Orbital Debris Wire Harness Failure Assessment for the Joint Polar Satellite System

The objective of this paper is to present the results of two hypervelocity impact failure risk assessments for critical wire bundles exposed aboard the Joint Polar Satellite System (JPSS-1) to an increased orbital debris environment at its 824 km, 98.8 deg inclination orbit. The first “generic” approach predicted the number of wires broken by orbital debris ejecta emerging from normal impact with multi-layer insulation (MLI) covering 36, 18, and 6 strand wire bundles at a 5 cm standoff using the Smooth Particle Hydrodynamic (SPH) code. This approach also included a mathematical approach for computing the probability that redundant wires were severed within the bundle. Based in part on the high computed risk of a critical wire bundle failure from the generic approach, an enhanced orbital debris protection design was examined, consisting of betacloth-reinforced MLI suspended at a 5 cm standoff over a seven layer betacloth and Kevlar blanket, draped over the exposed wire bundles. A second SPH-based risk assessment was conducted that also included the beneficial effects from the high (75 degree) obliquity of orbital debris impact owing to the flight orientation of the exposed wiring and shadowing by other spacecraft components. These factors resulted in a considerably reduced likelihood of critical wire bundle failure compared to the original baseline design with normal impacts and no shadowing.