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Project Reports

• Astronomical Observations of Planetary Atmospheres and Exoplanets

  This task encompasses remote-sensing observations of Solar System and extrasolar planets made by the VPL team. These observations, while providing scientific exploration in its own right, also allow us to test our planetary models and help advance techniques to retrieve information from the astronomical data that we obtain. This can include improving our understanding of the accuracy of inputs into our models, such as spectral databases. This year we made and/or analyzed observations of Mars, Venus and Earth taken by ground-based and spaceborne observatories, to better understand how well we can determine planetary properties like atmospheric and surface temperature and pressure, when a terrestrial planet is observed only as a distant point of light.

  ROADMAP OBJECTIVES: 1.2 2.2 7.2

• Biosignatures in Ancient Rocks

  The Biosignatures in Ancient Rocks group investigates the co-evolution of life and environment on early Earth using a combination of geological field work, geochemical analysis, genomics, and numerical simulation.

  ROADMAP OBJECTIVES: 1.1 3.2 4.1 4.2 4.3 5.1 5.2 5.3 6.1 6.2 7.1 7.2

• BioInspired Mimetic Cluster Synthesis: Bridging the Structure and Reactivity of Biotic and Abiotic Iron-Sulfur Motifs

  Bioinspired synthetic techniques are bridging the gap between iron sulfur (FeS) mineral surfaces that demonstrate chemical reactivity and the highly evolved FeS cluster centers observed in biological metalloenzymes. An emerging paradigm in biology relating to the synthesis of certain complex iron sulfur clusters involves the modification of standard FeS clusters through radical chemistry catalyzed by radical S-adenosylmethionine (SAM) enzymes. In our attempts to examine potential sources for prebiotic and/or early biotic catalysts, we have initiated a new experimental line that probes the ability of short conserved FeS amino acid motifs that are present in modern day enzymes for their ability to coordinate FeS clusters capable of initiating small molecule radical reactions.

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 3.4 7.1 7.2

• Amino Acid Alphabet Evolution

  A genetically encoded alphabet of just 20 amino acids has produced the universe of protein structures and functions found throughout Earth’s biosphere. Relationships within this amino acid alphabet are responsible for fundamental biological phenomena, such as protein folding and patterns of molecular evolution. In attempting to unravel these relationships, considerable scientific ingenuity has been spent developing systems to simplify the genetically encoded alphabet of 20 amino acids while minimizing the associated loss of chemical diversity. These efforts present an opportunity to generate a composite picture of the properties that link the amino acids as a set. We are therefore investigating whether different simplification schemes (“simplified amino acid alphabets”), including those derived from very different approaches, can be combined to create a coherent description of amino acid similarity. By understanding the organization and relationships between amino acids on Earth, we hope to shed light on the chemical logic to be expected as a product of evolution in extraterrestrial environments.

  An extensive scientific literature has converged on surprisingly clear agreement that a subset of only around half of the 20 genetically encoded amino acids was likely present from the inception of genetic coding (the “early” amino acids), and an equal sized subset was incorporated through subsequent evolution (the “late” amino acids). A further widespread assumption is that, as the set expanded, natural selection favored the addition of amino acids that extended the range of protein structures and functions. We initiated a quantitative investigation for consilience between these two important ideas.

  ROADMAP OBJECTIVES: 3.2 4.1 4.2 6.2 7.1 7.2

• Cosmic Distribution of Chemical Complexity

  The three tasks of this project explore the connections between chemistry in space and the origin of life. We start by tracking the formation and evolution of chemical complexity in space, from simple carbon-rich molecules such as formaldehyde and acetylene to complex species including amino acids, nucleic acids and polycyclic aromatic hydrocarbons. The work focuses on carbon-rich species that are interesting from a biogenic perspective and on understanding their possible roles in the origin of life on habitable worlds. We do this by measuring the spectra and chemistry of analog materials in the laboratory, by remote sensing with small spacecraft, and by analysis of extraterrestrial samples returned by spacecraft or that fall to Earth as meteorites. We then use these results to interpret astronomical observations made with ground-based and orbiting telescopes.

