Two unmanned Chinese spacecraft successfully docked together for a second time Monday, state-run media reported, in China's latest step toward placing its own space station in orbit.
The Shenzhou 8 craft re-docked with the Tiangong 1 module that will form part of a future space lab, and the two were jointly orbiting Earth, Xinhua News Agency reported, citing the mission's control center.
About half an hour before the Monday evening docking, Shenzhou 8 had successfully disengaged from the module after a 12-day flight together, Xinhua said.
In a commentary, Xinhua said the Shenzhou 8 mission had "laid a solid steppingstone for deep space exploration."
"The autonomous docking know-how now enables China to build space stations, resupply them, transfer astronauts and rescue them," it said.
One expert said not having to have crews on board when docking spacecraft was a big step toward building a space station and developing a human spaceflight program.
"They have plans to build a space station, and of course that's not possible without perfecting docking between two different craft, and the fact that they have perfected automated docking is a big step forward. The Americans didn't do it for decades after they launched their space program," said Peter Bond, consultant editor for Jane's Space Systems and Industry.
Shenzhou 8 was launched Nov. 1 and first docked with the already orbiting Tiangong 1 on Nov. 3. China's first space docking took place in an orbit 213 miles (343 kilometers) above Earth, Xinhua said. The Shenzhou craft is due to return to Earth on Thursday.
The docking mechanism, composed of 10,000 parts, and the more than 600 instruments aboard Shenzhou 8 were all developed and made in China, Wu Ping, spokeswoman for China's manned space program, was quoted as saying.
China will conduct two more space docking missions next year, and plans to establish its own space lab around 2016 and a manned space station around 2020, Wu said.
At about 60 tons when completed, the Chinese station will be considerably smaller than the 16-nation International Space Station, which is expected to continue operating through 2028.
China launched its own space station program after being rebuffed in its attempts to join the space station, largely on objections from the United States. The U.S. is wary of the Chinese program's military links and the sharing of technology with its chief economic and political rival.
Xinhua said Monday that "tiny adjustments" could make the Chinese docking mechanism compatible with the ports of the space station, as it allows any two similarly equipped spacecraft to dock with each other.
It also said that China allowed Germany to conduct biological experiments in a docking vehicle — the first instance of international cooperation since the beginning of China's manned space program.
Bond said Europe seems "more open" to collaborating with China in space. "I think that's to their mutual benefit," he said.