Notice: This is an archived and unmaintained page. For current information, please browse

2012 Annual Science Report

Astrobiology Roadmap Objective 6.2 Reports Reporting  |  SEP 2011 – AUG 2012

Project Reports

  • Biosignatures in Ancient Rocks

    The Biosignatures in Ancient Rocks group investigates the co-evolution of life and environment on early Earth using a combination of geological field work, geochemical analysis, genomics, and numerical simulation.

    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
  • Amino Acid Alphabet Evolution

    A genetically encoded alphabet of just 20 amino acids has produced the universe of protein structures and functions found throughout Earth’s biosphere. Relationships within this amino acid alphabet are responsible for fundamental biological phenomena, such as protein folding and patterns of molecular evolution. In attempting to unravel these relationships, considerable scientific ingenuity has been spent developing systems to simplify the genetically encoded alphabet of 20 amino acids while minimizing the associated loss of chemical diversity. These efforts present an opportunity to generate a composite picture of the properties that link the amino acids as a set. We are therefore investigating whether different simplification schemes (“simplified amino acid alphabets”), including those derived from very different approaches, can be combined to create a coherent description of amino acid similarity. By understanding the organization and relationships between amino acids on Earth, we hope to shed light on the chemical logic to be expected as a product of evolution in extraterrestrial environments.

    An extensive scientific literature has converged on surprisingly clear agreement that a subset of only around half of the 20 genetically encoded amino acids was likely present from the inception of genetic coding (the “early” amino acids), and an equal sized subset was incorporated through subsequent evolution (the “late” amino acids). A further widespread assumption is that, as the set expanded, natural selection favored the addition of amino acids that extended the range of protein structures and functions. We initiated a quantitative investigation for consilience between these two important ideas.

    ROADMAP OBJECTIVES: 3.2 4.1 4.2 6.2 7.1 7.2
  • 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 6.1 6.2 7.1 7.2
  • Biosignatures in Extraterrestrial Settings

    Exploring the prospects for biosignatures in extraterrestrial settings is a multi

    ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 3.1 4.1 4.3 6.2 7.1 7.2
  • Atmospheric Oxygen and Complex Life

    Our team is working to understand what the world looked like just before and just after the evolution of animals. This encompasses field geology (identifying rocks of that age), chemical analysis of those rocks, and close examination of the small, enigmatic fossilized forms within those same geologic units. To synthesize these interdisciplinary approaches, our team also works to contribute overview/review papers that speak to the contribution from each field.

    ROADMAP OBJECTIVES: 4.1 4.2 6.1 6.2
  • 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
  • Charting the Universe of Amino Acid Structures

    More than 3.5 billion years ago, life on our planet evolved a precise alphabet of 20 amino acids to function as building blocks which cells use to construct proteins according to genetic instructions. However, the twenty genetically encoded amino acids are but a tiny fraction of the chemical structures that could plausibly play such a role. Any science of the origins, distribution and future of life in the universe must take into account this larger context of chemical structures. But while astrochemistry, prebiotic chemistry, and bioengineering all hint at the chemical structures it contains, until now this amino acid universe has remained largely unexplored. Efforts to describe the structures it contains, or even estimate their number, have been hampered by the complexity inherent to the combinatorial properties of organic molecules. We have formed a new collaboration to combine European (DLR) advances in computational chemistry with NAI expertise in organic chemistry and amino acid biology to address this gap in current scientific understanding. Our early results have provided the first ever sketch of the amino acid structure universe, showing it to be far larger and more complex than previously supposed. This forms an important milestone in defining and exploring the principles of “universal biology”

    ROADMAP OBJECTIVES: 3.1 3.2 6.2 7.1 7.2
  • Project 5: Geological-Biological Interactions

    This project seeks to better understand the interplay between microbes and extreme environments. Towards this end our NAI supported scientists study hot spring environments, both continental and sub marine, environments of active serpentinization where pH may exceed 11, and in the high Arctic. We use molecular, isotopic, and molecular biological approaches to get at the core of the relationship between the microbial world and the natural energy provided by geological processes.

    ROADMAP OBJECTIVES: 4.1 5.1 6.1 6.2 7.1
  • Postdoctoral Fellow Report: Steven Mielke

    S. P. Mielke completed an NAI NASA Postdoctoral Program (NPP) fellowship during September 1, 2011 to February 29, 2012. His postdoctoral research has provided the basis for the project: “The Long-Wavelength Limit for Oxygenic Photosynthesis.” He continues this research as a Research Associate at Rockefeller University.

    ROADMAP OBJECTIVES: 3.2 4.2 5.1 5.3 6.2 7.2
  • Habitability of Extrasolar Planets

    We model if and under what conditions some of the recently detected Super-Earths – small, Earth-sized planets that have been discovered in in the classical Habitable Zone Sun-like stars – could be habitable. These models explore the underlying physics of planetary atmospheres and their remotely detectable features.

    ROADMAP OBJECTIVES: 1.1 1.2 4.1 4.2 6.2 7.2
  • The Subglacial Biosphere – Insights Into Life-Sustaining Strategies in an Extraterrestrial Analog Environment

    Sub-ice environments are prevalent 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
  • The Long Wavelength Limit for Oxygenic Photosynthesis

    Photosynthesis produces signs of life (biosignatures) on a planetary scale: atmospheric oxygen and the reflectance signature of photosynthetic pigments. Oxygenic photosynthesis is therefore a primary target in NASA’s search for life on habitable planets in other solar systems. An unanswered question is what the upper limit is to the photon wavelength at which oxygenic photosynthesis can remain viable. On other planets that have a parent star very different spectrally from our Sun, can we expect oxygen from plants of different colors from those on Earth?

