Scaling Laws for Impacts into Wet Substrates: Applied to the Bomb Sag at Home Plate, Mars
Abstract
The Mars Exploration Rover Spirit imaged a volcanic bomb sag in Gusev crater at Home Plate (Squyres et al., Science 2007). In order to gain a more complete understanding of these types of craters, we perform laboratory experiments to identify controls on the main features of bomb sags. In our previous work (Manga et al., GRL 2012), we were able to identify clear qualitative differences in the crater morphology, which allowed us to determine that the substrate at Home Plate was fully saturated. The current study focuses on further understanding the relationship between the depth of particle penetration, crater radius, impact velocity, impactor radius and substrate grain size for impacts into a fully saturated substrate. The results of these measurements provide a physical understanding to the previous empirical scaling relationships in crater morphology at intermediate impact velocities between 10 m/s and 100 m/s. By gaining insight into the mechanisms of how a saturated granular medium deforms under the load of an impacting sphere we are able to obtain revised scaling laws for the penetration depth of bomb sags with respect to impact velocity for observable bomb sags. With an inferred impact velocity for the case of the Home Plate bomb sag, we can provide a more accurate estimate of a paleo-Mars atmospheric density.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.P41F1989B
- Keywords:
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- 6022 PLANETARY SCIENCES: COMETS AND SMALL BODIES Impact phenomena;
- 6225 PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS Mars