![Artist's impression of an Electron first stage re-entering the atmosphere. Credit: rocketlabusa.com Uncontrolled rocket re-entries are a bigger problem than you think](https://oponame.com/wp-content/uploads/2022/10/Uncontrolled-rocket-re-entries-are-a-bigger-problem-than-you-think.jpg)
Artist’s impression of an Electron first stage re-entering the atmosphere. Credit: rocketlabusa.com
More than 60% of launches in 2020 resulted in one or more rocket parts performing an uncontrolled re-entry into the atmosphere. Although fortunately no one was injured by this debris, with the expected increase in rocket launches over the next decade, the risk of accidents increases. A new study paints the picture of how current risk assessment methods are inadequate and new measures need to be taken.
The rocket is a complex business. A typical lunch will usually require several steps to get the payload into orbit. Most of the time, it all goes well, with individual stages designed to either burn up in the atmosphere or end up on an escape route away from Earth. But in 2020 alone, 60% of launches into low Earth orbit resulted in at least one significant-sized rocket part simply being dropped into uncontrolled orbit. This space junk is no longer under any human control and will eventually fall back to Earth.
When they do, they will first enter through our atmosphere. Although the heat of this reentry will vaporize most materials, scientists estimate that for each piece of rocket, about 20 to 40 percent of its mass will reach the Earth’s surface.
This represents a significant risk to lives and property. Although to date there have been no serious consequences from uncontrolled rocket debris, we cannot assume that this will be true in the future. Many companies plan to launch fleets of communications satellites, and the number of rocket launches is expected to increase dramatically over the next decade.
Some space agencies, such as NASA, require that any launch pose no more than a 1 in 10,000 risk of injury to people or property from uncontrolled debris re-entering the atmosphere after launch. But in a new study, several astronomers have pointed out that this is insufficient. Many companies have waivers to avoid having to comply with this rule if it is too costly to comply. And this ratio may be fine for a limited number of lunches each year, but it ignores the cumulative effect of thousands of launches occurring year after year.
Researchers are analyzing the current orbits of 600 known pieces of space junk and estimating where they will return to Earth. They found that most unchecked space debris is associated with geostationary orbits, meaning the risk of re-entry is concentrated near the equator.
This means that people living near the equator are at much higher risk than those living at higher latitudes. But the countries that typically conduct these launches are located far from the equator, so they actually transfer the risk of debris from their own populations to countries that weren’t even involved in the launch process.
Overall, the researchers found about a 10-20% risk of an accident over the next decade from uncontrolled debris. This victim could take the form of a single person being hit, or it could be something more catastrophic like a large building or plane being hit.
The researchers call for more honest and consistent risk assessments and more consistent application of the rules by the community to properly address the next generation of spaceflight.
Scientists calculate the risk of a person being killed by space debris
Michael Byers, Ewan Wright, Aaron Boley, Cameron Byers, Unnecessary Risks Created by Uncontrolled Rocket Re-entries. arXiv:2210.02188v1 [physics.soc-ph]arxiv.org/abs/2210.02188
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