INTRODUCTION

Descriptions of the magnitude of the low earth orbit (LEO) meteoroid and debris populations are provided by others at this conference. These populations suggest the existence of a significant orbital debris flux which may endanger the survival and functional success of large, long duration vehicles. LEO debris populations place two interrelated constraints on designers and operators of manned vehicles intended to operate in, or transit, this region. Firstly, survival of manned vehicles and their flight crews requires careful consideration of numerous, and often indirect, failure modes and associated risk mitigation procedures. Secondly, catastrophic failure of a manned vehicle by hypervelocity impact may lead to measurable increases in the debris population, which then place additional risk and cost on other LEO users. For both reasons, the risk to survival of vehicles to be used in LEO for human exploration presents significant new challenges for vehicle managers. This paper presents an overview of the critical issues now being recognized and addressed by manned vehicle designers. It describes some of the elements of the process being used to assess and mitigate the true risks imposed by the low earth orbit space debris environment.

An essential feature of human survival problem in the LEO orbital debris environment is that many of the issues are best presented in probabilistic form. As is well known by conference attendees, the “natural” orbital debris environment is often represented as a plot of cumulative object flux vs size, as is illustrated in Figure 1.