Unexpected Ejection of Material from Asteroid Bennu

Of obvious interest to any panspermia hypotheses, especially those which favor replicators (Von Neumann probes or otherwise) using organics on low-gravity bodies as building blocks. Paper here. Abstract:

In early 2019, the OSIRIS‐REx spacecraft discovered small particles being ejected from the surface of the near‐Earth asteroid Bennu.sww Although they were seen to be ejected at slow speeds, on the order of tens of cm/s, a number of particles were surprisingly seen to orbit for multiple revolutions and days, which requires a dynamical mechanism to quickly and substantially modify the orbit to prevent re‐impact upon their first periapse passage. This paper demonstrates that, based on simulations constrained by the conditions of the observed events, the combined effects of gravity, solar radiation pressure, and thermal radiation pressure from Bennu can produce many sustained orbits for ejected particles. Furthermore, the simulated populations exhibit two interesting phenomena that could play an important role in the geophysical evolution of bodies such as Bennu. First, small particles (less than 1 cm radius) are preferentially removed from the system, which could lead to a deficit of such particles on the surface. Second, re‐impacting particles preferentially land near or on the equatorial bulge of Bennu. Over time, this can lead to crater in‐filling and growth of the equatorial radius without requiring landslides.

McMahon JW, Scheeres DJ, Chesley SR, French A, Brack D, Farnocchia D, Takahashi Y, Rozitis B, Tricarico P, Mazarico E, Bierhaus B, Emery JP, Hergenrother CW, Lauretta DS. JGR Planets. Dynamical Evolution of Simulated Particles Ejected From Asteroid Bennu. First published: 18 May 2020 https://doi.org/10.1029/2019JE006229