His crazy fall kept the whole world in suspense: in May 2021, the main stage of the Chinese Long March 5B rocket headed straight to Earth, at full speed, without predicting the place of impact. It has finally finished its race in the Indian Ocean, off the Maldives, without causing any harm. isolated case? Not right. A year ago, debris from a similar package crashed in Côte d’Ivoire, causing damage to buildings. In 2018, it was the Chinese space station Tiangong-1 that randomly landed in the Pacific Ocean; Already in 2016, the stage of a SpaceX rocket destroyed an animal container in Indonesia, without injuring the hosts. If no human tragedy has yet been recorded, what are the risks of “the sky falling on someone’s head”? Researchers from Canadian universities pulled out a calculator … and the result is far from zero.
Michael Byers and colleagues from the University of British Columbia analyzed data from the past 30 years. More than 1,500 missile bodies were absorbed during this period, 70% of which were out of control, according to their estimates. “When intact phases return to Earth, a significant portion of their mass escapes the heat of atmospheric re-entry as debris. Their article in Nature Astronomy warns that many of the surviving bits are potentially lethal and pose serious risks to land, sea, and aircraft passengers. During the period 1992 -2022, the probability of a missile tip causing at least one victim was 14%.” Although such an event did not occur, or at least went unreported, calculations show that the risks involved were far from negligent. »
Southern countries are more vulnerable
Given the increasing number of missile launches, the risk is rising: over the next decade alone, the probability of a fatal accident is estimated at 10%! But debris that resists the atmosphere can be very large, as well as very small. Aaron Pooley, co-author of the study, stresses that “recoil has to be taken into account, just like a ‘typical size of a person.’” To make their calculations despite the differences, the researchers created an average to estimate the danger zone on the ground where the deadly debris would spread: it would be 10 square metres.
However, not all of us will be equal in the face of this danger. While missiles are launched by a handful of economically powerful countries, the countries of the South will be the most exposed. In fact, the probability of missiles landing at the latitudes of Dhaka, Jakarta or Lagos will be three times more than in New York, Moscow or Beijing. This disparity can be explained by the fact that uncontrolled reentries are often associated with launches to orbits that dominate near the equator.
The study authors urged space players to stop playing Russian roulette and call for multilateral agreements: “We argue that recent improvements in technology and mission design make most unsupervised re-entries unnecessary, but states and companies (responsible for these launches) are hesitant In bearing the increased costs involved, “national governments whose populations are at risk should demand that major space nations work together to force the controlled re-entry of rockets.”