2011 Annual Science Report

Astrobiology Roadmap Objective 7.1 Reports Reporting  |  SEP 2010 – AUG 2011

Project Reports

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

    Bioinspired synthetic approaches are being utilized to bridge the gap between Fe-S minerals and highly evolved biological Fe-S metalloenzymes. Biology builds complex Fe-S clusters by first synthesizing standard Fe-S clusters and then modifying them through radical chemistry catalyzed by radical SAM enzymes. In an effort to examine hypothetical early biocatalysts, we probing simple Fe-S motifs capable of coordinating Fe-S clusters in aqueous solutions that can initiate radical chemistry.

    ROADMAP OBJECTIVES: 3.1 3.2 3.3 3.4 7.1 7.2
  • Cosmic Distribution of Chemical Complexity

    The central theme of this project is to explore the possible connections between chemistry in space and the origins of life. We start by tracking the formation and development of chemical complexity in space from simple molecules such as formaldehyde to complex species including amino and nucleic acids. The work focuses on molecular 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 in 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
  • AIRFrame Technical Infrastructure and Visualization Software Evaluation

    We have analyzed over four thousand astrobiology articles from the scientific press, published over ten years to search for clues about their underlying connections. This information can be used to build tools and technologies that guide scientists quickly across vast, interdisciplinary libraries towards the diverse works of most relevance to them.

    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
  • 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
  • Advancing Techniques for in Situ Analysis of Complex Organics

    Our research in laser mass spectrometry is part of the overall program of the Goddard Center for Astrobiology to investigate the origin and evolution of organics in planetary systems. Laser mass spectrometry is a technique that is used to determine the chemical composition of sample materials such as rocks, dust, ice, meteorites in the lab. It also may be miniaturized so it could fit on a robotic spacecraft to an asteroid, a comet, or even Mars. On such a mission it could be used to discover any organic compounds preserved there, which in turn would give us insight into how Earth got its starting inventory of organic compounds that were necessary for life. The technique uses a high-intensity laser to “zap” atoms and molecules directly off the surface of the sample. The mass spectrometer instantly captures these particles and provides data that allow us to determine their molecular weights, and therefore their chemical composition. Our recent work has been to understand the different kinds of spectra one obtains when analyzing complex samples that are analogs of Mars and other planetary bodies, such as desert-varnished basalts and extracts of the Murchison meteorite. We also have been improving the instrument to better detect certain kinds of organic compounds in such complex rocks, such as to selectively ionize certain hydrocarbons and simplify data analysis, and to maintain high vacuum integrity while changing out samples. Finally, our work on improving operational protocols for laser analysis of samples had helped the design of the mass spectrometer on the 2018 ExoMars rover mission, which includes a pulsed laser mode.

    ROADMAP OBJECTIVES: 2.1 2.2 7.1
  • Project 2: Origin and Evolution of Organic Matter in the Solar System

    This project focuses on understanding the origin and evolution primitive bodies in the solar system (e.g. comets, interplanetary dust particles [IDPs], and primitive, undifferentiated, meteorites). The first focus area involves detailed studies of the water/ice content of bodies in the outer solar system. We seek to learn more about the mechanism by which water is retained in these bodies and learn more about what water(ice)/rock ratios tell us about the evolution of the early solar system. The second part of this study involves understanding the origin and evolution of organic solids in comets, IDPs, and primitive meteorites. These organic solids are one of the largest reservoirs of carbon, outside of the Sun, and are only now being understood from the perspective of their origin and the unique history they record of processes that occurred in the early solar system.

    ROADMAP OBJECTIVES: 2.2 3.1 7.1
  • Project 1B: U-Th-Pb Geochronology and Fe Isotopes of the 3.4 Ga Marble Bar Chert Indicates Early Anoxygenic Photosynthesis

    The origin of the spectacular red jasper (hematite+chert) at Marble Bar, Australia, has been a subject of debate for decades. Previous work has argued that oxidation occurred at the time of deposition 3.5 b.y. ago, and that the mechanism of oxidation was free oxygen in the atmosphere. This in turn would indicate that oxygenic photosynthesis had evolved by 3.4 Ga. By measuring Fe isotopes in the jasper, we can show that oxidation was extremely limited, and U-Th-Pb isotope geochronology on the same samples shows that the jasper precipitated form U-poor ocean water. This in turn indicates that there was no free oxygen in seawater at the time of deposition of the jasper. This in turn suggests that the mechanism was more likely to have been an anaerobic process, such as anoxygenic photosynthetic Fe(II) oxidation.

