The three astronauts of China's Shenzhou-21 mission entered the China Space Station and met the Shenzhou-20 crew early Saturday morning, beginning a new round of in-orbit crew handover.

The Shenzhou-20 crew opened the hatch at 4:58 a.m. to welcome the arriving Shenzhou-21 crew aboard the space station, according to the China Manned Space Agency.

This marks the seventh space rendezvous in the history of China's space exploration. The two mission commanders reunited in orbit three years after their first meeting in space.

The six crew members took group photos to commemorate the occasion.

The two crews will live and work together for about five days to complete planned tasks and the handover process.

(Cover: Group photo of China's Shenzhou-20 and Shenzhou-21 crew members. /China Manned Space Agency)