China's second orbital space laboratory, Tiangong II, which is to accommodate two Chinese astronauts for 30 days, has been delivered to the Jiuquan Satellite Launch Center in the Inner Mongolia autonomous region.

It set off from Beijing on Thursday by rail and arrived on Saturday, marking the start of the Tiangong II and Shenzhou XI missions, according to the China Manned Space Agency. The lab will now be assembled and undergo tests.

As part of China's manned space program, a Long March FT2 rocket will carry Tiangong II into orbit in mid-September. The Shenzhou XI spacecraft will carry two male astronauts in mid-October to dock with the lab, with the astronauts returning to Earth a month later.

The lab's major missions are to dock with manned and cargo spacecraft, test life-support systems, conduct experiments and demonstrate in-space refueling and other key technologies for the manned space station China plans to build by 2022.

With a designed life span of two years, Tiangong II comprises two cabins with separate functions - the "experiment cabin" will be hermetically sealed and will act as the astronauts' living quarters, while the "resource cabin" will contain solar panels, storage batteries, propellant and engines.

Compared with its predecessor, Tiangong I, the inner environment of the new space lab will be more comfortable to live and work in, the China Manned Space Agency said. It added that the spacecraft will carry 14 payloads to perform various experiments.

In April next year, a Long March 7 will transport the Tianzhou 1 cargo spacecraft to dock with Tiangong II. The cargo ship will carry fuel and other materials as well as test in-orbit replenishment technologies for a manned space station.

If everything goes well, the agency says China will be the only nation with a space station in 2024, which is when the International Space Station is to be retired.

China launched the Tiangong I in late 2011. The lab stopped operating in March, exceeding its designed life span by nearly two and a half years. It successfully conducted six automatic and astronaut-controlled dockings with manned Shenzhou spacecraft.

zhaolei@chinadaily.com.cn