  Recent observations of asteroidal surfaces indicate the presence of materials
that do not match the bulk lithology of the body. A possible explanation for
the presence of these exogenous materials is that they are products of
inter-asteroid impacts in the Main Belt, and thus interest has increased in
understanding the fate of the projectile during hypervelocity impacts. In order
to gain insight into the fate of impactor we have carried out a laboratory
programme, covering the velocity range of 0.38 - 3.50 km/s, devoted to
measuring the survivability, fragmentation and final state of the impactor.
Forsterite olivine and synthetic basalt projectiles were fired onto low
porosity (<10%) pure water-ice targets using the University of Kent's Light Gas
Gun (LGG). We developed a novel method to identify impactor fragments which
were found in ejecta and implanted into the target. We applied astronomical
photometry techniques, using the SOURCE EXTRACTOR software, to automatically
measure the dimensions of thousands of fragments. This procedure enabled us to
estimate the implanted mass on the target body, which was found to be a few
percent of the initial mass of the impactor. We calculated an order of
magnitude difference in the energy density of catastrophic disruption, Q*,
between peridot and basalt projectiles. However, we found very similar
behaviour of the size frequency distributions for the hypervelocity shots (>1
km/s). After each shot, we examined the largest peridot fragments with Raman
spectroscopy and no melt or alteration in the final state of the projectile was
observed.
