BEIJING - China's unmanned spacecraft Shenzhou-IIX departed from the prototype space lab Tiangong-1 at 6:30 pm Wednesday, preparing for return to earth, a spokesperson for China's manned space program said.

This came after China had successfully completed its first two space docking tests that joined the Shenzhou-IIX spacecraft, launched on November 1, and the target orbiter Tiangong-1 on November 3 and November 14, respectively.

Tiangong-1, a module of a planned space lab, has been in orbit since its launch on September 29.

The Beijing Aerospace Control Center (BACC), which is in command of the mission, will signal Shenzhou-IIX back to earth Thursday after conducting a series of examinations, tests and preparations, the spokesperson said.

Shenzhou-IIX will fly alone for a period of time after disengagement from Tiangong-1, which will leave room for any fine tuning of the orbit for the spacecraft's return, deputy chief engineer of the BACC Li Jian said.

The re-entry capsule of Shenzhou-IIX is set to land back on earth around 7 pm Thursday, the spokesperson said, adding that all arrangements are in place for the search and rescue of the re-entry capsule after it lands.

The successful space docking tryouts provide vital know-how to China for its three-phase development strategy of the manned space program, Chinese technologists said.

China has announced its plan of another two docking missions with Tiangong-1 next year, with at least one manned. The country plans to establish its own space lab around 2016 and a manned space station around 2020.