Sulfur Ion Implantations Into Condensed CO2: Implications for Europa

TL;DR

This study investigates sulfur ion implantation into condensed CO2 ice at different temperatures, finding SO2 formation at 20 K but not at 70 K, suggesting alternative mechanisms for SO2 on Europa.

Contribution

It provides experimental evidence on sulfur ion implantation into CO2 ice at Europa-relevant temperatures, clarifying conditions for SO2 formation.

Findings

SO2 forms at 20 K after sulfur ion implantation.

No SO2 formation observed at 70 K, relevant to Europa conditions.

Implantation at higher temperatures does not produce SO2.

Abstract

The ubiquity of sulfur ions within the Jovian magnetosphere has led to suggestions that the implantation of these ions into the surface of Europa may lead to the formation of SO2. However, previous studies on the implantation of sulfur ions into H2O ice (the dominant species on the Europan surface) have failed to detect SO2 formation. Other studies concerned with similar implantations into CO2 ice, which is also known to exist on Europa, have offered seemingly conflicting results. In this letter, we describe the results of a study on the implantation of 290 keV S+ ions into condensed CO2 at 20 and 70 K. Our results demonstrate that SO2 is observed after implantation at 20 K, but not at the Europa-relevant temperature of 70 K. We conclude that this process is likely not a reasonable mechanism for SO2 formation on Europa, and that other mechanisms should be explored instead.