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Worlds Beyond: A Strategy for the Detection and Characterization of Exoplanets Report of the ExoPlanet Task Force: with ERRATUM Astronomy and Astrophysics Advisory Committee
, 808
"... ii Round and round, round and round Round and round the Sun The wandering stars go on forever Can you name them one by one? A Child’s Introduction to Outer Space, 1958 iii Acknowledgements ..."
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ii Round and round, round and round Round and round the Sun The wandering stars go on forever Can you name them one by one? A Child’s Introduction to Outer Space, 1958 iii Acknowledgements
Discipline: Sciences de la Terre et de l’Univers
"... Caractérisation des processus d’altération à la surface de Mars primitive par approche expérimentale et télédétection tel-00774415, version 1-___________ THÈSE DE DOCTORAT ..."
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Caractérisation des processus d’altération à la surface de Mars primitive par approche expérimentale et télédétection tel-00774415, version 1-___________ THÈSE DE DOCTORAT
Ecole doctorale des Sciences de l’Environnement
, 2011
"... Spécialité: Chimie de la Pollution Atmosphérique et Physique de l’Environnement Recherche d’indices de vie sur Mars: Caractérisation de l’évolution de molécules organiques soumises aux conditions d’irradiation et d’oxydation représentatives de la surface de Mars Thèse dirigée par Patrice COLL et Cyr ..."
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Spécialité: Chimie de la Pollution Atmosphérique et Physique de l’Environnement Recherche d’indices de vie sur Mars: Caractérisation de l’évolution de molécules organiques soumises aux conditions d’irradiation et d’oxydation représentatives de la surface de Mars Thèse dirigée par Patrice COLL et Cyril SZOPA Soutenue le 29 septembre 2011
Astrobiology
"... If life emerges readily under Earth-like conditions, the possibility arises of multiple terrestrial genesis events. We seek to quantify the probability of this scenario using estimates of the Archean bombardment rate and the fact that life established itself fairly rapidly on Earth once conditions b ..."
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If life emerges readily under Earth-like conditions, the possibility arises of multiple terrestrial genesis events. We seek to quantify the probability of this scenario using estimates of the Archean bombardment rate and the fact that life established itself fairly rapidly on Earth once conditions became favorable. We find a significant likelihood that at least one more sample of life, referred to here as alien life, may have emerged on Earth, and could have coexisted with known life. Indeed, it is difficult to rule out the possibility of extant alien life. We offer some suggestions for how an alternative sample of life might be detected. Key Words: Origin of life---Biogenesis---Impact frustration. Astrobiology 5, 154--163.
unknown title
, 2008
"... I am pleased to transmit to you the report of the Exoplanet Task Force. The report is a comprehensive study of the search for and study of planets around other stars (exoplanets). The young but maturing field of exoplanets is perhaps one of the most compelling fields of study in science today—both b ..."
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I am pleased to transmit to you the report of the Exoplanet Task Force. The report is a comprehensive study of the search for and study of planets around other stars (exoplanets). The young but maturing field of exoplanets is perhaps one of the most compelling fields of study in science today—both because of the discoveries made to date on giant planets around other stars, and because the detection of planets just like our Earth (“Earth analogs”) is at last within reach technologically. In the Report we outline the need for a vigorous research program in exoplanets to understand our place in the cosmos: whether planets like our home Earth are a common or rare outcome of cosmic evolution. The strategy we developed is intended to address the following fundamental questions, in priority order, within three distinct 5-yr long phases, over a 15 year period: 1. What are the physical characteristics of planets in the habitable zones around bright, nearby stars? 2. What is the architecture of planetary systems? 3. When, how and in what environments are planets formed? The Report recommends a two-pronged strategy for the detection and characterization of planets
David Catling, in Encyclopedia of Paleoclimatology and Ancient Environments 1 ATMOSPHERIC EVOLUTION OF MARS
"... Today, Mars is a cold, dry global desert. However, there is considerable evidence that Mars ’ climate and its inventory of volatiles (substances that tend to form gases or vapor) have changed greatly during the planet’s history. The evidence comes from a ..."
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Today, Mars is a cold, dry global desert. However, there is considerable evidence that Mars ’ climate and its inventory of volatiles (substances that tend to form gases or vapor) have changed greatly during the planet’s history. The evidence comes from a
Ices
, 2011
"... a b s t r a c t The two orders of magnitude drop between the measured atmospheric abundances of non-radiogenic argon, krypton and xenon in Earth versus Mars is striking. Here, in order to account for this difference, we explore the hypothesis that clathrate deposits incorporated into the current mar ..."
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a b s t r a c t The two orders of magnitude drop between the measured atmospheric abundances of non-radiogenic argon, krypton and xenon in Earth versus Mars is striking. Here, in order to account for this difference, we explore the hypothesis that clathrate deposits incorporated into the current martian cryosphere have sequestered significant amounts of these noble gases assuming they were initially present in the paleoat-mosphere in quantities similar to those measured on Earth (in mass of noble gas per unit mass of the pla-net). To do so, we use a statistical-thermodynamic model that predicts the clathrate composition formed from a carbon dioxide-dominated paleoatmosphere whose surface pressure ranges up to 3 bars. The influence of the presence of atmospheric sulfur dioxide on clathrate composition is investigated and we find that it does not alter the trapping efficiencies of other minor species. Assuming nominal struc-tural parameters for the clathrate cages, we find that a carbon dioxide equivalent pressure of 0.03 and 0.9 bar is sufficient to trap masses of xenon and krypton, respectively, equivalent to those found on Earth in the clathrate deposits of the cryosphere. In this case, the amount of trapped argon is not sufficient to explain the measured Earth/Mars argon abundance ratio in the considered pressure range. In contrast, with a 2 % contraction of the clathrate cages, masses of xenon, krypton and argon at least equivalent to
Article history:
"... allowing liquid water to flow at the surface of the planet and carv-ing the presently observed valley networks and outflow channels. However, the cooling from sulfur gases as a result of sulfate aerosol formation is an observational fact for the current atmosphere of Earth. On early Mars, the coolin ..."
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allowing liquid water to flow at the surface of the planet and carv-ing the presently observed valley networks and outflow channels. However, the cooling from sulfur gases as a result of sulfate aerosol formation is an observational fact for the current atmosphere of Earth. On early Mars, the cooling effect of sulfate aerosols would also have counteracted efficiently the warming effect due to SO2 so far, suggesting a cold and wet early Mars. Much of the aqueous activity on Mars could have occurred in subsurface hydrothermal systems powered by magmatic or impact activity (Squyres and Kasting, 1994; Griffith and Shock, 1995; Segura et al., 2002, 2008), rather than at the surface of the planet. Sulfur, under both oxidized (SO2) and reduced (H2S) forms, could have been released in large amount by volcanism during the Noachian. From several 100 millibar to around one bar of sul-fur could have been outgassed along martian history, most of which during the Noachian and the Hesperian (see e.g. Craddock
on R e
, 1999
"... geogra have b cap on of colo tatives bacter cores, cultur the clo were r gion th or from their c riboso were r or to n erable cating and/or By ide terrest surviv will be ..."
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geogra have b cap on of colo tatives bacter cores, cultur the clo were r gion th or from their c riboso were r or to n erable cating and/or By ide terrest surviv will be
