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Microgravity Experiments on Accretion
in the Protoplanetary Disk

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


We conducted 34 trials, 10 of which resulted in observable mass transfer. The amount of mass transferred in these trials (Figures 4 and 5) was visually more significant than the monolayer of granular material transferred in 1-g testing, but also consistently less than the mass transfer observed in COLLIDE and PRIME during flight-based experiments (Figure 1).

Figure 4: A steel marble rebounding from quartz sand
at 2.48 m/s2 with observable mass transfer.

Figure 5: A Teflon-coated steel marble rebounding from JSC-1
at 2.34 m/s2 with observable mass transfer.

Because rebound velocity is not well-defined with the spring mechanism attached to the marble, we focused on the relationship between rebound acceleration and observed mass transfer. We observed mass transfer only in trials with rebound accelerations from ~1.00–4.00 m/s2 (Figure 6). Mass transfer was observed within this acceleration range for both quartz sand (75-250 µm) and JSC-1 (250-500 µm).

Figure 6: Mass transfer events observed for various granular materials,
marbles, and rebound accelerations.

Table 4 shows the specific rebound accelerations at which mass transfer was observed in trials using various granular material simulants.

Table 4: Rebound Accelerations at which Mass Transfer
was Observed for Various Granular Materials