Electrical response of current-carrying space-grade harnesses to hypervelocity impact

The micrometeoroid and orbital debris (MM/OD) environment poses a threat to satellites and manned spacecraft. This threat lies in the risk of individual components being affected by an impact of a particle from the MM/OD population. Among spacecraft components, harnesses are especially exposed to that risk due to their ubiquity inside a spacecraft and their importance for fundamental spacecraft functions such as supplying power and relaying digital and analog communications. The degradation or breakdown of such a mission-critical component can shorten the lifetime of a satellite or, in the worst case, lead to loss of a mission. Past impact tests have shown that mechanical damage to cables like cratering and removal of insulation can result in permanent functional degradation after impact. However, during the impact event, transient processes develop which until now have not yet been characterized. These processes include voltage spikes that propagate along a cable poten tially damaging connected equipment such as on-board computers, sensors and other electronics. A hypervelocity impact test campaign was performed on space-grade unshielded single conductor, screened twisted pair and radio-frequency coaxial lines in a representative experimental setup. This comprised both representative operational parameters and a representative mechanical setup behind an aluminum sandwich panel similar to an actual spacecraft structure wall. Impactors were aluminum spheres with diameters ranging from 2 mm to 5 mm with impact velocities between 3 km/s and 7 km/s. Impact-induced transient responses were recorded. Observed voltage spikes go up to twice the nominal voltage level. The work presented in the paper at hand was performed as part of a European Space Agency contract. Copyright ©2011 by Fraunhofer EMI. Published by the LAF, with permission and released to the LAF to publish in all forms.