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Project Reports

• Astronomical Observations of Terrestrial Planet Atmospheres

  In this project we use telescopes and spectrometers on the Earth to study the atmospheres of Venus and Mars to learn more about the current conditions and history of water on these planets. This work also supports ongoing space-based observations of these worlds.

  ROADMAP OBJECTIVES: 1.2 7.2

• 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

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

  Synthetic approaches are being utilized to bridge the gap between Fe-S minerals and highly evolved biological Fe-S metalloenzymes. These studies are focusing on organic template (protein) mediated cluster assembly (biomineralization), probing properties of synthetic clusters, both as homogeneous and heterogeneous catalysts, investigating the impact of size scale on the properties of synthetic Fe-S clusters, and computational modeling of the structure and catalytic properties of synthetic Fe-S nanoparticles in the 5-50 nm range.

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 3.4 7.1 7.2

• Computational Chemical Modeling the Link Between Structure and Reactivity of Iron-Sulfur Motifs

  The Fe-S mineral catalysis, Fe-S enzyme catalysis, and a biomimetic thrust areas of ABRC have their own unique ways to probe the relationships between structure and reactivity at the active sites of iron-sulfur enzymes and the structure and reactivity of iron-sulfur minerals. We have developed a cohesive link among these thrust areas through bridging the enzymatic/mineral catalysis and molecular structure/chemical reactivity by computational chemistry.

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 7.1 7.2

• Climate, Habitability, and the Atmosphere on Early Mars

  Atmospheric chemistry has profound implications for the climate and habitability of Mars throughout its history. The presence and stability of greenhouse gases and aerosols, for example, may regulate climate or force climate change. Chemical reactions in the atmosphere initiated by light (“photochemistry”) may also produce gases or aerosols that serve as a shield against ultraviolet light (as stratospheric ozone does on earth) and possibly warm or cool the surface, which, in turn, has implications for the presence and stability of water on Mars. Thus, understanding the chemical composition and physical properties of possible Martian atmospheres over time is vital to the understanding of the opportunities and challenges for early life on Mars, as well as the importance of habitat features that provide radiation protection. In this project, we are investigating in laboratory experiments how quickly photochemistry can destroy and produce various greenhouse gases and aerosols and whether or not the aerosols may serve to warm or cool the surface. We are also investigating whether or not these photochemical reactions can produce carbon-rich aerosols that might be depleted in the stable isotope carbon-13 relative to carbon-12, and thus might be mistaken for an isotopic signature produced by biological processes after the aerosols settle out of the atmosphere and become incorporated into the martian rock record or meteorites that have made it to earth.

  ROADMAP OBJECTIVES: 1.1 1.2 3.1 6.1 7.1 7.2

• Earth as an Extrasolar Planet

  In this project we are comparing an existing model of the Earth with images and spectra of the Earth obtained from a distance spacecraft. The VPL Earth model uses Earth observing satellite data including atmospheric conditions and cloud cover to simulate both images and spectra of the Earth on a given day of observation. The comparision between the model and data will help us improve our model, and will also provide information on how detectable some of the Earth’s environmental characteristics would be to an observer in another planetary system.

  ROADMAP OBJECTIVES: 1.2 7.2

• Molecular Beam Studies of Nitrogen Reactions on Iron-Sulfur Surfaces

  It is generally accepted that surface-mediated reactions occur on defect sites. The role of defects in the formation of ammonia is being evaluated using molecular beam-surface scattering experiments in which a deuterium atom plasma source is used to hydrogenate a pyrite surface with D atoms. The hydrogenated surface is subsequently bombarded with a molecular beam of energetic N2 molecules and the conversion of N2 to products such as ammonia is probed through mass spectrometry.

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 7.1 7.2

• Effects of Stellar Flares on Atmospheres of Habitable Planets

  Stellar flares, sudden energy bursts from a star, produce a cascade of particles and radiation that can affect that can affect the atmospheres of orbiting planets. Our research is focused on understanding how the atmospheric chemistry of a planet is affected by flares. We want to know if flares can modify the concentrations of compounds that are produced by life and released to the planetary atmosphere and if the ultraviolet radiation during a flare can reach the planetary surface and damage the possible organisms on that planet.

  ROADMAP OBJECTIVES: 1.1 4.3 7.2

• Expanding the List of Target Stars for Next Generation SETI Searches

  For decades the conventional wisdom considered M dwarf stars unsuitable hosts for habitable planets. We convened an interdisciplinary workshop of thirty scientists to reconsider the issue. They concluded that life could evolve on planets orbiting higher mass M dwarfs. This improves the prospects for finding extraterrestrial life since M dwarfs account for about 75% of all stars. Based on these results, we are preparing a list of more than a million “target” stars for a search for extraterrestrial intelligence (SETI) project.

  ROADMAP OBJECTIVES: 1.1 1.2 4.3 6.2 7.2

• 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

• 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

• 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

• 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

• Probing the Structure and Nitrogen Reduction Activity of Iron-Sulfur Minerals

  Fe-S compounds are common in both biological and geological systems. The adaptation of Fe-S clusters from the abiotic world to the biological world may have been an early event in the development of life on Earth and possibly a common feature of life elsewhere in the universe. The Iron-sulfur mineral thrust of the ABRC is focused on examining the structure and reactivity of FeS minerals using nitrogen fixation as a model reaction.

