Effects of oblique impacts on the impact strength of porous gypsum and glass spheres: Implications for the collisional disruption of planetesimals in thermal evolution

Bennu’s near-Earth lifetime of 1.75 million years inferred from craters on its boulders

“…For example, Bennu's 1-m-radius boulders require a factor of 4 to 10 less specific impact energy to disrupt than 1-m-radius basalt and pumice boulders. The values of ) * measured for basalt and pumice were for oblique impacts, which lead to higher ) * , as demonstrated in laboratory impact experiments [18]. Furthermore, we find that 1-cm radius targets have a ) * = 1.1 × 10 E − 3.0 × 10 E erg/g, which is comparable to experimentally determined values of ) * for hydrated carbonaceous chondrites, which have a lower limit of ) * > 1.4 × 10 E erg/g.…”

Cratering Experiments on Granular Targets With a Variety of Particle Sizes: Implications for Craters on Rubble‐Pile Asteroids

“…One of the most important results in our experiments is that the cratering efficiency of the "C-10" Mix T and F was smaller than that for the Mix F without "C-10" results. We calculated the 𝐴𝐴 𝐴𝐴 of the "C-10" targets using the impact strength of glass sphere obtained by Yasui et al (2020) (in this calculation, we assumed that the impact strength did not depend on size), and compared them with the appearance of the recovered fragments of impacted 10 mm-sized glass bead or itself. As a result, the impacted 10 mm-sized bead was cracked at 𝐴𝐴 𝐴𝐴 = 0.05-1.3 or disrupted into some fragments at 𝐴𝐴 𝐴𝐴 = 2.0-27.8.…”

“…We calculated the $$\xi $$ of the “C‐10” targets using the impact strength of glass sphere obtained by Yasui et al. (2020) (in this calculation, we assumed that the impact strength did not depend on size), and compared them with the appearance of the recovered fragments of impacted 10 mm‐sized glass bead or itself. As a result, the impacted 10 mm‐sized bead was cracked at $$\xi $$ = 0.05–1.3 or disrupted into some fragments at $$\xi $$ = 2.0–27.8.…”