Hypervelocity impact experiments on water ice targets have been performed using a two stage light gas gun. The resulting craters were measured to obtain the crater depth and diameter. From the data set for 23 impact craters, damage equations have been obtained which give the crater depth (diameter) in terms of the dependence on impact velocity, projectile diameter and projectile density. The resulting damage equations are compared to those for another brittle material, glass. Scaling of the excavated crater volume with energy is shown to obey a simple power law over 10 orders of magnitude in energy (10(-7) to 10(3) J). (C) 2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved.