2023-05-19 10:15:01
Most satellite launches leave the upper stage of the rocket floating in space just around the Earth, and this space junk will eventually fall to Earth.
The researchers found that falling debris from space launches, particularly rocket upper stages, has a one in 10 chance of hitting or killing a person over the next decade.
Experts promise to do more to remove space debris from orbit and develop more sustainable launch systems that don’t add more waste.
In 2020, it was estimated that nearly two-thirds of all space launches resulted in a rocket object being left in orbit. This “space junk” poses a threat to other active satellites, and if it is large enough to survive, it will later fall to Earth’s surface.
In a paper published in Nature Astronomy last July, Professor Michael Byers of the University of British Columbia (UBC) and colleagues examined the risk of discarded rocket bodies seriously injuring, or even killing, a person while falling to the ground.
Using nearly 30 years of data from CelesTrak’s public satellite catalog, the team calculated the potential risks to human life over the next decade.
The analyzes took into account the estimated rate of uncontrolled re-entry of rocket hulls, their orbits, and population projections and human distribution.
The researchers assumed that each return event spread the debris over an area of just over 100 square feet.
Using two different methods, Professor Byers and his team have estimated that, if the space industry continues with its current practices, there is a 6 to 10% chance of one or more casualties from space debris falling from orbit.
The Panel notes that this does not include potential mass casualty events resulting from such worst-case scenarios as debris falling onto an aircraft in flight.
Furthermore, the analysis revealed that, given the distribution of typical satellite orbits, the risk posed by falling space junk is “disproportionately” higher in the Southern Hemisphere, even though most spacefaring nations are located in the Northern Hemisphere.
For example, the team notes, the latitudes of the Southern Hemisphere cities of Dhaka, Jakarta and Lagos are nearly three times more likely to be hit by falling missile debris than those in Beijing, Moscow or New York.
Co-author of the paper and University of British Columbia astronomer Professor Aaron Polley said: “The risk has been assessed on a per-launch basis so far, which gives people the sense that the risk is so small that it can be safely ignored. But the cumulative risk is not that small. It has not been reported.” There have been no casualties so far… But do we wait for that moment and then respond, especially when it comes to human life, or do we try to stand up to it?”
Although no one has been hurt by falling space junk so far, incidents of property damage have been noted, including damage to two villages in Côte d’Ivoire in 2020.
This happened because parts of the Chinese Long March 5B rocket, which is 39 feet long, fell from the sky.
There are ways to reduce the risks posed by space junk, both already in orbit and those that may be produced in the future.
Several space agencies and private companies are developing “space tugs,” for example, that might be used to safely eject orbital waste over unpopulated areas.
Fully reusable rockets, such as the Super Heavy booster developed by SpaceX, might also be developed as part of its spacecraft.
Besides missiles, some large operational satellites also present a future challenge when it comes to ensuring that they are safely deorbited. This includes, in particular, the 400-ton International Space Station, which is expected to be decommissioned sometime following 2030.
Earlier this year, NASA revealed plans to develop a space tug to drop the orbital station safely over the South Pacific Ocean. A similar strategy would likely be used to de-orbit the 12-tonne Hubble Space Telescope, which has no maneuverability of its own.
Much of the space station will burn up upon re-entry, but there will still be a great deal of debris expected and it might be a fascinating sight for anyone looking at the night sky in its relative vicinity.
The space station is supposed to return to Earth in January 2031.
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