This Chinese-made Long March 5B Y2 rocket was launched in April 2021, but this type of rocket has been cited at least twice for parts left in orbit hitting Earth on re-entry. Photo: The Yomiuri Shimbun (AP)
Sorry kids, but when you wish on a shooting star, those twinkling streaks in the night sky might actually be parts of a burning rocket. And as new research shows, some of those flaming rocket parts may be headed in your general direction.
Scientists say there is an increasing likelihood that falling rocket parts could cause injury or harm to people on Earth. While it’s still extremely unlikely you’ll get a rocket fuselage in the face when you’re staring at the stars, researchers are urging the world’s space nations to consider controlled re-entries for ship components left floating in low Earth orbit.
In a Nature Communications paper published today, Canada-based researchers said there is a 10 percent chance of one or more casualties from falling rocket parts in the next decade, based on data extrapolated from publicly released reports. The high probability that these rocket parts are more likely to land in the global south means that most space nations and private companies are effectively “exporting risk to the rest of the world,” especially the global south, the scientists wrote in their study.
But what is the probability that parts of a missile will fall on areas occupied by people? Well, more nations and private companies are launching rockets into space, which means more detached parts are hanging in orbit. There were 133 successful launch attempts in 2021, a new world record, and we aim to break this record in 2022. According to the report, more than 60% of the launches left rocket bodies in orbit, where they were left to circle the Earth for days, months or years.
Previous research has shown that less than 50% of Earth that is not permanently covered in ice has remained relatively uninhabited and untouched by humans. But as new research shows, there is still a chance that parts of the rockets could hit population centers. The team used data on average orbit angles and population statistics at different latitudes to show that there is a probability curve for pieces crashing into places with at least some human habitation.
And because so many of these launches take place near the equator, there is a higher risk for developing nations in the southern hemisphere. The scientists note that cities like Jakarta (Indonesia), Mexico City (Mexico) or Lagos (Nigeria) are three times more likely to be hit than somewhere like New York, Beijing or Moscow.
Charts A and B detail the number of missiles each of the major space nations has produced and the likelihood that they will result in a casualty. Chart C refers to the orbit angle of the missile parts left in orbit and their probability of expecting casualties, so those missiles orbiting between 30 and 60 degrees latitude have a greater chance of causing death. Graph D shows how the higher population density at this 30 to 60 degree latitude increases the chance of a falling missile causing a fatal outcome. Graphic: M. Byers et al., 2022/Nature Astronomy
“Disproportionate risk from missile bodies is further exacerbated by poverty, with buildings in the Global South generally providing a lower degree of protection,” the study authors wrote. And citing NASA research, the scientists said that roughly “80 percent of the world’s population lives “unprotected or in poorly protected structures that provide limited protection against falling debris.”
How many times have parts of rockets hit near a population?
Scientists have twice cited rocket debris landing back on Earth. In 2020, parts of a Long March 5B rocket main stage that was used to launch an unmanned experimental capsule fell on two villages in Côte d’Ivoire, damaging buildings but causing no reported injuries or deaths. In April 2021, another Chinese-made Long March 5B missile main stage – a part weighing almost 23 tons – landed in the Indian Ocean. It was the largest man-made object to make an uncontrolled re-entry. Last April, investigators also said parts of another Chinese missile landed on villages in India’s westernmost state of Maharashtra.
Yes, the chance of rocket parts raining down, causing injury or death, is still small. In an interview with The Independent last year, Harvard astrophysicist Jonathan McDowell gave a “one in several billion” chance that the 18-tonne core could actually hit someone. McDowell said, “Experts say it’s impossible to predict where those parts of the rocket that didn’t burn up on re-entry might land.”
Still, researchers in this latest study said countries are extremely lax in their approach to ship re-entry. The US Air Force abandoned standard orbital debris reduction practices (which require the risk of a re-entry accident to be below 1 in 10,0000) for 37 of 66 launches between 2011 and 2018.
So what should nations try to do to stop uncontrolled re-entries? Although controlled re-entry technology is becoming more common, “most of these measures cost money.” With the rise of private companies like SpaceX, enforcing controlled re-entry could become a matter of competitiveness. Still, the authors of the new document argue that it may be necessary to go as far as imposing an international treaty through the United Nations.
“The states of the Global South hold the moral high ground; their citizens bear most of the risks, and unnecessarily so, as the technologies and mission designs needed to prevent casualties already exist,” the researchers said.
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