Hazard Analysis for Uncontrolled Space Vehicle Reentry

Abstract

*Satellites in low earth orbit ultimately reenter the earth’s atmosphere at end of mission due to orbital decay. Although most of the mass of a typical space vehicle is destroyed and rendered harmless, a significant portion survives to ground impact. As the number of reentry events increased in recent years, some surviving components have impacted near populated areas and drawn attention to the casualty risk. In response to this hazard, the US government developed guidelines to mitigate the danger posed by randomly reentering space objects. If an upper bound for casualty expectation is exceeded, a controlled deorbit/reentry into a sparsely populated region is recommended. This paper develops the mathematical methods needed to compute risk to people and property. The impact probability density function for randomly reentering debris is derived and used with the population density function to compute the casualty expectation. Examples of casualty expectation and risk of damage to property are provided.