神舟二十号航天员顺利返回地球，将择机发射神舟二十二号飞船

Core Points - The Shenzhou-20 crew successfully completed a 204-day mission in space, setting a new record for the longest duration for a single crew in China's space history [1] - Astronaut Chen Dong became the first Chinese astronaut to spend over 400 days in space and holds the record for the most extravehicular activities [1] - The Shenzhou-20 mission involved significant scientific experiments across various fields, including microgravity physics and space medicine [1] Summary by Sections Mission Duration and Achievements - The Shenzhou-20 crew spent 204 days in orbit, completing four extravehicular activities and multiple cargo operations [1] - The mission contributed to extensive research in microgravity basic physics, space materials science, space life science, aerospace medicine, and aerospace technology [1] Return Mission and Safety Concerns - The Shenzhou-20 crew will return aboard the Shenzhou-21 spacecraft due to concerns over potential damage from space debris [1][2] - The Shenzhou-20 return capsule was found to have minor cracks in the window glass, likely caused by external impacts from space debris, which do not meet safety conditions for a manned return [2] - An emergency backup mission with the Shenzhou-22 spacecraft is planned to ensure safe return for the crew, with the launch timing dependent on the space station's operational status [2]