China’s space agency performed a successful launch of a Long March 5B rocket on Sunday, delivering a new module to its fledgling space station. Similar to previous launches, however, the rocket’s core stage remained in orbit and is now set to perform an uncontrolled reentry.
The Long March 5B blasted off from Wenchang Space Launch Center in Hainan on Sunday, June 24, at 2:22 p.m. Beijing time. Packed atop the rocket was the 22-ton Wentian laboratory, which arrived at China’s Tiangong space station 13 hours later, according to state-run China Daily. Waiting for the 59-foot-long (18-meter) module were Chen Dong, Liu Yang, and Cai Xuzh, making them the first astronauts in China’s space history to attend an orbital docking. Wentian docked to the front port of the Tianhe core module, creating a T-shaped space station.
Instead of celebrating this accomplishment, however, we’re forced to wonder when the 21-metric-ton core stage will slip back into the atmosphere and where it will crash. Such is the pattern with Long March 5B launches, as two previous missions resulted in chaotic reentries (during controlled reentries, rocket stages are brought down with reignited engines, allowing launch providers to steer the rocket body away from populated areas, typically into the ocean). In May 2020, debris from an out-of-control core stage fell onto an inhabited area along the west coast of Africa, while a rocket launched in April 2021 crashed in the Indian Ocean near the Maldives.
The odds of rocket debris landing on your house are exceptionally low, but the risk to human life and property does exist. According to research published earlier this month, the chance of someone getting killed or hurt from falling rocket parts will rise to 10% in the coming decade. China has been admonished for not taking better care of its incoming rockets, but the stage appears to be set—yet again—for a recurrence of the previous two episodes.
And indeed, U.S. Space Command cataloged two objects from Sunday’s launch, one being Wentien and the other the discarded core stage. Astronomer Jonathan McDowell from the Harvard-Smithsonian Center for Astrophysics expects the stage to reenter Earth’s atmosphere within a week or so.
“Unfortunately we can’t predict when or where,” he explained to me in an email. “Such a large rocket stage should not be left in orbit to make an uncontrolled reentry; the risk to the public is not huge, but it is larger than I am comfortable with.”
During a livestream of the launch on China Global Television Network, Xu Yangson, director general of the Asia-Pacific Space Cooperation Organization, said China took measures this time to make sure that the core stage will come back down in a controlled manner, but did not elaborate. When I asked about Xu’s comment, McDowell said: “I think he is misinformed.” McDowell is likely correct, as the Long March 5B core stage would require a significant upgrade or revision to suddenly have the capacity for controlled reentry.
As for the Wentien module, it will now be used to support a host of scientific experiments ranging from microgravity studies and the effects of space radiation through to experiments to study the growth of plants, insects, small mammals, and microbes. A third module, named Mengtian, is scheduled to launch in October. China intends to use its Tiangong space station for 10 years, during which astronauts will work for stints lasting six months.
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