Surface Packages for Geophysical Exploration of Small Bodies

Abstract:

The geophysical exploration of small rubble pile bodies is fundamentally important for understanding the mechanics of gravitationally bound aggregates. The mechanical and geotechnical properties of these bodies are not understood from an experimental perspective, and have only been studied theoretically and using numerical simulations. To carry out experiments in this environment requires the development and deployment of surface packages to the body surface to enable physical interactions and measurements. This talk will discuss how such experiments can be developed and used in the small body environment. It will particularly focuse on one approach that uses a combination of surface seismic sources and probes to measure the seismic properties of a rubble pile.

The small body dynamical environment is particularly well suited for the deployment of such surface packages for exploration and scientific measurement purposes. This is mainly due to their meager gravity fields, which allow the delivery of complex instruments to the surface with impact speeds that are at most a meter per second — equivalent to dropping an object from less than a 5 cm height on Earth. Despite this seeming advantage, the delivery and mobility of such packages on the surface of a small body remains a challenging endeavor, and to date the delivery of surface packages to small bodies has had a mixed success rate. Issues that must be accounted for include the delivery trajectories for probes to the surface, motion on the surface of a small body, and interactions between a probe and a small body surface. Studies of all of these issues both theoretically and experimentally will be presented, along with proposed applications to achieve scientific goals on the surfaces of small bodies.