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Project Reports

• 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 for geological time. Researchers have recognized a variety of mineralogical and geochemical characteristics in ancient rocks (sedimentary and igneous rocks; paleosols) that may be used as indicators of: (i) specific types of organisms that lived in the oceans, lakes and on land; and (ii) their environmental conditions (e.g., climate; atmospheric and oceanic chemistry). Our project addresses the following questions: Are some or all of these characteristics true or false signatures of organisms and/or indicators of specific environmental conditions? Do a “biosignature” in a specific geologic formation represent a local or global phenomenon? How are the biosignatures on Mars and other planets expected to be similar to (or different from) those in ancient terrestrial rocks?

  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

• Astrobiology of Icy Worlds

  Icy worlds such as Titan, Europa, Enceladus, and others may harbor the greatest volume of habitable space in the Solar System. For at least five of these worlds, considerable evidence exists to support the conclusion that oceans or seas may lie beneath the icy surfaces. The total liquid water reservoir within these worlds may be some 30 to 40 times the volume of liquid water on Earth. This vast quantity of liquid water raises two questions: Can life emerge and thrive in such cold, lightless oceans beneath many kilometers of ice? And if so, do the icy shells hold clues to life in the subsurface? We will address these questions through four major investigations namely, the habitability, survivability, and detectability of life of icy worlds coupled with “Path to Flight” Technology demonstration. We will also use a wealth of existing age-appropriate educational resources to convey concepts of astrobiology, spectroscopy, and remote sensing; develop standards-based, hands-on activities to extend the application of these resources to the search for life on icy worlds.

  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

• Alternative Formation Mechanisms for Banded Iron Formations

  Based on field observations during the 2008 BIF filed trip and laboratory investigation, we have proposed a new generation mechanism for the banded iron formations, very important rocks that recorded early earth conditions and environment. Our new model shows how BIFs could have formed when hydrothermal fluids from the interaction between seawater and komatiite (Al-depleted rock) that comes from hot and deep Earth’s mantle, mixed with surface seawater. This mixing triggered the dynamics of oscillation between iron- and silica-rich minerals, which were deposited in layers on the seafloor.

  ROADMAP OBJECTIVES: 4.1

• AbGradCon 2009

  The Astrobiology Graduate Student Conference (AbGradCon) was held on the UW campus July 17 – 20 2009. AbGradCon supports NAI’s mission to carry out, support and catalyze collaborative, interdisciplinary research, train the next generation of astrobiology researchers, provide scientific and technical leadership on astrobiology investigations for current and future space missions, and explore new approaches using modern information technology to conduct interdisciplinary and collaborative research amongst widely-distributed investigators. This was done through a diverse range of activities, ranging from formal talks and poster sessions to free time for collaboration-enabling discussions, social activities, web 2.0 conference extensions, public outreach and grant writing simulations.

  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

• AIRFrame Technical Infrastructure and Visualization Software Evaluation

  To create visualizations of interdisciplinary relationships in the field of astrobiology, this component of the AIRFrame project involves creating a data model for source documents, a database structure, and evaluating off-the-shelf visualization software for possible application to the final project.

  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

• Amino Acid Alphabet Evolution

  All life on earth uses a standard “alphabet” of just 20 amino acids. Members of this alphabet links together into different sequences to form proteins that then interact to produce living metabolism (rather like the English of 26 letters can be linked into words that interact in sentences and paragraphs to produce meaningful writing). However, a wealth of scientific research from diverse disciplines points to the idea that many other amino acids are made by non-biological processes throughout the universe: put simply, we have no idea why life has “chosen” the members of its standard alphabet. Our project seeks to gather and organize the disparate information that describes these non-biological amino acids, to understand their properties and potential for making proteins and thus to understand better whether the biology that we know is a clever, predictable solution to making biology – or just one of countless possible solutions that may exist elsewhere.

  ROADMAP OBJECTIVES: 1.1 3.1 3.2 3.4 4.1 4.3 5.1 5.3 6.2 7.1 7.2

• Biosignatures in Extraterrestrial Settings

  This project looks at the evolution of the composition of gases in the cold disk from which planets form; the evolution of the atmosphere after planet formation, in particular, the role of trace gases in the early greenhouse effect; and, some aspects of the the formation and later dynamical evolution of extrasolar planets.