  ROADMAP OBJECTIVES: 1.1 2.1 2.2 3.1 3.2 3.4 4.3 7.1 7.2

• Habitability of Icy Worlds

  Habitability of Icy Worlds investigates the habitability of liquid water environments in icy worlds, with a focus on what processes may give rise to life, what processes may sustain life, and what processes may deliver that life to the surface. Habitability of Icy Worlds investigation has three major objectives. Objective 1, Seafloor Processes, explores conditions that might be conducive to originating and supporting life in icy world interiors. Objective 2, Ocean Processes, investigates the formation of prebiotic cell membranes under simulated deep-ocean conditions, and Objective 3, Ice Shell Processes, investigates astrobiological aspects of ice shell evolution.

  ROADMAP OBJECTIVES: 1.1 2.1 2.2 3.1 3.2 3.3 3.4 4.1 5.1 6.1 6.2 7.1 7.2

• Biosignatures in Extraterrestrial Settings

  Exploring the prospects for biosignatures in extraterrestrial settings is a multi

  ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 3.1 4.1 4.3 6.2 7.1 7.2

• Survivability of Icy Worlds

  Survivability of Icy worlds (Investigation 2) focuses on survivability. As part of our Survivability investigation, we examine the similarities and differences between the abiotic chemistry of planetary ices irradiated with ultraviolet photons (UV), electrons, and ions, and the chemistry of biomolecules exposed to similar conditions. Can the chemical products resulting from these two scenarios be distinguished? Can viable microbes persist after exposure to such conditions? These are motivating questions for our investigation.

  ROADMAP OBJECTIVES: 2.2 3.2 5.1 5.3 7.1 7.2

• Detectability of Biosignatures

  In this project VPL team members explore the nature and detectability of biosignatures, global signs of life in the atmosphere or on the surface of a planet. This year we submitted for publication modeling work that explores the potential for non-biological generation of oxygen and ozone in early Earth-like atmospheres, which could result in a “false positives” for photosynthetic life. In parallel, we worked with three simulators for telescopes that will one day be able to observe and determine the properties of extrasolar terrestrial planets, and used these simulators to calculate the relative detectability of gases produced by life.

  ROADMAP OBJECTIVES: 1.1 1.2 4.1 7.2

• Charting the Universe of Amino Acid Structures

  More than 3.5 billion years ago, life on our planet evolved a precise alphabet of 20 amino acids to function as building blocks which cells use to construct proteins according to genetic instructions. However, the twenty genetically encoded amino acids are but a tiny fraction of the chemical structures that could plausibly play such a role. Any science of the origins, distribution and future of life in the universe must take into account this larger context of chemical structures. But while astrochemistry, prebiotic chemistry, and bioengineering all hint at the chemical structures it contains, until now this amino acid universe has remained largely unexplored. Efforts to describe the structures it contains, or even estimate their number, have been hampered by the complexity inherent to the combinatorial properties of organic molecules. We have formed a new collaboration to combine European (DLR) advances in computational chemistry with NAI expertise in organic chemistry and amino acid biology to address this gap in current scientific understanding. Our early results have provided the first ever sketch of the amino acid structure universe, showing it to be far larger and more complex than previously supposed. This forms an important milestone in defining and exploring the principles of “universal biology”

  ROADMAP OBJECTIVES: 3.1 3.2 6.2 7.1 7.2

• Biosignatures in Relevant Microbial Ecosystems

  PSARC is investigating microbial life in some of Earth’s most mission-relevant modern ecosystems. These environments include the extremely salty Dead Sea, the impact-fractured crust of the Chesapeake Bay impact structure, methane seeps on the ocean floor, deep ice in the Greenland ice sheet, and oxygen-free waters including deep subsurface groundwater. We target environments that, when studied, provide fundamental information that can serve as the basis for future solar system exploration. Combining our expertise in molecular biology, geochemistry, microbiology, and metagenomics, and in collaboration with some of the planet’s most extreme explorers, we are deciphering the microbiology, fossilization processes, and recoverable biosignatures from these mission-relevant environments.

  ROADMAP OBJECTIVES: 4.1 4.3 5.1 5.2 5.3 6.1 7.1 7.2

• Detectability of Life

  Detectability of Life investigates the detectability of chemical and biological signatures on the surface of icy worlds, with a focus on spectroscopic techniques, and on spectral bands that are not in some way connected to photosynthesis.Detectability of life investigation has three major objectives: Detection of Life in the Laboratory, Detection of Life in the Field, and Detection of Life from Orbit.

