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2011 Annual Science Report

Carnegie Institution of Washington Reporting  |  SEP 2010 – AUG 2011

Executive Summary

The NASA Astrobiology Institute team led by the Carnegie Institution of Washington is dedicated to the study of the extrasolar planets, solar system formation, organic rich primitive planetary bodies, deep sequestration of CHON volatiles in terrestrial planets, prebiotic molecular synthesis through geocatalysis, and the connection between planetary evolution the emergence, and sustenance of biology – processes central to the missions of the NAI. Our program attempts to integrate the sweeping narrative of life’s history through a combination of bottom-up and top-down studies. On the one hand, we study processes related to chemical and physical evolution in plausible prebiotic environments – circumstellar disks, extrasolar planetary systems and the primitive Earth. Complementary to these bottom-up investigations of life’s origin, we will continue our field and experimental top-down efforts to document the nature of microbial life at extreme conditions, as well as the characterization of organic matter in ancient fossils. Both types of efforts inform our development of biotechnological approaches to life detection on other worlds.

Our team’s research focus on life’s chemical and physical evolution, from the interstellar medium, through planetary systems, to the emergence and detection of life, across six integrated and interdisciplinary areas of research:

1. We continue to apply theory and observations to investigate the nature and distribution of extrasolar planets both through radial velocity and astrometric methods, the composition of circumstellar disks, early mixing and transport in young disks, and late mixing and planetary migration in the Solar System, and Solar System bodies.

2. We conduct observational analytical research on the volatile and organic rich Solar System Bodies by focusing on astronomical surveying of outer solar system objects and performing in-house analyses of meteorite, interplanetary dust particle, and Comet Wild 2/81P samples with an emphasis on characterizing the distribution, state and chemical history of primitive organic matter.

3. We study the origin and evolution of the terrestrial planets with a special emphasis on CHON volatiles, their delivery and retention in the deep interiors of terrestrial planets. We will experimentally investigate how CHON volatiles may be retained even during magma ocean phases of terrestrial evolution. We investigate the early Earth’s recycling processes studying the isotopic composition of diamonds, diamond inclusions, and associated lithologies. We address how early geotectonic processes lead to the diversification of minerals perhaps required for the origin of life and certainly later modified by the presence of life.

4. We investigate the geochemical steps that may have lead to the origin of life, focusing on identifying and characterizing mineral catalyzed organic reaction networks that lead from simple volatiles, e.g., CO2, NH3, and H2, up to greater molecular complexity. We explore the role of minerals to enhance molecular selection, both isomeric and chiral selection, as well as molecular organization on mineral surfaces.

5. We continue to study the intersection between geology and biology. We continue to explore how sub-seafloor interactions support deep ocean hydrothermal ecosystems. We study life’s adaption to extremes of pressure, cold, and salinity. We adapt and apply multiple isotopic sulfur geochemistry towards the understanding of microbial metabolism and as a means of detecting ancient metabolisms recorded in the rock record through characteristic sulfur isotopic signatures. We apply state-of-the-art methods to derive chemical and isotopic biosignatures of life in the Earth’s most ancient rocks.

6. We are continuing work coordinating advanced instrument testing with our involvement with the Arctic Mars Analogue Svalbard Expedition (AMASE) in support of Mars Science Laboratory, including ChemMin, SAM as well as elements of the ExoMars payload including Raman and Life Marker Chip Instruments.

Fuller understanding of life’s origin, evolution, and distribution requires major advances on all these topics, as well as the extensive challenge of integrating these topics. During the next three years of NAI support we anticipate significant progress in each of these six areas, as well as considerable advances derived from integrating these theoretical, experimental, and field studies.

