2008 Annual Science Report

NASA Ames Research Center Reporting  |  JUL 2007 – JUN 2008

Executive Summary

The Ames team pursued complementary lines of research on the development of habitable planetary environments, the origins of biological functions, the biosignatures created by microbial ecosystems fueled by light or by chemical energy, and the survival of life in space and in changing environments on Earth. These investigations broadly address NASA’s Astrobiology Roadmap. Their direct involvement in multiple NASA missions provides context, motivation, and collaborative opportunities for our research, and education and public outreach efforts. Please visit www.amesteam.arc.nasa.gov.

Ames team astrophysicists continued to investigate the formation of habitable planetary systems with a focus on key processes in protoplanetary disks. It had been proposed that the lifetimes of planet-forming disks might attain a maximum for central star masses of order 1 to 3 solar masses. It was found that there is no such maximum but rather that stars in the range 0 ... Continue reading.

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7 Project Reports
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Project Reports

  • Hindcasting Ecosystems

    Using the vegetation of South America as an analog to the biosphere of an earth-like planet, this project links Earth Science to Astrobiology. A past-ecosystem-process model was created to predict the history of the carbon cycle in terms of Net Primary Production (NPP). Proxy data were used to reconstruct the past sea surface temperature (SST) of the last 754 years at 1-year resolution. Based upon the high correlation between SST and the vegetation index (NDVI), soil types, potential evapotranspiration, water retention capacity, and nitrogen concentration in soils, the model predicted past NPP for most continental ecosystems of South America.

  • Ecosystem to Biosphere Modeling

    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.

  • Early Metabolic Pathways

    The project is aimed at characterizing the emergence of functional proteins and their early evolution leading to the formation of primitive metabolism in ancestors of contemporary cells. Through a combination of molecular biology and computer modeling we investigate the origins of both water-soluble enzymes and membrane proteins that mediate transport of small molecules and ions across cell walls.

  • Interplanetary Pioneers

    The possibility of life traveling from Earth to beyond, and, in general, life traveling from planet to planet, has captured the public’s imagination for a century or more. We are now poised to assess this possibility with experimentation. In this project, we focus on halophiles — organisms that live in high salt environments — as potential Earth life to survive space travel. Thus we have explored high UV and high salt environments, and have flown some of these organisms on European space missions. This year we also began to develop the use of high altitude ballooning to mimic travel beyond the surface of the earth.

  • Habitable Planets

    This task is concerned with understanding planetary bodies as they form in habitable zones. The planet formation process begins with fragmentation of large molecular clouds into flattened protoplanetary disks. This disk is in many ways an astrochemical “primeval soup” in which cosmically abundant elements are assembled into increasingly complex hydrocarbons and mixed in the dust and gas envelope within the disk. Gravitational attraction among the myriad small bodies leads to planet formation. If the newly formed planet is a suitable distance from its star to support liquid water at the surface, it is in the so called “habitable zone.” The formation process and identification of such life-supporting bodies is the goal of this project.

    ROADMAP OBJECTIVES: 1.1 1.2 2.1 4.3
  • Prebiotic Organics From Space

    This project has three components, all aimed to better our understanding of the connection between chemistry in space and the origin of life on Earth and possibly other worlds. Our approach is to trace the formation and evolution of compounds in space, with particular emphasis on identifying those that are interesting from a prebiotic perspective, and understand their possible roles in the origin of life on habitable worlds. We do this by first measuring the spectra and chemistry of materials under simulated space conditions in the laboratory. We then use these results to interpret astronomical observations made with ground-based and orbiting telescopes. We also carry out experiments on simulated extraterrestrial materials to analyze extraterrestrial samples returned by NASA missions or that fall to Earth in as meteorites.

    ROADMAP OBJECTIVES: 1.1 2.1 2.2 3.1 3.4 4.3 7.1 7.2
  • Biosignatures in Chemosynthetic and Photosynthetic Systems

    Our work examines the microbiology and geochemistry of microbial ecosystems on Earth in order to better understand the production of “biosignatures” — chemical or physical features or patterns that can only have been formed by the activities of life. More specifically, in photosynthetic (light-eating) microbial mats, we examine the factors that control the formation of biosignature gases (such as could be seen by telescope in the atmospheres of planets orbiting other stars) and isotopic and morphological features that could be preserved in the rock record (such as could be examined by rovers on Mars). Additionally, we study the formation of morphological and mineral signatures in chemotrophic (chemical-eating) systems that have no direct access to light or the products of photosynthesis. Such systems likely represent the only viable possibility for extant life on modern day Mars or Europa.

    ROADMAP OBJECTIVES: 2.1 4.1 5.1 5.2 6.1 7.1 7.2