  ROADMAP OBJECTIVES: 1.2 2.1 2.2 4.1 5.3 6.1 6.2 7.1 7.2

• Path to Flight

  The (Field Instrumentation and) Path to Flight investigation’s purpose is to enable in-situ measurements of organics and biological material with field instrumentation that have high potential for future flight instrumentation. The preceding three Investigations (Habitability, Survivability and Detectability) provide a variety of measurable goals that are used to modify or “tune” instrumentation that can be placed in the field. In addition the members involved with Investigation provide new measurement capabilities that have been developed with the specific goal of life-detection and organic detection using both non-contact/non-destructive means and ingestion based methods. The developments under this investigation (Inv 4) incorporate state-of-the-art laboratory instruments and next generation in-situ instrumentation that have been developed under programs that include NASA as well as NSF and DOD. These include mass-spectrometers, gas analyzers, and fluorescence/Raman spectrometry instruments.

  ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 3.1 3.2 7.1 7.2

• Nitrate and Nitrate Conversion to Ammonia on Iron-Sulfur Minerals

  Conversion of nitrate and nitrite may have contributed to the formation of ammonia—a key reagent in the formation of amino acids—on the prebiotic Earth. Results suggest that the presence of iron mono sulfide facilitates the conversion of nitrate and nitrite. Nitrite conversion is, however, much faster than the conversion of nitrate.

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 7.1 7.2

• Earth as an Extrasolar Planet

  Earth is the only known planet that can support life on its surface, and often serves as the typical example of what a habitable planet looks like. In anticipation of future discoveries of observable, potentially habitable worlds around other stars, this task seeks to understand how we would characterize and understand the distant Earth. To accomplish this, we have developed several tools and approaches for simulating and investigating the Pale Blue Dot. In particular, we have demonstrated how an airless moon can affect observations of a habitable planet, developed new metrics to measure atmospheric pressure, and modeled light reflected off liquid water surfaces.

  ROADMAP OBJECTIVES: 1.2 7.1 7.2

• Radical SAM Chemistry and Biological Ligand Accelerated Catalysis

  Iron sulfur (FeS) clusters are thought to be among the most ancient cofactors in living systems. The FeS enzyme thrust is focused on examining the structure, mechanism, and biosynthesis of the complex FeS enzymes nitrogenase and hydrogenase. Exciting recent results have identified important links between the biosynthesis of the H-cluster and FeMo-co and have outlined a new paradigm for the biosynthesis of complex FeS clusters. The observations made have provided direct links to the evolution of FeS biocatalysts from their mineral-based precursors.

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 7.1 7.2

• Surface Chemistry of Iron-Sulfur Minerals

  The exposure of pyrite surfaces to energetic particle beams creates an activated surface that is capable of facilitating the reduction of nitrogen molecules to ammonia. Experimental results and complementary theoretical calculations indicates that the exposure of pyrite surfaces creates anomalously reduced iron atoms. The chemical state of the surface iron atoms is somewhat similar to iron in the active center of several key enzymes. The triple bond in dinitrogen sorbed onto these reduced surface iron atoms weakens, which is a key step in the conversion to ammonia, a key reagent in the formation of amino acids on the prebiotic Earth

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 7.1 7.2

• Astrophysical Controls on the Elements of Life, Task 7: Update Catalog of Elemental Ratios in Nearby Stars

  We have created the first complete database of bioessential elements for the stars closest to the Sun, including those hosting exoplanets.

  ROADMAP OBJECTIVES: 1.1 7.2

• Postdoctoral Fellow Report: Steven Mielke

  S. P. Mielke completed an NAI NASA Postdoctoral Program (NPP) fellowship during September 1, 2011 to February 29, 2012. His postdoctoral research has provided the basis for the project: “The Long-Wavelength Limit for Oxygenic Photosynthesis.” He continues this research as a Research Associate at Rockefeller University.

