After a potential space debris impact, the Shenzhou-20 spaceship, currently docked with China's space station, will make an uncrewed return to Earth, according to Ji Qiming, a project spokesperson with the country's manned space program.
Following a suspected debris strike on Shenzhou-20's viewport, the three astronauts originally scheduled to return to Earth aboard the spacecraft were redirected to Shenzhou-21, which brought them home safely on Nov. 14.
China launched the Shenzhou-22 on Nov. 25 to provide a new return vehicle for the orbiting crew -- completing the first emergency launch in the history of its manned space program.
During a subsequent spacewalk, the Shenzhou-21 crew, who are now undertaking a six-month orbital stay, may be tasked with inspecting the cracked viewport. They may also perform protective work on it using specialized devices delivered by the Shenzhou-22 launch -- a procedure still being validated in ground tests, said Ji in a recent CCTV interview.
A day prior to their planned return on Nov. 5, the Shenzhou-20 crew spotted an anomaly on the viewport's edge -- a triangular, paint-like mark. They photographed it from multiple angles and under different lights, while the station's robotic arm cameras were employed to take supplemental external pictures.
The flaw was later identified as "penetrating cracks," said Jia Shijin, chief designer of the crewed spaceship system from China Academy of Space Technology. "The space debris responsible is preliminarily judged to be less than a millimeter in size, but struck with extremely high speed."
After this initial investigation, ground teams conducted extensive simulations and tests -- and commissioned two research institutions to perform wind tunnel tests for independent verification, Jia revealed.
In a worst-case scenario, the cracks could spread, causing the outer pane to detach -- with this leading to the failure of the inner pressure-sealing glass, resulting in cabin depressurization and the ingress of high-speed gases, Jia explained.
Guided by the principle of astronaut safety first, China opted for the historic alternative return and emergency launch procedures.
Ji said that Shenzhou-20's unmanned return mission will generate meaningful real-world experimental data for subsequent missions.
Four mice traveled to space aboard Shenzhou-21 spaceship. They were initially scheduled for a 5-to-7-day experiment on orbit, but instead stayed for about two weeks before returning with the Shenzhou-20 crew, according to Wu Dawei from the China Astronaut Research and Training Center. All mice returned in healthy condition, Wu said.
