Variable particulate environment around the Shuttle.

The Particle Analysis Cameras for Shuttle experiment was flown on Mission STS61C (Columbia). This experiment involved a pair of cameras in a stereo-viewing configuration and a coaligned strobe light flash to permit particle observation throughout the entire orbit. Although only one camera functioned properly, significant trends and particle counts were still obtained from the film data. We report the analysis and conclusions from that mission. Comparisons with other Shuttle observations and predictions for occurrence rates above other manned structures such as the International Space Station are presented.