  ROADMAP OBJECTIVES: 3.2 4.2 5.1 5.3 6.2 7.2

• Habitability of Extrasolar Planets

  We model if and under what conditions some of the recently detected Super-Earths – small, Earth-sized planets that have been discovered in in the classical Habitable Zone Sun-like stars – could be habitable. These models explore the underlying physics of planetary atmospheres and their remotely detectable features.

  ROADMAP OBJECTIVES: 1.1 1.2 4.1 4.2 6.2 7.2

• Stellar Radiative Effects on Planetary Habitability

  Habitable environments are most likely to exist in close proximity to a star, and hence a detailed and comprehensive understanding of the effect of the star on planetary habitability is crucial in the pursuit of an inhabited world. We looked at how the Sun’s brightness would have changed with time providing wavelength-dependent scaling factors for solar flux anywhere in the solar system from 0.6 to 6.7Gyr. Extrasolar planetary systems can only be determined through studying the host star; therefore we have also worked on determining the ages of Kepler planet host stars. We have constructed far ultraviolet to mid-infrared stellar spectra for 44 stars for being used as input in climate and photochemical models that are applied for determining habitable zones and possible characteristics of habitable planets. We have looked into the effect of methane (CH₄) and hydrogen (H₂) on the outer edge of the habitable zone for F, G, and M stars. We have studied the effect of host star stellar energy distribution (SED) and ice-albedo feedback on the climate of extrasolar planets.

  ROADMAP OBJECTIVES: 1.1 1.2 2.1 4.1 4.3 7.2

• Project 2C: Roles of EPS Excreted From Anaerobic Microorganism in Governing Dolomite Composition and Crystallization

  EPS from anaerobic microorganisms of sulfate-reducing bacteria, fermentation bacteria, and methanogen can catalyze dolomite nucleation and growth. Compositions of dolomite and Ca-Mg-carbonates is related to the amount of dissolved EPS. Polysaccharide in the EPS is the key to the dehydration of surface water and dolomite crystallization at room temperature. Low temperature dolomite / sedimentary dolomite can be a potential biosignature. The discovery also provides key to solving the “Dolomite Problem” that has puzzled geologists for decades.

  ROADMAP OBJECTIVES: 7.1 7.2

• Project 2D: Catalytic Role of Adsorbed Hydrogen Sulfide in Dolomite Crystallization: Density Functional Theory Study

  The key kinetic barrier in dolomite crystal formation is believed to be the surface Mg²⁺-H₂O complex which hinder the accessibility of surface Mg²⁺ ions to the CO₃²⁺ ions in the solution. Our recent experiments demonstrated that hydrogen sulfide acting as a catalyst can overcome the barrier and promote dolomite nucleation and growth. Our results from ab initio simulations based on density functional theory (DFT) show that hydrogen sulfide can be adsorbed on (104) surface of dolomite from solution. Aqueous hydrogen sulfide produced by sulfate-reducing bacteria adsorbed on the surface can also increase the surrounding surface Mg²⁺-H₂O distances and thus weaken the electrostatic interactions between surface Mg²⁺ and water molecules.

  ROADMAP OBJECTIVES: 7.1 7.2

• The Subglacial Biosphere – Insights Into Life-Sustaining Strategies in an Extraterrestrial Analog Environment

  Sub-ice environments are prevalent on Earth today and are likely to have been more prevalent the Earth’s past during episodes of significant glacial advances (e.g., snow-ball Earth). Numerous metabolic strategies have been hypothesized to sustain life in sub-ice environments. Common among these hypotheses is that they are all independent of photosynthesis, and instead rely on chemical energy. Recently, we demonstrated the presence of an active assemblage of methanogens in the subglacial environment of an Alpine glacier (Boyd et al., 2010). The distribution of methanogens is narrowly constrained, due in part to the energetics of the reactions which support this functional class of organism (namely carbon dioxide reduction with hydrogen and acetate fermentation). Methanogens utilize a number of metalloenzymes that have active site clusters comprised of a unique array of metals. During the course of this study, we identified other features that were suggestive of other active and potentially relevant metabolic strategies in the subglacial environment, such as nitrogen cycling. The goals of this project are 1) identifying a suite of biomarkers indicative of biological CH4 production 2). quantifying the flux of CH4 from sub-ice systems and 3). developing an understanding how life thrives at the thermodynamic limits of life. This project represents a unique extension of the ABRC and bridges the research goals of several nodes, namely the JPL-Icy Worlds team and the ASU-Follow the Elements team.