  ROADMAP OBJECTIVES: 1.1 1.2 2.1 4.1

• Advancing Methods for the Analyses of Organics Molecules in Microbial Ecosystems

  Eigenbrode’s GCA work over the past year has largely focused on advancing protocols for the extraction and analysis of complex organics molecules in iron-oxide rich samples regarded as analogs to groundwater seeps and ancient surface water environments on Mars and ancient Earth. Eigenbrode has succeeded with some advance in methods for organic extraction and analysis for samples that include iron seep sediments, cultured iron bacteria, and terrace sediments of the Rio Tinto. In addition, Eigenbrode has been part of a successful study aimed at understanding microbial metabolisms and ecological evolution of Neoarchean using Fe, S, and C isotopic records.

  ROADMAP OBJECTIVES: 2.1 4.1 5.1 5.2 5.3 6.1 7.1

• Environmental Oxygen and the Rise of Metazoans

  We seek to understand when and how levels of oxygen rose in the environment,
  and how this rise may have impacted the evolution of complex life.

  ROADMAP OBJECTIVES: 4.1 4.2

• Chemolithotrophic Microbial Oxidation of Insoluble Fe(II)-Bearing Minerals

  Ferrous iron (Fe(II)) can serve as an energy source for a wide variety of chemolithotrophic microorganisms (organisms that gain energy from metabolism of inorganic compounds). Thought to be one of the oldest forms of microbial metabolism on Earth, Fe(II) oxidation may also have played a role in past (and possibly, present) life on Mars, whose crust is rich in Fe(II)-bearing silicate minerals (e.g. ultramafic basalt rocks). The initial goal of this project is to determine whether an established chemolithoautotrophic Fe(II)-oxidizing, nitrate-reducing culture can grow by oxidation of Fe(II) in basalt glass. Preliminary experiments suggest that the culture is able to oxidize a significant portion of the Fe(II) content of fresh basalt glass from Kilauea, a shield volcano in Hawaii that represents an analog for ancient volcanic activity on Mars.

  ROADMAP OBJECTIVES: 4.1 6.1 7.1

• Delivery of Volatiles to Terrestrial Planets

  Terrestrial planets are too small to trap gas from the circumstellar disk in which they formed and so must be built from solid materials (rock and ices). In this task, we explore how and when Earth, Mars and other potentially-habitable worlds accumulated water and organic carbon. The main challenge is that water and organic carbon are relatively volatile elements (compared to rock and metal). Therefore, during the period of time in which solids condensed at the current position of Earth, water and carbon would have been mainly in the gas phase. Getting these materials to earth required that inward transportation of material from further out in the disk.

  ROADMAP OBJECTIVES: 1.1 3.1 4.1 4.3

• Co-Evolution of Microbial Metabolisms in the Neoarchean and Paleoproterozoic

  The interplay between the biosphere, lithosphere, hydrosphere, and atmosphere has produced a complex evolution of microbial metabolisms that significantly affect the geochemical and mineralogical compositions of surface environments. One approach to tracing the evolution of very ancient microbial metabolisms is through studies of the isotopic compositions of elements that are cycled by life and preserved in the rock record. The Neoarchean and Paleoproterozoic (~3.1 to 2.4 billion years ago) record very large changes in C, S, and Fe isotope compositions in marine sedimentary rocks that are interpreted to reflect an explosion in microbial diversity, including establishment of oxygenic and anaerobic photosynthesis, aerobic methanotrophy, methanogenesis, and dissimilatory sulfate and iron reduction. The ecosystems on Earth in the Neoarchean and Paleoproterozoic juxtaposed oxidized and reduced environments, reflecting unique conditions during the time leading up to the first significant increase in atmospheric oxygen at ~2.4 b.y. ago.

  ROADMAP OBJECTIVES: 4.1 5.1 6.1 7.1

• Biosignatures in Relevant Microbial Ecosystems

  In this project, PSARC team members explore the isotope ratios, gene sequences, minerals, organic biomarkers, and other biosignatures in modern ecosystems that function as analogs for early earth ecosystems, or for 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

• Ecosphere to Biosphere Modeling – Final CAN-3 Report

  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 6.1

• Evolution and Development of Sensory and Nervous Systems in the Basal Branches of the Animal Tree

  Sensory and Nervous systems are intimately related to the complexity, motility and environmental responsiveness that characterize animal life. We examine the early evolution of animal sensory and nervous systems through investigation of neural markers, as well as developmental gene expression and function in basal branching animals, including jellyfish, polychaete worms, and sponges.

