Solid state physics of impact crater formation: a detail
  Impact craters exist on solid surface planets, their satellites and many asteroids.The aim of this paper is to propose a theoretical expression for the product $\rho r^{3} v_{1}^{2}$,where the three symbols denote the mass density,radius and speed of the impactor. The expression is derived using well known results of solid state physics,and it can be used in estimating parameters of impactors which have led to formation of craters on various solid bodies in the Solar System. 
V. Celebonovic
astro-ph.EP