2015.A.1.3. A CubeSat Microgravity Experiment on Collisions in the Protoplanetary Disk


Joshua Colwell (1)
Julie Brisset (1)
Adrienne Dove (1)

  1. University of Central Florida, United States of America




Microgravity, Planetesimal, Protoplanetary, Collision


The CubeSat Particle Aggregation and Collision Experiment (Q-PACE) is a microgravity collision experiment to study low-velocity collisions between cm-scale and smaller particles in the protoplanetary disk. For 40 years there have been two main ideas about how the pieces of future planets grow through the critical range from mm-sized aggregates and chondrules to km-sized planetesimals. These are gravitational instability and growth by binary sticking collisions. The experiments we propose will make it possible to determine whether collisional growth can proceed into this size range, confronting the decades-old question of how bodies grow past the meter-size barrier into planetesimals that can go on to become planets through gravitational accretion.

Knowing the outcomes of collisions across a broad range of speeds and impactor properties will also enable us to connect the growth of the solid bodies to the properties of the particles observed in protoplanetary disks and meteorites. If dust agglomerates easily stick and there is little or no fragmentation of the clusters that form, all the primordial grains are incorporated into bigger bodies in a small fraction of the protoplanetary disk’s lifetime.

The experiment is a 2U CubeSat with a particle collision test cell and several particle reservoirs that contain meteortic chondrules, dust particles, dust aggregates, and larger spherical monomers. Particles will be introduced into the test cell for a series of separate experimental runs. The test cell will be mechanically agitated to induce collisions which will be recorded by on-board video for later downlink and analysis. The objectives of Q-PACE require a long-duration and high-quality (low residual acceleration) microgravity environment that is only available on an orbital platform. The experiments proposed here will extend our understanding of the outcomes of relevant collisions between so-called “pebbles” (cm-scale object) in the protoplanetary disk and the accretion of pebbles from smaller particles. The large number of collisions we will observe will enable a stochastic approach to the evolution of the size distribution. Q-PACE extends the parameter range of collisions to smaller velocities than have previously been studied and expands the number of collisions observed by orders of magnitude over the current experimental database.


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