Highlights in the area of Studies of the Physical and chemical evolution of planetary systems during the past year (2010-2011) include the following:

  • The Planet Finding Spectrometer on the Magellan telescope is now producing 1 m/s precision and finding terrestrial mass planet candidates in and near the habitable zone of M dwarf stars.
  • A new automated Planet Finding telescope at the Lick Observatory has been built and tested and will go into science mode late in 2011.
  • The CIW CAPSCam-S instrument has preliminary data on ~ 100 target stars, 23 of which now have sufficient data to confirm low mass binary companions or to place upper mass limits on known Doppler Planets.
  • CoI Sheppard has surveyed the southern sky and Galactic plane for bright Trans-Neptunian objects and detected eighteen new objects, several of which may be dwarf planets.
  • CoI Weinberger completed her Spitzer Space Telescope study of the dust star BD+20 307, which has orders of magnitude more hot dust than any other star its age (>1Ga), this dust is not primordial and could be the signature of a giant planetary collision.
  • Compositional analysis of Kuiper Belt objects reveal variation in water and methane content that may result from the collisional history of Haumea family objects.
  • Molecular spectroscopic analysis of organic solids extracted from new fragments of the Tagish lake meteorite reveal a very high degree of chemical variation that reflects molecular modification in response to a, as yet, poorly understood history of this enigmatic early Solar System relic.
  • Studies of Comet 81P/Wild 2 particles, Interplanetary Dust Particles, and primitive chondritic meteorites reveal that all share a common origin for the abundant extraterrestrial organic solids contained within them, where the ultimate origin of such solids is interstellar formaldeyde and its condensation products.
  • Coordinated micro-analysis of carbonaceous nano-globules reveals a range of textures and chemically distinct classes of material, suggesting a complex history of organic synthesis early in Solar System history.
  • A strong correlation between stellar abundance trends and metallicity suggests that planetesimal formation increases with stellar metallicity.
  • The MESSENGER spacecraft was successfully inserted into orbit about Mercury on 18 March 2011. Preliminary data are helping inform us about how Mercury formed and evolved.
  • Experiments reveal that the capacity of C-O-H bearing fluids to hold onto carbon during ascent from the Earth’s deep mantle decreases and carbon precipitates into different carbon species. This may change our assessment of the amount of carbon stored in the Earth’s deep mantle.
  • High pressure-high Temperature studies of ammonia indicate high chemical reactivity at conditions relevant to the interiors of giant planets and may explain the presence of nitrogen in the atmosphere of Neptune.
  • The analysis of mineral inclusions in diamonds reveal the clear chemical signature of recycled oceanic lithosphere pointing to a long-lived and very deep carbon cycle.
  • Radiogenic isotopic analysis of sulfide inclusion within diamonds indicates that modern style plate tectonics likely started at 3.2 Ga. Earlier in Earth history, crustal growth likely occurred through vertical accretion.
  • The evolution of mercury bearing minerals over Earth history reveal striking trends that reflect significant geotectonic events.
  • The catalytic formation of simple peptides from amino acids by transition metal sulfides is enhanced considerably at lower temperatures. Specific amino acid-mineral surface interactions are detected that likely explain the catalytic nature of metal sulfides.
  • Field investigation of microbial ecosystems in active serpentinization systems reveal novel alkaliphilic microorganisms.
  • Analysis of molecular pigment tracing in arctic ices and associated stable isotopic analyses reveal the potential for storing biosignatures in polar ices. Life can be transported and stored in ice for extended periods of time, which may be relevant for searching for signs of life in Martian icy soils and polar ice caps.
  • Microbial communities in subsurface hydrothermal fluids are exposed to very high rates of viral infection. Viruses likely play a crucial role in facilitating adaptability to extreme conditions in the deep biosphere.
  • Multiple sulfur isotopic studies reveal the signature of rising sulfidic deep waters at the end of the Permian mass extinction. Experiments reveal confirm that large mass independent sulfur isotopic fractionation cannot be explained by purely thermal chemistry.
  • Microspectral analysis of Paleozoic trilobite fossils using Scanning Transmission X-ray Microscopy reveals molecular evidence for the extensive preservation of chitin-protein complex back to 505 Ma. It is likely that the organic fossil record owes its existence to the recalcitrant nature of chitin-protein complex.
  • An investigation into the evolution of borate minerals on Earth reveal that the extent to which borate minerals were present on the Earth’s surface depends upon whether a granitic continental crust had differentiated. This may limit the role of borate minerals as a means of stabilizing ribose for the gain of RNA world hypotheses.
  • Instruments designed for flight for NASA’s Mars Science Laboratory and ESA’s ExoMars programs were tested on Svalbard Island Norway, a Mars analog site, under harsh arctic conditions. These tests are invaluable to gain insight of instrumentation operation prior to launch and ultimate operation on Mars.