2011 Annual Science Report

Astrobiology Roadmap Objective 3.2 Reports Reporting  |  SEP 2010 – AUG 2011

Project Reports

  • AIRFrame Technical Infrastructure and Visualization Software Evaluation

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

    ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 3.1 3.2 3.3 3.4 4.1 4.2 4.3 5.1 5.2 5.3 6.1 6.2 7.1 7.2
  • An Atomic Level Description of the Specific Interactions Between Nascent Peptide and Ribosome Exit Tunnel

    The ribosome exit tunnel is an ancient path that must be traveled by all peptides/proteins synthesized by the ribosome. We have synthesized peptolides and demonstrated their potential as probes to decipher the interaction between the nascent peptide and the exit tunnel. This study is yielding vital information about attributes that confer nucleic acids with selective advantage as building blocks for exit tunnel construction.

    ROADMAP OBJECTIVES: 3.2
  • Cosmic Distribution of Chemical Complexity

    The central theme of this project is to explore the possible connections between chemistry in space and the origins of life. We start by tracking the formation and development of chemical complexity in space from simple molecules such as formaldehyde to complex species including amino and nucleic acids. The work focuses on molecular species that are interesting from a biogenic perspective and on understanding their possible roles in the origin of life on habitable worlds. We do this by measuring the spectra and chemistry of analog materials in the laboratory, by remote sensing in small spacecraft and by analysis of extraterrestrial samples returned by spacecraft or that fall to Earth as meteorites. We then use these results to interpret astronomical observations made with ground-based and orbiting telescopes.

    ROADMAP OBJECTIVES: 1.1 2.1 2.2 3.1 3.2 3.4 4.3 7.1 7.2
  • Task 1.1.1 Models of the Internal Dynamics: Formation of Liquids in the Subsurface and Relationships With Cryovolcanism

    The internal and external geologic evolution of Titan was investigated so as to constrain the environment in which organic evolution has proceeded over time.

    ROADMAP OBJECTIVES: 1.1 2.2 3.1 3.2 3.3
  • BioInspired Mimetic Cluster Synthesis: Bridging the Structure and Reactivity of Biotic and Abiotic Iron-Sulfur Motifs

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

    ROADMAP OBJECTIVES: 3.1 3.2 3.3 3.4 7.1 7.2
  • Task 1.1.2 Models of the Reaction Between Hydrocarbons and Water Ice

    Reactions between hydrocarbons and water ice was modeled to assess the possible extent of prebiotic compound formation in this context. Various environments where organics and liquids could be in contact were considered.

    ROADMAP OBJECTIVES: 1.1 2.2 3.1 3.2 3.3
  • Project 2: Processing of Precometary Ices in the Early Solar System

    The discovery of numerous planetary systems still in the process of formation gives us a unique opportunity to glimpse how our own solar system may have formed 4.6 billion years ago. Our goal is to test the hypothesis that the building blocks of life were synthesized in space and delivered to the early Earth by comets and asteroids. We use computers to simulate shock waves and other processes that energize the gas and dust in proto-planetary disks and drive physical and chemical processes that would not otherwise occur. Our work seeks specifically to determine (i) whether asteroids and comets were heated to temperatures that favor prebiotic chemistry; and (ii) whether the requisite heating mechanisms operate in other planetary systems forming today.

    ROADMAP OBJECTIVES: 1.1 3.1 3.2
  • A Phylogenomic Approach to the Ur-Ribosome

    A macromolecular complex emulating ancient ribosomal function would sharpen understanding of the peptide bond’s emergence in a biological context. Reconstructing evolutionary adaptive paths (1) offers a straightforward approach to building an ancient ribosome, in principle: the sequences of the ribosomal proteins and ribosomal RNA are aligned, and subjected to likelihood-based phylogenetic reconstruction, followed by over-expression and purification of the ancestral components. In practice, sequence retrieval is complicated by inconsistent annotation, gene absence, and database redundancy. One accomplishment of the past year was development and implementation of a novel algorithm for large-scale protein sequence retrieval and family discernment.

