Long March 5B uncontrolled reentry (May 2021)

On 9 May 2021, the massive core stage of a Chinese Long March 5B rocket — the booster that had launched the Tianhe core module of China's space station days earlier — made an uncontrolled re-entry, with surviving debris falling into the Indian Ocean near the Maldives.

Why this design drew criticism Unlike most large rockets, the Long March 5B places its enormous core stage directly into orbit, where it then re-enters uncontrolled. At roughly 21 tonnes, it was one of the largest objects to make an uncontrolled re-entry in decades, and the inability to predict or target its splashdown drew sharp public criticism, including from NASA's administrator.

A recurring pattern This was one of several Long March 5B uncontrolled re-entries tied to China's space-station construction campaign. Each followed the same pattern — a very large core stage left to the atmosphere — keeping the design at the center of the debate over responsible launch practices.