  ROADMAP OBJECTIVES: 2.1 2.2 5.1 5.2 5.3 6.1 6.2 7.1 7.2

• Project 2E: Preferential Dolomitization of Carbonate Microbialites From a Modern Hypersaline Lake and in Ancient Dolomite

  Modern stromatolite from a hypersaline lake displays micro-laminated layers of calcite and protodolomite high-Mg calcite. The oscillatory layers indicate variations of microbial activity. The dolomite layers with micro-crystals are rich in organic. Extracellular polymeric substance (EPS) from photosynthetic microbes enhance precipitation of high-Mg calcite, and EPS from anaerobic bacteria catalyzes the transformation from high-Mg calcite into protodolomite. Atomic resolution Z-contrast images indicate that protodolomite is consisted of very weakly ordered dolomite domains ranging from 3 to 10 nm and disordered dolomite.

  ROADMAP OBJECTIVES: 7.1 7.2

• Ice Chemistry of the Solar System

  We are currently in the process of establishing a research program at the University of Hawai’i at Manoa to investigate the evolution of Solar System and interstellar ices; these grains are chemically processed continuously by radiation from either our Sun, or galactic cosmic radiation (GCR). The nature of the chemistry that occurs here is an important component of understanding the origin of complex biomolecules that could have seeded the primordial Earth, helping to kick-start the origin of life. We have constructed one of the leading laboratory facilities in the world capable of carrying out this research, and we focus on establishing the underlying chemical pathways.

  ROADMAP OBJECTIVES: 1.1 2.2 3.1 3.2 3.3 4.1 7.1 7.2

• The Long Wavelength Limit for Oxygenic Photosynthesis

  Photosynthesis produces signs of life (biosignatures) on a planetary scale: atmospheric oxygen and the reflectance signature of photosynthetic pigments. Oxygenic photosynthesis is therefore a primary target in NASA’s search for life on habitable planets in other solar systems. An unanswered question is what the upper limit is to the photon wavelength at which oxygenic photosynthesis can remain viable. On other planets that have a parent star very different spectrally from our Sun, can we expect oxygen from plants of different colors from those on Earth?

  The cyanobacterium, Acaryochloris marina serves as a model organism for oxygenic photosynthesis adapted to low light and red-shifted light environments similar to what may be found on habitable planets orbiting M stars. Until A. marina was discovered in 1996, all known oxygenic photosynthesis relied on the pigment chlorophyll a (Chl a). A. marina instead uses chlorophyll d, which can absorb the far-red and near-infrared light in A. marina’s habitat. We use photoacoustics in the lab to measure the energy storage efficiency of A. marina with lasers, and molecular electrostatics modeling to surmise how replacement of Chl a by Chl d in A. marina affects arrangements within the photosystem molecules. We are finding that A. marina can perform oxygenic photosynthesis quite efficiently in its unique light niche.

  ROADMAP OBJECTIVES: 3.2 4.2 5.1 5.3 6.2 7.2

• The VPL Life Modules

  The VPL Life Modules involve development of simulation models of how biological processes – such as photosynthesis, breathing, and decay of organic materials – work on a planetary scale. When this is combined with the work of the atmospheric and planetary modeling teams, we are able simulate how these processes impact the atmosphere and climate of a planet. This information helps us understand how we might be able to detect whether or not a planet has life by looking at its atmosphere and surface. The Life Modules team has engaged in previous work coupling early Earth biogeochemistry and 1D models in the VPL’s suite of planetary models. Current work now focuses on the development of a land biosphere model coupled with a previously developed ocean biogeochemistry model and a 3D general circulation model (GCM). This terrestrial biosphere model is designed to simulate geographic distributions of life adapted to different climate zones, surface albedo, and carbon dioxide exchange and other biogenic gases with the atmosphere. These coupled models are first tested against Earth ground and satellite observations. A large data mining effort is now under way for the model of land-based ecosystem dynamics to uncover vegetation adaptations to climate that may be generalizable for both the Earth and alternative planetary environments.

