Planetary Penetrators for Sample Return Missions.

摘要

Sample return missions offer a greater science yield when compared to missions that only employ in situ experiments or remote sensing observations, since they allow the application of more complicated technological and analytical methodologies in controlled terrestrial laboratories that are both repeatable and can be independently verified. The successful return of extraterrestrial materials over the last four decades has contributed to our understanding of the solar system, but retrieval techniques have largely depended on the use of either soft-landing, or touch-and-go procedures that result in high DeltaV requirements, and return yields typically limited to a few grams of surface materials that have experienced varying degrees of alteration from space weathering. Hard-landing methods using planetary penetrators offer an alternative for sample return that significantly reduce a mission's DeltaV, increase sample yields, and allow for the collection of subsurface materials, and lessons can be drawn from previous sample return missions. The following details progress in the design, development, and testing of penetrator/sampler technology capable of surviving subsonic and low supersonic impact velocities (<700 m/s) that would enable the collection of geologic materials using tether technology to return the sample to a passing spacecraft. The testing of energy absorbing material for protecting the sample, as well as the design evolution and field testing of the penetrator are discussed. It is shown through field testing that penetrators at speeds between 300-600 m/s (∼Mach 1-2) can penetrate into the ground to depths of 1-2 m with overall structural integrity maintained. Four series of test flights are discussed that demonstrate the arc of the research from penetrator survivability, to successful sample collection and ejection of the sample return container. The potential for metamorphic effects during sampling is discussed along with future work that will assist in defining parameters for selecting appropriate primitive bodies for future sample return missions.