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 3.4 7.1 7.2

• DDF: Geomicrobiology of a Unique Ice-Sulfur Spring Ecosystem in the High Arctic

  A glacial, active sulfide spring environment at Borup Fiord Pass on Ellesmere Island in the Canadian High Arctic provides an excellent opportunity to study microbial life at a site that may be an analog to Europa, an ice-covered moon of Jupiter. During the past year we have collected samples from the extensive mats of sulfur-minerals that precipitate in discharge channels to identify the microbial communities hosted in the sulfur-ice, and to cultivate key key organisms mediating the oxidation of H2S to elemental sulfur.

  ROADMAP OBJECTIVES: 5.1 5.2 5.3 6.1 7.1 7.2

• 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

• 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

• Structure, Function, and Biosynthesis of the Complex Iron-Sulfur Clusters at the Active Sites of Nitrogenases and Hydrogenases

  Iron-sulfur clusters are thought to be among the most ancient cofactors in living systems. The Fe-S enzyme thrust is focused on examining the structure, mechanism, and biosynthesis of the complex Fe-S enzymes nitrogenase and hydrogenase.

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 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

• Identifying Microbial Life at Crustal Rock-Water Interfaces

  We are working to cultivate and characterize microorganisms which directly derive energy from reactions between mafic rocks and water. We are particularly targeting organisms that colonize the surfaces of the rocks during alteration. Thus we are also developing high-resolution chemical measurements capable of detecting reaction fronts and mineral by-products that form over time at the microbe-mineral interface.

  ROADMAP OBJECTIVES: 5.2 5.3 6.1 6.2 7.2

• Prebiotic Organics From Space

  This project has three components, all aimed to better our understanding of the connection between chemistry in space and the origin of life on Earth and possibly other worlds. Our approach is to trace the formation and evolution of compounds in space, with particular emphasis on identifying those that are interesting from a prebiotic perspective, and understand their possible roles in the origin of life on habitable worlds. We do this by first measuring the spectra and chemistry of materials under simulated space conditions in the laboratory. We then use these results to interpret astronomical observations made with ground-based and orbiting telescopes. We also carry out experiments on simulated extraterrestrial materials to analyze extraterrestrial samples returned by NASA missions or that fall to Earth in as meteorites.

  ROADMAP OBJECTIVES: 1.1 2.1 2.2 3.1 3.4 4.3 7.1 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

• Microbial Diversity of a Hypersaline Microbial Mat

  The goal of this project is to survey the microbial life that comprises a hypersaline microbial mat at Guerrero Negro, Mexico using culture independent technology (ribosomal and other gene sequences). The results have expanded significantly our knowledge of microbial diversity, bacterial, archaeal and eucaryotic.

  ROADMAP OBJECTIVES: 3.2 3.3 5.1 5.2 5.3 7.2

• The Virtual Planetary Laboratory – The Life Modules – Photosynthesis

  Photosynthesis provides the foundation for nearly all life on our planet and produces unique life signs — atmospheric oxygen and pigment colors — that are detectable from space at the global scale. This project seeks to determine the adapative rules for why photosynthetic pigments absorb particular wavelengths of light, and to quantify what is the long wavelength limit for oxygenic and also anoxygenic photosynthesis. This work will allow us to predict the plausible spectral properties and detectable properties of photosynthesis on other planets, especially those orbiting M stars, where longer wavelengths of light dominate the planetary surface radiation.

  ROADMAP OBJECTIVES: 5.1 6.1 6.2 7.2

• 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

• Chemistry and Biology of Ultramafic-Hosted Alkaline Springs

  Ultramafic rock makes up Earth’s mantle and is an abundant material in the inner solar system. When water is added it converts to serpentinite, producing in the process H₂ and, when CO₂ is present, methane, both of which are ideal fuels for microbial activity. We are studying serpentinite mud volcanoes in the Mariana forearc, where water ascends from the subducting Pacific plate into the overlying mantle, producing large volumes of serpentinite that exhibits unusual fluid chemistry (e.g., pH 12.6) and extremophilic microbial activity, as an analog to extraterrestrial environments such as on Mars and the asteroids.

  ROADMAP OBJECTIVES: 5.3 7.2

• 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

• Stability of Methane Hydrates in the Presence of High Salinity Brines on Mars

  Laboratory experiments were used to monitor the influence of increasing salinity on the stability of ices composed of water, methane, and carbon dioxide. New data show that these types of hydrates decease in stability as salinity increases, suggesting that lateral or vertical migration of brines in the subsurface of Mars could cause release of methane and carbon dioxide to surface sediments and the atmosphere. These experimental results are important for interpreting reports of methane in the Martian atmosphere.

  ROADMAP OBJECTIVES: 2.1 2.2 3.1 7.1 7.2

• Untitled

  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

• 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

• 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