  ROADMAP OBJECTIVES: 1.2 6.1 6.2 7.2

• Interdisciplinary Studies of Earth’s Seafloor Biosphere

  The remote deep sediment-buried ocean basaltic crust is Earth’s largest aquifer and host to the least known and potentially one of the most significant biospheres on Earth. CORK observatories have provided unparalleled access to this remote environment. They are enabling groundbreaking research in crustal fluid flow, (bio)geochemical fluid/crustal alteration, and the emerging field of deep crustal biosphere

  ROADMAP OBJECTIVES: 4.1 4.2 5.1 5.2 5.3 6.1 6.2 7.1 7.2

• Project 3A: Stable Isotope and Mineralogical Studies of Banded Iron Formations – O Isotopes by SIMS

  During the past year, we have made advances in technique development for analysis of mineral chemistry and stable isotope ratios in minerals. Applications to magnetite in Banded Iron Formation (BIF) have lead to the proposal that silician magnetite forms only in low oxygen fugacity conditions and are thus a signature for the former presence of reduced organic matter. Petrography and in situ analysis of δ¹⁸O by SIMS has shown that the earliest quartz cements in 1.85 Ga Granular Iron formation (GIF) consistently have high δ¹⁸O showing that earlier reports of more variable compositions included altered material.

  ROADMAP OBJECTIVES: 4.1 4.2 7.2

• Measuring Interdisciplinarity Within Astrobiology Research

  To integrate the work of the diverse scientists working on astrobiology, we have harvested and analyzed thousands of astrobiology documents to reveal areas of potential connection. This framework allows us to identify crossover documents that guide scientists quickly across vast interdisciplinary libraries, suggest productive interdisciplinary collaborations, and provide a metric of interdisciplinary science.

  ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 3.1 3.2 3.3 3.4 4.1 4.2 4.3 5.1 5.2 5.3 6.1 6.2 7.1 7.2

• Progress Report From G. Blake – CIT

  The Blake group has been carrying out joint observational and laboratory program with NAI node scientists on the water and simple organic chemistry in the protoplanetary disk analogs of the solar nebula and in comets. Scientific results continue to flow at a rapid clip. We have followed up our major overview papers outlining the results from our extensive (>100 disks) Spitzer IRS survey of the molecular emission from the terrestrial planet forming region with follow-up work with GSFC scientists on the high spectral resolution ground-based observations of such emission and that from cometary comae (and possible non-transiting exoplanets) using the Keck telescope and the VLT. We have measured the angular scale of the disk emission, and discovered a new transitional disk class characterized by a wide angle molecular wind. We have probed the outer disk’s water emission with the Herschel HIFI instrument, and also measured the (D/H)water ratio in a Jupiter Family Comet for the first time with Herschel – finding a value consistent with that in the Earth’s oceans. Our first Cycle 0 ALMA data are now in hand, and beautifully demonstrate the high angular resolution observations of simple organics in the outer regions of disks and comets that will become possible over the coming years. The full suite of results will permit the first detailed examination of the radial water and gas phase organic chemistry in planet-forming environments.

  ROADMAP OBJECTIVES: 1.1 1.2 3.1 7.2

• VPL Databases, Model Interfaces and the Community Tool

  The Virtual Planetary Laboratory (VPL) develops computer models of planetary environments, including planets orbiting other stars (exoplanets) and provides a collaborative framework for scientists from many disciplines to coordinate their research. As part of this framework, VPL develops easier to use interfaces to its models, and provides model output datasets, so that they can be used by more researchers. We also collect and serve to the community the scientific data required as input to the models. These input data include spectra of stars, data files that tell us how atmospheric gases interact with incoming stellar radiation, and plant photosynthetic pigments. We also develop tools that allow users to search and manipulate the scientific input data. This year we provided Earth model datasets, new tools for searching the molecular spectroscopic database, and a new database of biological pigments. All of these products and others are published on the VPL Team Website at: http://depts.washington.edu/naivpl/content/models-spectra.

