A review of the Solar Probe Plus dust protection approach

Abstract

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.

The Wide-Field Imager for Solar Probe Plus (WISPR)

“…Since the mass and size distribution is unknown close to the Sun, the design relies on the JHUAPL/UTEP models developed specifically for SPP (Mehoke et al 2012). The model predicts about 100 impacts from 10-micron particles and 1000 impacts from 0.1-micron particles at the heat shield during the seven years of the mission.…”

Interplanetary Dust Particle Shielding Capability of Spacecraft Multilayer Insulation

“…This paper presents a multiphysics shock-hydrocode-computations-based approach that combines impact shock physics analyses, high-rate material thermodynamic and strength response models, verified and validated shock hydrocode computations, and HVI test data with design considerations, described previously for monolithic shielding materials and layered solids such as solar arrays [5,6], to explicitly address the range of Whipple shield debris/ vapor cloud phases specific to the extreme SPP impact speeds and develop a broadly applicable BLE for normal (nonoblique) impacts. Figure 3 depicts an existing well-known two-wall Whipple shield BLE for normal impacts [1].…”