The unmanned Shenzhou 8 craft, launched earlier this week, made contact with the Tiangong-1 space lab at 1729 GMT. The union occurred over China itself.

Although no astronauts were in the Shenzhou craft this time, future missions will carry people.

Shenzhou 8 was the active craft in the docking. It fired its thrusters to push its front end towards the docking port of Tiangong-1. Once the vehicles' docking rings had made a good capture, 12 hooks were deployed to fix the craft in place. Protruding pins made electrical connections.

Shenzhou 8 and Tiangong-1 will spend two weeks circling the globe together before Shenzhou 8 heads back to Earth.

The return capsule will land by parachute to allow experiments carried into orbit to be recovered for analysis. The German space agency (DLR) has supplied an experimental box containing fish, plants, worms, bacteria and even human cancer cells for a series of biological studies.

Being able to dock two space vehicles together is a necessary capability for China if it wants to start building a space station towards the decade's end.