An enormous rocket component that China recently launched into space is out-of-control in orbit and is expected to make a chaotic reentry into the atmosphere this week, provoking concerns about a possible impact in a populated area.
The rocket debris, which is estimated to weigh more than 20 metric tons, will most likely splash down in remote ocean waters, but its current trajectory also passes over urban areas as far north as New York state and as far south as New Zealand, reports Andrew Jones of SpaceNews.
China’s Long March 5B rocket blasted off last Wednesday, and successfully delivered the first “Tianhe” module of the nation’s new space station into orbit. Unfortunately, the massive core stage of this particular rocket, known as the CZ-5B, also ended up in orbit.
Expendable rocket parts that enter orbit are often equipped to perform “deorbit burns,” maneuvers that guide them into controlled reentries of the atmosphere over unpopulated regions. Ground-based radar trackers have revealed that the 30-meter-tall CZ-5B core is tumbling in space, confirming that Chinese space officials do not have control over the component and therefore cannot perform a deorbit burn that would ensure a safe reentry.
China already sparked worldwide criticism when it initially debuted the CZ-5B in May 2020, a launch that also placed the core booster into an uncontrolled orbit. Debris from its wild reentry was reportedly scattered across villages in Cote d’Ivoire; luckily, there were no accounts of injuries or fatalities caused by the impacts.
“It was seemingly a successful launch, until we started getting information about a reentry of a rocket body, a reentry that was really dangerous,” said Jim Bridenstine, who was NASA’s administrator at the time, according to Jeff Foust of SpaceNews. “It flew over population centers and it reentered Earth’s atmosphere. It could have been extremely dangerous. We’re really fortunate in the sense that it doesn’t appear to have hurt anybody.”
It’s not unusual for rocket parts to fail to safely deorbit. Just a few weeks ago, the second stage booster of SpaceX’s Falcon 9 made an uncontrolled reentry that ultimately dumped a heavy pressure tank onto a farm in Washington state.
However, China has drawn another round of consternation and rebuke from international space officials due to the sheer size of its CZ-5B core, which is about seven times larger than the Falcon 9 second stage.
“Both CZ-5B launches have left their core stage in orbit for uncontrolled reentry,” Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, told George Dvorsky of Gizmodo. “They are over 20 [metric tons]. It has been standard practice for 30 years for the rest of the world not to leave objects this big—or even half this big—in orbit without controlled deorbit.
“This design choice in 2021 is unacceptable and tarnishes China’s great achievement in launching Tianhe,” McDowell added.
To that point, objects of this size haven’t been left to fall out of orbit in such a dangerous manner since the Russian Salyut 7 spacecraft, which weighed 39 metric tons, burned up over Argentina in 1991. The United States holds the record for the largest uncontrolled reentry ever, which occurred in 1979 when the 79-ton Skylab station scattered debris across the Indian Ocean and Western Australia.
The CZ-5B core may well burn up completely in the atmosphere, and any leftover debris will most likely strike uninhabited stretches of our planet. But until the booster’s reentry has been confirmed by ground trackers, it’s impossible to predict exactly where it will end up, or whether anyone will be affected by its unmoored demise.