CubeSat Particle Aggregation Collision Experiment (Q-PACE): Design of a 3U CubeSat mission to investigate planetesimal formation

Observations of the collisional evolution of particle ensembles in a microgravity environment are necessary to characterize the processes that lead to the formation of planetesimals, km-size and larger bodies, within the protoplanetary disk. The two current theories of planetesimal formation, namely growth through binary sticking collisions and gravitational instability within the protoplanetary disk, have difficulties in explaining how particles grow beyond a centimeter in size. In this paper we describe the CubeSat Particle Aggregation and Collision Experiment (Q-PACE), a Low Earth Orbit 3U CubeSat mission that will provide a high-quality, long duration microgravity environment in which we will observe collisions between particles under conditions relevant to planetesimal formation. We have designed a series of experiments involving a broad range of particle size, density, surface properties, and collision velocities to observe collisional outcomes from bouncing to sticking as well as aggregate disruption in tens of thousands of collisions.