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2008 Annual Science Report

Astrobiology Roadmap Objective 4.1 Reports Reporting  |  JUL 2007 – JUN 2008

Project Reports

  • Biosignatures in Chemosynthetic and Photosynthetic Systems

    Our work examines the microbiology and geochemistry of microbial ecosystems on Earth in order to better understand the production of “biosignatures” — chemical or physical features or patterns that can only have been formed by the activities of life. More specifically, in photosynthetic (light-eating) microbial mats, we examine the factors that control the formation of biosignature gases (such as could be seen by telescope in the atmospheres of planets orbiting other stars) and isotopic and morphological features that could be preserved in the rock record (such as could be examined by rovers on Mars). Additionally, we study the formation of morphological and mineral signatures in chemotrophic (chemical-eating) systems that have no direct access to light or the products of photosynthesis. Such systems likely represent the only viable possibility for extant life on modern day Mars or Europa.

    ROADMAP OBJECTIVES: 2.1 4.1 5.1 5.2 6.1 7.1 7.2
  • Describing the Anaerobic Thermophilic Microbial Community: A Metagenomic Strategy

    The ocean is one of the least explored parts of the microbial world, including at deep-sea hydrothermal vents, where the unique geochemistry creates many habitats for microbial and animal communities. These organisms encounter many conditions that we humans consider too extreme- too hot, too toxic, too little oxygen- but microbes seem to find a way and continue to push the limits of life. An impetus for studying life at deep-sea hydrothermal vents is that life may have originated and evolved near hydrothermal systems, and that organisms currently living in these likely analogues of early habitats may still harbor characteristics of early life. In addition, microbes unique to the hydrothermal vents could provide insight into metabolic processes, strategies for growth, and survival of life on solar bodies with a water history, such as Mars and Jupiter’s moon Europa. Our research on diffuse flow vents at deep-sea hydrothermal seamounts provides insight into the diversity, physiology, and genetic potential of these unique microbial communities within the context of their dynamic and complex geochemical habitat.

    ROADMAP OBJECTIVES: 4.1 5.1 5.2
  • Biogenic Formation of High-Magnesium Calcite in Sulfide-Rich Systems

    Calcite minerals that contain high proportions of magnsium are well-known biogneic minerals in modern marine environments, reflecting metastable incorporation of Mg in the calcite lattice. In the modern oceans, calcite may form in the presence of sulfide in hydrothermal systems, or, in the ancient Earth, high-magnesium calcite may have formed in the presence of high ambient sulfide (produced by bacterial sulfate reduction or hydrothermal systems), and this project is aimed at understanding the mechamisms involved in producing high-magnesium calcite in the presence of high dissolved sulfide.

    ROADMAP OBJECTIVES: 4.1 6.1 7.1
  • Castleman Report

    The evolving isotope composition of sulfur compounds pertains to the questions of the composition of the Earth’s early atmosphere. We are currently in the process of finalizing our interpretation of our investigations on the influence of photolysis, and the subsequent oxygen dissociation of sulfur dioxide on the isotope ratios. During the report period, we began the interpretation of the experimental results obtained from our spectrometer, which, coupled with a new detection scheme, has enabled us to overcome conventional difficulties encountered in making isotopic measurements. This scheme facilitates the study of individual isotopes without the need for a “spiked sample”, a process that is fraught with difficulties due to the inability to reliably acquire accurate and uniform mixtures.

    ROADMAP OBJECTIVES: 4.1
  • Iron Isotope Biosignatures: Laboratory Studies and Modern Environments

    This project seeks to define the biotic and abiotic mechanisms of Fe isotope fractionation in modern sedimentary environments and laboratory model systems. Such information is required to evaluate the potential role of Fe isotopes in understanding the evolution of microbial redox metabolism on the early Earth, and to evaluate their ability to serve as biosignatures of microbial metabolism on other planets (e.g. Mars).

