The Shenzhou-21 crew conducted multiple space science experiments.
The Shenzhou-21 crew performed their first full-system pressure emergency drill.
The second option in China's backup strategy is to return the astronauts first on Shenzhou-21.
The accelerated launch of Shenzhou-22 ensures Shenzhou-21 astronauts Zhang Lu, Wu Fei, and Zhang Hongzhang have a safe return option.
The Shenzhou-20 team returned aboard Shenzhou-21 on November 14, nine days later than planned.
Astronauts returned to Earth aboard the Shenzhou 21 spacecraft instead of Shenzhou 20.
Shenzhou-21 astronauts have their lifeboat.
Once docked, Shenzhou-22 will be assigned to the Shenzhou-21 taikonauts currently aboard the Tiangong Space Station.
Three astronauts from the Shenzhou-20 mission returned aboard Shenzhou-21 on November 15, which served as an emergency vehicle.
The crew of the Shenzhou-20 spacecraft returned on November 14 on the Shenzhou-21 spacecraft, which had delivered a new crew to Tiangong at the end of October.
China launched the uncrewed Shenzhou-22 spacecraft to Tiangong to serve as the return spacecraft for the Shenzhou-21 crew.
Shenzhou-22 is heading to Tiangong to provide a lifeboat for the Shenzhou-21 crew.
The astronauts arriving on Shenzhou 21 currently do not have a return capsule available.
The three astronauts ultimately returned to Earth on November 14 using the capsule from Shenzhou 21, which had arrived at Tiangong on October 31.
On November 14th, the Shenzhou-20 crew returned to Earth via the Shenzhou-21 spacecraft after a space debris strike damaged their vehicle's window.
China will take the opportunity to send food and additional cargo to the Shenzhou 21 crew, who began their six-month stay at the orbital laboratory on October 31.
The Shenzhou-21 return capsule brought back samples from research in life sciences, materials science, and combustion.
The crew of Shenzhou 21 is without a return spacecraft since the Shenzhou 20 was damaged by a micrometeoroid.
The remaining samples will be sent later together with the Shenzhou-21 return capsule.
The Shenzhou-21 crew includes Commander Zhang Lu, Flight Engineer Wu Fei, and Payload Expert Zhang Hongzhang.