  ROADMAP OBJECTIVES: 4.1 4.2

• Project 3: The Origin, Evolution, and Volatile Inventories of Terrestrial Planets

  The origin and Sustenance of life on Earth strongly depends on the fact that volatile elements H-C-O-N where retained in sufficient abundance to sustain an ocean-atmosphere. The research in this project involves studies of how terrestrial planets form, why differences exist among the terrestrial planets, how volatiles behave deep within the Earth, and how volatiles and life influence the large and small scale composition of the near surface Earth.

  ROADMAP OBJECTIVES: 1.1 3.1 4.1

• Bioastronomy 2007 Meeting Proceedings

  The 9th International Bioastronomy coneference: Molecules, Microbes and Extraterrestrial Life was organized by Commission 51 (Bioastronomy) of the International Astronomical Union, and by the UH NASA Astrobiology team. The meeting was held in San Juan, Puerto Rico from 16-20 July 2007. During the reporting period the Proceedings were finalized and will have a publication date of 2009.

  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 Biosignatures

  This goal of this project is to study our ability to remotely detect life on planets. Primarily, this applies to extrasolar planets – those that exist outside our solar system. The way we will search for life on these planets is by attempting to detect gases produced by life. For example, we could detect the life on modern-day Earth if we detected gases the presence of molecular oxygen (O2, the gas we breathe that is produced by plants and bacteria) and methane (CH4, which is produced by bacteria). These two gases can co-exist only with production rates so high that they are unsustainable without the presence of life on the planet.

  ROADMAP OBJECTIVES: 1.1 1.2 4.1 6.2

• Developing New Biosignatures

  The development and experimental testing of potential indicators of life is essential for providing a critical scientific basis for the exploration of life in the cosmos. In microbial cultures, potential new biosignatures can be found among isotopic ratios, elemental compositions, and chemical changes to the growth media. Additionally, life can be detected and investigated in natural systems by directing cutting-edge instrumentation towards the investigation of microbial cells, microbial fossils, and microbial geochemical products. Over the next five years, we will combine our geomicrobiological expertise and on-going field-based environmental investigations with a new generation of instruments capable of revealing diagnostic biosignatures. Our efforts will focus on creating innovative approaches for the analyses of cells and other organic material, finding ways in which metal abundances and isotope systems reflect life, and developing creative approaches for using environmental DNA to study present and past life.

  ROADMAP OBJECTIVES: 2.1 2.2 3.1 3.4 4.1 5.2 5.3 7.1 7.2

• CASS Planning

  The computational astrobiology summer school (CASS) is a two week program, followed by a semester of mentored independent work, which has the following goals:

  - To introduce computer science and engineering (CS&E) graduate students to the field of astrobiology, – To introduce astrobiologists to the tools and techniques that current methods in CS&E can provide, and – To encourage interdisciplinary projects that will result in advances in astrobiology.

  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

• Metabolic Networks From Single Cells to Ecosystems

  Metabolic networks perform some of the most fundamental functions in living cells, including energy transduction and building block biosynthesis. While these are the best characterized networks in living systems, understanding their evolutionary history and complex wiring is still a major open question in biology. Here we use mathematical models and computer simulations to understand how metabolic networks gradually evolved the degree of organization necessary to sustain complex multicellular life. In particular, we ask (i) how metabolism changed as the level of oxygen gradually rose in the atmosphere, (ii) what metabolic structures are associated with cell-cell communication, and (iii) whether general optimality principles can help understand the architecture of biochemical networks.

  ROADMAP OBJECTIVES: 4.1 4.2 5.2 6.1

• Project 5: Geological-Biological Interactions

  This project focuses on a wide range of questions spanning understanding microbial diversity in extreme environments to the identification of biosignatures in modern and ancient rocks. In terms of environments, research in this project focuses on research at deep sea hydrothermal vents, desert sulfate deposits, arctic hydrothermal fields, as well as Paleoproterozoic terrains of Australia, Canada, and India. By learning more how life adapts to extreme environments on Earth, we hope to gain a better understanding of the limits of life on other worlds. By understanding better the signature of life recorded in ancient rocks, we hope to better refine our search stategies for the presence of life on other worlds.