    ROADMAP OBJECTIVES: 4.1 6.1 7.1
  • Microbial Pyrite Oxidation in Nature and the Lab: Sulfate Mineral Biosignature Investigation

    In the laboratory the project aims to culture bacteria that oxidize iron and sulfur under various conditions (a range of temperatures and different degrees of acidity). The goal is to develop criteria to distinguish minerals that formed as indirect result of bacterial activity from those that form with no biological association. It s anticipated that such distinctions may involve subtle, but distinctive differences in chemical and isotopic compositions, including variations in the ratios of the naturally occurring stable (non-radioactive) isotopes of iron, sulfur and oxygen. Analyses will be made of similar minerals, formed naturally in an acid mine drainage area of SW Spain, that may be an analog for processes that are believed to have happened on the surface of Mars four billion years ago.

    ROADMAP OBJECTIVES: 2.1 4.1 7.1
  • 3. Prebiotic Chemical and Isotopic Evolution on Earth
    ROADMAP OBJECTIVES: 3.1 4.1 4.2 7.1
  • Evolution of a Habitable Planet (Stewart)

    This project has several foci, including (1) using novel isotope techniques to determine the ages of soils formed very early in Earth’s history; (2) studying the detailed cycling of iron sulfide minerals and the possible isotopic “signatures” of primitive life forms that might be contained within them; (3) tracking the fluxes of dust and salt in extreme Earth environments (the Atacama Desert, Chile) to better understand processes on the surface of Mars.

    ROADMAP OBJECTIVES: 4.1 6.1
  • Ecosystem to Biosphere Modeling

    We have created a working model of a microbial mat called MBGC (for Microbial Biogeochemistry). The model examines the internal cycling of oxygen, carbon, and sulfur through a complex microbial ecosystem that may be similar to those found on early Earth.

    ROADMAP OBJECTIVES: 4.1 5.3
  • Modeling Early Earth Environments

    In this project, scientists from different disciplines model the conditions likely to have been found on the Early Earth, prior to 2.3 billion years ago. Specific areas of research include understanding the gases, many biologically produced, and mechanisms that controlled early Earth’s surface temperature, the nature of hazes that shielded the planetary surface from UV and may be responsible for signatures in sulfur isotopes that were left in the rock record, the chemical nature of the Earth’s environment during and after a planet-wide glaciation (a “Snowball event”), the evolution of planetary atmospheres over time due to loss of atmosphere to space, and the use of iron isotopes as a tracer of the oxidative state of the Earth’s ocean over time.

    ROADMAP OBJECTIVES: 1.1 1.2 2.1 4.1 4.2 5.1 5.2 5.3 6.1 7.2
  • 4. Prebiotic Molecular Selection and Organization
    ROADMAP OBJECTIVES: 3.1 3.2 3.4 4.1 7.1
  • Design, Construction and Testing of a Cavity-Ring Down Spectrometer for Determination of the Concentration and Isotopic Composition of Methane

    The recent detection of CH4 in the Martian atmosphere and observations suggesting that it varies both temporally and spatially argues for dynamic sources and sinks. CH4 is a gaseous biomarker on Earth that is readily associated with methanogens when its H and C isotopic composition falls within a certain range. It is imperative that a portable instrument be developed that is capable of measuring the C and H isotopic composition of CH4 at levels comparable to that on Mars with a precision similar to that of an isotope ratio mass spectrometer and that such an instrument be space flight capable. Such an instrument could guide a rover to a site on Mars where emission of biogenic gases is occurring and samples could be collected for Mars sample return.

    ROADMAP OBJECTIVES: 2.1 2.2 3.3 4.1 5.1 5.2 5.3 6.1 6.2 7.1 7.2
  • New Frontiers in Micro-Analysis of Isotopic Compositions of Natural Materials: Development of Fe Isotopes

    The isotopic composition of iron is an excellent signature of past redox processes and the presence of a hydrologic cycle. Moreover, Fe isotope compositions promise to be a unique marker for dissimilatory iron reduction by bacteria, making this isotope system an excellent biosignature. Our goal is to develop analytical methods to make precise Fe isotope analysis on individual Fe-bearing minerals at a 10 micron diameter spot resolution. This technology will allow assessment of the Fe isotope heterogeneity within an individual Fe-bearing mineral and between different mineral grains. Documentation of such inter- and intra-mineral variations is critical to establishing if the Fe isotope variations measured in ancient rocks is a primary signature indicative of the environment in which the rock formed, or if it is a result of later metamorphic or diagenetic processes. Moreover, performing such spot mineral analyses will allow one to correlate Fe isotope variations that are associated with petrographic and mineral/chemical variations that cannot easily be done using conventional techniques.

