Falling Rocket Parts Becoming More Likely to Cause Fatalities

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A crowd of people stand on the shore to watch a rocketship blast office from its station

This Chinese-made Long March 5B Y2 rocket launched in April, 2021, but this type of rocket has been cited at least twice for parts left in orbit striking the Earth upon reentry.
Photo: The Yomiuri Shimbun (AP)

Sorry kids, but when you’re wishing on a falling star, those flashing streaks in the night sky might actually be flaming rocket parts. And as new research suggests, some of those flaming rocket parts could be headed in your general direction.

Scientists say there’s a growing likelihood that raining rocket parts could cause injury or harm for people down on Earth. Though it’s still extremely unlikely you’ll receive a rocket fuselage to the face when staring up at the stars, researchers are calling on the world’s spacefaring nations to consider controlled reentries for ship components left floating in low-Earth orbit.

In a Nature Communications paper released today, Canada-based researchers said there’s a 10% chance of one or more casualties from falling rocket parts in the next decade based on data extrapolated from publicly released reports. The strong possibility that these rocket parts are more likely to land in the global south means that most spacefaring nations and private companies are effectively “exporting risk to the rest of the world,” especially the southern part of the globe, as the scientists write in their study.

But what is the likelihood that parts of a rocket might fall on areas occupied by humans? Well, more nations and private companies are putting rockets into space, which means more decoupled parts are hanging out in orbit. There were 133 successful launch attempts in 2021, a new world record, and we’re looking to smash that record in 2022. According to the report, more than 60% of launches abandoned rocket bodies in orbit, where they’re left circling the Earth for days, months, or years.

Prior research shows that less than 50% of the Earth that isn’t permanently covered in ice has remained relatively uninhabited and untouched by humans. But as the new research shows, there’s still a chance that rocket parts can hit populated centers. The team used data on average orbit angles and population statistics at different latitudes to show there’s a curve in the likelihood for parts to crash at locations with at least some human habitation.

And since so many of these launches take place near the equator, there’s a higher risk for developing nations in the southern hemisphere. Scientists noted cities like Jakarta (Indonesia), Mexico City (Mexico), or Lagos (Nigeria), are three times more likely to get hit than somewhere like New York, Beijing, or Moscow.

The A and B graphics detail the number of rockets each of the major space-faring nations have produced and the likelihood that they’ll result in a casualty. The C graphic refers to the orbit angle of lingering rocket parts in orbit and their likelihood of casualty expectation, so those rockets orbiting between 30 and 60 degrees latitude have a higher chance of causing death. D graphic shows how higher population density at those 30 through 60 degrees latitude increases the chance a falling rocket could cause a fatality.

The A and B graphics detail the number of rockets each of the major space-faring nations have produced and the likelihood that they’ll result in a casualty. The C graphic refers to the orbit angle of lingering rocket parts in orbit and their likelihood of casualty expectation, so those rockets orbiting between 30 and 60 degrees latitude have a higher chance of causing death. D graphic shows how higher population density at those 30 through 60 degrees latitude increases the chance a falling rocket could cause a fatality.
Graphic: M. Byers et al., 2022/Nature Astronomy

“The disproportionate risk from rocket bodies is further exacerbated by poverty, with buildings in the global south typically providing a lower degree of protection,” the study’s authors wrote. And referencing NASA research, the scientists said that roughly “80% of the world’s population lives ‘unprotected or in lightly sheltered structures providing limited protection against falling debris.’”

How Many Times Have Rocket Parts Hit Near Populations?

Scientists cited two times debris from rockets landed back on Earth. Back in 2020, parts of a Long March 5B rocket core stage, which were used to launch an experimental uncrewed capsule, fell onto two villages in the Ivory Coast, damaging buildings but causing no recorded injuries or fatalities. In April 2021, another China-made core stage of a Long March 5B rocket body—a piece that weighed nearly 23 tons—landed in the Indian Ocean. It had been the largest human-made object to do an uncontrolled reentry. This last April, investigators also said parts of another Chinese rocket landed on villages in the state of Maharashtra on the western end of India.

Yes, the probability of raining rocket parts causing injury or fatalities is still small. In an interview with The Independent last year, Harvard astrophysicist Jonathan McDowell gave it a “one in several billion” chance that the 18-ton core stage might actually hit anyone. Said McDowell: “Experts say that it is impossible to predict where those parts of the rocket not burned up on re-entry could land.”

Yet the researchers in this latest study said countries are being extremely lax in their attitudes toward ship re-entry. The U.S. Air Force waived Orbital Debris Mitigation Standard Practices (which require that the risk of casualty for reentry to be below 1 in 10,0000) for 37 of 66 launches between 2011 and 2018.

So what should nations be trying to do to stop uncontrolled reentries? Though the technology for controlled re-entries is becoming more common, “most of these measures cost money.” With the rise of private companies like SpaceX, mandating controlled reentry could become a matter of competitiveness. Still, the authors of the new paper argued that going as far as forcing a international treaty through the United Nations might be necessary.

“The states of the global south hold the moral high ground; their citizens are bearing most of the risks, and unnecessarily so, since the technologies and mission designs needed to prevent casualties exist already,” researchers said.

More: China Tests Gigantic Drag Sail for Removing Space Junk.

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