by China successfully launched the third and final piece of its new Tiangong space station on Monday, and the 23-ton rocket body is returning somewhere on Earth this weekend.
The Mengtian module, which carries scientific experiments, took off on the Chinese Long March 5B rocket. As it climbed into space, the rocket’s central stage gave the space station module a final push into Earth’s orbit before detaching.
Unlike most modern rocket bodies, designed to propel themselves into a remote part of the Pacific Ocean, Long March 5B’s body fell into its own orbit around Earth. It is well on its way to descending back into the atmosphere – an event called “reentry” – and falling to Earth on Friday or Saturday morning in the Eastern time zone.
Nobody knows where the rocket body will fall and nobody is checking it. But any debris from space is extremely unlikely to hit you.
Forecast: parts of rockets will rain
Experts can only estimate how much of the Long March rocket body, which is roughly the size of a 10-story building, will crash into Earth. Some will likely burn as it plows through the atmosphere, but the rocket’s body is too large to completely disintegrate.
A rule of thumb is that 20% to 40% of the mass of a large object will survive its fall through the atmosphere, experts from the Aerospace Corporation previously told Insider.
It is still too early to say exactly where the central stage might fall, most likely in pieces. But the Aerospace Corporation is monitoring the rocket’s stage and predicting possible routes it could take to return to Earth.
The area where the debris could fall covers about 88 percent of the human population, according to those analysts’ calculations. But that population is strongly condensed in some places. Most of the area where debris could rain is open ocean or uninhabited land.
However, space industry leaders have denounced China’s practice of uncontrolled reentry, saying it poses an unnecessary risk to human life and property.
Estimates will improve in the coming days as the rocket’s body approaches reentry.
This marks the fourth time that a remnant of the Chinese Long March 5B rocket has threatened lives and property. Each of the three times the rocket was launched – in 2020, 2021 and July 2022 – fragments of its body fell back to Earth.
In May 2020, debris from one of those rockets was discovered near two Ivory Coast villages, causing property damage. According to the New York Times, in 2021, China claimed that the remains of the rocket landed in the Indian Ocean near the Maldives.
Earlier this year, in July, parts of the rocket’s booster also crashed to Earth, with several likely pieces discovered on both the Malaysian and Indonesian sides of the island of Borneo, as well as in the ocean near the Philippines.
Most of the rocket stages crash by re-igniting the engines shortly after taking the load into orbit, moving away from populated areas and into the Pacific Ocean. But in the case of the Long March 5B, China did not design the rocket for controlled reentry.
“Rockets are fired all the time and very rarely do we worry about reentry,” John Logsdon, founder of the George Washington University Space Policy Institute, told Insider in May 2021 as the world waited for the rocket’s body to fall. “So yeah, I’m a little confused as to why this is happening.”
“Is this just a deliberate non-compliance with international guidelines? Or because it’s a new vehicle, isn’t it designed properly so you can do a controlled re-entry? Anything,” Logsdon said, adding, “It’s a shame he puts a lot of people at risk. “
In a study published in the journal Nature in July, researchers calculated a roughly 10% chance that the debris would hit one or more people within a 10-year period. It’s not just Chinese rocket bodies. Satellites and fragments of unknown debris regularly fall out of orbit.
“If you roll the dice too many times, someone will be lucky,” Jonathan McDowell, a Harvard astronomer who meticulously tracks objects in Earth’s orbit, previously told Insider.
Ted Muelhaupt, a consultant working on the Aerospace Corporation’s re-entry database, previously told Insider that an object weighing at least 1 ton falls from orbit and re-enters the atmosphere on a weekly basis.
Long March 5B boosters are among the largest objects to fall back to Earth, but uncontrolled reentry is not unique to China. In 1979, NASA’s Skylab space station descended rapidly, spreading debris over Australia. Today, however, controlled reentry is standard practice.
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