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2008 Annual Science Report

Pennsylvania State University Reporting  |  JUL 2007 – JUN 2008

Executive Summary

The Penn State Astrobiology Research Center (PSARC) was created in 1998 as part of the NASA Astrobiology Institute. PSARC is currently comprised of 19 (Co)-PIs and their research teams: Mike Arthur, Sue Brantley, Jean Brenchley, Will Castleman, Greg Ferry, Kate Freeman, Blair Hedges, Chris House, Jim Kasting, Lee Kump, Jenn Macalady, Hiroshi Ohmoto, Mark Patzkowsky, Steinn Sigurdsson, and Alex Wolszczan of The Pennsylvania State University; Rosemary Capo and Brian Stewart of The University of Pittsburgh; and Martin Schoonen from SUNY Stony Brook. During the period of July 1, 2007 — June 30, 2008, PSARC has supported all or part of the research/education/PO activities carried out by 93 persons (19 (Co)PIs, 6research associates, 9 postdoctoral fellows, 41 graduate students, 13 undergraduate students, 1 technician, and 4 staff in administration/IT/EPO). The total number of PSARC personnel has remained about the same ... Continue reading.

Field Sites
24 Institutions
12 Project Reports
0 Publications
0 Field Sites

Project Reports

  • Genomics of Sulfidic Cave Extremophiles (Supplement to NNA04CC06A)

    We investigated the ecology and evolutionary relationships among extremely acid-loving bacteria and archaea living in biofilms called “snottites” in sulfidic caves in Italy and Mexico. The acid-loving microbes form the base of food chains cut off from the surface, and present rare examples of microbially dominated ecosystems (like ecosystems present for much of earth history and those potentially elsewhere in the universe). The snottites are also important because they help us learn how life adapts to environmental conditions much different from the ones that can be tolerated by our own species (pH 0-1). Future work based on the foundation presented here will reveal how subsurface microorganisms in geographically isolated “geochemical islands” are related to each other and to microorganisms living at the earth’s surface.

    ROADMAP OBJECTIVES: 5.1 5.3 6.2
  • Evolution of a Habitable Planet (Brantley)

    As rocks interact with water and air, they transform chemically. Sometimes this chemical transformation is affected by the presence of organisms that leave biological signatures. The chemistry of metals and minerals are being probed to elucidate possible biosignatures that may be identified on Earth and Mars.

  • Ferry Report

    The research addresses how anaerobic Archaea cope with oxidative stress, with the long-term view of how anaerobic life evolved to adapt to rising oxygen levels before, during and after the evolution of oxygenic photosynthesis. The research also addresses ancient enzymes involved in metabolic pathways with a focus on energy conservation in methanogenic Archaea.

    ROADMAP OBJECTIVES: 3.3 4.1 4.2 5.1 6.1
  • Molecular Signatures of Life on the Edge (DDF Project)

    We have investigated the Dead Sea, as a possible analog of early Mars environments — slightly acidic and highly saline. We have used metagenomics, lipid analysis, and amino acid analysis.

    ROADMAP OBJECTIVES: 2.1 5.1 5.2 5.3 7.1
  • Modeling Early Atmospheric Composition and Climate

    We have updated our methane greenhouse model for the early Earth by including the greenhouse effect of ethane and the anti-greenhouse effect of organic haze. We analyzed the mass-independent sulfur isotopic record to find evidence for the existence of such haze during the mid-Archean, between 3.2 and 2.8 Ga. And we worked on the problem of hydrogen escape from the early Earth.

  • Genomic Record of the Earth’s Early Biosphere (Hedges)

    Our research involves molecular evolutionary genetics in an effort to better understand the relationship between planetary history and the evolution of life. We continue to update our public database TimeTree (, which presents divergence times of organisms. Most of the work during the past year involved editing and contributing to a book, The Timetree of Life, which summarizes the current state of knowledge in the field and presents new data, with 81 chapters and 105 authors (Oxford University Press, in production).

    ROADMAP OBJECTIVES: 4.1 4.2 4.3
  • Evolution of a Habitable Planet (Stewart)

    This project has several foci, including (1) using novel isotope techniques to determine the ages of soils formed very early in Earth’s history; (2) studying the detailed cycling of iron sulfide minerals and the possible isotopic “signatures” of primitive life forms that might be contained within them; (3) tracking the fluxes of dust and salt in extreme Earth environments (the Atacama Desert, Chile) to better understand processes on the surface of Mars.

  • Untitled

    We are exploring the geological and geochemical record of ancient Earth for clues about the co-evolution of life and environment. We’re focusing on three events in Earth history: the apparent rise of atmospheric oxygen at 2.45 billion years ago, the establishment of life on land during the Cambrian (about 540 milliion years ago), and the greatest mass extinction of all time at the end of the Permian, 252 million years ago. We use a combination of computer modeling, field work, and laboratory analysis.

    ROADMAP OBJECTIVES: 4.1 6.1 7.1 7.2
  • Examination of the Microbial Diversity Found in Ice Cores (Brenchley)

    Our goal is to discover microorganisms surviving in cold or frozen environments and to use this information to understand how different microorganisms survive extreme habitats. Our recent results demonstrated that abundant populations, including many bacteria representing novel taxa, exist frozen in a Greenland glacier ice core for at least 120,000 years. Current isolates are being characterized as new species of ultra-small celled bacteria. This research provides insight into microbial survival in extreme environments that might exist elsewhere in the solar system.

    ROADMAP OBJECTIVES: 2.1 5.1 5.2 5.3 6.1 6.2 7.1
  • Laboratory Microbial Simulations: Astrobiological Signatures

    We aim to use laboratory and field environments to investigate microorganisms and their biogeochemical signatures. We have investigated methanotrophic seeps and deeply-buried marine environments, as well as used laboratory pure-cultures to further our understanding of diverse metabolisms.

    ROADMAP OBJECTIVES: 2.1 4.1 5.1 5.2 5.3 7.1
  • Castleman Report

    The evolving isotope composition of sulfur compounds pertains to the questions of the composition of the Earth’s early atmosphere. We are currently in the process of finalizing our interpretation of our investigations on the influence of photolysis, and the subsequent oxygen dissociation of sulfur dioxide on the isotope ratios. During the report period, we began the interpretation of the experimental results obtained from our spectrometer, which, coupled with a new detection scheme, has enabled us to overcome conventional difficulties encountered in making isotopic measurements. This scheme facilitates the study of individual isotopes without the need for a “spiked sample”, a process that is fraught with difficulties due to the inability to reliably acquire accurate and uniform mixtures.

  • PSARC (Sigurdsson Report)

    Theoretical modeling of planetary dynamics, in particular the later stages of planet formation and the role of giant planet migration in the formation of terrestrial planets.
    Also, direct detection of planets around burned out stars using existing space based telescopes, and planets around pulsars.