2011 Annual Science Report

Astrobiology Roadmap Objective 5.3 Reports Reporting  |  SEP 2010 – AUG 2011

Project Reports

  • Detectability of Life

    Detectability of Life investigates the detectability of chemical and biological signatures on the surface of icy worlds, with a focus on spectroscopic techniques, and on spectral bands that are not in some way connected to photosynthesis.Detectability of life investigation has three major objectives: Detection of Life in the Laboratory, Detection of Life in the Field, and Detection of Life from Orbit.

    ROADMAP OBJECTIVES: 1.2 2.1 2.2 4.1 5.3 6.1 6.2 7.1 7.2
  • Advancing Methods for the Analyses of Organics Molecules in Sediments

    Eigenbrode’s astrobiological research focuses on understanding the formation and preservation of organic and isotopic sedimentary records of ancient Earth, Mars, and icy bodies. To this end, and as part of GCA’s Theme IV effort, Eigenbrode seeks to overcome sampling and analytical challenges associated with organic analyses of astrobiology relevant samples with modification and development of contamination tracking, sampling, and analytical methods (primarily GCMS) that improve the recovery of meaningful observations and provide protocol guidance for future astrobiological missions. Advances have been made in five sub-studies and manuscript writing is in progress. Studies include: 1 & 2. Advancing protocols for organic molecular studies of iron-oxide rich sediments and sediments laden with perchlorate, 3. Carbon Isotopic Records of the Neoarchean, 4. Solid-phase sorbtive extraction of organic molecules in glacial ice, and 5. Amino acid composition of glacial ice.

    ROADMAP OBJECTIVES: 2.1 4.1 5.1 5.2 5.3 6.1
  • 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
  • Biosignatures in Relevant Microbial Ecosystems

    In this project, PSARC team members explore the isotope ratios, gene sequences, minerals, organic molecules, and other signatures of life in modern environments that have important similarities with early earth conditions, or with 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
  • 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
  • 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
  • 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
  • Mineralogical Traces of Early Habitable Environments

    The goal of our work is to discern the habitability (potential to support life) of ancient Martian environments, with an emphasis on understanding which environments could have supported more life than others. This information will help to guide the selection of sites on the Martian surface, for future missions designed to seek direct evidence of life. Our approach has two main parts: 1. We will use the presence of specific minerals or groups of minerals – an analysis that can be performed robotically on Mars — to constrain the chemical and physical conditions of the ancient environments in which they formed. 2. We will characterize the distribution of life on Earth in a series of environments spanning those same parameters, in order to inform the first portion of the investigation.

    ROADMAP OBJECTIVES: 2.1 5.3
  • 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
  • Evolution of Metabolism

    Our astrobiology research focus for VPL is to understand the evolution of different metabolic groups of microorganisms during the course of Earth’s history, and how the emergence of different metabolisms, such as methanogenesis, anoxic and oxygenic photosynthesis, and other anaerobic metabolisms that involve sulfur, metal, and nitrogen could effect the chemical composition of the atmosphere.

    ROADMAP OBJECTIVES: 5.1 5.3 6.2
  • Deep (Sediment-Buried Basement) Biosphere

    The ocean crust comprises the largest aquifer on earth. Deep sediment cover provides an environ-ment for a unique biosphere hosting microorganisms surviving under extreme conditions. Frac-tured rock provides abundant surfaces that can be colonized by diverse microbes and water-rock reactions promote chemical conditions that influence key geochemical cycles within the Earth’s crust and oceans. Team members participated in a 14-day research cruise to study the sediment-buried basement (basaltic crust) biosphere, to provide unprecedented and unique insight into the mobility and origin of microorganisms within this remote biosphere.

    ROADMAP OBJECTIVES: 4.1 4.2 5.2 5.3 6.1 6.2 7.1 7.2
  • 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
  • The Subglacial Biosphere – Insights Into Life-Sustaining Strategies in an Extraterrestrial Analog Environment