    ROADMAP OBJECTIVES: 4.1 7.2
  • A Search for Primordial Water From Deep in the Earth’s Mantle

    This project is designed to provide information on the origin of Earth’s water. Comparing the isotopic composition of Earth’s primordial water (D/H ratio) with the ratios of other solar system objects can help to constrain possible sources of the water. The current ocean, other surface waters, and water in the upper mantle have experiences 4.5 billion years of geologic processing that has changed the original isotopic composition. By concentrating on rapidly quenched, under-gassed lavas from hot spots like Hawaii and Iceland, we hope to identify water that has not been through the extensive processing experienced by the surface water. Such a reservoir may have survived unaltered since shortly after the accretion of the Earth and thus may provide a better idea of the original composition of the Earth’s water.

    ROADMAP OBJECTIVES: 1.1 4.1
  • Ferry Report

    The research addresses how anaerobic Archaea cope with oxidative stress, with the long-term view of how anaerobic life evolved to adapt to rising oxygen levels before, during and after the evolution of oxygenic photosynthesis. The research also addresses ancient enzymes involved in metabolic pathways with a focus on energy conservation in methanogenic Archaea.

    ROADMAP OBJECTIVES: 3.3 4.1 4.2 5.1 6.1
  • Planetary Habitability

    In this research project, members of the VPL team explore different aspects of planetary habitability, and the detectability of habitability and life, using a combination of theoretical models, astronomical observations and Earth-based field work.

    ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 4.1 5.3 6.1 7.2
  • Iron and Sulfur-Based Biospheres and Their Biosignatures

    This project focuses on the geochemical and microbiological properties of iron (Fe) and sulfur (S) based lithotrophic microbial ecosystems. Recent aspects of this research have been supported by a Director’s Discretionary Fund (DDF) project entitled “Biogeochemical forensics of Fe-based microbial systems: defining mission targets and tactics for life detection on Mars”. The Banfield group is examining Fe concretions at the hypersaline Lake Tyrell in Victoria, Australia as analogs for those which formed at Meridiani Planum on Mars, as well as novel uncultivated, ultra-small Archaea in pyrite oxidation-based microbial communities at Iron Mountain, CA. The latter organisms have only a very small number of ribosomes per cell (ca. 92, compared to ca. 10,000 for E. coli in culture), which are positioned around the inside of the inner membrane. The size and highly organized internal structure of these organisms provide clues to the strategies of life at its lower size limits. The Emerson group is investigating natural populations and pure cultures of Fe(II)-oxidizing bacteria in an attempt to better understand how their physiology and ecology influences the mineralogy and geochemistry that are hallmarks of these organisms in the environment. A major focus of this work, in collaboration with the Luther group, has been to gain a better understanding the contribution that neutrophilic, oxygen-dependent Fe(II)-oxidizing bacteria make to Fe(II) oxidation kinetics both in situ and in the laboratory. Additional work has focused on the ultrastructure and behavior of a unique Fe-oxidizing bacterium, Mariprofundus ferrooxydans, isolated from a deep-sea hydrothermal vent that had extensive mats of Fe(II)-oxidizing bacteria. The Luther group has been examining a variety of environments where microbially-driven Fe(II) oxidation occurs, including areas where free sulfide is not present (creeks in VA and Chocolate Pots, Yellowstone National Park) and locations where free sulfide is present [local Delaware Inland Bays and the hydrothermal vents at Kilo-Moana (20°3’S, 176°8’W), located on the East Lau Spreading Centre (ELSC), in the Lau Basin, SW Pacific Ocean]. These studies demonstrate that it is possible to distinguish between abiotic and biotic mechanisms for Fe(II) oxidation using real time measurements. Roden’s group has examined microbial communities and biosignatures in several different Fe-dominated natural systems, including circumneutral pH groundwater Fe seeps in Tuscaloosa, AL; a Pliocene-age weathered volcanic tuff unit in Box Canyon, ID; hypersaline Lake Tyrell; and chemically-precipitated sediments in the Spring Creek Arm of the Keswick Reservoir downstream of the Iron Mountain acid mine drainage site in northern CA. We have also evaluated the composition and function of an anaerobic, nitrate-dependent Fe(II)-oxidizing enrichment culture which is capable of chemolithoautotrophic growth coupled to oxidation of the insoluble ferrous iron-bearing phyllosilicate mineral biotite.

