A review of the Solar Probe Plus dust protection approach

The Solar Probe Plus (SPP) spacecraft will go closer to the Sun than any manmade object has gone before, which has required the development of new thermal and micrometeoroid protection technologies. During the 24 solar orbits of the mission, the spacecraft will encounter a thermal environment that is 50 times more severe than any previous spacecraft. It will also travel through a dust environment previously unexplored, and be subject to particle hypervelocity impacts (HVI) at velocities much larger than anything previously encountered. New analytical methodologies and designs have been developed to meet this environment's extreme micrometeoroid protection challenge while also fulfilling the mission's low mass requirement. These new analytical capabilities and protection system concepts could produce similar benefits if applied to Earth orbiting and deep space missions. The SPP dust study was developed to overcome the velocity limitations in the existing micrometeoroid and orbital debris (MMOD) analysis capability. In this study, we developed the hydrocode modeling techniques needed to characterize the material behaviors for a high-shock particle impact event. An additional novel development was an algorithm to calculate the particle flux on specific spacecraft surfaces. Our approach predicts particle impacts for a given spacecraft geometry, including the aforementioned effects. In addition, our approach introduces a size-velocity particle correlation, which lowers the shielding needed for a given protection level. This paper covers the new analytical capabilities developed for the SPP dust environment and how they dramatically lower the mass of the protective systems. The paper also discusses the application of these new analytical capabilities to spacecraft protection in the LEO debris field.