Astrochemistry

Electron-Induced Radiolysis of Water Ice and the Buildup of Oxygen On Icy Worlds

By Keith Cowing
Status Report
astro-ph.EP
December 9, 2024
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Electron-Induced Radiolysis of Water Ice and the Buildup of Oxygen On Icy Worlds
Experiment setup of the TOF-MS in the MEFISTO chamber. Left panel: Lateral view of the experiment setup with the TOF-MS box mounted on the cooling plate. The electron beam from the top of the chamber impacts the ice in the sample holder at an incidence angle of 45◦ . Right panel: Photograph from the vantage point to the right of the sketch, showing the sample holder underneath the TOF-MS. The distance from the upper edge of the sample holder to the TOF-MS entrance is 100 mm. — astro-ph.EP

Irradiation by energetic ions, electrons, and UV photons induces sputtering and chemical processes (radiolysis) in the surfaces of icy moons, comets, and icy grains.

Laboratory experiments, both of ideal surfaces and of more complex and realistic analog samples, are crucial to understand the interaction of surfaces of icy moons and comets with their space environment.

This study shows the first results of mass spectrometry measurements from porous water ice regolith samples irradiated with electrons as a representative analogy to water-ice rich surfaces in the solar system.

Previous studies have shown that most electron-induced H2O radiolysis products leave the ice as H2 and O2 and that O2 can be trapped under certain conditions in the irradiated ice. Our new laboratory experiments confirm these findings. Moreover, they quantify residence times and saturation levels of O2 in originally pure water ice.

H2O may also be released from the water ice by irradiation, but the quantification of the released H2O is more difficult and the total amount is sensitive to the electron flux and energy.

Chantal Tinner, André Galli, Fiona Bär, Antoine Pommerol, Martin Rubin, Audrey Vorburger, Peter Wurz

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2412.04079 [astro-ph.EP] (or arXiv:2412.04079v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2412.04079
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Journal reference: Journal of Geophysical Research: Planets, 129
Related DOI:
https://doi.org/10.1029/2024JE008393
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Submission history
From: André Galli
[v1] Thu, 5 Dec 2024 11:26:41 UTC (1,357 KB)
https://arxiv.org/abs/2412.04079

Astrobiology, Astrochemistry, Astrogeology,

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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