    ROADMAP OBJECTIVES: 4.1 6.1 7.1
  • Amino Acid Alphabet Evolution

    We study the question why did life on this planet “choose” a set of 20 standard building blocks (amino acids) for converting genetic instructions into living organisms? The evolutionary step has since been used to evolve organisms of such diversity and adaptability that modern biologists struggle to discover the limits to life-as-we-know-it. Yet the standard amino acid alphabet has remained more or less unchanged for 3 billion years.
    During the past year, we have found that the sub-set of amino acids used by biology exhibits some surprisingly simple, strikingly non-random properties. We are now building on this finding to solidify a new insight into the emergence of life here, and what it can reveal about the distribution and characteristics of life elsewhere in the universe.

    ROADMAP OBJECTIVES: 3.1 3.2 4.1 4.2 4.3 5.2 5.3 6.2 7.1
  • Biosignatures in Relevant Microbial Ecosystems

    In this project, PSARC team members explore the isotope ratios, gene sequences, minerals, organic molecules, and other signatures of life in modern environments that have important similarities with early earth conditions, or with life that may be present elsewhere in the solar system and beyond. Many of these environments are “extreme” by human standards and/or have conditions that are at the limit for microbial life on Earth.

    ROADMAP OBJECTIVES: 4.1 4.3 5.1 5.2 5.3 6.1 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 5.3 6.1 6.2 7.1 7.2
  • Path to Flight

    Our technology investigation, Path to Flight for astrobiology, utilizes instrumentation built with non-NAI funding to carry out three science investigations namely habitability, survivability and detectability of life. The search for life requires instruments and techniques that can detect biosignatures from orbit and in-situ under harsh conditions. Advancing this capacity is the focus of our Technology Investigation.

    ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 3.1 3.2 7.1 7.2
  • Biosignatures in Ancient Rocks

    The Earth’s Archean and Proterozoic eons offer the best opportunity for investigating a microbial world, such as might be found elsewhere in the cosmos. The ancient record on Earth provides an opportunity to see what geochemical signatures are produced by microbial life and how these signatures are preserved over geologic time. As part of our integrated plan, we will study geochemical, isotopic, and sedimentary signatures of life in order to understand the context in which these biosignatures formed.

    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
  • Minerals to Enzymes: The Path to CO Dehydrogenase/Acetyl – CoA Synthase

    We have through NAI Director’s discretionary initiated a project to probing the structural determinants for nickel-iron-sulfur based reversible carbon monoxide oxidation. We are probing whether we can mimic the reactivity of carbon monoxide dehydrogenase to some extent by simple organic nesting and synthesis of nickel-iron-sulfur clusters using a model system we have developed.

    ROADMAP OBJECTIVES: 3.1 3.2 3.3 3.4 7.1 7.2
  • Project 1C: U-Th-Pb Geochronology of the 3.4 Ga Apex Basalt Suggests an Anoxic Early Earth Atmosphere

    Direct determination of the age of oxidative weathering in ancient rocks is difficult, but bears on when the surface environments of the Earth contained free oxygen, which in turn constrain when oxygenic photosynthesis was sufficient to overwelm reduced sinks for oxygen. It has been proposed that oxidized zones of the 3.4 Ga Apex Basalt in the Pilbara Craton formed in the Archean, at least 2.8 b.y. ago, and possibly as old at 3.4 b.y. ago. However, application of U-Th-Pb geochronology to these rocks indicate that oxidation was recent, probably within the last 200 m.y., reflecting deep Phanerozoic weathering that occurred across Australia. The oxidized zones therefore do not reflect the presence of free oxygen in the Archean.

    ROADMAP OBJECTIVES: 4.1 7.1
  • Analogue Environment Deployments on the Big Island

    We are using the saddle region on the Big Island of Hawaii, in collaboration with NASA teams and the Canadian Space Agency in order to test technology related to sustainable living on the moon. My group will evaluate the utility of 3-D visualization in robotic navigation, in particular for the ex-ploration of lava tubes.

    ROADMAP OBJECTIVES: 1.1 2.1 4.1 4.3 6.1 6.2 7.1
  • 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
  • Beyond the Drake Equation: Can We Find New Integrative Frameworks for Astrobiology Research?

    The Drake equation (in its current formulation) is a scheme used to estimate the number of detectable intelligent aliens around us. It does so by collecting together what is considered as the leading terms that represent what we know about astronomy, planetary science, biological evolution and social de-velopment. However, after ~50 years of rapid scientific progress, much of what we have discovered challenges us to either improve our estimates of the factors in Drake’s equation, re-work the equation according to current knowledge in the field of astrobiology, or change the question that we are asking and the way we ask them altogether.

