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P. Szabo, H. Biber, N. Jäggi, M. Wappl, R. Stadlmayr, D. Primetzhofer, A. Nenning, A. Mutzke, J. Fleig, K. Mezger, H. Lammer, A. Galli, P. Wurz, F. Aumayr:
"Experimental insights into space weathering of Phobos: Laboratory investigation of sputtering by atomic and molecular planetary ions";
Journal of Geophysical Research Planets, 125, e2020JE006583 (2020), 1 - 17.

Investigating the space weathering of the Martian moon Phobos represents an important step toward understanding the development from its origin to its present-day appearance. Depending on Phobos´ orbital position, its surface is continuously sputtered by the solar wind and planetary ions that originate in the Martian atmosphere. Based on Mars Atmosphere and Volatile Evolution measurements, it has been proposed that sputtering by planetary O+ and O2+ ions dominates in the Martian tail region, where the planet mostly shadows Phobos from the solar wind. In these models, uncertainties for sputtering yield inputs still exist due to the lack of sufficient analog experiments. Therefore, sputtering measurements with O+, O2+, C+, and CO2+ ions between 1 and 5 keV were performed using augite samples as Phobos analogs. The experimental results for O+ irradiations show smaller mass changes than predicted by SDTrimSP simulations, which probably can be attributed to O implantation enabled by the Fe content of the target. Sputtering with O2+ and CO2+ in the low keV range shows no deviations in the sputtering yields attributable to molecular effects. Therefore, CO2+ ions will most likely be negligible
for the sputtering of Phobos according to the current understanding of ion fluxes on the Martian moon. Ultimately, our experiments suggest that the sputtering contribution on Phobos by O ions is about 50% smaller than previously assumed. This does not change the qualitative outcome from previous modeling stating that planetary O ions are by far the dominant sputtering contribution on Phobos in the Martian tail region.

. Experiments with Phobos analogs were carried out to evaluate the sputtering by O+, C+, O2+, and CO2+ ions from the Martian atmosphere . The sputter yield from O ions is lower than previously assumed, and no yield increases due to molecular effects were

http://dx.doi.org/10.1029/2020JE006583

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JE006583