By 1981, NASA had instituted its first de facto orbital debris mitigation policy with a requirement for Delta second stages to be depleted of residual propellants at the end of mission.
到1981年，美国航天局已经制订了第一项事实上的轨道碎片缓减政策，要求Delta的第二级在飞行任务结束时排空剩余的推进剂。