    ROADMAP OBJECTIVES: 7.1 7.2
  • Biosignatures in Extraterrestrial Settings

    The focus of this project is to explore indicators of life outside of Earth, both within the Solar System and on extrasolar planets. The work includes studies of the chemistry and composition of the Solar System, and the past history of conceivable sites for life in the Solar System. We also look for habitable planets outside the Solar System; work on developing new techniques to find and observe potentially habitable planets; and model the dynamics, evolution and current status of a variety of extrasolar planets.

    ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 4.1 4.3 6.2 7.1 7.2
  • Project 5: Vistas of Early Mars: In Preparation for Sample Return

    To understand the history of life in the solar system requires knowledge of how hydrous minerals form on planetary surfaces, and the role these minerals play in the development of potential life forms. One hydrous mineral found on Earth and inferred from in situ measurements on Mars, is the mineral Jarosite, KFe3(SO4)2(OH)6. We are investigating whether radiometric ages, specifically 40Ar/39Ar ages on jarosite can be interpreted to accurately record climate change events on Mars. This project not only requires understanding the conditions required for jarosite formation and preservation on planetary surfaces, but also assessing under what conditions its “radiometric clock” can be reset (e.g., during changes in environmental conditions such as temperature). By studying jarosites formed by a variety of processes on Earth, we will be prepared to analyze and properly interpret ages measured from jarosite obtained from future Mars sample return missions.

    ROADMAP OBJECTIVES: 1.1 2.1 7.1
  • 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
  • Project 5: Geological-Biological Interactions

    This project involves multiple researchers exploring life in extreme environments, the signature of life (chemical, isotopic and mineralogical), and the adaption of life. All together the many sub-topics of this project seek to inform us about where to search for life on other worlds and how to seek evidence that life once existed on other worlds.

    ROADMAP OBJECTIVES: 4.1 5.1 6.1 6.2 7.1
  • Deep (Sediment-Buried Basement) Biosphere

    The ocean crust comprises the largest aquifer on earth. Deep sediment cover provides an environ-ment for a unique biosphere hosting microorganisms surviving under extreme conditions. Frac-tured rock provides abundant surfaces that can be colonized by diverse microbes and water-rock reactions promote chemical conditions that influence key geochemical cycles within the Earth’s crust and oceans. Team members participated in a 14-day research cruise to study the sediment-buried basement (basaltic crust) biosphere, to provide unprecedented and unique insight into the mobility and origin of microorganisms within this remote biosphere.

    ROADMAP OBJECTIVES: 4.1 4.2 5.2 5.3 6.1 6.2 7.1 7.2
  • Project 2C: Role of Extracellular Polymeric Substances (EPS) and Bacteria Cell Wall Structure in Shielding Against Specific Mineral Toxicity – Implications for Cell Surface Evolution

    Our interdisciplinary project examined the hypotheses that (1) bacterial cell membranes are ruptured in contact with specific mineral surfaces, (2) biofilm-forming extra-cellular polymeric substances (EPS) may have evolved to shield against membrane rupture (cell lysis), (3) differences in cell-wall structure of Gram-negative and Gram-positive bacteria may influence the susceptibility of cells to toxic minerals and (4) mineral toxicity depends on its surface chemistry and nanoparticle size.

    Previously, we have examined Gram-negative P. aeruginosa strains, wild-type (PAO1) that is capable of generating copious amount of EPS and producing biofilms, as well as the knock-out mutant (Δ-psl) that is defective in its ability to form EPS and biofilms. In the 2010-2011 year of funding, we have expanded our study to include Gram-positive B. subtilis strains, biofilm-producing wild-type NCIB3610 and biofilm-defective mutant yhxBΔ. We confirmed the hypotheses (1), (2) and (4) for both Gram-negative and Gram-positive bacteria, with toxicity increasing as amorphous β-TiO2 < γ-Al2O3. We also confirmed hypothesis (3) that Gram-positive bacteria are less susceptible to mineral toxicity than Gram-negative because of the most robust cell-wall structure of the former. Finally, we have shown that the mechanisms of toxicity depends on mineral surface charge for initial adhesion of nanoparticles to the cell surface, nanoparticle size which determines whether the particles can enter the intracellular space (e.g., for γ-Al2O3), the presence of surface free radicals (e.g., β-TiO2 ) which would have been generated by UV-radiation and meteorite impacts on early Earth, Mars, and other worlds.

    By understanding the mechanisms for membranolysis, especially under the extreme conditions of high radiation and heavy impacts during early planetary history, the project addresses the NASA Astrobiology Institute’s (NAI) Roadmap goals of understanding the origins of cellularity, the evolution of mechanisms for survival at environmental limits, and preservation of biosignatures, and NASA’s Strategic Goal of advancing scientific knowledge of the origin and evolution of the Earth’s biosphere and the potential for life elsewhere.

