Cassini finds an oxygen-carbon dioxide atmosphere at Saturn's icy moon Rhea

B. D. Teolis, G. H. Jones, P. F. Miles, R. L. Tokar, B. A. Magee, J. H. Waite, E. Roussos, D. T. Young, F. J. Crary, A. J. Coates, R. E. Johnson, W. L. Tseng, R. A. Baragiola

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Abstract

The flyby measurements of the Cassini spacecraft at Saturn's moon Rhea reveal a tenuous oxygen (O2)-carbon dioxide (CO2) atmosphere. The atmosphere appears to be sustained by chemical decomposition of the surface water ice under irradiation from Saturn's magnetospheric plasma. This in situ detection of an oxidizing atmosphere is consistent with remote observations of other icy bodies, such as Jupiter's moons Europa and Ganymede, and suggestive of a reservoir of radiolytic O2 locked within Rhea's ice. The presence of CO2 suggests radiolysis reactions between surface oxidants and organics or sputtering and/or outgassing of CO2 endogenic to Rhea's ice. Observations of outflowing positive and negative ions give evidence for pickup ionization as a major atmospheric loss mechanism.

Original languageEnglish
Pages (from-to)1813-1815
Number of pages3
JournalScience
Volume330
Issue number6012
DOIs
Publication statusPublished - 2010 Dec 24

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    Teolis, B. D., Jones, G. H., Miles, P. F., Tokar, R. L., Magee, B. A., Waite, J. H., Roussos, E., Young, D. T., Crary, F. J., Coates, A. J., Johnson, R. E., Tseng, W. L., & Baragiola, R. A. (2010). Cassini finds an oxygen-carbon dioxide atmosphere at Saturn's icy moon Rhea. Science, 330(6012), 1813-1815. https://doi.org/10.1126/science.1198366