Threat of Space Debris

An overview of the threat of space debris to spacecraft operations is presented for both low altitude spacecraft and geosynchronous operations. These two regimes are treated separately by addressing the following four questions. First, what is the magnitude of the current problem? This is assessed for three classes of debris; those which can be observed, small particles which cannot be detected from the ground, and micro particles (e.g., solid rocket motor exhaust). Second, what can change in the future? The only natural mechanism for debris removal, orbit decay, impacts only those particles at the lower altitudes. Some segments of space activity are increasing, notably Shuttle and Ariane, while others (Soviet) will continue at a high level. Additionally, there are other countries such as Japan, India, and China become more active. Additional potential changes in the future could result from ASAT tests, explosions, and collisions. Third, what is the potential damage? The damage to spacecraft depends primarily on two factors: particle size and impact velocity. Different particle sizes are assessed separately for low Earth orbits and geostationary orbits. Fourth, what alternatives are available to enhance survivability? The possibilities for enhancing survivability of a spacecraft program can be grouped into three categories: design alternatives, operations, and programmatics. Additionally, those things which can be done to minimize the growth of debris are discussed.