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Microgravity Experiments on Accretion
in the Protoplanetary Disk

By: Addison Brown and Stephanie Jarmak | Mentor: Dr. Joshua Colwell


We have shown that mass transfer is possible in lowacceleration (<5 m/s2) interactions between small particles (µm-cm size) in a laboratory-based microgravity environment at standard pressure. The observation of more significant mass transfer in this experiment than in the 1-g experimental analogue reinforced the importance of a microgravity environment for the occurrence of mass transfer. However, the amount of mass transfer we observed in this experiment was less significant than the mass transfer observed in COLLIDE and PRIME, which suggests that differences between these experiments may be critical to the occurrence of mass transfer. It is also possible that compression of the regolith due to the mass of the projectile plays a role in the mass transfer process.

The data presented here suggests that there may be an inverse relationship between rebound acceleration and the likelihood of a mass transfer event. We observed mass transfer only in trials with rebound accelerations below 5 m/s2, the majority of which had rebound acceleration values below 3 m/s2. However, it should be noted that the acceleration parameter space was not covered equally by the trials conducted, so further trials must be conducted before a more robust conclusion can be made regarding the relationship between rebound acceleration and the likelihood of a mass transfer occurrence.

In future work, we plan to modify our experimental apparatus so that we can conduct trials in a vacuum environment. This will allow us to explore the relationship between ambient air pressure and mass transfer, and make our data more comparable to that of previous experiments. We also plan to probe lower acceleration rebound parameters using more massive marbles and the more precise control provided by the new servoretraction rebound mechanism.