  ROADMAP OBJECTIVES: 4.1 5.1 6.1 6.2 7.1

• Project 6: The Environment of the Early Earth

  Our project entitled “Environment of the Early Earth” involves the development of capabilities that will allow scientists to obtain information about the conditions on early Earth (3.0 to 4.5 billion years ago) by performing chemical analyses of crystals (minerals) that have survived since that time. When they grow, minerals incorporate trace concentrations of ions and gaseous molecules from the local environment. We are conducting experiments to calibrate the uptake of these “impurities” that we hope will serve as indicators of temperature, moisture, oxidation state and atmosphere composition. To date, our focus has been mainly on zircon (ZrSiO₄), but we have recently turned our attention to quartz as well.

  ROADMAP OBJECTIVES: 1.1 4.1 4.3

• Modelling Planetary Albedo

  What kind of environments could provide opportunities for life in general and for the advent of complex life specifically to emerge? If there were complex life present, what features would it produce? Could we remotely characterize such habitats and the features of complex life on extrasolar planets light-years away with current and future NASA missions?
  These are the three main questions we work on in this part of the project.

  ROADMAP OBJECTIVES: 1.1 1.2 4.1 4.2 6.2 7.2

• Iron Isotope Biosignatures: Laboratory Studies and Modern Environments

  The isotopic fingerprints of biological carbon and sulfur cycling in modern and ancient marine environments is well established by research over several decades, but, until recently, potential iron isotope fingerprints of microbial iron cycling in the ancient Earth have not been pursued. Next to carbon, iron was probably the most important element cycled by early life, given the high abundance of iron in early Earth environments and the energy gains that may be obtained by microbes during iron redox changes. Our new laboratory studies moved away from simple systems to those more analogous to nature, and we demonstrated that iron isotope fractionations can be produced by biological cycling in complex systems. Moreover, in a field study, we isolated natural iron cycling microbes and demonstrated that the iron isotope fractionations produced by natural microbial ecosystems are the same as those produced by pure strains in the laboratory; these are key components to confidently applying Fe isotopes as a biosignature for ancient life.

  ROADMAP OBJECTIVES: 2.1 4.1 5.2 6.1 7.1 7.2

• Planetary Surface and Interior Models and SuperEarths

  In this project, we model the processes that continually reshape the interiors and the surfaces of terrestrial (rocky) planets. The models we develop and use give us insight into how these processes (e.g. weathering, volcanism, and plate tectonics) affect a planet’s habitability as the planet evolves. In addition to Earth- and Mars-like planets, we now seek to model two sorts of planets not observed in our Solar System: 1) “super-Earths” (rocky planets up to 10 times as massive as Earth) and 2) planets so close to their star that the tides actually heat the interior of the planet.

  ROADMAP OBJECTIVES: 1.1 1.2 4.1 5.2 6.1

• New Frontiers in Micro-Analysis of Isotopic Compositions of Natural Materials: Development of Fe Isotopes

  We are developing micro-analytical techniques to perform in situ Fe isotope analysis of Fe-bearing minerals by ion microprobe and laser ablation mass spectrometry. Iron isotope compositions are important signatures in tracking redox processes, chemical weathering, and dissimilatory iron reduction by bacteria. In situ micro analysis procedures will allow us to better apply the Fe isotope system by allowing one to determine Fe isotope compositions within a petrographic framework, minimize sample requirements, evaluate microscale heterogeneity, and inter-mineral isotopic equilibrium. Such in situ procedures are critical for analysis of samples that may be returned from future space missions or for analysis by instruments that can be deployed on space craft.

  ROADMAP OBJECTIVES: 2.1 4.1 7.1 7.2

• Postdoctoral Fellow Report: Mark Claire

  I am interested in how biological gases affect the atmosphere of Earth (and possibly other planets.) Specifically, I use computer models to investigate how biogenic sulfur gases might build up in a planetary atmosphere, and if this would lead to observable traces in Earth’s rock record or in the atmospheres of planets around other stars. I’m also working on how anaerobic oxidizers of methane affected the rise of oxygen on Earth, and if evolutionary changes in nitrogen-using bacteria may have changed global N2 levels and planetary climate.

