Microgravity Experiments On The First Steps of Planet Formation

In the very first steps of planet formation, dust particles inside the protoplanetary disk collide with each other and grow from micrometer sizes to aggregates of a few centimeters. In order to investigate the dust collision behavior at low velocities, the SPACE (Suborbital Particle Aggregation and Collision Experiment) set-up was flown at the drop tower in Bremen, Germany (9 s of microgravity time), and on the REXUS 12 suborbital rocket from Kiruna, Sweden (170 s of microgravity time). The results of these experiments allowed for the measurement of critical collision properties of sub-mm-sized dust aggregates, especially in the transition regimes between sticking, bouncing and fragmentation. In particular, the formation and characteristics of clusters composed of a high number of aggregates were observed and yielded relevant information for future protoplanetary disk simulations.