Improving casualty risk estimates for uncontrolled rocket body reentries

Abstract

Approximately 70 % of launches in 2022 resulted in an uncontrolled rocket body reentry, creating an unnecessary casualty risk to people on the ground, at sea, and in aircraft. Rocket bodies have masses ranging from tens of kilograms to 20 tonnes. Using known rocket body masses and correlations between mass and casualty area, we present revised estimates for the expected risk, finding a 20–29 % probability of one or more casualties over the next decade.

Some states use a 1-in-10,000 threshold for accepting an uncontrolled reentry casualty risk when approving a space activity. This threshold, which is not universally agreed upon, represents a risk acceptance by one country, but imposed on the world population. As the use of space expands, with a record 180 successful launches in 2022, states and other launch providers should adopt technologies and mission designs that ensure controlled reentries. Uncontrolled reentries, particularly of large rocket bodies, constitute an unsafe and unnecessary practice.