    ROADMAP OBJECTIVES: 3.4 5.1 7.1
  • Project 2D: Establishing Biogenicity and Environmental Setting of Precambrian Kerogen and Microfossils

    Stable carbon isotope ratios preserved in ancient organic matter provide valuable information about the origin and evolution of metabolic pathways, and the evolution of the carbon cycle in general. In situ carbon isotope analysis allows organic matter to be measured in petrographic context. The microtexture and spatial relationship of sedimentary organic matter and its mineral matrix offers clues about source and diagenetic history – essential elements in the interpretation of isotopic data. We have developed protocols with the IMS-1280 ion microprobe to analyze carbon isotope ratios in organic matter with a spot size of 1–10 μm. A suite of new standards allows correction of matrix effects due to variable chemical composition. Four suites of Proterozoic microfossils of uncontested biogenicity have been analyzed, showing distinct values of δ13C that correlate with taxonomy and metabolism (Williford et al. 2011a in prep). Studies of kerogen and pyrobitumen from 2.7–2.5 Ga sediments support prior conclusions about differential impacts of aerobiosis and methane metabolisms in shallow versus deep-water depositional environments and reveal a degree of isotopic heterogeneity obscured by conventional, bulk analyses (Williford et al, 2011b in prep). Analysis of organic matter from the 3.35 Ga Strelley Pool Chert yield low and consistent values of δ13C, consistent with a biogenic origin (Lepot et al. 2011, in prep).

    ROADMAP OBJECTIVES: 4.1 7.1
  • Exploring the Atmosphere of Mars at Infrared Wavelengths and the Organic Volatile Composition of Comet 2P/Encke

    Yana L. Radeva is a Research Associate at The Catholic University of America, conducting her postdoctoral research at NASA’s Goddard Space Flight Center. During the time period September 1, 2010 – August 30, 2011, she analyzed high-resolution infrared spectra of the Martian atmosphere, searching for biomarker gases (such as methane), and studying the spatial distribution, diurnal and seasonal evolution of trace species. Dr. Radeva analyzed data-sets acquired with the NIRSPEC instrument on the Keck II telescope during the 2009-2010 observing campaign, covering a range of Ls = 8 – 83° (early through late spring in the Martian Northern hemisphere). Dr. Radeva also analyzed data acquired with the ultra-high resolution infrared spectrometer CRIRES at ESO’s VLT, and retrieved abundances and rotational temperatures from the spectral lines of O2 (a1Δg), used as a tracer for ozone. She presented spatial maps of ozone on Mars, and a comparison with models of the ozone distribution, at the annual American Geophysical Union meeting (December 2010). Dr. Radeva published a paper on results of her dissertation work, entitled “A Newly Developed Fluorescence Model for C2H6 ν5 and Application to Cometary Spectra Acquired with NIRSPEC at Keck II” (ApJ, 729, 2, 135). She also presented results of her analysis of the organic composition of comet 2P/Encke at the annual AAS Division for Planetary Sciences conference (October 2010).

    ROADMAP OBJECTIVES: 2.1 2.2 7.1
  • 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
  • Ice Chemistry Beyond the Solar System

    The molecular inventory available on the prebiotic Earth was likely derived from both terrestrial and extraterrestrial sources. Many molecules of biological importance have their origins via chemical processing in the interstel-lar medium, the material between the stars. Polycyclic aromatic hydrocarbons (PAHs) and related species have been suggested to play a key role in the astrochemical evolution of the interstellar medium, but the formation mechanism of even their simplest building block, the aromatic ben¬zene molecule, has remained elusive for decades. Formamide represents the simplest molecule contain-ing the peptide bond. Conse¬quently, the formamide molecule is of high interest as it is considered as an important precursor in the abiotic synthesis of amino acids, and thus significant to further prebiotic chemistry, in more suitable environments. Ultra-high vacuum low-temperature ice chem-istry experiments have been conducted to understand the formation pathways in the ISM for many astrobiologcally important molecules.

    ROADMAP OBJECTIVES: 1.1 1.2 3.1 3.2 3.3 6.2 7.1
  • Project 3A: Stable Isotope and Mineralogical Studies of Banded Iron Formations – O and Si Isotopes by SIMS

    We have studied the mineralogy and microscopic textures of four banded iron formations (BIFs): Isua, Greenland (3.8 Ga); Hamersley, Western Australia (2.5 Ga); Transvaal, South Africa (2.5 Ga), and Biwabik, Minnesota, USA (1.9 Ga). These rocks have been interpreted to preserve records of conditions and chemistry of Precambrian oceans. This hypothesis is evaluated with in situ SIMS analysis of oxygen (δ18O) and silicon isotope ratios (δ30Si) in chert domains within the BIFs. The paragenesis of magnetite and hematite is important to understanding the fluid and thermal history of unmetamorphosed or low-temperature (sub-greenschist facies) oxide-facies BIFs. We identified silician (up to 3 wt% SiO2) magnetite overgrowths in samples of the Dales Gorge BIF from Wittenoom. We hypothesize that silician magnetite is stabilized by organic matter and thus is a biosignature. We investigated the distribution of δ18O values in quartz, magnetite, silician magnetite, and hematite by SIMS and found that while quartz is homogeneous (average δ18O = 22.0 ±1.3‰ 2SD, VSMOW), values of δ18O for magnetite and hematite vary by 13‰ (-5 to +7‰) and are correlated with different generations of magnetite and hematite.