    Sub-ice environments are prevalant on Earth today and are likely to have been more prevalent the Earth’s past during episodes of significant glacial advances (e.g., snow-ball Earth). Numerous metabolic strategies have been hypothesized to sustain life in sub-ice environments. Common among these hypotheses is that they are all independent of photosynthesis, and instead rely on chemical energy. Recently, we demonstrated the presence of an active assemblage of methanogens in the subglacial environment of an Alpine glacier (Boyd et al., 2010). The distribution of methanogens is narrowly constrained, due in part to the energetics of the reactions which support this functional class of organism (namely carbon dioxide reduction with hydrogen and acetate fermentation). Methanogens utilize a number of metalloenzymes that have active site clusters comprised of a unique array of metals. During the course of this study, we identified other features that were suggestive of other active and potentially relevant metabolic strategies in the subglacial environment, such as nitrogen cycling. The goals of this project are 1) identifying a suite of biomarkers indicative of biological CH4 production 2). quantifying the flux of CH4 from sub-ice systems and 3). developing an understanding how life thrives at the thermodynamic limits of life. This project represents a unique extension of the ABRC and bridges the research goals of several nodes, namely the JPL-Icy Worlds team and the ASU-Follow the Elements team.

    ROADMAP OBJECTIVES: 2.1 2.2 5.1 5.2 5.3 6.1 6.2 7.1 7.2
  • Stromatolites in the Desert: Analogs to Other Worlds

    In this task biologists go to field sites in Mexico to better understand the environmental effects on growth rates for freshwater stromatolites. Stromatolites are microbial mat communities that have the ability to calcify under certain conditions. They are believed to be an ancient form of life, that may have dominated the planet’s biosphere more than 2 billion years ago. Our work focuses on understanding these communities as a means of characterizing their metabolisms and gas outputs, for use in planetary models of ancient environments.

    ROADMAP OBJECTIVES: 4.1 4.2 5.2 5.3 6.1 6.2
  • Viral Ecology and Evolution

    This project is aimed at probing the occurrence and evolution of archaeal viruses in the extreme environments in the thermal areas in Yellowstone National Park. Viruses are the most abundant life-like entities on the planet and are likely a major reservoir of genetic diversity for all life on the planet and these studies are aimed at providing insights into the role of viruses in the evolution of early life on Earth.

    ROADMAP OBJECTIVES: 5.1 5.2 5.3 6.1 6.2
  • Project 3C: Integration of Multiple Isotope Proxies to Study the Pre-GOE Oxygenation of the Earth

    The period 2.7 to 2.5 b.y. ago, the period leading you to the Great Oxidation Event (GOE), is becoming increasingly recognized as a time of major environmental change. A holistic understanding of the changes that occurred in microbial ecology, and their effects of the environment, are only possible by integrating multiple geochemical proxies. By simultaneously looking at C, O, S, Fe, Mo, and Sr isotopes, we develop a picture of extensive oxygenic photosynthesis, but approximate balance with reduced resevoirs such as reduced Fe and reduced volcanic gases, such that free oxygen did not yet become abundant on the planet. Although many workers have questioned a rise in oxygenic photosynthesis significantly before the GOE, these new data clearly indicate that this metabolism was widespread at least 400 m.y. before the GOE.

    ROADMAP OBJECTIVES: 4.1 5.3 6.1 7.1 7.2
  • 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
  • Proxies for Ocean Anoxia

    Episodes of widespread anoxia in past oceans are known as “Ocean Anoxic Events”. The ecosystem consequences of these events are actively debated. In this project, we are examining the chemical and isotopic signatures of the photosynthetic pigment, chlorophyll, to understand changes in ecosystems and the nutrients that fueled them. The seasonal oxygen minimum zone (OMZ) offshore Chile is being used as a modern analog.

    ROADMAP OBJECTIVES: 4.1 4.2 5.2 5.3 6.1
  • Stoichiometry of Life – Task 1 – Laboratory Studies in Biological Stoichiometry

    This project component involves a diverse set of studies of various microorganisms with which we are trying to better understand how living things use chemical elements (nitrogen, phosphorus, iron, etc) and how they cope, in a physiological sense, with shortages of such elements. For example, how does the “elemental recipe of life” change when an organism is starved for phosphorus? Is this change similar for diverse species of microorganisms? Are the changes the same if the organism is limited by a different key nutrient? Furthermore, how does an organism shift its patterns of gene expression when it is starved by various nutrients? This will help in interpreting studies of gene expression in natural environments. At an even more profound level: can an organism substitute an element that is similar to the one that is limiting, as in the case of arsenic for phosphorus?

