And now the May 1 Astronomical Journal (vol. 167 #5):
Ofek, E. O. Polishook, D. Kushnir, D. et al. Asteroid Collisions: Expected Visibility and Rate a 190 ad2c03
Ding, X. Song, Z-M Wang, C-J et al. Detection of Contact Binary Candidates Observed by TESS… a 192 ad3048
Hasegawa, S. Marsset, M. DeMeo, F. Candidate Main-Belt Asteroids for Surface Heterogeneity a 224 ad3045
Sorry to beat the horse, but… boring rocks, indeed. Just boring old rocks. Given the number of asteroids (over one million catalogued- not detected, catalogued), some are bound to collide in any given accounting period. It’s just a question of spotting it, and (in the case of Earth) spotting it soon, and far in advance. Over the life of an asteroid, collisions (and sometimes spinup) results in mass shedding; mass shedding may then result in a satellite (“asteroid moon”) or binary object. Asteroid satellites, due to dynamic effects, may result in orbital decay, and the two recontact, forming a bilobed body.
Less spectacularly, variations in formation or contamination may result in “mixed” asteroids: asteroids whose surfaces show regions of differing composition. We’ve already seen Vesta; we may also see something on Psyche. How many more are there, and in what combinations?