    ROADMAP OBJECTIVES: 3.2
  • Habitability of Icy Worlds

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

    ROADMAP OBJECTIVES: 1.1 2.1 2.2 3.1 3.2 3.3 3.4 4.1 5.1 5.3 6.1 6.2 7.1 7.2
  • 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
  • Amino Acid Alphabet Evolution

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

    ROADMAP OBJECTIVES: 3.1 3.2 4.1 4.2 4.3 5.2 5.3 6.2 7.1
  • Minerals to Enzymes: The Path to CO Dehydrogenase/Acetyl – CoA Synthase

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

    ROADMAP OBJECTIVES: 3.1 3.2 3.3 3.4 7.1 7.2
  • Biosignatures in Ancient Rocks

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

    ROADMAP OBJECTIVES: 1.1 3.2 4.1 4.2 4.3 5.1 5.2 5.3 6.1 6.2 7.1 7.2
  • Path to Flight

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

    ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 3.1 3.2 7.1 7.2
  • Survivability of Icy Worlds

    Investigation 2 focuses on survivability. As part of our Survivability investigation, we examine the similarities and differences between the abiotic chemistry of planetary ices irradiated with ultraviolet photons (UV), electrons, and ions, and the chemistry of biomolecules exposed to similar conditions. Can the chemical products resulting from these two scenarios be distinguished? Can viable microbes persist after exposure to such conditions? These are motivating questions for our investigation.

    ROADMAP OBJECTIVES: 2.2 3.2 5.1 5.3 7.1 7.2
  • Origins of Functional Proteins and the Early Evolution of Metabolism

    The main goal of this project is to identify critical requirements for the emergence of biological complexity in early habitable environments by examining key steps in the origins and early evolution of functional proteins and metabolic reaction networks. In particular, we investigate whether protein functionality can arise from an inventory of polymers with amino acid sequences that might have naturally existed in habitable environments. We attempt the first demonstration of multiple origins of a single enzymatic function, and investigate experimentally how primordial proteins could evolve through the diversification of their structure and function. Building on this work and on our knowledge of ubiquitous proto-cellular functions and constraints of prebiotic chemistry, we conduct computer simulations aimed at elucidating fundamental principles that govern coupled evolution of early metabolic reactions and their catalysts, and transport across cell walls.

    ROADMAP OBJECTIVES: 3.2 3.4
  • Project 4: Geochemical Steps Leading to the Origins of Life

    This project involves research designed to aid understanding the geochemical roots of life focusing in particular on the role of mineral surfaces play in catalyzing organic reactions that may have biochemical utility.

    ROADMAP OBJECTIVES: 3.1 3.2
  • Molecular Evolution: A Top Down Approach to Examine the Origin of Key Biochemical Processes

    The emergence of metalloenzymes capable of activating substrates such as CO, N2, and H2, were significant advancements in biochemical reactivity and in the evolution of complex life. Examples of such enzymes include [FeFe]- and [NiFe]-hydrogenase that function in H2 metabolism, Mo-, V-, and Fe-nitrogenases that function in N2 reduction, and CO dehydrogenases that function in the oxidation of CO. Many of these metalloenzymes have closely related paralogs that catalyze distinctly different chemistries, an example being nitrogenase and its closely related paralog protochlorophyllide reductase that functions in the biosynthesis of bacteriochlorophyll (photosynthesis). While the amino acid composition of these closely related paralogs are often quite similar, their biochemical reactivity and substrate specificity are often very different. This phenomenon is a direct consequence of the composition and molecular structure of the active site metallocluster, which requires a number of accessory proteins to synthesize. By specifically focusing on the origin and subsequent evolution of these metallocluster biosynthesis proteins in relation to paralogous proteins that have left clear evidence in the geological record (photosynthesis and the rise of O2), we have been able to obtain significant insight into the origin and evolution of these functional processes, and to place these events in evolutionary time.

