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China is preparing to rescue three astronauts who took refuge in the Tiangong space station after a suspected space-junk strike on their spacecraft last week, Chinese officials said on Tuesday. In a statement, the China Manned Space Engineering Office (CMSE) said engineers have carried out extensive tests on a backup capsule that they plan to use to bring the three men back to Earth. “All work is progressing steadily and orderly according to plan,” the agency said. On supporting science journalism If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today. China’s Tiangong, which spans some 180 feet, typically hosts a crew of three astronauts in six-month stints. A new three-person crew arrived at the space station to take over from the stranded astronauts in October. But because of the space debris emergency, both crews remain onboard. While unusual, the station is designed to support two crews in orbit simultaneously, CMSE said. “The Shenzhou-20 astronaut crew is working and living normally and is conducting in-orbit scientific experiments together with the Shenzhou-21 astronaut crew,” the agency said. “It’s probably a bit crowded,” says Jonathan McDowell, an astronomer at the Center for Astrophysics | Harvard & Smithsonian. “It’s cramped, but it’s big enough for them to float around in.” McDowell adds that Chinese officials have been vague about the debris that allegedly struck the Shenzhou 20 spacecraft and the extent of the damage. “That’s frustrating,” he says. “Is it a small hole, a big hole? Is it a pressure drop? Is it a visible scar on the spacecraft? We don’t know.”