Oxygen production from dissociation of Europa's water-ice surface.

Autor: Szalay JR; Department of Astrophysical Sciences, Princeton University, Princeton, NJ USA., Allegrini F; Southwest Research Institute, San Antonio, TX USA.; Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX USA., Ebert RW; Southwest Research Institute, San Antonio, TX USA.; Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX USA., Bagenal F; Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, Boulder, CO USA., Bolton SJ; Southwest Research Institute, San Antonio, TX USA., Fatemi S; Department of Physics, University of Umeå, Umeå, Sweden., McComas DJ; Department of Astrophysical Sciences, Princeton University, Princeton, NJ USA., Pontoni A; Southwest Research Institute, San Antonio, TX USA., Saur J; Institute of Geophysics and Meteorology, University of Cologne, Cologne, Germany., Smith HT; The Johns Hopkins University Applied Physics Laboratory, Baltimore, MD USA., Strobel DF; The Johns Hopkins University, Baltimore, MD USA., Vance SD; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA USA., Vorburger A; Physics Institute, University of Bern, Bern, Switzerland., Wilson RJ; Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, Boulder, CO USA.
Jazyk: angličtina
Zdroj: Nature astronomy [Nat Astron] 2024; Vol. 8 (5), pp. 567-576. Date of Electronic Publication: 2024 Mar 04.
DOI: 10.1038/s41550-024-02206-x
Abstrakt: Jupiter's moon Europa has a predominantly water-ice surface that is modified by exposure to its space environment. Charged particles break molecular bonds in surface ice, thus dissociating the water to ultimately produce H 2 and O 2 , which provides a potential oxygenation mechanism for Europa's subsurface ocean. These species are understood to form Europa's primary atmospheric constituents. Although remote observations provide important global constraints on Europa's atmosphere, the molecular O 2 abundance has been inferred from atomic O emissions. Europa's atmospheric composition had never been directly sampled and model-derived oxygen production estimates ranged over several orders of magnitude. Here, we report direct observations of H 2 + and O 2 + pickup ions from the dissociation of Europa's water-ice surface and confirm these species are primary atmospheric constituents. In contrast to expectations, we find the H 2 neutral atmosphere is dominated by a non-thermal, escaping population. We find 12 ± 6 kg s -1 (2.2 ± 1.2 × 10 26  s -1 ) O 2 are produced within Europa's surface, less than previously thought, with a narrower range to support habitability in Europa's ocean. This process is found to be Europa's dominant exogenic surface erosion mechanism over meteoroid bombardment.
Competing Interests: Competing interestsThe authors declare no competing interests.
(© The Author(s) 2024.)
Databáze: MEDLINE
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