Abstract
Abstract We mapped all boulders larger than 105 m on the surface of dwarf planet Ceres using images of the Dawn framing camera acquired in the Low Altitude Mapping Orbit. We find that boulders on Ceres are more numerous toward high latitudes and have a maximum lifetime of 150 ± 50 Ma, based on crater counts. These characteristics are distinctly different from those of boulders on asteroid (4) Vesta, an earlier target of Dawn, which implies that Ceres’ boulders are mechanically weaker. Clues to their properties can be found in the composition of Ceres’ complex crust, which is rich in phyllosilicates and salts. As water ice is thought to be present only meters below the surface, we suggest that boulders also harbor ice. Furthermore, the boulder size–frequency distribution is best fit by a Weibull distribution rather than the customary power law, just like for Vesta boulders. This finding is robust in light of possible types of size measurement error.
Highlights
We find that boulders on Ceres are more numerous towards high latitudes and have a maximum lifetime of 150 ± 50 Ma, based on crater counts
The boulder size-frequency distribution is best fit by a Weibull distribution rather than the customary power law, just like for Vesta boulders
In the previous section we described the properties of the population of large boulders on Ceres and compared them to those of the Vesta population
Summary
Boulders on planetary bodies bear information on past and present surface processes. In particular, the boulder properties and spatial distribution are related to the bulk properties of the parent body and the surface environmental conditions. Boulders on its surface may be affected by more processes than on small bodies, but by fewer than on the larger, more complex terrestrial planets. We investigate the boulder population of Ceres and compare it with that of Vesta (Schroder et al 2020). Both bodies were imaged by the same camera aboard the Dawn spacecraft (Russell & Raymond 2011). Such a comparison benefits from the fact that Vesta and Ceres have comparable distances to the Sun and very similar surface gravities (Basilevsky et al 2013). “boulder” has typically been used for clasts on small airless bodies irrespective of their size, and for consistency with the Vesta study we retain the term boulder
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