A falling Chinese missile is expected to enter Earth’s atmosphere
The Chinese rocket that will fall back to Earth in a few days is about the size of two semi-truck trailers, and 40 percent of that metal will reach the Earth’s surface, experts say.
Although the overall risk of harm to humans is low; There’s only a 0.5 percent chance of human injury or death based on one model, but those risks are still higher than most space-faring nations acknowledge, says Ted Muehlhaupt, who re-enters and debris expert at The Aerospace Corporation.
Muellhaupt and other analysts spoke to reporters on a conference call Wednesday, about two days ahead of the projected re-entry of the long March 5B main stage. As it acquires more orbital data, the nonprofit Aerospace Corporation plans to continue the upgrade its entry prediction. As of Thursday morning, it forecast a return at 7:17 PM ET Friday (23:17 UTC), plus or minus 10 hours.
The Long March 5B launched a 23-ton rocket Mengtian module at China’s Tiangong space station on Monday. This modified version of China’s most powerful rocket uses a massive nuclear stage to propel the space station’s modules into low Earth orbit. Since this main stage does not have the ability to re-ignite its engines to control a barren part of the world’s oceans, the rocket can eventually return anywhere in the tropics and most of the planet’s mid-latitudes.
In three previous launches of the Long March 5B booster, in 2020, 2021 and 2022, pieces of debris damaged villages in the Republic of Ivory Coast, fell harmlessly into the Indian Ocean and landed near villages in Borneo, respectively. Fortunately, no one has yet been hurt by this fall.
According to The Aerospace Corporation, this 21.6-metric-ton re-entry of nuclear stages includes four of the six largest uncontrolled launches from space in the past 50 years. They stand behind only NASA’s Skylab space station in 1971 and the Soviet Union’s Salyut 7 space station in 1991.
Based on the stage’s main orbit, it could affect land masses that are home to about 88 percent of the world’s population, Muellhaupt said. Based on a simple model, he estimates the odds of a casualty, defined as death or injury, to be between 1 in 230 and 1 in 1,000. The individual risk for each individual is extremely low, about 6/10 of a trillion. You are likely to be struck by lightning many, many times.
However, the individual risk of falling debris from a Chinese missile is not really a problem, officials at The Aerospace Corporation say. Space agencies and companies in the US, Europe and elsewhere follow “norms” of behavior for much lower risks. For example, the acceptable risk of casualties is 1 in 10,000 from a man-made object re-entering space.
In this configuration, there are probably about half a dozen Long March 5B launches with the main stage reaching orbit. Mühlhaupt acknowledged that the country is unlikely to change the design of this rocket because it has proven successful in delivering large vehicles into space. But he hopes future Chinese missile designs will find a better way to destroy such large equipment without dropping tons of metal on Earth.
“We are trying to adopt a norm of behavior,” he said. “Treaties and laws are difficult. Accepted norms can come from scratch. Next time they make a design like this, hopefully they’ll take the feedback from this one into account.”
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