China’s Long March 5B rocket was originally launched in late April to carry the first part of China’s Tianhe module, which will serve as the core of its planned crewed space station. But the rocket booster itself went into orbit, and began an uncontrolled re-entry that led to fears it could come down above a populated area.
It had been difficult to predict where or when the spacecraft might fall back down to Earth because of an array of unknown details, both about the rocket itself but also the way that the atmosphere would act on it.
The rocket made its re-entry at 3.24 UK time, just west of the Maldives, according to Chinese officials posting on Weibo. Most of the debris was destroyed during the re-entry, and those remains fell into the ocean, the post said, though it gave no indication of how it had gathered that information.
The website Space-Track, which had been publishing official data from the US Space Force, said in a tweet that people tracking the rocket “can relax”. “The rocket is down,” it wrote.
“We believe the rocket went down in the Indian Ocean, but are waiting on official data from” the Space Force squadron tasked with cataloguing objects in orbit, it said.
It will be difficult to confirm for sure where and when the rocket re-entered for some time. Much of it will be destroyed by the re-entry and then impact, and the organisations tracking it watch for radar signals and so can only say for sure that it has stopped its orbit when they decisively stop.
Given the fact the rocket appears to have re-entered above the ocean, there may also be no eyewitnesses or video footage of the rocket’s arrival.
It was not immediately clear that the re-entry was definitively safe, and the co-ordinates given by Chinese authorities were close to the Maldives. But there were no immediate reports of problems, and no indication that any debris from the re-entry had been found.
Despite fears that the arrival of the rocket could endanger people on the ground, experts had cautioned that a re-entry over water was most likely, simply because it makes up three-quarters of the surface of the Earth. The chances of actually being hit by any piece of the rocket were miniscule.
“An ocean re-entry was always statistically the most likely,” tweeted Harvard astrophysicist Jonathan McDowell, who had been tracking the spacecraft throughout its descent. “It appears China won its gamble (unless we get news of debris in the Maldives). But it was still reckless.”
The Long March 5B rocket is one of the biggest pieces of space debris to return to Earth. China launched another version of the rocket, almost exactly a year ago, which crashed into houses in Ivory Coast when it came back down to Earth in a similar uncontrolled re-entry.
The rockets have been integral to China’s near-term space ambitions - from the delivery of modules and crew of its planned space station to launches of exploratory probes to the Moon and even Mars.
Debris from Chinese rocket launches is not uncommon within China. In late April, authorities in the city of Shiyan, Hubei Province, issued a notice to people in the surrounding county to prepare for evacuation as parts were expected to land in the area.