Institution
NASA Astrobiology Institute
Facility•Mountain View, California, United States•
About: NASA Astrobiology Institute is a facility organization based out in Mountain View, California, United States. It is known for research contribution in the topics: Planet & Exoplanet. The organization has 318 authors who have published 440 publications receiving 19554 citations.
Topics: Planet, Exoplanet, Planetary system, Stars, Biosphere
Papers published on a yearly basis
Papers
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TL;DR: This paper presents a probabilistic analysis of the stationary phase replacement of Na6(CO3)(SO4)/ Na2SO4 in horseshoe clusters and shows clear trends in the number of stationary phases and in the stationary phases of Na2CO3.
Abstract: Kepa Ruiz-Mirazo,†,∥ Carlos Briones,‡,∥ and Andreś de la Escosura* †Biophysics Unit (CSIC-UPV/EHU), Leioa, and Department of Logic and Philosophy of Science, University of the Basque Country, Avenida de Tolosa 70, 20080 Donostia−San Sebastiań, Spain ‡Department of Molecular Evolution, Centro de Astrobiología (CSIC−INTA, associated to the NASA Astrobiology Institute), Carretera de Ajalvir, Km 4, 28850 Torrejoń de Ardoz, Madrid, Spain Organic Chemistry Department, Universidad Autońoma de Madrid, Cantoblanco, 28049 Madrid, Spain
616 citations
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TL;DR: A bacterium is described, isolated from Mono Lake, California, that is able to substitute arsenic for phosphorus to sustain its growth and exchange of one of the major bio-elements may have profound evolutionary and geochemical importance.
Abstract: Life is mostly composed of the elements carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus Although these six elements make up nucleic acids, proteins, and lipids and thus the bulk of living matter, it is theoretically possible that some other elements in the periodic table could serve the same functions Here, we describe a bacterium, strain GFAJ-1 of the Halomonadaceae, isolated from Mono Lake, California, that is able to substitute arsenic for phosphorus to sustain its growth Our data show evidence for arsenate in macromolecules that normally contain phosphate, most notably nucleic acids and proteins Exchange of one of the major bio-elements may have profound evolutionary and geochemical importance
455 citations
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TL;DR: In this article, Keck telescope HIRES echelle observations of DA white dwarfs in a continuation of an extensive search for metals were used to compare the predictions of previously published models involving the accretion of interstellar matter and of comets.
Abstract: We report Keck telescope HIRES echelle observations of DA white dwarfs in a continuation of an extensive search for metals. These spectra are supplemented with new JHK magnitudes that are used to determine improved atmospheric parameters. Of the DA white dwarfs not in binary or common proper motion systems, about 25% show Ca II lines. For these, Ca abundances are determined from comparison with theoretical equivalent widths from model atmosphere calculations; in a few cases we also obtain Mg, Fe, Si, and Al abundances. If Ca is not observed, we generally determine very stringent upper limits. We compare the data to predictions of previously published models involving the accretion/diffusion of interstellar matter and of comets. The derived abundances are not obviously compatible with the predictions of either model, which up to now could only be tested with traces of metals in helium-rich white dwarfs. By modifying certain assumptions in the published interstellar accretion model we are able to match the distribution of the elements in the white dwarf atmospheres, but, even so, tests of other expectations from this scenario are less successful. Because comet accretion appears unlikely to be the primary cause of the DAZ phenomenon, the data suggest that no more than about 20% of F-type main-sequence stars are accompanied by Oort-like comet clouds. This represents the first observational estimate of this fraction. A plausible alternative to the accretion of cometary or interstellar matter is disruption and accretion of asteroidal material, a model first suggested in 1990 to explain excess near-infrared emission from the DAZ G29-38. An asteroidal debris model to account for the general DAZ phenomenon does not presently disagree with the HIRES data, but neither is there any compelling evidence in support of such a model. The HIRES data indicate that in close red dwarf/white dwarf binaries not known to be cataclysmic variables there is, nonetheless, significant mass transfer, perhaps in the form of a wind flowing off the red dwarf. As a by-product we find from the kinematics of GD 165 a likely age of more than 2 Gyr for its probable brown dwarf companion GD 165B.
