  The surface conditions of terrestrial bodies strongly reflect their
geological evolutionary processes and vary among various terrestrial bodies.
This diversity is attributed to variations in the timescales of boulder
formation through processes such as impact cratering, rockfalls from crater
walls, seismic motion, and boulder fragmentation caused by micrometeoroid
impacts and thermal stress. In this study, we examined boulders on Ceres using
high-resolution images with a resolution of approximately 5 m/px obtained
during the Ceres Extended Mission 2 Orbit 7 of the Dawn mission. Almost all
boulders were present around impact craters, even at a resolution of 5 m/px,
thus indicating that the boulders on Ceres were created by impact cratering
alone. The maximum boulder size on Ceres is approximately 200 m, even around
large craters, which may indicate the upper size limit determined by the
mechanical strength of the boulders, such as the tensile strength, the scale
effect, and/or shattering strength. The slope of the size-frequency
distribution of boulders on Ceres varied significantly across the range of
boulder sizes, thus making it difficult to describe it using a single function
of a power-law relationship; in particular, it changed at approximately 100 m,
thus indicating that destructive or formation mechanisms may be different for
large boulders > 100 m and for small boulders < 100 m. There may also be a
subsurface structure that prevents the formation of small boulders, although
this is difficult to argue conclusively. We estimated that the lifetime of
boulders larger than 50 m was equivalent to or shorter than 100 Myr. This
lifetime is consistent with a theoretical estimation assuming that
micrometeoroid impacts are the primary destructive mechanism.