    ROADMAP OBJECTIVES: 4.1 6.1 7.1 7.2
  • 6. Molecular and Isotopic Biosignatures
    ROADMAP OBJECTIVES: 2.1 3.1 4.1 4.2 5.3 6.1 7.1 7.2
  • New Frontiers in Micro-Analysis of Isotopic Compositions of Natural Materials: Development of O, Si, and Li Isotopes

    The isotope ratios of oxygen and silicon are a sensitive monitor of sedimentary and hydrothermal processes for deposition of banded iron formation. Our focus on banded iron formations reflects the importance these unusual units have in biogeochemical cycling in the early Earth. In particular, we are examining the deposition of microlaminated sections of the Dales Gorge member of the Brockman Iron Formation from the Hamersley basin, which have alternatively been interpreted to represent annual varves in chemical precipitates from seawater, or variations in a sub-surface hydrothermal system. These conflicting models have relevance for interpreting the role of microbial life in precipitation of the Fe-oxides. In addition, δ18O and δ34S values from coexisting minerals can be used to estimate the temperature of the Archean ocean, or of the hydrothermal system. δ7Li and δ18O values in zircons allow these tests to be applied to magmas that may have assimilated sedimentary materials, and, in the case of Jack Hills samples from SW Australia, provide a record of the earliest Earth (4.4 to 4.0 Ga), before the formation of all known rocks.

    ROADMAP OBJECTIVES: 4.1 7.1
  • Genomic Record of the Earth’s Early Biosphere (Hedges)

    Our research involves molecular evolutionary genetics in an effort to better understand the relationship between planetary history and the evolution of life. We continue to update our public database TimeTree (www.timetree.org), which presents divergence times of organisms. Most of the work during the past year involved editing and contributing to a book, The Timetree of Life, which summarizes the current state of knowledge in the field and presents new data, with 81 chapters and 105 authors (Oxford University Press, in production).

    ROADMAP OBJECTIVES: 4.1 4.2 4.3
  • Planetary-Scale Transition From Abiotic to Biotic Nitrogen Cycle

    Nitrogen is an essential element for life. Understanding the planetary nitrogen cycle is critical to understanding the origin and evolution of life. The earth’s atmosphere is full of nitrogen gas (N2). However, this large pool of nitrogen is unavailable to most of the life on earth except a few microbes capable of “fixing” nitrogen into a form that can be used by other organisms (e.g., NH3, NH4+, NOx, organic-N). Without fixed nitrogen life would not have originated on earth and would most likely not occur on any other planet. The Atacama Desert in Chile is an enigma in that it contains vast nitrate (a type of fixed nitrogen) deposits. Elsewhere on earth, nitrate is either denitrified (transformed into N2 and released back into the atmosphere) through the activity of microorganisms, or is dissolved and leached from the system. Although the Atacama is the driest desert in the world we have shown that lack of water alone cannot account for the lack of nitrogen cycling in this desert. Preliminary data suggest that it may be due to the high oxidation level of the soil in combination with a lack of organic material in the soil.