    The genomes of extant organisms provide detailed histories of key events in the evolution of complex biological processes such as CO, N2, and H2 metabolism. Advances in sequencing technology continue to increase the pace by which unique (meta)genomic data is being generated. This now makes it possible to seamlessly integrate genomic information into an evolutionary context and evaluate key events in the evolution of biological processes (e.g., gene duplications, fusions, and recruitments) within an Earth history framework. Here we describe progress in using such approaches in examining the evolution of CO, N2, and H2 metabolism.

    ROADMAP OBJECTIVES: 3.2 4.1 5.1
  • Project 2A: Estimation of Pre-Biotic Amino Acids Delivery to Earth by Carbonaceous Chondrite Meteorites

    The role of mineral surfaces in extraterrestrial organic synthesis, pre-biotic chemistry, and the early evolution of life remains an open question. Mineral surfaces could promote synthesis, preservation, or degradation of chiral excesses of organic small molecules, polymers, and cells. Different minerals, crystal faces of a mineral, or defects on a face may selectively interact with specific organics, providing an enormous range of chemical possibilities. We focus here on amino-acid isomer adsorption, conformation, and racemization on minerals representing primitive and altered peridotite found in chondritesand on planetary bodies. The study is inspired by the discovery of an excess of L-isovaline, a non-biologic amino acid, in a few carbonaceous meteorites by (Glavin and Dworkin, 2009), which suggests that the chiral nature of biology may have been due to excess L-amino acids delivered pre-biotically by meteorites.

    In the present year of funding, we expanded our study to determine the conformation and binding modes of the acidic amino-acids, glutamate (Glu) and aspartate (Asp), adsorbed on model oxide, γ-Al2O3, using Attenuated Total Reflectance-Fourier Transform Infra-Red Spectroscocpy (ATR-FTIR) and the Triple Layer surface complexation model fits to bulk adsorption data over a wide range of pHs and amino-acid concentrations.

    We also examined adsorption of L- and D- Glu, Asp, and a non-biological; amino acid, iso-valine on peridotite and serpentinte as pristine and altered analogs of carbonaceous chondrites, using LC-FD/ToF-MS. Preliminary results do not indicate preferential adsorption of either L- or D-amino-acids on peridotite and serpentinite, within detection limits. More detailed studies are required to improve the sensitivity and accuracy of the experiments involving the chiral amino-acids adsorption on chondritic analog materials.

    The project addresses NASA Astrobiology Institute’s (NAI) Roadmap Goal 3 of understanding how life emerges from cosmic and planetary precursors , and Goal 4 of understanding organic and biosignature preservation mechanisms. The work is relevant to NASA’s Strategic Goal of advancing scientific knowledge on the origin and evolution life on Earth and potentially elsewhere, and of planning future Missions by helping to identify promising targets for the discovery of organics.

    ROADMAP OBJECTIVES: 3.1 3.2 4.1
  • Geochemical Signatures of Multicellular Life

    We continued our studies of the sterol complements of basal metazoa and their closest unicellular relatives and discerned what appears to be an evolutionary trend toward the universal use of cholesterol by higher animals. Inverse carbon isotope patterns of lipids and kerogen, that are a distinctive characteristic of organic matter found in Neoproterozoic sediments, record heterogeneous primary biomass comprising a dominant input from bacteria.

