Radiation Sputtering of Hydrocarbon Ices at Europa-relevant Temperatures

The surfaces of some icy moons, such as Jupiter’s moon Europa, are heavily bombarded by energetic particles that can alter the surface materials and affect the composition of its exosphere. Detection of CO₂ on Europa’s surface indicate that Europa’s interior may be transporting freshly exposed carbon-containing material to the surface.

It is unknown whether this CO₂ is a product of radiation of carbon-containing precursors or whether it is present in the initial deposits. Regardless, further radiolysis by high-energy electrons or ions can sputter CO₂ (and organic fragments if present) into Europa’s exosphere.

In this study, we investigate the radiation sputtering of CO₂ and organic fragments from hydrocarbon water ice mixtures at different Europa-relevant surface temperatures to identify how its sputtering products evolve over time. This study shows that the sputtering of hydrocarbon water ice leads to the production of mostly CO₂, CO, and fragmented hydrocarbons. The onset of sputtered hydrocarbons is immediate, and quickly reaches a steady state, whereas CO₂ and CO are formed more gradually.

It is found that higher temperatures cause more sputtering, and that there are some notable differences in the distribution of species that are sputtered at different temperatures, indicating local heterogeneity of sputtering yields depending on the surface temperature.

Experimental setup for the electron sputtering experiments of ice surfaces, installed at the Jet Propulsion Laboratory’s Ice Spectroscopy Laboratory (ISL). Left: the vacuum chamber with electron gun and quadrupole mass spectrometer. H₂O and hexane are vapor deposited on the top of the cold copper rod. Right: a photograph of the system. — astro-ph.EP

Sankhabrata Chandra, Bryana L. Henderson, Murthy S. Gudipati

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Materials Science (cond-mat.mtrl-sci)
Cite as: arXiv:2502.00257 [astro-ph.EP] (or arXiv:2502.00257v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2502.00257
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Submission history
From: Bryana Henderson
[v1] Sat, 1 Feb 2025 01:35:09 UTC (2,743 KB)
[v2] Sat, 1 Mar 2025 00:32:29 UTC (2,743 KB)
https://arxiv.org/abs/2502.00257

Astrobiology,