Falling rocket parts become more likely to cause fatalities

Falling rocket parts become more likely to cause fatalities

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

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 during its reentry.
Photo: The Yomiuri Shimbun (PA)

Sorry kids, but when you wish for a shooting star, those flashing streaks the night sky could actually be flaming rocket parts. And as new research suggests, some of those flaming rocket parts could be heading in your general direction.

Scientists say it is increasingly likely that the rain of rocket parts could cause injury or damage to people on Earth. While it’s still extremely unlikely that you’ll get a rocket fuselage in the face when gazing at the stars, researchers are calling on space nations around the world to consider controlled re-entries for ship components left floating in low Earth orbit.

In a Nature Communications paper Released today, Canada-based researchers say there is a 10% chance that one or more victims will fall victim to falling rocket parts within the next decade, based on data extrapolated to from publicly available reports. The strong possibility 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 southern part of the globe, as write the scientists in their study.

But how likely are parts of a rocket to fall on areas occupied by humans? Well, more and more countries and private companies are putting rockets into space, which means more decoupled parts are lying around in orbit. There was 133 successful launch attempts in 2021, a new world record, and we are looking to break this record in 2022. According to the report, more than 60% of rocket launches have abandoned rocket bodies in orbit, where they are left to circle the Earth for days, months or years.

Prior to research shows that less than 50% of the Earth that is not 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 could hit populated centers. The team used data on average orbit angles and population statistics at different latitudes to show that there is a curve in the likelihood of pieces crashing into places with at least one human habitation.

And since so many of these launches take place near the equator, the risk is higher for developing countries in the southern hemisphere. Scientists have noted that cities like Jakarta (Indonesia), Mexico City (Mexico) or Lagos (Nigeria) are three times more likely to be affected than cities like New York, Beijing or Moscow.

Charts A and B detail the number of rockets produced by each of the major space nations and the likelihood of their causing casualties.  Chart C refers to the orbit angle of persistent rocket parts in orbit and their probability of waiting for casualties, so rockets orbiting between 30 and 60 degrees latitude are more likely to cause the dead.  Chart D shows how higher population density at these 30-60 degree latitudes increases the risk that a falling rocket could cause a fatality.Charts A and B detail the number of rockets produced by each of the major space nations and the likelihood of their causing casualties. Chart C refers to the orbit angle of persistent rocket parts in orbit and their probability of waiting for casualties, so rockets orbiting between 30 and 60 degrees latitude are more likely to cause the dead. Chart D shows how higher population density at these 30-60 degree latitudes increases the risk that a falling rocket could cause a fatality.
Chart: M. Byers et al., 2022/Nature Astronomy

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

How many times have rocket parts hit nearby populations?

Scientists have twice cited debris from rockets that landed on Earth. In 2020, parts of a Long March 5B rocket core stage, which was used to launch an experimental unbolted capsule, fell on two villages in Ivory Coast, damaging buildings but causing no recorded injuries or fatalities. In April 2021, another Chinese-made core stage of a Long March 5B rocket body – a piece that weighed nearly 23 tons –landed in the Indian Ocean. It was the largest man-made object to effect an uncontrolled re-entry. Last April, investigators also said that parts from another Chinese rocket landed on the villages in the state of Maharashtra at the western end of India.

Yes, the probability of it raining down rocket parts causing injury or death is still low. In a interview with The Independent last year, Harvard astrophysicist Jonathan McDowell gave him a chance in billions that the 18-tonne core stage could in fact hit anyone. Says McDowell: “Experts say it’s impossible to predict where parts of the rocket not burned during re-entry might land.”

Yet the researchers of this latest study said countries were extremely lax in their attitude towards the re-entry of ships. The US Air Force waived standard orbital debris mitigation practices (which require the accident risk for re-entry to be less than 1 in 10,0000) for 37 of 66 launches between 2011 and 2018.

So what should nations try to do to stop the uncontrolled inflows? Although controlled re-entry technology is becoming more common, “most of these measures cost money.” With the rise of private companies like SpaceX, imposing a controlled re-entry could become a question of competitiveness. Still, the authors of the new paper argued that it might be necessary to go so far as to force an international treaty through the United Nations.

“The states of the Global South hold high morality; their citizens bear most of the risk, and unnecessarily, since the technologies and mission designs needed to prevent casualties already exist,” the researchers said.

After: China is testing a gigantic drag sail to dispose of space junk.

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