A large crater is formed in a thick aluminum slab target by a
lexan (plastic) projectile similar to the one shown in the photograph (above right). Note the petaled
lip surrounding the crater. The impact velocity in this test was about 6.92 km/s.
A hypervelocity impact usually manifests itself through cratering and perforation.
A typical crater will have a frozen raised lip around its perimeter. The extreme energies generated
during the hypervelocity impact event cause the material to melt momentarily. This melted material is ejected out
the front surface by the force of the impact, where it quickly cools to solid and is "frozen" in time. If the impacted material is thin enough,
the crater will perforate the rear surface.
This cratering phenomena, observed during testing and in actual impacts with spacecraft, is analogous to that observed on a larger
scale with those craters found on the moon, or those observed when comet Shoemaker-Levy crashed into Jupiter.
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