JIUQUAN, Gansu -- Shenzhou VII will lift off between 9:07 pm and 10:27 pm Thursday, carrying three astronauts, one of who will become the first Chinese to walk in space, senior space program officials said Wednesday.
One of the astronauts, Zhai Zhigang will walk in space around 4:30 pm on Saturday, media reports said.
The spacecraft will carry astronauts Liu Boming and Jing Haipeng, too.
One of the major tasks of the three-day mission is extra-vehicular activity (EVA), or spacewalk in this case, mission spokesman Wang Zhaoyao said at a news conference Wednesday. The success of the task will mark a remarkable step forward for China.
The other tasks include releasing a small monitoring satellite and satellite data relay trials, said Wang, who is also deputy director of China's manned space program office.
"The Shenzhou VII mission marks a historic breakthrough in China's manned space program. It is a great honor for all three of us to be part of the mission, and we are fully prepared for the challenge," Zhai Zhigang said when he and the other two astronauts met the media Wednesday.
Tonight's mission will be the second stage of China's three-stage manned space program, which eventually is aimed at building a space lab and a space station by 2020.
Engineers began loading fuel in the carrier rocket at 4 pm Wednesday, a process that would take seven hours and meant the launch was "irreversible", Jiuquan Satellite Launch Center officials said.
Shenzhou VII will be launched from atop the Long-March II-F carrier rocket into orbit 343 km from Earth.
Two of the astronauts will enter the orbital module, put on EVA spacesuits and prepare for the spacewalk. One of them will put on a China-made "Feitian" EVA suit and the other, a Russian Orlan-M "Haiying" suit.
And "one of the two will get out of the cabin and retrieve the test samples loaded outside the module," Wang said.
Compared with the previous two manned space flights, the Shenzhou VII mission faces unprecedented technical difficulties, he said, even though China has achieved a series of technical breakthroughs, including making an EVA suit and airlock module.
During the mission, the astronauts will have to assemble and test the 120-kg EVA suits, depressurize and re-pressurize the cabin, and exit and re-enter the orbital module.
"The process of EVAs cannot be simulated completely on the ground and some of the newly developed products have to be tested in flight for the first time," Wang said.
Thirteen Orlan-M spacesuits, three for actual EVAs, were received from Russia under a contract signed in April 2004, he said. Moscow developed the spacesuits, while Beijing gave the power supply and communication systems.
"Russian experts have provided technical assistance throughout the mission," he said.
Thanks to the collaboration, China took only three and half years to design the EVA spacesuit. Or else it would have taken eight years to do so, Chen Shanguang, head and chief designer of the project's astronaut suits and other accessories, said.
Russia helped train the astronauts and develop the Shenzhou spacecraft, too.
But soon China could train foreign astronauts, Xinhua quoted Chen as having said. "China's two successful manned space missions have showed it has the technical ability to independently train astronauts in future."
In 2003, China became the first country after the US and Russia to send a man into space. It followed it with a two-man mission in 2005.