    ROADMAP OBJECTIVES: 3.2 4.2
  • 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
  • Cosmochemical Search for the Origin of Water in Planetary Bodies

    The ultimate goal of our study is to understand the origin of water in planetary bodies (asteroids, comets and terrestrial planets). In particular we want to understand better the water-based chemis-try that happens on these bodies. This gives important insights into the role(s) played by water dur-ing the origin of our Solar System. We are taking a new approach to understanding aqueous altera-tion processes in carbonaceous chondrites by investigating the distribution and composition of or-ganic compounds in aqueously altered chondrites. This research will also shed light on the nature of organic compounds in asteroids and in planetesimals that might have delivered organic compounds to the early Earth. This research will use a variety of micro-analytical techniques (optical microscopes, scanning electron microscope, electron microprobe, transmission electron microscope, ion microprobe, Raman spectroscopy) to investigate the aqueous alteration that has affected the CR chondrites. These meteorites were chosen because they exhibit a complete series of alteration, from very lightly altered to completely altered, and they have experience almost no thermal metamorphism.

    ROADMAP OBJECTIVES: 1.1 2.1 2.2 3.1 3.2
  • Paradigms for Complex Iron-Sulfur Cluster Assembly and the Origin and Evolution of Iron-Sulfur Enzymes

    We have presented seminal results in the past year that define paradigms for iron-sulfur cluster assembly in biology that are shared between several important enzymes systems. This work has allowed for the formulation of new models for the origin and evolution of iron sulfur enzymes. An evolutionary origin that involves a mineral beginning and the stepwise refinement of catalytic function in response to selective pressure.

    ROADMAP OBJECTIVES: 3.1 3.2 3.3
  • Domain III of the 23S rRNA: An Independent Domain

    The three-dimensional structure of the ribosomal large subunit (LSU) reveals a single morphological element, although the 23S rRNA is contained in six secondary structure domains. Based upon maps of inter- and intra-domain interactions and proposed evolutionary pathways of development, we hypothesize that Domain III is a truly independent structural domain that can fold to a near-native state in the absence of the remainder of the LSU. Domain III is primarily stabilized by intra-domain interactions, negligibly perturbed by inter-domain interactions, and is not penetrated by proteins or other rRNA. We have probed the structure of Domain III rRNA alone and when contained within the intact 23S rRNA using SHAPE (selective 2’-hydroxyl acylation analyzed by primer extension), in the absence and presence of magnesium. The combined results support the hypothesis that Domain III alone folds to a near-native state with secondary structure, intra-domain tertiary interactions and inter-domain interactions that are independent of whether or not it is embedded in the intact 23S rRNA or within the LSU. The data presented support previous suggestions that Domain III was added relatively late in ribosomal evolution.

    ROADMAP OBJECTIVES: 3.2 4.2
  • Radical SAM Chemistry and Biological Ligand Accelerated Catalysis

    A number of key reactions in biological systems are catalyzed by iron-sulfur enzymes. Iron-sulfur clusters in biology have a number of features in common with iron-sulfur minerals and their derivatives. We are using iron sulfur motifs as a model system to understand how chemistry in the abiotic mineral world was incorporated into biology on a path to the origin of life. We have found that iron-sulfur motifs in biology are synthesized and modified by reactions and mechanisms that we envision minerals could have been modified on the early prebiotic Earth. The results have had a profound impact on our ability to understand a stepwise trajectory from the nonliving to the living Earth.

    ROADMAP OBJECTIVES: 3.1 3.2 3.3
  • Cosmic Ice Laboratory Progress Report

    Scientists at the Cosmic Ice Laboratory with the Goddard Center for Astrobiology study the formation and stability of molecules under conditions found in outer space. During the past year, studies of amino-acid destruction were continued with a manuscript in preparation. Projects on sulfuric-acid hydrates were completed, and a new project involving thermal chemistry at Europa-like temperatures was begun. All of this work is part of the Comic Ice Laboratory’s continuing contributions toward understanding the chemistry of biologically-related molecules and chemical reactions in extraterrestrial environments.

