unusual autofluorescence of their biomolecules are some of their extraordinary properties. Their molecular composition is yet to be identified. In this paper we report the growth pattern of these novel microbes at temperatures below 100°C as a minimal approach to show their biological nature. Automated turbidity measurement of the cell culture indicate standard microbial growth curve. Increase in the cell population is faster at higher temperatures. Details of this investigation and results are discussed.

Archaea are important potential candidates in astrobiology as their metabolism includes solar, inorganic and organic energy sources. Archaeal viruses would also be expected to be present in a sustainable archaeal exobiological community. Genetic sequence Shannon entropy and fractal dimension can be used to establish a two-dimensional measure for classification and phylogenetic study of these organisms. A sequence fractal dimension can be calculated from a numerical series consisting of the atomic numbers of each nucleotide. Archaeal 16S and 23S ribosomal RNA sequences were studied. Outliers in the 16S rRNA fractal dimension and entropy plot were found to be halophilic archaea. Positive correlation (R-square ~ 0.75, N = 18) was observed between fractal dimension and entropy across the studied species. The 16S ribosomal RNA sequence entropy correlates with the 23S ribosomal RNA sequence entropy across species with R-square 0.93, N = 18. Entropy values correspond positively with branch lengths of a published phylogeny. The studied archaeal virus sequences have high fractal dimensions of 2.02 or more. A comparison of selected extremophile sequences with archaeal sequences from the Humboldt Marine Ecosystem database (Wood-Hull Oceanography Institute, MIT) suggests the presence of continuous sequence expression as inferred from distributions of entropy and fractal dimension, consistent with the diversity expected in an exobiological archaeal community.

Daytime photosynthesis and nighttime nitrogen fixation metabolic processes have been reported in the bacterium, Cyanothece 51142. The organism's auto-fluorescence with 532 nm excitation would place cyanobacteria at the forefront in the remote sensing of microbial activity in astrobiology. The sensitivity of nitrogenase to oxygen was studied in terms of sequence nucleotide fluctuation. A nucleotide sequence fractal dimension can be calculated from a numerical series consisting of the atomic numbers of each nucleotide. The fractal dimension and Shannon entropy form a two-dimensional measure that is useful in assessing evolutionary pressures. The studied sequences include nitrogenase iron protein NifH, nitrogenase molybdenum-iron protein alpha chain NifD and beta chain NifK. The photosynthesis-lacking UCYN-A cyanobacterium as reported recently in the journal, Nature, was observed to have the lowest entropy with relatively high fractal dimension values in the studied NifH, NifD and NifH sequences. The fractal dimension of NifH sequences correlates with the NifD sequence values with an R-square of 0.91 (N = 8). The Shannon mononucleotide entropy of NifD sequences correlates with the NifK sequence values with an R-square value of 0.92 (N = 8). The observed strong correlation suggests the presence of gradual evolutionary pressure among the studied cyanobacteria, and throws light on the reported paradox in evolution for the case of UCYN-A. The results show that diurnal oscillation metabolic processes in cyanobacteria (including the photosynthesis-deficient case) are not associated with extraordinary evolutionary pressures and thus are processes consistent with putative astrobiological organisms.

The Zn-metalloprotease family contains conserved amino acid structures such that the nucleotide fluctuation at the DNA level would exhibit correlated randomness as described by fractal dimension. A nucleotide sequence fractal dimension can be calculated from a numerical series consisting of the atomic numbers of each nucleotide. The structure's vibration modes can also be studied using a Gaussian Network Model. The vibration measure and fractal dimension values form a two-dimensional plot with a standard vector metric that can be used for comparison of structures. The preference for amino acid usage in extremophiles may suppress nucleotide fluctuations that could be analyzed in terms of fractal dimension and Shannon entropy. A protein level cold adaptation study of the thermolysin Zn-metalloprotease family using molecular dynamics simulation was reported recently and our results show that the associated nucleotide fluctuation suppression is consistent with a regression pattern generated from the sequences's fractal dimension and entropy values (R-square ~ 0.98, N =5). It was observed that cold adaptation selected for high entropy and low fractal dimension values. Extension to the Archaemetzincin M54 family in extremophiles reveals a similar regression pattern (R-square = 0.98, N = 6). It was observed that the metalloprotease sequences of extremely halophilic organisms possess high fractal dimension and low entropy values as compared with non-halophiles. The zinc atom is usually bonded to the histidine residue, which shows limited levels of vibration in the Gaussian Network Model. The variability of the fractal dimension and entropy for a given protein structure suggests that extremophiles would have evolved after mesophiles, consistent with the bias usage of non-prebiotic amino acids by extremophiles. It may be argued that extremophiles have the capacity to offer extinction protection during drastic changes in astrobiological environments.

Extreme conditions such as low temperature, dryness, and constant UV-radiation in terrestrial Antarctica are limiting factors to the survival of microbial populations. The objective of this study was to investigate the microbial diversity and enumeration between the open water lakes of Schirmacher Oasis and the permanently ice-covered Lake Untersee. The lakes in Schirmacher Oasis possessed an abundant and diverse group of microorganisms compared to Lake Untersee. Furthermore, the microbial diversity between two lakes in Schirmacher Oasis (Lake L27C and L47) was compared by culture-based molecular approach. It was determined that L27C had a richer microbial diversity representing 4 different phyla and 7 different genera. In contrast L47 consisted of 3 different phyla and 6 different genera. The difference in microbial community could be due to the wide range of pH between L27C (pH 9.1) and L47 (pH 5.7). Most of the microbes isolated from these lakes consisted of adaptive biological pigmentation. Characterization of the microbial community found in the freshwater lakes of East Antarctica is important because it gives a further glimpse into the adaptation and survival strategies found in extreme conditions.

