Asteroids have diverse lithologies as reflected in the range of recovered meteorites. Size distributions of clasts of asteroid 25143 Itokawa (LL-chondrite) and Tagish Lake meteorites (ungrouped C2 carbonaceous chondrite) indicate variation in fragmentation behavior. The steeper size distribution of the carbonaceous lithology apparently reflects its lower strength. A comparison between the smooth and rough terranes on Itokawa shows that fracturing or intracrater flows apparently eliminate larger fragments.
Carbonaceous chondrites’ P- and S-wave velocities, which are indicators of the elastic moduli, exhibit variation with bulk density, petrologic type, and cosmic-ray exposure ages. The hydrated carbonaceous chondrites apparently record damage from collisions with weaker objects as indicated by their decrease of elastic velocities in proportion to their cosmic ray exposure ages. These inferred collisions are frequent relative to exposure ages of other major meteorite groups. These weaker impactors are not sampled in our meteorite collections, but are evidenced in the fireball population.