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Project Reports

• Habitability of Icy Worlds

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

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

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

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

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 3.4 7.1 7.2

• Ecology of Extreme Environments: Characterization of Energy Flow, Bioenergetics, and Biodiversity in Early Earth Analog Ecosystems

  The distribution of organisms and their metabolic functions on Earth is rooted, at least in part, to the numerous adaptive radiations that have resulted in the ability to occupy new ecological niches through evolutionary time. Such responses are recorded in extant organismal geographic distribution patterns (e.g., habitat range), as well as in the genetic record of organisms. The extreme variation in the geochemical composition of present day hydrothermal environments is likely to encompass many of those that were present on early Earth, when key metabolic processes are thought to have evolved. Environments such Yellowstone National Park (YNP), Wyoming harbor >12,000 geothermal features that vary widely in temperature and geochemical composition. Such environments provide a field laboratory for examining the tendency for guilds of organisms to inhabit particular ecological niches and to define the range of geochemical conditions tolerated by that functional guild (i.e., habitat range or zone of habitability). In this aim, we are examining the distribution and diversity of genes that encode for target metalloproteins in YNP environments that harbor geochemical properties that are thought to be similar to those that characterize early Earth. Using a number of newly developed computational approaches, we have been able to deduce the primary environmental parameters that constrain the distribution of a number of functional processes and which underpin their diversity. Such information is central to constraining the parameter space of environment types that are likely to have facilitated the emergence of these metal-based biocatalysts.

  ROADMAP OBJECTIVES: 3.2 3.3 3.4 4.1 4.2 5.1 5.2 5.3

• 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

• Radical SAM Chemistry and Biological Ligand Accelerated Catalysis

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

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 7.1 7.2

• Surface Chemistry of Iron-Sulfur Minerals

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

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 7.1 7.2

• Ice Chemistry of the Solar System

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

  ROADMAP OBJECTIVES: 1.1 2.2 3.1 3.2 3.3 4.1 7.1 7.2

• Measuring Interdisciplinarity Within Astrobiology Research

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

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