As countries and private companies ramp up space exploration, the issue of where and how abandoned rockets re-enter Earth is becoming more significant. Over the next decade, if current practices of uncontrolled rocket re-entries continue, there is a roughly 10 percent chance that one or more casualties will occur, and they will most likely be in the Global South, according to a new study published in Nature Astronomy on Monday.
In the study, titled “Unnecessary risks created by uncontrolled rocket entries,” researchers led by Dr. Michael Byers, a professor in the University of British Columbia’s department of political science, say that governments need to take action and mandate that rockets are guided back to Earth after their use rather than falling wildly.
The team of researchers, which included Canada Research Chair in Planetary Astronomy at UBC Dr. Aaron Boley and two students, used more than 30 years of data from a public satellite catalog to calculate the potential risk that uncontrolled rocket body re-entries have on human life in the next ten years. Rockets are used to launch satellites and other spacecraft and are often left in orbit following the launch. But what goes up must eventually come down, and the study’s researchers found that the majority of orbits are located in equatorial regions, which puts the Global South at a greater risk when rocket debris falls back to earth.
Wealthier nations in the northern hemisphere have a responsibility to deal with this problem before somebody gets killed, the authors write, because they are responsible for the majority of rocket launches.
“Jakarta, Dhaka, Mexico City, Bogotá and Lagos are at least three times as likely as Washington, DC, New York, Beijing and Moscow to have a rocket body reenter over them, on the basis of the current rocket body population in orbit,” the paper states.
The disproportionate risk that the Global South faces is exacerbated by poverty, said the study, with buildings providing less protection, for example. According to NASA, approximately 80 percent of the world’s population lives in “unprotected or in lightly sheltered structures providing limited protection against falling debris.”
Many companies and governments choose to abandon rockets in orbit simply to save money. Previously, the casualty risk has been low, but there exists a greater possibility of human impact as space exploration increases. The paper’s researchers say that spacefaring countries and companies have the technology and mission designs to remove this risk.
One solution includes having engines that reignite and using extra fuel to guide the rocket bodies to remote ocean areas. Another solution would be for national governments to create new standards for launches from their territories and companies.
The study also encourages the national governments whose populations are at a disproportionate risk of injury or death from rocket debris to demand major spacefaring states mandate controlled rocket entries and negotiate a resolution or treaty. A multilateral treaty, the paper states, may not be passed by spacefaring countries but would set new expectations and bring attention to the issue.
So far, in the last thirty years of collected data on rocket orbits, no casualties have been reported. According to Byers, this is both due to luck, and perhaps a lack of reporting.
“One could imagine someone in a mega city in the Global South or in a rural area in a developing country being mysteriously killed by a small piece of metal falling from the sky. Is that going to be reported as a piece of rocket body? Will the global media find out about that development? I mean, the point here is that we're talking about an absence of reported deaths,” he said.
When intact rocket stages return to the Earth, they enter as debris—with many of the pieces potentially lethal to people on land, sea, and in airplanes.
Currently there are no treaties that address rocket body reentries or widely agreed casualty risk thresholds, despite that approximately 60 percent of all space launches result in a rocket body being abandoned in orbit. To Byers and the researchers in the study, there is a disconnect between the advanced technologies being used to create these space missions and the following neglect to how rockets re-enter earth.
“This problem is solvable with political will and current technology,” Byers, who is continuing to research the issue of space debris, said. “Our paper is just one piece of this larger puzzle as to how we achieve the sustainable development of space.”