    ROADMAP OBJECTIVES: 5.2 5.3 6.1 6.2
  • Stoichiometry of Life, Task 2a: Field Studies – Yellowstone National Park

    Field work and subsequent laboratory analysis is an integral part of following the elements. One of our field areas is the hot spring ecosystems of Yellowstone, which are dominated by microbes, and where reactions between water and rock generate diverse chemical compositions. These natural laboratories provide numerous opportunities to test our ideas about how microbes respond to different geochemical supplies of elements. Summer field work and lab work the rest of the year includes characterizing the natural systems, and controlled experiments on the effects of changing nutrient and metal concentrations (done so as to not impact the natural features!).

    ROADMAP OBJECTIVES: 5.1 5.2 5.3 6.1 6.2 7.2
  • Stoichiometry of Life, Task 2b: Field Studies – Cuatro Cienegas

    Cuatro Cienegas is a unique biological preserve in México (state of Coahuila) in which there is striking microbial diversity, potentially related to extreme scarcity of phosphorus. We aim to understand this relationship via field sampling of biological and chemical characteristics and a series of enclosure and whole-pond fertilization experiments.

    ROADMAP OBJECTIVES: 5.1 5.2 5.3 6.1 6.2
  • Permafrost in Hawaii

    We investigate microclimates on the Hawaiian Islands that serve as possible analogues to Mars. The summit of Mauna Kea is exceptionally dry, but sporadic permafrost exists in cinder cones near the summit. Additionally, ice caves are known to exist on the flanks of Mauna Loa. They are the world’s most isolated ice caves. Theoretical models have been developed for microclimatic effects in craters and caves. Preparations for upcoming fieldwork have been made and interdisciplinary collabora-tions have been developed.

    ROADMAP OBJECTIVES: 2.1 5.3 6.2
  • Stoichiometry of Life – Task 2c – Biological Soil Crusts: Metal Use and Acquisition

    Desert biological soil crusts (BSCs) are a complex consortia of microorganisms including cyanobacteria, algae, and fungi. BSCs are the primary colonizers of desert soils, supplying both carbon and nitrogen to these arid-land ecosystems. As such, they may represent an analog for soil development on the early Earth. BSCs occupy an extremely nutrient-poor niche, and meet their nutrient and metal requirements by manipulating their surroundings via the production of metal-binding ligands called siderophores. The soil crust’s metabolism affects the chemical composition of soil porewaters and soil solid phases; these alterations to soil metal contents may represent a biosignature for biological soil crusts that can be preserved over long time scales.

    ROADMAP OBJECTIVES: 4.1 5.3 6.1 6.2 7.1
  • Stoichiometry of Life – Task 2d – Field Studies – Marine Hydrothermal Systems: Deep Hot Biosphere – Lead

    The deep hot biosphere beneath the seafloor remains one of the most extremely poorly understood ecosystems on Earth. Collaborator Hartnett participated in Leg 331 Deep Hot Biosphere of the Integrated Ocean Drilling Program and collected sediments drilled from hydrothermal mounds in the Okinawa Trough region. The organic geochemistry of the sediments will be assessed and related to the presence and activity of microorganisms beneath the seafloor. The scientific party included NAI scientists from three teams (ASU, Penn State, Hawaii) as well as astrobiologists from Japan; the main research objective was to document the existence of an active, metabolically diverse subvent biosphere associated with hydrothermal activity.

    ROADMAP OBJECTIVES: 5.2 5.3
  • Stoichiometry of Life, Task 3b: Ancient Records – Genomic

    The goal of Task 3b is to advance understanding of elemental cycling in ancient ecosystems. Team members are developing experimental and computational approaches aimed at genomic analysis of modern ecosystems, and extending these approaches in novel ways to infer the function and composition of ancient communities.

    ROADMAP OBJECTIVES: 5.1 5.2 5.3
  • Project 7C: Improving Accuracy of in Situ Stable Isotope Analysis by SIMS

    Isotopic analysis of biologically important elements in petrographic context is a fundamental tool for astrobiology. Secondary ion mass spectrometry (SIMS) is a powerful tool used to understand biogeochemical processes at the spatial scale of the individual microorganisms that drive them. The benefits of the extremely high spatial resolution offered by SIMS do not come without costs, however. Unconstrained physical and chemical variables in the sample of interest can introduce biases leading to inaccurate measurements. Understanding and constraining these barriers to accuracy as we move towards ever finer spatial resolution and analytical precision is a primary focus at WiscSIMS.

    ROADMAP OBJECTIVES: 4.1 5.1 5.2 5.3 7.1