    ROADMAP OBJECTIVES: 4.1 5.2 7.1
  • Ice Chemistry of the Solar System

    The overall goals of this project are to understand the chemical evolution of the Solar System, in particular leading to the development of astrobiologically important molecules. This is being achieved by investigation the formation of key organic carbon-, hydrogen-, oxygen-, and nitrogen-bearing (CHON) molecules in ices of Kuiper belt objects by reproducing the space environment experimentally in a unique ultra-high vacuum surface scattering machine. During this reporting period, our team worked on six projects towards our research goal to better understand the ice-based astrochemistry of chemical synthesis for carbon-containing compounds within the solar system. The Keck Astrochemistry Laboratory was also completed during this reporting period.

    ROADMAP OBJECTIVES: 1.1 2.2 3.1 3.2 3.3 6.2 7.1
  • Project 3B: In Situ Sulfur Isotope Studies in Archean-Proterozoic Sulfides

    Using new protocols developed at WiscSIMS, we made in situ measurements of three stable isotopes of sulfur (32S, 33S and 34S) in pyrite from the Meteorite Bore Member with unprecedented small spot sizes and accuracy (Williford et al. 2011). We have found a moderate range of S-MIF (> 1‰) in authigenic pyrite before, during and after the Early Proterozoic glaciation as well as a 90‰ range of mass dependent sulfur isotope fractionation (δ34S) larger than any observed in sediments older than 700 Ma. Furthermore, abundant detrital pyrite preserved in one glacial sandstone unit from the Meteorite Bore Member exhibits a range of mass-independent sulfur isotope fractionation slightly larger than the largest published range, from 2.5 Ga sediments of the Hamersley and Transvaal Basins (> 15‰), suggesting that these detrital grains may have originated in rocks of similar age. Taken together, these data imply that the Meteorite Bore Member was deposited during the transitional interval when atmospheric oxygen had risen sufficiently for enhanced continental weathering and ocean sulfate to occur, yet remained low enough to permit the preservation of detrital pyrite and moderate S-MIF.

    ROADMAP OBJECTIVES: 1.1 4.1 4.2 7.1
  • The Subglacial Biosphere – Insights Into Life-Sustaining Strategies in an Extraterrestrial Analog Environment

    Sub-ice environments are prevalant 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 3C: Integration of Multiple Isotope Proxies to Study the Pre-GOE Oxygenation of the Earth

    The period 2.7 to 2.5 b.y. ago, the period leading you to the Great Oxidation Event (GOE), is becoming increasingly recognized as a time of major environmental change. A holistic understanding of the changes that occurred in microbial ecology, and their effects of the environment, are only possible by integrating multiple geochemical proxies. By simultaneously looking at C, O, S, Fe, Mo, and Sr isotopes, we develop a picture of extensive oxygenic photosynthesis, but approximate balance with reduced resevoirs such as reduced Fe and reduced volcanic gases, such that free oxygen did not yet become abundant on the planet. Although many workers have questioned a rise in oxygenic photosynthesis significantly before the GOE, these new data clearly indicate that this metabolism was widespread at least 400 m.y. before the GOE.

    ROADMAP OBJECTIVES: 4.1 5.3 6.1 7.1 7.2
  • Organic Chemistry in a Dynamic Solar Nebula: Lab Studies and Flight Mission Implementation

    Over the past year we have concentrated on four major activities. The first is laboratory research on the generation of organics and the trapping of noble gases via Fischer-Tropsch type (FTT) reactions. The second is an attempt to understand and model the interrelated carbon and oxygen chemical cycles in a dynamic, turbulent nebula. The third is preparation for the design phase of the OSIRIS-REx mission, especially the characterization of regolith properties of the Type B asteroid that we are targeting. The final is proposal activity leading to the (possible) selection of a Discovery-class comet exploration mission (Comet Hopper or CHopper). In both of the mission activities, my goal has been to ensure that the missions can extract the maximum knowledge of the chemical and physical processes that occurred in the early solar system from the bodies that will be visited.

