Quantifying and Reducing International Space Station Vulnerability Following Orbital Debris Penetration

Abstract

The increase in the orbital debris environment in low Earth orbit has prompted NASA to develop new strategies to examine the effects of penetration on spacecraft and crew. In 1992, NASA’ s Marshall Space Flight Center developed the Manned Spacecraft and Crew Survivability computer program to quantify the likelihood of an orbital debris particle causing loss of the International Space Station or its crew following penetration, i.e., vulnerability. The personal computer-based model computes the likelihood of occurrence for six failure modes that may lead to crew or station loss: 1 ) critical cracking, 2 ) critical equipment loss, 3 ) thrust-induced loss of control or joint failure, 4 ) fatal and nonfatal injury to crew, 5 ) crew hypoxia during escape and injured crew member rescue, and 6 ) station late loss due to critical module depressurization. The ability of the crew to perform countermeasures, i.e., shut hatches, rescue the injured, or egress the station, has been implemented into the model to assess the effectiveness of different crew protocols in reducing the overall probability of loss. By varying these parameters and selecting alternate crew operations and internal equipment designs, one can identify the optimum cone gurations that, if implemented, may quantie ably increase overall station and crew member survivability.