    ROADMAP OBJECTIVES: 3.1 3.2
  • Extremophile Ribosomes

    One of the biggest challenges facing eukaryote extremophiles is the loss of water leading to desiccation. Resistance to desiccation as adults, juveniles, seeds, or spores is found in species of five animal phyla and four divisions of plants. Little is understood about the biochemistry of desiccation tolerance in eukaryotes, but ribosomes are likely to figure prominently in this phenomenon. The model for our investigations are animals from the phylum Rotifera which are capable from going from completely desiccated to an active, swimming animal in minutes to hours. We are examining how their ribosomes are capable of tolerating near complete dehydration, then rehydrate and engage in translation within minutes. Our hypothesis is that specific proteins associate with ribosomes during desiccation, protecting them from damage and then dissociate upon rehydration. We want to enumerate these proteins and discover the underlying genes. In the future, this knowledge could be used to engineer desiccation tolerance into organisms that currently lack this ability.

    ROADMAP OBJECTIVES: 3.2 4.2 5.3
  • Project 7: Prebiotic Chemical Catalysis on Early Earth and Mars

    The “RNA World” hypothesis is the current paradigm for the origins of terrestrial life. Our research is aimed at testing a key component of this paradigm: the efficiency with which RNA molecules form and grow under realistic conditions. We are studying abiotic production and polymerization of RNA by catalysis on montmorillonite clays. The catalytic efficiency of different montmorillonites are determined and compared, with the goal of determining which properties distinguish good catalysts from poor catalysts. We are also investigating the origin of montmorillonites, to test their probable availability on the early Earth and Mars, and the nature of catalytic activity that could have led to chiral selectivity on Earth.

    ROADMAP OBJECTIVES: 3.1 3.2
  • High Level Theory – the Role of Mg2+ in Ribosome Assembly

    Magnesium plays a special role in RNA function and folding. Although water is magnesium’s most common first-shell ligand, magnesium has significant affinity for the oxyanions of RNA phosphates. Here we provide a quantum mechanical (QM) description of first shell RNA-magnesium and DNA-magnesium interactions, demonstrating unique features that appear to be required for folding of large RNAs. Our work focuses on multidentate chelation of magnesium by RNA and DNA, where multiple phosphate oxyanions enter the first coordination shell of magnesium. The results suggest that magnesium, compared to calcium and sodium, has enhanced ability to form bidentate chelation complexes with RNA. Sodium complexes, in particular, are unstable and spontaneously open. A magnesium cation is closer to the oxyanions of RNA than the other cations, and is stabilized not only by electrostatic interaction with the oxyanions but also by charge transfer and polarization interactions. Those interactions are quite substantial at close distances. The quantum effects are less pronounced for calcium due to its larger size, and for sodium due to its smaller charge. Additionally, we find that magnesium complexes with RNA are more stable than those with DNA. The nature of the additional stability is twofold: it is due to a slightly greater energetic penalty of ring closure to form chelation complexes for DNA, and elevated electrostatic interactions between the RNA and cations. In sum it can be seen that even at high concentration, sodium and calcium cannot replicate the structures or energetics of RNA-magnesium complexes.

    ROADMAP OBJECTIVES: 3.2 4.2
  • 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
  • Neoproterozoic Carbon Cycle

    The rock record late Neoproterozoic (540-800 Ma) appears to exhibit strong
    perturbations to Earth’s carbon cycle. This project seeks an understanding
    of the mechanisms that drive such events and their biogeochemical significance.

    ROADMAP OBJECTIVES: 3.2 4.2 5.1 5.2 6.1
  • Project 9: Microenvironmental Influences on Prebiotic Synthesis

    Before biotic, i.e., “biologically-derived” pathways for the formation of essential biological molecules such as RNA, DNA and proteins could commence, prebiotic pathways were needed to form the molecules that were the basis for the earliest life. Much research has been done on possible non-biological routes to synthesis of RNA, thought by many to be the best candidate or model for the emergence of life. Our work focuses on possible physicochemical microenvironments on early earth that could have influenced and even directed or templated the formation of RNA or its predecessors.