    ROADMAP OBJECTIVES: 3.1 3.2 7.1
  • Project 4B: Iron Isotope Biosignatures – Synthesis of Abiotic and Biotic Laboratory Experiments

    Experimental studies in geochemical systems analogous to ancient rock precursors are required to gain insight into the biogeochemical processes responsible for generating unique chemical or isotopic compositions in ancient rocks. We conducted a synthesis of prior and ongoing laboratory studies of Fe isotope fractionation during abiotic and biologically catalyzed (by dissimilatory microbial iron reduction, DIR) interaction between Fe(II) and Fe(III) oxide phases in the presence of dissolved silica, which was likely abundant in Precambrian oceans. In particular, previous studies of iron isotope fractionation during microbial reduction of an amorphous iron oxide-silica coprecipitate in high-silica, low-sulfate artificial Archean seawater were analyzed in combination with fractionation during abiotic Fe(II)-Fe(III) interaction to assess the rates and mechanisms of Fe isotope fractionation. The results show that although isotopic exchange rates were a function of solid and solution compositions, in all cases they were much higher than that determined in previous studies of aqueous Fe(III) and ferrihydrite interaction, highlighting the importance of electron exchange in promoting Fe atom exchange. When compared to analogous microbial reduction experiments with overlapping Fe(II) to Fe(III) ratios, isotopic exchange rates are faster in the biological experiments, likely due to promotion of atom exchange by the solid-phase Fe(II) produced during DIR. These findings provide constraints on the range of equilibrium iron isotope fractionations that may be produced by different geochemical processes. In addition, when interpreted in a Fe mass-balance context, our findings provide strong support for DIR as a mechanism for producing Fe isotope variations observed in Neoarchean and Paleoproterozoic marine sedimentary rocks.

    ROADMAP OBJECTIVES: 4.1 7.1
  • Radio Observations of Simple Organics: Tracing the Origins and Preservation of Solar System Materials

    We have continued observational programs designed to explore the chemical composition of comets and establishing their potential for delivering pre-biotic organic materials and water to the young Earth and other planets. State of the art, international facilities are being employed to conduct multiwavelength, simultaneous, studies of comets in order to gain more accurate abundances, distributions, temperatures, and other physical parameters of various cometary species. Additionally, observational programs designed to test current theories of the origins of isotopically fractionated meteorite (and cometary) materials are currently underway. Recent chemical models have suggested that in the cold dense cores of star forming regions, significant isotope enrichment can occur for nitrogen and possibly vary between molecular species and trace an object’s chemical evolution. Observations are being conducted at millimeter and submillimeter wavelengths of HCN and HNC isotopologues for comparison to other nitrogen-bearing species to measure fractionation in cold star forming regions.

    ROADMAP OBJECTIVES: 2.2 3.1 3.2 7.1
  • Remote Sensing of Organic Volatiles in Planetary and Cometary Atmospheres

    We developed state-of-the-art spectroscopic methods to analyze our extensive infrared database of Mars and cometary spectra. In the last two years, we acquired the deepest and most comprehensive search for biomarkers on Mars using powerful infrared high-resolution spectrometers (CRIRES, NIRSPEC, CSHELL) at high-altitude observatories (VLT, Keck-II, NASA-IRTF respectively). In order to analyze this unprecedented wealth of data, we developed highly automated and advanced processing techniques that correct for bad-pixels/cosmic-rays and perform spatial and spectral straightening of anarmophic optics data with milli-pixel precision. We also constructed line-by-line models of the ν7 band of ethane (C2H6), the ν3 and ν2 bands of methanol (CH3OH), we compiled spectral information for H2O and HDO using 5 databases (BT2, VTT, HITEMP, HITRAN and GEISA), and compiled spectral information NH3 using 4 databases (BYT2, TROVE, HITRAN and GEISA). These great advancements have allowed us to understand the infrared spectrum of planetary bodies with unprecedented precision.

    ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 4.1 7.1 7.2
  • Project 5A: Production of Mixed Cation Carbonates in Abiologic and Biologic Systems

    In the fourth year of our NAI project, a series of free drift experiments and one chemo-stat experiment were completed to determine the effect of temperature, chemical composition, pCO2, pH and precipitation rate on the incorporation of Mg in calcite in relatively dilute solutions. These experiments will permit geochemical relationships to be established between carbonate minerals and the solutions from which they form to gain a better understanding of the origin and occurrence of carbonates in ancient terrestrial and extraterrestrial environments.