  ROADMAP OBJECTIVES: 1.1 1.2 4.1 7.2

• Timscales of Events in the Evolution and Maintenance of Complex Life

  This project involves high precision dating of major events in earth history. Using the decay of uranium (U) to lead (Pb) in the mineral zircon we are able to date 600 million year old rocks to ± less than 1 millon years. Such precision allows us to investigate rates of change in the ancient past from climate to evolution.

  ROADMAP OBJECTIVES: 4.1 6.1

• New Frontiers in Micro-Analysis of Isotopic Compositions of Natural Materials: Development of O, S, 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. Values of δ7Li and δ18O in zircons allow these tests to be applied to magmas that may have assimilated sedimentary materials, and in the case of pre-4 Ga Jack Hills zircons from SW Australia, provide a record of the earliest Earth before the formation of all known rocks.

  ROADMAP OBJECTIVES: 4.1 7.1

• Production of Mixed Cation Carbonates in Abiologic and Biologic Systems

  Carbonate minerals commonly occur on Earth and they are found in extraterrestrial materials such as meteorites and interplanetary dust particles. The chemistry of carbonates provides clues about their formation and alteration of over time. For example, carbonate minerals that form inorganically have chemical compositions that are highly constrained by the environmental conditions under which they grow, however, it is now known that microorganisms can produce carbonates that deviate from these generally accepted patterns. As such, when carbonate minerals are placed in the appropriate environmental context, certain compositions may represent a biosignature for microbially mediated formation. The goal of this project is to develop a broader understanding of how carbonate minerals grow so that we may formulate explicit criteria for their origin based on their chemical and isotopic composition.

  ROADMAP OBJECTIVES: 4.1 7.1

• Stellar Effects on Planetary Habitability

  Habitable environments are most likely to exist in close proximity to a star, and hence a detailed and comprehensive understanding of the effect of the star on planetary habitability is crucial in the pursuit of an inhabited world. We model how stars with different masses, temperatures and flare activity affect the habitability of planets. We also address the effect that tides between a star and a planet have on planetary habitability, including the power to turn potentially habitable planets like Earth into extremely volcanically active bodies like Io.

  ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 4.1 4.3 5.3 6.1 7.2

• Origin and Evolution of Organics in the Planetary Systems

  This progress report summarizes astrobiology research done during the past 12 months (July 2008 – June 2009) at Washington University in St. Louis under the direction of Professor Bruce Fegley, Jr. This research is part of the NASA Goddard Center for Astrobiology (GCA) Team.
  During the past year we (Professor Fegley and Ms. Laura Schaefer) worked on two related topics. These topics are (1) chemistry during metamorphism on chondrite parent bodies, (2) chemistry during accretion of the Earth and Earth-like planets. We published (or have in press) two refereed papers, two invited book chapters, and four abstracts. A third paper has been submitted to Icarus. A fourth paper, with French astronomers who discovered Corot 7-b is in preparation and will be submitted shortly. All ten publications are listed on the attached list.

  ROADMAP OBJECTIVES: 1.2 4.1

• Stromatolites in the Desert: Analogs to Other Worlds

  Cuatro Cienegas Basin, a desert oasis in the Chihuahua desert of central Mexico, provides a proxy for an earlier time in Earth’s history when microbes dominated the scenery. The basin hosts active, growing stomatolites, communities of microbes that are covered in carbonates, principally through the action of metabolic processes within the community. Researchers from several NAI teams are actively researching and creating experimental procedures to understand small scale and large scale evolution within these communities, using tools from biology, geology, and astronomy.

  ROADMAP OBJECTIVES: 4.1 4.2 5.2 5.3 6.1 6.2

• Developing New Sampling System, Collection of Juan De Fuca Ridge Basement Fluids

  Our Deep Biosphere project is designed to exploit the unprecedented opportunities provided by the new generation of long-term borehole- observatories installed on the flanks of the Juan de Fuca Ridge (JdFR) by the Integrated Ocean Drilling Program, to study the microbial geochemistry and ecology of the sediment-buried ocean basement. The Drill ship drills deep holes through the sediments into the underlying basaltic rocks and then installs a 'CORK’ observatory consisting of casings, fluid delivery lines with seafloor access-spigots, downhole instruments, and a top plug.