The modern ribosome is a complex biological machine that is responsible for chiral synthesis of cellular proteins according to the genetic code as specified by a mRNA. Major portions of the ribosomal machinery were likely in place before the last universal common ancestor (LUCA) of life. The early evolution of the ribosome has implications for the origin of the genetic code, the emergence of chirality in peptide synthesis, and the emergence of LUCA. Although codon assignments may remain a mystery, the history of the ribosome provides a context for dating the first usage of mRNA. In the case of chirality, the modern ribosome suggests that a small initial chiral preference for L-amino acids in the environment may have been greatly enhanced by a two step process in which the charging of a primitive tRNA and the subsequent synthesis of a peptide bond both had the same chiral preference. The resulting ability to make largely chiral peptides may have provided an advantage over other prebiotic mechanisms for making peptides. Finally, the late addition of factors such as EF-G may have greatly accelerated the emerging ribosome's ability to synthesize proteins, thereby allowing entities with this novel capability to emerge as the LUCA.

While "life" may universally be a self-sustaining chemical system capable of Darwinian evolution, alien life may be quite different in its chemistry from the terran life that we know here on Earth. In this case, it will be difficult to recognize, especially if it has not advanced beyond the single cell life forms that have dominated much of the terran biosphere. This review summarizes what we might infer from general physical and chemical law about how such "weird" life might be structured, what solvents other than water it might inhabit, what genetic molecules it might contain, and what metabolism it might exploit.

Origin of life theories have produced numerous schools of thought, two of which are termed RNA World and Snowball Earth. Complex organic molecules can be produced by RNA catalysis. This chemistry would be hindered by ice formation that would sequester moecules in the frozen water matrix. We present experimental data showing that RNA retains antifreeze properties that would enable the exchange of reactants/products of the catalytic reactions.

Three decades ago the first convincing evidence of microbial fossils in carbonaceous chondrites was discovered and reported by Hans Dieter Pflug and his collaborators. In addition to morphology, other data, notably laser mass spectroscopy, confirmed the identification of such structures as putative bacterial fossils. Balloon-borne cryosampling of the stratosphere enables recovery of fragile cometary dust aggregates with their structure and carbonaceous matter largely intact. SEM studies of texture and morphology of particles in the Cardiff collection, together with EDX identifications, show two main types of putative bio-fossils - firstly organic-walled hollow spheres around 10μm across, secondly siliceous diatom skeletons similar to those found in carbonaceous chondrites and terrestrial sedimentary rocks and termed 'acritarchs'. Since carbonaceous chondrites (particularly Type 1 chondrites) are thought to be extinct comets the data reviewed in this article provide strong support for theories of cometary panspermia.

A key result of hydrogravitational dynamics cosmology relevant to astrobiology is the early formation of vast numbers of hot primordial-gas planets in million-solar-mass clumps as the dark matter of galaxies and the hosts of first life. Photon viscous forces in the expanding universe of the turbulent big bang prevent fragmentations of the plasma for mass scales smaller than protogalaxies. At the plasma to gas transition 300,000 years after the big bang, the 10⁷ decrease in kinematic viscosity ν explains why ~3x10⁷ planets are observed to exist per star in typical galaxies like the Milky Way, not eight or nine. Stars form by a binary accretional cascade from Earth-mass primordial planets to progressively larger masses that collect and recycle the stardust chemicals of life produced when stars overeat and explode. The astonishing complexity of molecular biology observed on Earth is possible to explain only if enormous numbers of primordial planets and their fragments have hosted the formation and wide scattering of the seeds of life virtually from the beginning of time. Geochemical and biological evidence suggests that life on Earth appears at the earliest moment it can survive, in highly evolved forms with complexity requiring a time scale in excess of the age of the galaxy. This is quite impossible within standard cold-dark-matter cosmology where planets are relatively recent, rare and cold, completely lacking mechanisms for intergalactic transport of life forms.

The Raman Laser Spectrometer (RLS) is one of the Pasteur Payload instruments, within the ESA's Aurora Exploration Programme, ExoMars mission. The RLS Instrument will perform Raman spectroscopy on crushed powered samples deposited on a small container after crushing the cores obtained by the Rover's drill system. This is the first time that a Raman spectrometer will be launched in an out planetary mission. The Instrument will be accommodated and operate inside the Rover's ALD (Analytical Laboratory Drawer), complying with COSPAR (Committee on Space Research) Planetary Protection requirements. The RLS Instrument is composed by the following units: SPU (Spectrometer Unit); iOH: (Internal Optical Head); ICEU (Instrument Control and Excitation Unit). Other instrument units are EH (Electrical Harness), OH (Optical Harness) and RLS SW On-Board.

The Drake Equation was originally composed as an attempt to quantify the potential number of extraterrestrial civilizations in our Galaxy which we might be able to detect using a radio telescope. Since this equation was first formulated, nearly 50 years ago, we have discovered that life on Earth arose very early in its history, and has filled virtually every habitable, potentially extreme, niche available. This suggests that simple forms of life might be plentiful where possible, and can be observed remotely by atmospheric biosignatures in the host planet. We consider modifications to the Drake Equation to reflect this new understanding.

Microorganisms may exist in Low Earth Orbit both from terrestrial sources, and potentially, from extraterrestrial origins. A simple, low cost method for in-situ detection is proposed, suitable for CubeSat and similar micro and nano-satellite implementation. A block of silica aerogel, similar to that used on the highly successful Stardust mission, is used as a collection medium. Edge-wise UV illumination by a LED array, and orthogonal optical emission detection by a photodetector array, is used for identification. The detection process is on-going, and no sample return is required. Potential terrestrial background sources and missions of extraterrestrial opportunity are discussed.