Project P7: Impact experiments at high speeds and fragment distributions (IGW/Jena)


Debris disks become observable through the enhanced thermal emission of dust grains, which are produced by collisional fragmentation. Numerical simulations of debris disks require knowledge of the fragment size distribution in collisions which, for instance in the extrasolar asteroid belt analogs and in the scattered parts of the extrasolar “Kuiper belts”, occur at high impact velocities. Accordingly, we propose to (1) perform high-speed collision experiments under controlled impact conditions and (2) determine the real fragment size distribution on an asteroid surface. The high-speed impact experiments will be carried out in cooperation with the Fraunhofer Institute for High-Speed Dynamics, Freiburg, Germany. We will use spherically shaped, mm- to cm-sized targets and projectiles made of realistic astromineralogical materials (chondritic meteorites with peridotitic composition). An important outcome will be the critical fragmentation energy QD* for high impact velocities (~3−5 km/s). The real fragment size distribution in the asteroid belt (i.e., debris disk in the solar system) will be derived from electron-microscopic observations of dust grains from asteroid Itokawa, which were returned by the Hayabusa 1 mission. The University of Jena has a formal cooperation agreement with JAXA. This project is complementary to P6 (impacts at low speed) and will yield data that will be implemented into the projects P1, P2, and P3.