Casualty risk assessment of uncontrolled reentries after the deployment of the first large satellite constellations

From 2019 to 2024, the risk due to uncontrolled orbital reentries of spacecraft, upper stages, and large debris for people on the ground and commercial aircraft in flight was estimated using realistic models for the number and casualty area of the surviving fragments, and for the latitudinal distribution of population and planes in the air. Each reentered object was modeled independently, considering its correct orbital inclination. In addition, the effects of complete object demise below certain mass thresholds were also evaluated. Although the reentry risks are still relatively small, they have grown considerably from 2019 to 2024, mainly due to increased space activities. In 2024, the collective casualty probability for people on the ground was between 4.5% and 9.8%, while the individual annual casualty probability was not more than 10E−11. Always in 2024, the likelihood of aircraft being impacted by fragments capable of causing a catastrophic failure was between 3×10E−5 and 7×10E−5, corresponding, on average, to one airplane struck every 30,000 and 14,000 years, respectively. For commercial aircraft passengers, the collective casualty probability ranged from 0.42% to 0.84%, while the individual casualty probability was between 9×10E−13 and 2×10E−12.