    ROADMAP OBJECTIVES: 1.1 2.1 3.2 4.1 5.1 5.2 5.3 6.1
  • Planetary Surface and Interior Models and Super Earths

    In this task we are developing and using models of a terrestrial planet’s surface and interior to understand
    the evolution of planetary environments. These models allow us to understand how interactions between the
    planetary surface and interior, and life, affect a planet’s atmosphere. New models are also exploring the possible habitability of “super-Earths”, rocky planets that have been found around other stars that can be up to 10 times more massive than our own Earth.

    ROADMAP OBJECTIVES: 1.1 1.2 4.1 5.2 6.1 7.2
  • Isotopic Signatures of Methane and Higher Hydrocarbon Gases From Precambrian Shield Sites: A Model for Abiogenic Polymerization of Hydrocarbons

    Methane and higher hydrocarbon gases in ancient rocks on Earth originate from both biogenic and abiogenic processes. The measured carbon isotopic compositions of these natural gases are consistent with formation of polymerization of increasing long hydrocarbon chains starting with methane. Integration of carbon isotopic compositions with concentration data is needed to delineate the origin of hydrocarbon gases.

    ROADMAP OBJECTIVES: 1.1 2.1 3.1 4.1 4.2 6.1 7.1 7.2
  • Production of Mixed Cation Carbonates in Abiologic and Biologic Systems

    Carbonate minerals commonly occur in terrestrial environments and they are found in extraterrestrial materials, such as meteorites and interplanetary dust particles. On earth, carbonates hold one of the earliest records of seawater chemistry. Carbonate minerals that form in thermodynamic equilibrium (abiotic formation) are constrained in Ca-Mg-Fe composition by the solvi that limit solid-solution to the magnesite-siderite join, the dolomite-ankerite join, and the calcite end member. However, it is now known that microorganisms may produce Ca-Mg-Fe compositions that lie between these solvi, and are therefore out of thermodynamic equilibrium, and such compositions may represent a biosignature for microbially mediated formation. The goal of this project is to understand the mechanisms by which carbonate minerals of unusual chemistry form at relatively low temperature so that we may better understand the processes that may form these minerals in the early Earth, on Mars, and other planetary bodies of the Solar System.

    ROADMAP OBJECTIVES: 4.1 7.1
  • The High Lakes Project (HLP)

    The High Lakes Project is a multi-disciplinary astrobiological investigation studying high-altitude lakes between 4,200 m and 5,916 m elevation in the Central Andes of Bolivia and Chile. Its primary objective is to understand the impact of increased environmental stress on lake habitats and their evolution during rapid climate change as an analogy to early Mars. Their unique geophysical environment and mostly uncharted ecosystems have added new objectives to the project, including the assessment of the impact of low ozone/high solar irradiance in non-polar aquatic environments, the documentation of poorly known ecosystems, and the quantification of the impact of climate change on lake environment and ecosystem.
    Data from 2003 to 2007 show that solar irradiance is 165% that of sea level with instantaneous UV-B flux reaching 17W/m2. Short UV wavelengths (260-270 nm) were recorded and peaked at 14.6 mW/m2. High solar irradiance occurs in an atmosphere permanently depleted in ozone falling below ozone hole definition for 33-36 days and between 30-35% depletion the rest of the year. The impact of strong UV-B and UV erythemally-weighted daily dose on life is compounded by broad daily temperature variations with sudden and sharp fluctuations. Lake habitat chemistry is highly dynamical with notable changes in yearly ion concentrations and pH resulting from low and variable yearly precipitation. The year-round combination of environmental variables define these lakes as end-members. In such an environment, they host surprisingly abundant and diverse ecosystems including a significant fraction of previously undescribed species of zooplankton, cyanobacterial, and bacterial populations.

    ROADMAP OBJECTIVES: 1.1 2.1 4.1 4.3 5.1 5.2 5.3 6.1 6.2 7.1
  • Laboratory Microbial Simulations: Astrobiological Signatures

    We aim to use laboratory and field environments to investigate microorganisms and their biogeochemical signatures. We have investigated methanotrophic seeps and deeply-buried marine environments, as well as used laboratory pure-cultures to further our understanding of diverse metabolisms.

