Comment Re:Why speed is important? (Score 2) 52
I think that's for momentum scaling. But impact craters generally scale with energy. A portion of the projectile's energy is transferred to the target and excavates a crater (O'Keefe and Ahrens, 1977). So the excavated crater scaling is really somewhere between momentum and energy. The pi-scaling relation's give a weak dependence of crater diameter on energy D ~ KE^0.22 (Melosh, 1989), or D ~ v^0.44. I believe depth-to-diameter ratio is more or less constant (Nagel and Fechtig, 1980), at least for simple craters. So you'd get a similar scaling for depth on velocity. Of course, 2 km/s is hardly even hypervelocity, so this scaling might not even apply yet.
(I know, these are some pretty ancient references.)