Availability and Aging Analysis of a Reusable Low-Earth Orbital Spacecraft

摘要

This paper provides a description of our methodology for performing an availability analysis of a reusable mannedspacecraft. The spacecraft was designed to be launched, maintained in orbit for an extended period of time, used forcrew return to Earth, and then reused for as many as thirty individual missions. Because of the extended orbit time,the analysis required a modeling of long dormant periods preceded and followed by short periods of high stress, aswell as treatment of common cause failures, effects of micrometeorite and orbital debris impact, and aging effects.Failure rates applicable to dormant periods in space and to periods of high stress during ascent and entry wereobtained by applying appropriate conversion factors to failure rates obtained from ground test data and space flightexperience. Common cause failures were modeled using a set of NASA-recommended generic common causefactors. Effects of impacts from micrometeorite and orbital debris were also estimated using data and analysesoriginating from NASA. Aging effects were modeled with a bathtub-shaped curve that was first fit to generalaviation failure data and then adjusted to space conditions. In addition to the methodology, a brief account of someof the more interesting conclusions drawn from the analysis is presented.