Surface refreshing of Martian moon Phobos by orbital eccentricity-driven grain motion

Experimental Insights Into Space Weathering of Phobos: Laboratory Investigation of Sputtering by Atomic and Molecular Planetary Ions

“…The fluence needed to reach this steady state corresponds to several hundred years of solar wind irradiation. A steady state on the exposed surface can be assumed as recent calculations estimate the timescales for surface refreshing to be 10 3 –10 6 years (Ballouz et al., 2019). An uncertainty for the total effect of multiply charged ions is introduced by the potential sputtering increase being constant for all investigated angles of incidence (Szabo et al., 2020a).…”

“…For example, near‐infrared spectrophotometry has uncovered “redder” and “bluer” regions (Rivkin et al., 2002). Simulations of grain motions due to the orbital eccentricity of Phobos show that blue regions are more likely to feature new material on the surface (Ballouz et al., 2019). Reddening of optical spectra as a result of space weathering is a common finding in general (Marchi et al., 2005).…”

The surface sensitivity of rubble-pile asteroids during a distant planetary encounter: Influence of asteroid shape elongation

“…Furthermore, if the slope variation is high enough to cause surface mobility, granular flows may occur for sub-critical slopes. Ballouz et al (2019) showed this mechanism operating on the surface of the Martian moon Phobos, leading to the resurfacing process; however, this mechanism may not be proper for the planetary encounter resurfacing because it is a non-periodic event. In our analysis, we use the slope variation to see how sensitive surfaces become during the distant planetary encounter.…”

“…The surface slope variation ( ) is the angle difference of a given element between the maximum surface slope during the flyby and the initial slope before the flyby. This quantity was used to analyze resurfacing on the martian moon, Phobos (Ballouz et al, 2019).…”

Granular flow on a rotating and gravitating elliptical body

“…Recently, in the context of resurfacing of Mars’ moon Phobos, Ballouz et al. (2019) demonstrated that a granular flow could be driven by even the gentle perturbations from the orbital eccentricity of the body. The primary mechanism for the accumulation of surface regolith is thought to be the agglomeration of impact ejecta.…”