  ROADMAP OBJECTIVES: 3.2 3.3 4.1 5.2 5.3

• The Role of Dissolved Sulfide in Controlling Carbonate Mineral Compositions

  Role of microbes in dolomite formation is still under debate. It was proposed that sulfate-reducing bacteria (SRB) can results in dolomite precipitation. We investigated the role of dissolved sulfide (a product of SRB metabolism) in controlling carbonate mineral compositions and even dolomite crystallization at low temperatures. Our results show that very high-magnesium calcite (VHMC) and disordered dolomite can precipitate from aqueous sulfide-bearing solutions at low temperature.

  ROADMAP OBJECTIVES: 4.1 7.1 7.2

• Understanding Past Earth Environments

  This project examines the evolution of the Earth over time. This year we examined and expanded the geological record of Earth’s history, and ran models to help interpret those data. Models were also used to simulate what the early Earth would look like if viewed remotely through a telescope similar to NASA’s Terrestrial Planet Finder mission concept. We focused our efforts on the Earth as it existed in prior to and during the rise of atmospheric oxygen 2.4 billion years ago, as this was one of the most dramatic and important events in the evolution of the Earth and its inhabitants.

  ROADMAP OBJECTIVES: 1.1 1.2 2.1 4.1 4.2 4.3 5.1 5.2 5.3 6.1

• Stoichiometry of Life, Task 3a: Ancient Records – Geologic

  The primary goal of this effort is to understand the evolving redox state of the atmosphere and ocean at critical intervals in Earth history, its effect on the availability of bioessential elements, and the consequences for evolution. In support of this goal, a major effort is underway to analyze, at high resolution, ~2.5- to 1.5-billion-year-old drill core samples so that we can better understand the distribution and evolution of early eukaryotic organisms at a variety of spatial and temporal scales. Additional efforts focus on characterizing life and environment leading in to the Cambrian explosion of metazoan life.

  ROADMAP OBJECTIVES: 4.1 4.2

• Stoichiometry of Life, Task 4: Biogeochemical Impacts on Planetary Atmospheres

  The abundance of molecular oxygen in planetary atmospheres may be a useful way to look for evidence of life. The amount of photosynthetically produced oxygen that accumulates in an atmosphere depends in part on the export of photosynthetically produced organic carbon from the ocean surface to the seafloor, which in turn may depend on the availability of bioessential elements. We are using a computer model to determine how this carbon export processes might operate in an ocean dominated by prokaryotes rather than eukaryotes, as may have been common in Earth’s past and as an analog for hypothetical extrasolar planets.

  ROADMAP OBJECTIVES: 4.1 4.2 5.2 6.1 7.2

• Mechanisms of Marine Microbial Community Structuring

  The sub-tropical open ocean is an extreme environment that presents the opportunity to examine the factors affecting microbial community structure across a number of environmental gradients. We have developed and utilized a novel assay that allows us to simultaneously determine the taxonomic composition of Archaea, Bacteria and microbial Eucarya in DNA extracted from environmental samples. Samples analyzed represent the epi-, meso- and bathy-pelagic zones of the ocean, which display gradients in temperature, pressure, oxygen content, nutrient content and photosynthetically available radiation.

  ROADMAP OBJECTIVES: 4.1

• Quantification of the Disciplinary Roots of Astrobiology

  The questions of astrobiology span many scientific fields. This project analyzes databases of scientific literature to determine and quantify the diverse disciplinary roots of astrobiology. This is one component of a wider study to build a map of relationships between the constituent fields of astrobiology, so relevant knowledge in diverse fields can be most efficiently inform the study of life in the universe.

  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

• Rare Subduction Zone Carbonate Mineral May Hold Clues to Early Life

  Recent work performed by Erik Melchiorre as part of a NASA Minority
  Institution Research Sabbatical indicates that the rare purple mineral
  stichtite Mg6Cr2[(OH)16|CO3] . 4H2O may provide a record of
  the carbon, hydrogen and ocygen isotope values of serpentizing fluids
  from ancient subduction zones. This could be of significant interest
  in the study of methane signatures on Mars, as well as the study of
  early life on Earth.

  ROADMAP OBJECTIVES: 4.1 4.3 7.1 7.2