The Shenzhou-8 spaceship is mounted to a Long March-2F rocket at Jiuquan Satellite Launch Center on Sunday. Photo: CFP

The Shenzhou-8 unmanned spacecraft and its carrier, the Long March-2F rocket, arrived at the launch pad of the Jiuquan Satellite Launch Center Wednesday, beginning the countdown toward China's first space rendezvous test.

The spacecraft and rocket were assembled and vertically transferred to the launch pad along a 1,500-meter-long rail at a speed of no more than 20 meters per minute. The whole process lasted roughly two hours, China Central Television reported.

In the days ahead, engineers will conduct a series of tests during assembly before adding fuel to the rocket for the scheduled launch in early November.

Within two days of blasting off, Shenzhou-8 will perform China's first space docking test with Tiangong-1, a space lab that went into orbit on September 29.

After a successful rendezvous, Tiangong-1 and Shenzhou-8 will fly together for about 12 days, after which they will separate for another docking test.

Shenzhou-8 will return to Earth after completing the two tests while Tiangong-1 will ascend to its original orbit and wait for its next rendezvous with the Tiangong-9 and 10 spacecrafts that are to be launched within two years.

"The specific technology used in Shenzhou-8 and its space docking will be kept confidential until it is successfully launched and docked with Tiangong-1," an anonymous official with the China Aerospace Science and Technology Corporation told the Global Times Wednesday.

Ye Peijian, a member of the Chinese Academy of Sciences, said at a recent seminar in Jiangsu Province that apart from docking, engineers will also conduct kinetics and maneuverability tests on the two spacecraft.

"Although Tiangong-1 is unmanned, it was designed as a space lab for astronauts to carry out experiments. So the temperature, humidity, oxygen and other aspects of Tiangong-1 will also be tested," said Ye, an expert in space exploration.

The docking experiment is a prelude for China's mission to build a space station around 2020 with a mass of less than 100 tons, roughly about the same year the International Space Station will end its operational life and crash into the ocean.

"After building the space station, China will continue its space exploration by mastering and making breakthroughs in station construction and operation, manned long-term space missions and large-scale space applications," Ye said.

A source inside the aerospace industry told the Global Times in a previous interview that docking is only one of the major challenges facing China's space ambitions.

"The construction of a space station needs heavy lift launch vehicles capable of putting payloads of over 20 tons into low-earth orbit (LEO). The Long March-2 rocket currently in use has only a LEO capability of about eight tons. But the Long March-5 rocket currently under development will fill in the gaps," the source said.

Apart from having a greater capability, the Long March-5, which is scheduled to make its maiden flight around 2014, will also comply with international environmentally friendly criteria.

Instead of the highly toxic hypergolic propellant used by previous Long March rockets, the new rocket will utilize liquid hydrogen-liquid oxygen fuel, which burns cleanly leaving behind water vapor, for its first and second stages, before switching to?liquid oxygen-kerosene fuel for the boosters.

The Wenchang Space Launch Center, situated in Wenchang city on the northeast coast of Hainan Province, will be mainly used for launching synchronous satellites, heavy satellites, space stations and deep space probe satellites.

It is built at a latitude of 19 degrees north of the equator, in order to better utilize the rotational velocity of the Earth so that the rocket can use less fuel and thrust to reach orbit.

Meanwhile, China is also pushing forward its lunar exploration projects.

The Yangtze Evening News reported Wednesday that Chang'e-3, China's third lunar probe, is scheduled to be launched in 2013.

Chinese scientists are currently conducting trials on a lunar rover in a desert 200 kilometers away from Dunhuang, Gansu Province, where conditions are most similar to the moon.

According to Ye, the rover will travel 10 kilometers on the lunar surface within a 3-kilometer radius of its landing site, sending back to Earth the data it collects.

According to Reuters, the US will not test a new rocket to take people into space until 2017. Russia has said manned missions are no longer a priority for its space program, which has struggled with delays and glitches.

US President Barack Obama's budget cut for 2011 practically ended NASA's Constellation program, which focused on sending US astronauts back to the moon and further missions to Mars.

Wang Fei and Zhu Shanshan contributed to this story