Microgravity and Planet Formation
Simulations of planet formation that begin with planetesimals have reached a state where the main properties of the solar system are reproduced. Formation of planetesimals themselves remains poorly understood, however. The role of gravitational instabilities in the disk is not known. The outcome of interactions of small aggregates and dust in the presence of the protoplanetary nebula is also poorly understood. We are studying the formation of planetesimals through experiments and numerical simulations. On the experimental side, we conduct low-speed impact experiments between aggregates and single particles in the lab and occasionally in microgravity flight environments (including on parabolic airplane flights, suborbital rocket flights, and experiments on the International Space Station (ISS)). The goal is to understand the role of surface forces in leading to adhesion between aggregates as well as the dissipation of energy in low-speed collisions. The results are also applicable to the collisions in planetary rings.