EVOLVE 4.0 orbital debris mitigation studies

Abstract

In a continuing effort to limit future space debris generation, the NASA Policy Directive 8710.3 was issued in May 1997. It requires all NASA-sponsored programs to conduct formal assessments in accordance with NASA Safety Standard 1740.14 to quantify the potential to generate debris and to consider debris mitigation options. Recent improvements to the NASA long-term debris environment model, EVOLVE 4.0, allow for a reassessment of the effects of NASA Safety Standard mitigation measures on the projected debris environment. The NASA Safety Standard guidelines requiring the passivation of upper stages and spacecraft through depletion of on-board energy sources, and the post-mission disposal of satellites may be studied with EVOLVE 4.0. In this paper, we present the results of a set of parametric EVOLVE 4.0 studies. We set our test matrix to include a draconian level of explosion suppression, i.e., passivation in future launches, and post-mission disposal decay time periods ranging from 100 years to 25 years. The post-mission disposal options are initiated at a time 10 years in the future. It is confirmed that explosion suppression alone effects only a minor change in the long-term environment. Post-mission disposal implementation is required to significantly reduce it. But complications arise for the longer tested post-mission disposal lifetime. The enhanced dwell time at low altitudes (the dominant manned spacecraft region of Earth orbits) increases the likelihood that a collision will occur there compared to the lower post-mission disposal lifetime of 25 years.