    ROADMAP OBJECTIVES: 2.1 4.1 5.1 5.2 5.3 7.1
  • Modeling Early Atmospheric Composition and Climate

    We have updated our methane greenhouse model for the early Earth by including the greenhouse effect of ethane and the anti-greenhouse effect of organic haze. We analyzed the mass-independent sulfur isotopic record to find evidence for the existence of such haze during the mid-Archean, between 3.2 and 2.8 Ga. And we worked on the problem of hydrogen escape from the early Earth.

    ROADMAP OBJECTIVES: 1.1 4.1
  • Training for Oxygen: Peroxy in Rocks, Early Life and the Evolution of the Atmosphere

    We try to find answers to a range of deep questions about the early Earth and about the origin and early evolution of life. How did the surface of planet Earth become slowly but inextricably oxidized during the first 2 billion years? We present evidence that it was not through the early introduction of oxygenic photosynthesis but through a purely abiotic process, driven by the tectonic forces of the early Earth and the weathering cycle. Only much later in Earth’s history, about 2.4 billion years ago, did photosynthesis kick in, boosting the oxygen level in the atmosphere to the levels that we enjoy now. If this is so, other Earth-like planets around other stars can be expected to undergo the same evolution from an early reduced state to an oxidized state.

    ROADMAP OBJECTIVES: 1.1 2.1 3.1 4.1 7.2
  • Philosophical Problems in Astrobiology; Issues on the Origin of Life,

    My project is exploring philosophical issues in astrobiology. My central focus this year was on the origin of life: what is the proper level of analysis for a successful theory of the origin of life? Among other things, I compared and contrasted contemporary scientific theories of the origin of life in light of what philosophers of science have learned about the structure and justification of scientific theories.

    ROADMAP OBJECTIVES: 3.1 3.2 3.3 3.4 4.1 4.2
  • Radiolytic Oxidation of Sulfide Minerals as a Source of Sulfate and Hydrogen to Sustain Microbial Metabolism

    Microbial ecosystems have been discovered in crustal environments up to 2.8 kilometers below the surface of Earth. Life in this extreme environment apapears to be sustained by high concentrations of dissolved sulfate and hydrogen. Splitting of water molecules by radiation from uranium can produce oxidation gradients that result in simple ionic products usable for maintenance and growth of microbial organisms. A set of experiments exposing water and common sulfide minerals to radiation in a laboratory reactor were conducted to test this hypothesis.

    ROADMAP OBJECTIVES: 1.1 2.1 3.3 4.1 5.1 5.3 6.2
  • VPL Model Interfaces and the Community Tool

    The Virtual Planetary Laboratory’s primary mission is to support NASA’s ongoing planet-finding efforts by building computer simulated Earth-sized worlds to discover the likely range of environments for planets around other stars. To that end, we are developing web-based community tools that allow researchers to collaborate on planetary climate models. These tools combine models and data that help predict the observable properties of planets orbiting other stars.

    ROADMAP OBJECTIVES: 1.1 4.1 7.2
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    We are exploring the geological and geochemical record of ancient Earth for clues about the co-evolution of life and environment. We’re focusing on three events in Earth history: the apparent rise of atmospheric oxygen at 2.45 billion years ago, the establishment of life on land during the Cambrian (about 540 milliion years ago), and the greatest mass extinction of all time at the end of the Permian, 252 million years ago. We use a combination of computer modeling, field work, and laboratory analysis.