    The cyanobacterium, Acaryochloris marina serves as a model organism for oxygenic photosynthesis adapted to low light and red-shifted light environments similar to what may be found on habitable planets orbiting M stars. Until A. marina was discovered in 1996, all known oxygenic photosynthesis relied on the pigment chlorophyll a (Chl a). A. marina instead uses chlorophyll d, which can absorb the far-red and near-infrared light in A. marina’s habitat. We use photoacoustics in the lab to measure the energy storage efficiency of A. marina with lasers, and molecular electrostatics modeling to surmise how replacement of Chl a by Chl d in A. marina affects arrangements within the photosystem molecules. We are finding that A. marina can perform oxygenic photosynthesis quite efficiently in its unique light niche.

    ROADMAP OBJECTIVES: 3.2 4.2 5.1 5.3 6.2 7.2
  • Interdisciplinary Studies of Earth’s Seafloor Biosphere

    The remote deep sediment-buried ocean basaltic crust is Earth’s largest aquifer and host to the least known and potentially one of the most significant biospheres on Earth. CORK observatories have provided unparalleled access to this remote environment. They are enabling groundbreaking research in crustal fluid flow, (bio)geochemical fluid/crustal alteration, and the emerging field of deep crustal biosphere

    ROADMAP OBJECTIVES: 4.1 4.2 5.1 5.2 5.3 6.1 6.2 7.1 7.2
  • The VPL Life Modules

    The VPL Life Modules involve development of simulation models of how biological processes – such as photosynthesis, breathing, and decay of organic materials – work on a planetary scale. When this is combined with the work of the atmospheric and planetary modeling teams, we are able simulate how these processes impact the atmosphere and climate of a planet. This information helps us understand how we might be able to detect whether or not a planet has life by looking at its atmosphere and surface. The Life Modules team has engaged in previous work coupling early Earth biogeochemistry and 1D models in the VPL’s suite of planetary models. Current work now focuses on the development of a land biosphere model coupled with a previously developed ocean biogeochemistry model and a 3D general circulation model (GCM). This terrestrial biosphere model is designed to simulate geographic distributions of life adapted to different climate zones, surface albedo, and carbon dioxide exchange and other biogenic gases with the atmosphere. These coupled models are first tested against Earth ground and satellite observations. A large data mining effort is now under way for the model of land-based ecosystem dynamics to uncover vegetation adaptations to climate that may be generalizable for both the Earth and alternative planetary environments.

    ROADMAP OBJECTIVES: 1.2 6.1 6.2 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
  • 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 or nitrogen or iron? Is this change similar for diverse species of microorganisms? 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, including extreme environments relevant to astrobiology.

    ROADMAP OBJECTIVES: 5.2 5.3 6.1 6.2
  • Permafrost in Hawaii

    Permanent ice can be found on the Hawaiian Islands at extremely few locations and as a result of microclimates. Ice exists in the form of permafrost in craters near the summit of Mauna Kea and in form of ice lakes in lava tubes on Mauna Loa; they are the world’s most isolated ice caves. We investigate the microclimates on the high summits of the Hawaiian Islands that serve as possible analogues to Mars. Exploratory fieldwork has been carried out at four field sites and interdisciplinary collaborations have been developed.

    ROADMAP OBJECTIVES: 2.1 5.3 6.2
  • Stoichiometry of Life, Task 2a: Field Studies – Yellowstone National Park

    Our stoichiometry studies are determining the relationships between the elemental compositions of organisms and the elemental compositions of their environments. We experimentally determine how changes in element availability (N, P, Fe) affect the community structure in hot spring ecosystems. We also use stable isotopes (15N and 13C) to trace which metabolisms actively utilize N and C and where in cells these elements are used. Recently, our team has shown for the first time that nitrogen (N2) fixation can occur at temperatures >85oC (Loiacono et al. 2012). We are also developing robust environmental sensors for hot springs that reveal chemical and thermal gradients at scales similar to the observed spatial distributions in hot spring microbial communities.

    ROADMAP OBJECTIVES: 5.1 5.2 5.3 6.1 6.2 7.2
  • The Neoproterozoic Carbon Cycle

    We are studying the dynamics of the rise of oxygen during the Neoproterozoic (1 billion years ago to 543 million years ago) through culturing experiments, models and observations (see the progress report on the Unicellular Protists). We are testing the predictions of the following “anti-priming” hypothesis: if more easily degradable organic matter was degraded in oxic environments, this may have slowed down the degradation of organic matter in anaerobic environments and the overall degradation of organic matter, increasing the concentration of oxygen in the atmosphere and the surface ocean. We are currently developing theoretical predictions and testing these ideas by laboratory enrichment cultures of anaerobic microbes that degrade complex substrates in the presence and absence of labile organic compounds.

    ROADMAP OBJECTIVES: 1.1 4.1 4.2 5.2 6.1 6.2
  • 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. These studies help in identifying the element signatures that microbes develop when key nutrient elements are scarce. Furthermore, the chemical and physical environments of the desert aquatic habitats at Cuatro Cienegas are analogous to those that may have existed on Mars during times in its past when it was losing its own surface water. Thus, these data may help in interpreting information about element signatures obtained from the Curiosity rover as it explores Gale Crater.

    ROADMAP OBJECTIVES: 5.1 5.2 5.3 6.1 6.2
  • Task 3.5.1 Titan Genetics

    This project seeks to determine what chemical structures might support the genetic component of Darwinian evolution in Titan environments.

    ROADMAP OBJECTIVES: 2.2 3.2 4.2 6.2