IMPACT REGIMES AND POST-FORMATION SEQUESTRATION PROCESSES: IMPLICATIONS FOR THE ORIGIN OF HEAVY NOBLE GASES IN TERRESTRIAL PLANETS

Journal Article · Mon May 10 04:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/714/2/1418· OSTI ID:21448817

Mousis, Olivier; Petit, Jean-Marc; Picaud, Sylvain; Thomas, Caroline ^[1]; Lunine, Jonathan I ^[2]; Schmitt, Bernard ^[3]; Marquer, Didier ^[4]; Horner, Jonathan ^[5]

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1. Universite de Franche-Comte, Institut UTINAM, CNRS/INSU, UMR 6213, 25030 Besancon Cedex (France)
2. Dipartimento di Fisica, Universita degli Studi di Roma 'Tor Vergata', Rome (Italy)
3. Universite Joseph Fourier, Laboratoire de Planetologie de Grenoble, CNRS/INSU, UMR 5109, Observatoire de Sciences de l'Univers de Grenoble (France)
4. Universite de Franche-Comte, Chrono-Environnement, CNRS/INSU, UMR 6249, 25030 Besancon Cedex (France)
5. Department of Physics, Science Laboratories, University of Durham, South Road, Durham, DH1 3LE (United Kingdom)

The difference between the measured atmospheric abundances of neon, argon, krypton, and xenon for Venus, Earth, and Mars is striking. Because these abundances drop by at least 2 orders of magnitude as one moves outward from Venus to Mars, the study of the origin of this discrepancy is a key issue that must be explained if we are to fully understand the different delivery mechanisms of the volatiles accreted by the terrestrial planets. In this work, we aim to investigate whether it is possible to quantitatively explain the variation of the heavy noble gas abundances measured on Venus, Earth, and Mars, assuming that cometary bombardment was the main delivery mechanism of these noble gases to the terrestrial planets. To do so, we use recent dynamical simulations that allow the study of the impact fluxes of comets upon the terrestrial planets during the course of their formation and evolution. Assuming that the mass of noble gases delivered by comets is proportional to the rate at which they collide with the terrestrial planets, we show that the krypton and xenon abundances in Venus and Earth can be explained in a manner consistent with the hypothesis of cometary bombardment. In order to explain the krypton and xenon abundance differences between Earth and Mars, we need to invoke the presence of large amounts of CO{sub 2}-dominated clathrates in the Martian soil that would have efficiently sequestered these noble gases. Two different scenarios based on our model can also be used to explain the differences between the neon and argon abundances of the terrestrial planets. In the first scenario, cometary bombardment of these planets would have occurred at epochs contemporary with the existence of their primary atmospheres. Comets would have been the carriers of argon, krypton, and xenon, while neon would have been gravitationally captured by the terrestrial planets. In the second scenario, we consider impacting comets that contained significantly smaller amounts of argon, an idea supported by predictions of noble gas abundances in these bodies, provided that they formed from clathrates in the solar nebula. In this scenario, neon and argon would have been supplied to the terrestrial planets via the gravitational capture of their primary atmospheres whereas the bulk of their krypton and xenon would have been delivered by comets.

• OSTI ID: 21448817
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 714; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
ARGON
ATMOSPHERES
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CLATHRATES
COMETS
EARTH PLANET
ELEMENTS
EVOLUTION
FLUIDS
GASES
KRYPTON
MARS PLANET
NEBULAE
NEON
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PLANETARY ATMOSPHERES
PLANETS
RARE GASES
SATELLITES
SOLAR NEBULA
SOLAR SYSTEM EVOLUTION
VENUS PLANET
XENON