中国将发射天宫1号太空实验室
China is due to launch its first space laboratory, Tiangong-1.
中国将发射首颗太空实验室，天宫1号。
China is taking a stepped approach to the development of its human spaceflight programme
Tiangong-1 will demonstrate the critical technologies needed by China to build a fully fledged space station - something it has promised to do at the end of the decade.
The space lab is set to ride to orbit atop a Long March 2F rocket.
State media say the lift-off from the Jiuquan Satellite Launch Centre in Gansu Province is likely to occur between 21:16 and 21:31 local time (13:16-13:31 GMT).
The Long March will put Tiangong in a near-circular path around the Earth, just a few hundred km above the surface.
It will operate in an autonomous（自主的） mode, monitored from the ground. Then, in a few weeks' time, China will launch another unmanned spacecraft, Shenzhou 8, and try to link the pair together.
This rendezvous（集合点） and docking capability is a prerequisite（先决条件） if larger structures are ever to be assembled in orbit.
Commentators say Russian technology, or a close copy of it, will be used to bring the two craft into line.
Assuming the venture goes well, two manned missions (Shenzhou 9 and 10) should follow in 2012. The yuhangyuans - two or three at a time - are expected to live aboard the conjoined（联合的） vehicles for up to two weeks.