Alex Sokolowska - From Ejecta to “Wind Streaks”: Interpreting New Impacts on Mars and the Moon

The surfaces of Mars and the Moon are continuously bombarded by meteoroids that excavate surface material and distribute it laterally around the impact point. Cataloging these impact events can advance research on the nature of the impact process, the structure of planetary subsurfaces, impact cratering rates, and even models of planetary interior structure. In particular, when captured, such impact events serve as fortunate natural subsurface probes. For example, they can reveal the presence of shallow subsurface water ice, which is of interest from an astrobiological perspective, or inform us about the physical properties of the subsurface through the geomorphology of impact sites. This is because crater size and morphology can be sensitive to target properties.

In this talk, I will discuss three research projects that decode the information carried by surface imaging of newly formed impact sites:

1. Craters are surrounded by ejecta blankets whose radii vary across the planetary surface. Our recent impact simulations test whether ejecta radius reflects the diversity of geologically motivated subsurface structures. (Spoiler: the results show great promise for using this observable as a new diagnostic of planetary subsurfaces.)

2. During the entry, descent, and landing of mission hardware such as Mars 2020 carrying Perseverance rover, some ejected ballast masses (intended as space debris) formed “artificial” craters. I will discuss the challenges involved in repurposing such mission hardware as subsurface probes.

3. Many, although not all, impact sites feature elongated morphological structures resembling “wind streaks,” which typically form on Mars around obstacles such as crater rims. However, the streaks observed around new craters, although morphologically similar, imply a very different formation mechanism. I will present analyses that help discriminate between competing formation theories.

I will conclude with an outlook on the future of studying meteoroids bombarding Mars, considering upcoming missions and concepts (e.g., Lunar Meteoroid Impacts Observer, METEORCAM, and HiRIME on LightShip propulsion tugs), as well as planetary defense efforts outlined in a recent white paper submitted to UK Space Frontiers 2035.