    ROADMAP OBJECTIVES: 3.1 3.2
  • In Vivo Deconstruction and Restoration of Ribosomal

    We are employing the yeast-three hybrid system to investigate in vivo interactions between a-RNA and ribosomal proteins. Our results demonstrate that a-RNA-γ binds in vivo to L2, L3, L4, L15, and L22. L2 is an initial protein in ribosomal assembly and binds to the intact 23S rRNA independently of other r-proteins. We are currently examining the potential for greater binding in vivo of L3, L4, L15, and L22 to the a-RNA-γ with co-expression of L2 in a yeast hybrid system.

    ROADMAP OBJECTIVES: 3.2 4.2
  • The ABRC Philosophy of Astrobiology and the Origin of Life Discussion Group

    A unique feature of Montana State’s ARBC is our Philosophy of Astrobiology Focus Group. Our group consists of faculty, undergraduate, and graduate students from philosophy, history, chemistry and bio-chemistry who are interested in examining the philosophical questions that intersect with astrobiology research.

    Specifically: • What are the defining characteristics of life? • What would we look for in searching for “alternative” life forms? • What is “intelligence” and how would we know when we had found it? • How do we choose between competing theories of the origins of life? • How are emerging sciences, such as astrobiology, different from mature sciences? • What are the social implications of discovering life on another planet or, alternatively, for failing to find life? • What are the ethical obligations of scientists in conducting research on other planets? • How should we assess potential environmental and health risks associated with astrobiological research?

    ROADMAP OBJECTIVES: 3.1 3.2
  • Ice Chemistry Beyond the Solar System

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

    ROADMAP OBJECTIVES: 1.1 1.2 3.1 3.2 3.3 6.2 7.1
  • Ice Chemistry of the Solar System

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

    ROADMAP OBJECTIVES: 1.1 2.2 3.1 3.2 3.3 6.2 7.1
  • High-Resolution Spectroscopy of Comets at Infrared Wavelengths

    Dr. Lucas Paganini has initiated a robust means for quantitative detections of sulfur compounds at submillimeter and infrared (IR). He was awarded 20 hours observing time with the ESO’s sub-millimeter and far-IR Herschel Space Observatory for a proposed investigation on the analysis of OPR and D/H of hydrogen sulfide in comets. And he collaborated extensively on astronomical observations and scientific interpretation of comets 103P/Hartley 2, C/2003 K4 (LINEAR), and 10P/Tempel 2.

    ROADMAP OBJECTIVES: 1.1 3.1 3.2
  • Resurrection of an Ancestral Peptidyl Transferase

    We have created and test both in silico and in vitro models of an ancestral pepidyl transerase center (PTC). Our most recent in silico and in vitro models contain a significantly reduced 23S rRNA (called a-rRNA-γ, Figure 1), retraining the rRNA that forms and surrounds the PTC. To complete the in silico and in vitro models of the ancestral PTC (a-PTC-γ in silico and a-PTC-γ in vitro), we have combined a-rRNA-γ with peptides derived from the ribosomal proteins. The results here indicate that the ribosome and its components are highly robust in folding and assembly. We have shaved around 2500 nucleotides from the 23S rRNA and the vast majority of amino acids from the protein components, excising the globular domains in toto. Yet, the remaining rRNA and peptides retain the ability to fold and specifically assemble.

    ROADMAP OBJECTIVES: 3.2 4.2
  • The Long Wavelength Limit for Oxygenic Photosynthesis

    Photosynthesis is process where plants and bacteria use solar energy to produce sugar and oxygen. It is also the only known process that produces signs of life (biosignatures) on a planetary scale. And, because starlight (or solar energy) is one of the most common sources of energy, it is expected that photosynthesis will be successful on habitable extrasolar planets. Our team is studying how photosynthetic pigments – the molecules that make photosynthesis possible – might function in unique or extreme environments on other planets. In our experiments, we use a bacteria called Acaryochloris marina to study how different photosynthetic pigments work. This bacterium is useful for our research because it uses a pigment known as chlorophyll d instead of chlorophyll a, which is more common on our planet. Chrolophyll a works well in Earth’s environment but, by studying chlorophyll d, we can begin to understand how photosynthesis might work on planets with different environments than Earth. So far, our research is revealing that photosynthesis can occur quite efficiently in environments that are very different from our planet.

