Astronomy: Casualty risk from uncontrolled rocket re-entries assessed

The risk to human life from the uncontrolled re-entry of rocket bodies into the Earth’s atmosphere is assessed in an analysis of 30 years of data, published in Nature Astronomy. The study — which reveals that, under current practices, if a typical rocket re-entry spreads debris across a 10 m2 area, there is a roughly 10% chance that one or more casualties will occur over the next decade — furthermore demonstrates that these risks are disproportionately borne by populations in the global south.

Although rocket launches vary, boosters and other sizeable parts from rockets fall back to Earth or are abandoned in orbit. In most cases, the abandoned rocket bodies re-enter the atmosphere in an uncontrolled fashion and debris may land anywhere along the flight path.

Using the past 30 years of satellite data, Michael Byers and colleagues projected the ‘casualty expectation’ — or risk to human life — over the next decade as a result of uncontrolled rocket re-entries. The team focussed on pieces of rockets that remain partially intact and pose a casualty risk on land, at sea or to aeroplanes. The authors reveal that current practices have, on average, a 10% chance of one or more casualties over the next decade if each re-entry spreads lethal debris over an area of 10 m2. Moreover, this risk is borne disproportionately by the global south, with rocket bodies being approximately three times more likely to land at the latitudes of Jakarta, Dhaka and Lagos than those of New York, Beijing or Moscow.

The authors further explain that we already have the technology for guided re-entry systems. What we lack, they state, is the collective will to employ these because of the associated costs. They conclude that without multilateral agreements for mandated controlled rocket re-entries, space faring nations will continue to export these risks unnecessarily.