Hazards of reentry disposal of satellites from large constellations

Abstract

This study looks at the history of debris surviving satellite reentries to develop a first-order estimate of the hazard level for people on the ground and in aircraft from falling debris after reentries of satellites from proposed large constellations. Projecting to the year 2030, when several proposed constellations are assumed to be operational, the results show that cumulative hazard to people on the ground due to reentries from a single constellation could be on the order of 0.1/year, or one casualty would be expected every 10 years. The probability of debris striking a commercial aircraft would be 0.001/year, and without emergency action by pilots, the maximum yearly casualty expectation for reentries of satellites disposed from a single large constellation for people in aircraft could be 0.3/year. Those estimates would be higher if commercial air traffic were updated to include all worldwide flights. While there are currently no guidelines or requirements to manage cumulative risks from the disposal of satellites, there are advisory USG standards on acceptable annual risks from launch and reentry vehicle disposal operations. Test-verified satellite designs that minimize survival of hazardous objects will certainly help reduce risks. The most effective mitigation technique would be to deorbit all satellites into a safe ocean area.