439 citations
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Lawrence Berkeley National Laboratory1, Massachusetts Institute of Technology2, Pacific Northwest National Laboratory3, Florida State University4, United States Department of Energy5, National Taiwan University6, Desert Research Institute7, University of Western Ontario8, NASA Astrobiology Institute9, Indiana University10, University of California, Berkeley11, Princeton University12
TL;DR: DNA from low-biodiversity fracture water collected at 2.8-kilometer depth in a South African gold mine was sequenced and assembled into a single, complete genome that indicates a motile, sporulating, sulfate-reducing, chemoautotrophic thermophile that can fix its own nitrogen and carbon by using machinery shared with archaea.
Abstract: DNA from low-biodiversity fracture water collected at 2.8-kilometer depth in a South African gold mine was sequenced and assembled into a single, complete genome. This bacterium, Candidatus Desulforudis audaxviator, composes >99.9% of the microorganisms inhabiting the fluid phase of this particular fracture. Its genome indicates a motile, sporulating, sulfate-reducing, chemoautotrophic thermophile that can fix its own nitrogen and carbon by using machinery shared with archaea. Candidatus Desulforudis audaxviator is capable of an independent life-style well suited to long-term isolation from the photosphere deep within Earth's crust and offers an example of a natural ecosystem that appears to have its biological component entirely encoded within a single genome.
421 citations
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University of California, Riverside1, Virtual Planetary Laboratory2, Ames Research Center3, Goddard Institute for Space Studies4, Columbia University5, University of Maryland, Baltimore6, Arizona State University7, Goddard Space Flight Center8, NASA Astrobiology Institute9, University of Washington10, University of Edinburgh11, German Aerospace Center12, Cornell University13, University of St Andrews14, California Institute of Technology15
TL;DR: A comprehensive overview of the current understanding of potential exoplanet biosignatures, including gaseous, surface, and temporal signatures, can be found in this article, with a focus on recent advances in assessing biosignature plausibility.
Abstract: In the coming years and decades, advanced space- and ground-based observatories will allow an unprecedented opportunity to probe the atmospheres and surfaces of potentially habitable exoplanets for signatures of life. Life on Earth, through its gaseous products and reflectance and scattering properties, has left its fingerprint on the spectrum of our planet. Aided by the universality of the laws of physics and chemistry, we turn to Earth's biosphere, both in the present and through geologic time, for analog signatures that will aid in the search for life elsewhere. Considering the insights gained from modern and ancient Earth, and the broader array of hypothetical exoplanet possibilities, we have compiled a comprehensive overview of our current understanding of potential exoplanet biosignatures, including gaseous, surface, and temporal biosignatures. We additionally survey biogenic spectral features that are well known in the specialist literature but have not yet been robustly vetted in the context of exoplanet biosignatures. We briefly review advances in assessing biosignature plausibility, including novel methods for determining chemical disequilibrium from remotely obtainable data and assessment tools for determining the minimum biomass required to maintain short-lived biogenic gases as atmospheric signatures. We focus particularly on advances made since the seminal review by Des Marais et al. The purpose of this work is not to propose new biosignature strategies, a goal left to companion articles in this series, but to review the current literature, draw meaningful connections between seemingly disparate areas, and clear the way for a path forward.
320 citations
Authors
Showing all 318 results
Name | H-index | Papers | Citations |
---|---|---|---|
James M. Tiedje | 150 | 688 | 102287 |
Barry Zuckerman | 105 | 624 | 40648 |
Jonathan Williams | 102 | 613 | 41486 |
Sara Seager | 100 | 510 | 45438 |
James F. Kasting | 96 | 276 | 31670 |
Drake Deming | 94 | 442 | 32023 |
Eric Agol | 93 | 429 | 37801 |
James J. Elser | 90 | 317 | 38800 |
Timothy W. Lyons | 89 | 292 | 27658 |
John W. Valley | 87 | 500 | 31230 |
Roger E. Summons | 86 | 471 | 30853 |
David Crisp | 79 | 328 | 18440 |
Robert M. Hazen | 76 | 365 | 19735 |
David J. Des Marais | 76 | 196 | 20998 |
Inseok Song | 74 | 260 | 19939 |