Impact cratering on volatile-rich targets: Some remarks related to the Deep Impact experiment

The NASA Deep Impact experiment has important implications to better understand cratering processes on planetary bodies and the production and evolution of ejecta. This manmade impact of a solid Cu body on the nucleus of a comet fills the large gap existing between data derived from small-scale cratering experiments and large-scale field or remote sensing observations of craters. DI thus complements hydrocode modeling of cratering processes. The majority of cratering studies focus on solid silicate-rich targets rather than on porous, poorly consolidated and or volatile rich materials. However, volatile targets are common in the Solar System. The lessons learned from the DI collision with comet 9P/Tempel not only clarify the composition and physical properties of the cometary nucleus, but also can shed light on cratering mechanisms and evolution of plume and ejecta.