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Hydrothermal Systems: Physical, Chemical, and Biological Evolution and Cosmic Environments

The astrobiology consortium led by the Carnegie Institution of Washington primarily studies the physical, chemical, and biological evolution of hydrothermal systems. Research areas include vent complexes associated with ocean ridges, deep aquifers, and other subsurface aqueous environments, both on Earth as well as on other solar system and extrasolar bodies. Such diverse systems are important environments for life on Earth and possibly elsewhere in the cosmos.

This research informs the central questions of astrobiology with discoveries of new planetary systems, exploration of possible hydrothermal regimes on other worlds, elucidation of robust hydrothermal synthetic pathways, documentation of novel microbial metabolic strategies, and finding unexpected high-pressure environments for life. Taken together, these discoveries are changing our views of life’s origin and its distribution.

Physical, Chemical, and Biological Evolution of Hydrothermal Systems

• Hydrothermal systems, including their roles in life’s origins and attention to interfaces among theoretical, experimental, and field approaches
• Planetary formation modeling, as well as detection and characterization of extrasolar planets
• Circumstances under which hydrothermal systems form on planets and other bodies, plus the expected physical and chemical characteristics of those systems as they evolve
• Geochemical processes in hydrothermal systems, especially those leading to abiotic organic synthesis, with focus on the role of mineral catalysis in these systems
• Origin and evolution of biological entities in hydrothermal systems through studies of the biochemistry of contemporary hydrothermal organisms

Studies in Planetary Formation and Evolution

• Detection and characterization of extrasolar planets by surveying the nearest 1,200 Sun-like stars then using an expanded program (early 2002) to add 800 stars and complete the first reconnaissance of all nearby dwarf stars, providing a target list for more intensive follow-up observations
• Study of gas-giant planet formation by developing extended 3-D hydrodynamical models to provide a complete thermodynamical description of the disk instability process, implying that the disk instability mechanism could obviate the core accretion mechanism in the solar nebula and elsewhere
• Understand the frequency of Earth-like planets and devise a quantitative planet formation model including observations of our solar system and extrasolar planets (considering both theory and observation and also studying a quantitative alternative to the standard model of planet formation)
• Study evolution of water on solar system objects other than Earth, considering the likelihood, timing, and physical / chemical environments of hydrothermal systems, with focus on Mars Global Surveyor data (especially for the Tharsis rise region with its possible influence on water inventory in the atmosphere-surface system of Mars)

Organic Matter and Water in Meteorites

• Research on organic material in primitive chondritic meteorites, with attention to evolution of water on Mars and water-bearing phases in Martian meteorites
• Study physics and chemistry in the early solar nebula by quantifying predictions of a leading theory for chondrule formation (melting by shock waves in the nebula gas) and by modeling chondrule thermal histories in great detail
• Analysis of macromolecular organic matter in carbonaceous chondrites, particularly in a Murchison meteorite organic macromolecule sample
• Study to determine most likely sources of water for the terrestrial planets, considering primitive meteorites (ordinary chondrites) and parent asteroids from the inner asteroid belt (in the region of Jupiter)
• Investigate Martian meteorites for hydrogen isotope composition and sources of extraterrestrial water
• Petrological studies of water in Martian magmas with investigation of magmatic crystallization of kaersutite from a Martian basalt to provide insight into water history on Mars
• Iron isotope measurements of terrestrial rocks and meteorites to search for isotopic biomarkers since isotopic mass fractionation of transition metals in chemical sediments has been cited as evidence for microbial utilization

Hydrothermal Organic Synthesis

• Abiotic hydrothermal chemistry and synthesis studies by exploring catalytic capabilities of transition-metal sulfides for promotion of organic reactions with biochemical utility
• Monitor hydrothermal chemistry and its effect on biological activity to expand the concept of what constitutes a habitable zone for life
• Investigate production of amphiphilic, membrane-forming molecules, as an essential step in protocell emergence
• Study amino acid synthesis from endogenous sources and investigate the endogenous basis for life under hydrothermal conditions
• Investigate prebiotic ocean production of ammonia by hydrothermal systems (via nitrite and nitrate reduction) in the presence of a variety of transition metal oxide and sulfide minerals

Theoretical Studies of Hydrothermal Synthesis Reactions

• Study energetics of hydrothermal ecosystems with thermodynamic calculations to establish viability of both biological and abiotic reactions relevant to astrobiological issues, plus analysis of potential abiotic synthesis of hydrocarbons detected in SNC meteorites, e.g., ALH84001
• Develop a theoretical foundation for organic synthesis with experiments to determine the ubiquity and origins of intermediary metabolism by studying a C,H, and O reaction model system for biogenesis

Biological Studies of Hydrothermal Systems

• Field studies and laboratory characterization of hydrothermal vent microbes to determine if hyperthermophilic archaea from the subseafloor near deep-sea vents are phylogenetically and physiologically different from similar organisms isolated from vent sulfide structures
• Studies of neutrophilic, lithotrophic, and Fe-oxidizing bacteria with a combination of biodiversity, morphological, physiological studies to examine the viewpoint that neutrophilic Fe-oxidizers are truly lithotrophic microorganisms
• Investigate the origin of chirality by examining selective adsorption of L- and D-amino acids on calcite for implications of biochemical homochirality to seek a plausible geochemical mechanism for chiral selection and subsequent homochiral polymerization of amino acids on the prebiotic Earth.
• Studies to elucidate possible emergent steps in geochemical sequences that progressively lead to the emergence of life, as indicated by characteristic isotopic, molecular, and structural “fossils,” which might be measured in extraterrestrial environments not subjected to reworking by biological activity.

Protein Chip-Based Molecular Recognition

• Utilize protein chip-based molecular recognition technology to detect life on Earth or other solar system bodies: microbial proteins; biologically produced (but chemically modified) microbial molecules; and abiotically synthesized organic matter
• Study the molecular weight distribution of organic molecules in dissolved organic matter for detection of large proteins or microbial cell wall fragments, in order to identify biosignatures in samples