China says it will launch a unmanned spacecraft on Tuesday that will dock with a capsule already orbiting the Earth.A rocket carrying Shenzhou 8 will blast off early in the morning from the Gobi Desert and rendezvous with the Tiangong 1.
The space capsule was launched in late September and has already been manoeuvred into position.
China is practising docking in order to build a space station by 2020.
Shenzhou 8 is due to be launched from Jiuquan Satellite Launch Centre in Gansu province at 05:58 (21:58 GMT).
The docking - which will take place 343km above the Earth - will happen within two days of the launch.
There will be two other attempts to dock with the capsule next year, at least one of which will be manned.
Astronauts - called taikonauts in China - are already being trained for that mission, according to the manned space programme's spokeswoman Wu Ping.
China hopes to construct and launch a space station by the end of the decade and these docking missions are part of that process.
'Key foundation' An orbiting station is just one part of the country's ambitious plans for space.
"The mastering of rendezvous and docking technologies will lay a key technical foundation for China's building of a space station and deep-space exploration," said Zhou Jianping, chief designer of China's manned space programme, according to the Xinhua news agency.
China came late to the space race: it launched its first manned mission in 2003 and carried out its first space walk only three years ago.
It maintains that its aims are purely peaceful.
"The new knowledge obtained through space science research should be common wealth for human beings and should benefit the whole world," Mr Zhou said.
Foreign observers have been invited to watch the launch of Shenzhou 8.
But China caused alarm in 2007 when it destroyed a defunct weather satellite by firing a land-based rocket at it.