    ROADMAP OBJECTIVES: 4.1 6.1 7.1 7.2
  • The Diversity of the Original Prebiotic Soup: Re-Analyzing the Original Miller-Urey Spark Discharge Experiments

    Recently obtained samples from some of the original Stanley Miller spark discharge experiments have been reanalyzed using High Pressure Liquid Chromatography-Flame Detection and Liquid Chromatography-Flame Detection/Time of Flight-Mass Spectrometry in order to identify lesser constituents that would have been undetectable by analytical techniques 50 years ago. Results show the presence of several isoforms of aminobutyric acid, as well as several serine species, isomers of threonine, isovaline, valine, phenylalanine, ornithine, adipic acid, ethanolamine and other methylated and hydroxylated amino acids. Diversity and yield increased in experiments utilizing an aspirating device to increase the gas flow rates; this could be applied as a simulation of prebiotic chemistry during a volcanic eruption. The variety of products formed in these experiments is significantly greater than previously published and mimic the assortment of compounds detected in Murchison and CM meteorites.

    ROADMAP OBJECTIVES: 2.1 3.1 3.2 3.4 4.1 4.2 5.1 6.2 7.1 7.2
  • Sulfur Biogeochemistry of the Early Earth

    Sulfur is widespread in surface geochemical systems and is abundant in many rock types. It is present in volcanic gases and marine waters, and has served a key role in geobiological processes since the origin of life. Like other low atomic number elements, sulfur isotope ratios in various compounds usually follow predictable mass-dependent fractionation laws; these different mass-dependent isotope fractionations serve as powerful tracers for igneous, metamorphic, sedimentary, hydrothermal and biological processes. Mass-independent sulfur isotope fractionation is a short-wavelength photolytic effect that occurs in space, as well as in gas-phase reactions in atmospheres transparent to deep penetration by ultraviolet light. Crucial aspects of the chemical evolution of the early atmosphere — and the surface zone as a whole — can be followed by mass-independent sulfur isotopes in Archean metasedimentary rocks. Metabolic styles of organisms in response to global changes in surface redox over geologic time can also be traced with multiple S isotopes.

    We have concluded from our various studies over the last year and before to the very inception of the NAI node at Colorado, that all Archean sulfur minerals previously documented for their 34S/32S compositions warrant a comprehensive re-examination of their 32S, 33S, 34S (and 36S), sulfur isotope systematics.

    ROADMAP OBJECTIVES: 1.1 1.2 4.1 4.2 5.1 5.2 5.3 6.1 7.1 7.2
  • Understanding the Microbial Ecology of Geologically-Based Chemolithoautotrophic Communities

    The objective of this project is to investigate the potential for geologic systems to support the production of biomass by chemosynthetic microorganisms that use inorganic chemical reactions rather than sunlight as a source of metabolic energy. The research focuses on hydrothermal and subsurface environments, where reaction of water with rocks produces sources of chemical energy like those that might have occurred on the early Earth, or that might occur now on other planetary bodies like Mars and Europa. Numerical geochemical models of fluid-rock interaction have been developed to understand the types and amounts of chemical energy that are generated in modern geologic environments, and to explore how these chemical energy sources may have differed under the different conditions present on the early Earth or in extraterrestrial environments.

    ROADMAP OBJECTIVES: 2.1 4.1
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    ROADMAP OBJECTIVES: 1.1 2.1 2.2 3.1 4.1
  • Icelandic Subglacial Lakes

    This project is describing the microbial community inhabiting the water column of a subglacial volcanic lake in Iceland. These systems are potential analogs for habitats on ice-covered worlds such as the outer planet satellites, and Mars.

    ROADMAP OBJECTIVES: 2.1 4.1 5.3 6.2
  • Sediment-Buried Basement Deep Biosphere

    There is growing evidence that a substantial subseafloor biosphere extends throughout the immense volume of aging basement (basaltic rock) of the ocean crust. Since most ocean basement rock is buried under thick, impermeable layers of sediment, the fluids circulating within the underlying ocean basement are usually inaccessible for direct studies. Circulation Obviation Retrofit Kit (CORK) observatories affixed to Integrated Ocean Drilling Program (IODP) boreholes offer an unprecedented opportunity to study biogeochemical properties and microbial diversity in circulating fluids from deep ocean basement. UH-NAI post doctoral fellows (e.g., Brian Glazer, Andrew Boal)

    ROADMAP OBJECTIVES: 1.1 3.3 4.1 5.1 5.2 5.3 6.1 6.2