  ROADMAP OBJECTIVES: 1.1 1.2 3.2 4.1 6.1 7.1 7.2

• Stoichiometry of Life, Task 2a: Field Studies – Yellowstone National Park

  Our stoichiometry studies are determining the relationships between the elemental compositions of organisms and the elemental compositions of their environments. We experimentally determine how changes in element availability (N, P, Fe) affect the community structure in hot spring ecosystems. We also use stable isotopes (¹⁵N and ¹³C) to trace which metabolisms actively utilize N and C and where in cells these elements are used. Recently, our team has shown for the first time that nitrogen (N₂) fixation can occur at temperatures >85oC (Loiacono et al. 2012). We are also developing robust environmental sensors for hot springs that reveal chemical and thermal gradients at scales similar to the observed spatial distributions in hot spring microbial communities.

  ROADMAP OBJECTIVES: 5.1 5.2 5.3 6.1 6.2 7.2

• Remote Sensing of Organic Volatiles in Planetary and Cometary Atmospheres

  In the last year, we have greatly advanced our capabilities to model spectra of cometary and planetary atmospheres (Villanueva et al. 2012a, 2012b). Using these newly developed analytical methods, we derived the most comprehensive search for biomarkers on Mars (Villanueva et al. 2012, submitted) from our extensive database of high-quality Mars spectra. Furthermore, we retrieved molecular abundances of several comets (Villanueva et al. 2012c, Gibb et al. 2012, Paganini et al. 2012a/b), and of several young circumstellar disks (Mandell et al. 2012). These great advancements have allowed us to understand the infrared spectrum of planetary bodies and their composition with unprecedented precision.

  ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 3.1 3.2 7.1 7.2

• Project 3D: Constraints on Oxygen Contents in Earth’s Early Atmosphere and Implications for Evolution of Photosynthesis

  The oxidation state of the atmosphere and oceans on the early Earth remains controversial. Although it is accepted by many workers that the Archean atmosphere and ocean were anoxic, hematite in the 3.46 billion-year-old (Ga) Marble Bar Chert (MBC) from Pilbara Craton, NW Australia has figured prominently in arguments that the Paleoarchean atmosphere and ocean was fully oxygenated. In this study, we report the Fe isotope compositions and U concentrations of the MBC, and show that the samples have extreme heavy Fe isotope enrichment. Collectively, the Fe and U data indicate a reduced, Fe(II)-rich, U-poor environment in the Archean oceans at 3.46 billion years ago. Given the evidence for photosynthetic communities provided by broadly coeval stromatolites, these results suggests that an important photosynthetic pathway in the Paleoarchean oceans may have been anoxygenic photosynthetic Fe(II) oxidation.

  ROADMAP OBJECTIVES: 4.1 6.1 7.1 7.2

• Project 5A: Improvement in the Accuracy of Stable Isotope Analysis by Laser Ablation

  In-situ isotopic analyses are critical for documenting spatial heterogeneities that can be related to the petrography of a sample. In the last decade, recognition of the power of in-situ analysis has spurred development of instrumentation that has improved the precision of in-situ isotopic analysis to unprecedented levels. With this improved precision, it is necessary to critically re-evaluate accuracy in order to identify true heterogeneities form analytical artifacts. We have evaluated the accuracy of in-situ Fe isotope analyses by femto second laser ablation (fs-LA) by evaluating the size and Fe isotope composition of aerosol particles generated by fs-LA, and to evaluate if fs-LA isotope analysis is free of matrix effects. Aerosols produced by fs-LA are small with ~70% of the particles, by mass of Fe, less than 100 nm in aerodynamic diameter, highlighting that the fs-LA particles can be effectively ionized by the plasma. By isotopic mass balance, the aerosols are a stoichiometric sample of the substrate, however, the smallest sized particles have light 56Fe/54Fe isotope compositions and the larger sized particles have heavy 56Fe/54Fe isotope compositions, which highlights the importance of quantitative transport of the aerosol by the ICP source. Matrix studies that include introduction of elements into the fs-LA aerosol by a desolvating nebulizer coupled with isotope analysis of iron oxide standards with variable chemical compositions suggest that matrix effects are driven by space charge processes where elements with low atomic Z relative to Fe such as Mg, and Si have no effects on the accuracy of the analysis but elements with a similar or higher Z such as Mn or U can produce accuracy issues on the order of +0.5 ‰ in δ56Fe.

  ROADMAP OBJECTIVES: 2.1 4.1 7.1 7.2