    ROADMAP OBJECTIVES: 3.2 4.2 5.1 5.3 6.2 7.2
  • Ribosome Paleontology

    The origins of the translation machinery remain imprinted in the extant ribosome. The conformations of ribosomal RNA and protein components can be seen to change over time indicating clear molecular fossils. We are establishing methodology to determine chronologies of ancient ribosomal evolution. It is hypothesized that substantial, though necessarily incomplete evidence, relating to the origins and early development of the translation machinery and its relation to other core cellular processes continues to exist in the primary sequences, three-dimensional folding and functional interactions of the various macromolecules involved in the modern versions of these processes. To this end, we are using ribosomal paleontology to determine the relative age of various ribosomal components and subsystems and thereby develop timelines for the history of the ribosome as a whole as well as various sub processes such as initiation, termination, translocation etc. The results of these studies will interface ribosomal history with other key relating to the origin of life including the emergence time of the genetic code, the origin of chirality and the nature of the last common ancestor. We have also been developing new tools of ribosomal paleontology, to visualize the changes, and to determine timelines for ribosomal origins.

    ROADMAP OBJECTIVES: 3.2 4.2
  • Project 4A: Characterization of Novel Solid-Phase Fe(II)-Oxidizing Chemolithotrophic Bacteria From Subsurface Environments

    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). Fe(II) oxidation may have played a role in past (and possibly, present) life on Mars, whose crust is rich in primary Fe(II)-bearing silicate minerals, as well as Fe-bearing clay minerals formed during weathering of primary silicates. This project examined the physiological and phylogenetic properties of novel solid-phase Fe(II)-oxidizing bacteria (FeOB) isolated from subsurface sediments from the Columbia River basin in eastern Washington, as well as clay-rich subsoils from Madison, WI. The organisms were enriched using biotite (a Fe(II)-bearing primary silicate mineral) as an energy source, and purified on organics-containing medium. The capacity of the isolates to oxidize soluble and solid-phase Fe(II) compounds was assessed, and the 16S rRNA gene sequence for each of the isolate was determined. The results revealed that a wide variety of Proteobacteria are capable of catalyzing solid-phase Fe(II) oxidation, including several groups of organisms not previously known as FeOB. These results confirm and expand our knowledge of solid-phase chemolithotrophic Fe(II) oxidation on Earth, and bolster the concept of mineral-associated Fe(II) oxidation as a potential basis for microbial life on other terrestrial planets.

    ROADMAP OBJECTIVES: 3.2 5.1
  • Organic Chemistry in a Dynamic Solar Nebula: Lab Studies and Flight Mission Implementation

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

    ROADMAP OBJECTIVES: 3.1 3.2 7.1
  • Radio Observations of Simple Organics: Tracing the Origins and Preservation of Solar System Materials

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

    ROADMAP OBJECTIVES: 2.2 3.1 3.2 7.1
  • Task 3.5.1 Titan Genetics

    An open question is: “What chemical structures might support the genetic component of Darwinian evolution in Titan environments?” This is being approached theoretically and experimentally.

    ROADMAP OBJECTIVES: 1.1 3.1 3.2
  • Water in Planetary Interiors

    We have synthesized samples of high pressure mineral phases that are likely hosts for H, and thus water, in planetary interiors, and measured physical properties including crystal structure, density, elasticity, and electrical conductivity to see if there is evidence of deep hydration in the Earth.

    ROADMAP OBJECTIVES: 1.1 2.1 3.1 3.2