Weight-Efficiency of Conventional Shielding Systems in Protecting Unmanned Spacecraft from Orbital Debris

Unmanned spacecraft typically require protection only from much smaller orbital debris as compared to manned missions. This paper presents quantification and comparison of the weight efficiency of conventional shielding concepts, which were originally developed for manned spacecraft, when designed to protect a robotic satellite against small-size (1 mm) orbital debris impacts. The shielding systems under comparison comprise two categories: “single-purpose orbital debris shields,” represented by the Whipple shield and the stuffed Whipple shield; and “multipurpose structural panels,” represented by honeycomb-core and foam-core sandwich panels. First-order estimates of the shields’ parameters are obtained using the well-known ballistic limit equations. These estimates are then used as starting points for further optimization of the shields conducted by means of hydrocode simulations. The simulations employ a combination of the ANSYS Autodyn finite element and smooth particle hydrodynamics solvers. The results obtained indicate that, in the single-purpose orbital debris shields category, the simpler Whipple shield concept provides better performance than the stuffed Whipple configuration; whereas for the multipurpose structural panels, the foam-core sandwich panel can have less than half the weight as compared to a honeycomb-core panel with a similar ballistic performance.