    ROADMAP OBJECTIVES: 4.1 7.1
  • Stoichiometry of Life – Task 2c – Biological Soil Crusts: Metal Use and Acquisition

    Desert biological soil crusts (BSCs) are a complex consortia of microorganisms including cyanobacteria, algae, and fungi. BSCs are the primary colonizers of desert soils, supplying both carbon and nitrogen to these arid-land ecosystems. As such, they may represent an analog for soil development on the early Earth. BSCs occupy an extremely nutrient-poor niche, and meet their nutrient and metal requirements by manipulating their surroundings via the production of metal-binding ligands called siderophores. The soil crust’s metabolism affects the chemical composition of soil porewaters and soil solid phases; these alterations to soil metal contents may represent a biosignature for biological soil crusts that can be preserved over long time scales.

    ROADMAP OBJECTIVES: 4.1 5.3 6.1 6.2 7.1
  • Research Activities in Planetary Environments Lab

    A new instrument called VAPoR (Volatile Analysis by Pyrolysis of Regolith) was developed to demonstrate an end-to-end pyrolysis time of flight mass spectrometer system with sufficient mass resolution, mass range, sensitivity, precision, and dynamic range to be applied to astrobiology missions. The mass spectrometer derived from this development can be used as an in situ detector of water, noble gases, oxygen, and other potential biomarkers such as organic molecules that are signatures of extinct or extant life and isotopic composition of elements such as C, H, and S that are fractionated by biological processes. A small lightweight mass spectrometer such as VAPoR will conserve precious mass, power, and volume resources in future missions to polar regions of the Moon, asteroids, comets, Mars, Europa, Enceladus, or Titan. The VAPoR instrument was tested most recently during the 2011vDesert Research and Technology Studies (DRATS) field campaign where detailed in situ bulk chemical characterization of volatiles released from regolith samples was carried out.

    ROADMAP OBJECTIVES: 2.1 2.2 7.1
  • Project 5B: Magnesium Isotope Fractionation Between Calcite and Aqueous Mg

    The isotopic composition of Mg in carbonate is of interest to studies on paleo environments because of the potential for constraining temperatures, vital effects, and Mg fluxes associated with precipitation of carbonate minerals. Indeed, Mg isotope fractionation during inorganic carbonate precipitation is important because this serves as the baseline for interpreting the Mg isotope variations and inferred fluid isotope compositions for both abiogenic and biogenic carbonate. We report the results of Mg-bearing calcite synthesis studies used to constrain the fractionation of Mg isotopes during calcite precipitation. The results provide the baseline data needed to interpret Mg-bearing carbonates from the early Earth, as well as carbonates that are likely to be found on Mars.

    ROADMAP OBJECTIVES: 4.1 7.1 7.2
  • Project 5C: Growth of Ca-Mg Carbonates in the Presence of Dissolved Hydrogen Sulfide – in Situ and AFM Studies

    Dissolved hydrogen sulfide, one of the major products of bacterial sulfate reduction can promote crystallization of Ca-Mg-carbonates and dolomite. Hydrogen sulfide can be adsorbed strongly on the surfaces of Ca-Mg-carbonates, which can catalyze dehydration of surface Mg-water complexes and promote Mg incorporation into the Ca-Mg-carbonates and dolomite.

    ROADMAP OBJECTIVES: 7.1 7.2
  • Research Activities in the Astrobiology Analytical Laboratory

    The Astrobiology Analytical Laboratory is a laboratory dedicated to the study of organic compounds derived from Stardust and future sample return missions, meteorites, lab simulations of Mars, interstellar, proto-planetary, and cometary ices and grains, and instrument development. This year, we conclusively demonstrated the presence of indigenous nucleobases and purines in carbonaceous chondrites, resolving a 50-year-old debate. We continued analyses of meteoritic amino acids, which led to both the first detection of these compounds in thermally altered meteorites and a more detailed understanding of their presence in aqueously altered meteorites. We collaborated with researchers at various institutions to bring our analytical expertise to the study of precious and unique samples. We look forward to our increased participation in the OSIRIS-REx asteroid sample return mission.

    ROADMAP OBJECTIVES: 2.1 3.1 7.1
  • Project 5D: A Computational Study of Mg2+ Dehydration in Aqueous Solution in the Presence of Sulfide – Insights Into Dolomite Formation

    Microbial activity has been invoked frequently in the literature to explain the formation of massive sedimentary dolomite at near-Earth’s surface temperatures in the ancient geological rock record and, more generally, for the formation of mixed cation carbonates. Carbonates have been found on Mars, and may serve as a biosignature, if the mechanisms of formation can be elucidated. Sulfide, the product of bacterial sulfate reduction, has been proposed previously to promote dolomite formation by facilitating desolvation of Mg2+ in solution and, thus, incorporation into the dolomite crystal structure. Chemical intuition, however, does not suggest any particular characteristic of HS- that would render it an efficient promoter of Mg2+ desolvation. We, therefore, conducted ab initio reaction path ensemble (RPE) and Molecular Dynamics simulations to determine the energy barrier for removal of a single water molecule from the first solvation shell compared to that for hydrated Mg2+ in the presence of HS- in the second coordination shell of Mg2+. We found that HS- had little, if any, effect on lowering the Mg2+ dehydration barrier in aqueous solution. Empirical observations of HS- promoted dolomite formation may then suggest a potential role for HS- in promoting Mg2+ desolvation at a solid precursor phase. Our project addresses NASA Astrobiology Institute’s (NAI) Roadmap goals of recognizing and preserving biosignatures and NASA’s Strategic Goal of advancing scientific knowledge of the origin and evolution of the Earth’s biosphere and the potential for life elsewhere.

    ROADMAP OBJECTIVES: 7.1
  • Project 5E: Disordered Dolomite Crystallization From Media Containing Agar Gel and Halophilic Bacteria

    Ca-Mg-carbonates ranging from Mg-calcite to Mg-dolomite can be synthesized in presence of halophilic bacteria with agar media and agar media only. Extracellular polysaccharides adsorbed on surfaces can catalyze dolomite formation because of strong hydrogen bonding between the polysaccharides and the carbonate surface. This study provides insight into the effect of similar polysaccharides produced by microorganisms on dolomite formation. Low-temperature Ca-Mg-carbonate solid solution with continuous composition between calcite and dolomite could be a potential biosignature, because it requires catalysts like polysaccharides.

    ROADMAP OBJECTIVES: 7.1 7.2
  • Project 5F: Roles of Extracellular Polysaccharides From Sulfate-Reducing Bacteria in Governing Dolomite Composition and Crystallization

    Ca-Mg-carbonates ranging from Mg-calcite to Mg-dolomite can be synthesized in presence of extracellular polymeric substances (EPS) excreted by sulfate-reducing bacteria (SRB). The role of EPS in catalyzing dolomite formation is similar to the agar-bearing systems, because polysaccharides are the major components in EPS. Low-temperature dolomite and Ca-Mg-carbonates with continuous compositional variations between calcite and dolomite could be potential biosignatures, because they require catalysts like polysaccharides.

    ROADMAP OBJECTIVES: 7.1 7.2
  • Project 6B: Detection of Biosignatures in Extreme Environments and Analogs for Mars

    We have continued to investigate the Río Tinto area an acid river in Spain analogous to the environment of early Mars. We are now using a sophisticated technique that analyses the three stable isotopes of oxygen and their relationship to each other with surprising results. Isotopic fractionation processes, change the relative proportions of the oxygen of masses 17 and 18 relative to 16 to an extent generally proportional to their mass difference, an approximately 2:1 effect for O-18 and O-17, respectively, shown by the slope of the line. Most terrestrial materials exhibit this same relationship perfectly, but oxygen in sulfate from waters and minerals in the Río Tinto area, produced by either microbial or inorganic processes, deviate from that: there is also the suggestion in preliminary data that these two processes can be differentiated from each other too. The measure of this relationship would provide a biosignature, independent of an measured oxygen isotope value of subsequent fractionation process.

    ROADMAP OBJECTIVES: 2.1 7.1
  • Project 7A: A New Way for Exploring Mars for Environmental History and Biosignatures

    Mobile exploration of Mars so far has been achieved by the use of rovers, powered by solar panels or in the near future, radioisotope thermoelectric generators (RTGs). The JPL team has been contributing to an effort to develop an alternative source of locomotion, wind power. A Tumbleweed rover is a large (maybe as big as 20 ft diameter), inflatable structure, equipped with suitable instruments and would be able to make long-range surveys of large areas of Mars. A rover would carry a suite of science instruments for surface and near-surface interrogation and be released to roam for the duration of a season or longer. Although direction will be at the mercy of the wind, location will be tracked precisely and randomized surveys of a large area are equivalent to conventional coordinate grid sampling.

    ROADMAP OBJECTIVES: 2.1 7.1
  • Project 7C: Improving Accuracy of in Situ Stable Isotope Analysis by SIMS

    Isotopic analysis of biologically important elements in petrographic context is a fundamental tool for astrobiology. Secondary ion mass spectrometry (SIMS) is a powerful tool used to understand biogeochemical processes at the spatial scale of the individual microorganisms that drive them. The benefits of the extremely high spatial resolution offered by SIMS do not come without costs, however. Unconstrained physical and chemical variables in the sample of interest can introduce biases leading to inaccurate measurements. Understanding and constraining these barriers to accuracy as we move towards ever finer spatial resolution and analytical precision is a primary focus at WiscSIMS.

    ROADMAP OBJECTIVES: 4.1 5.1 5.2 5.3 7.1