By David Cyranoski of Nature magazine

The International Space Station (ISS) is just one space-shuttle flight away from completion, but the construction boom in low-Earth orbit looks set to continue for at least another decade. Last week, China offered the most revealing glimpse yet of its plans to deploy its own station by 2020. The project seems to be overcoming delays and internal resistance and is emerging as a key part of the nation's fledgling human space-flight program. At a press briefing in Beijing, officials with the China Manned Space Engineering Office even announced a contest to name the station, a public-relations gesture more characteristic of space programs in the United States, Europe and Japan.

China first said it would build a space station in 1992. But the need for a manned outpost "has been continually contested by Chinese space professionals who, like their counterparts in the United States, question the scientific utility and expense of human space flight", says Gregory Kulacki, China project manager at the Union of Concerned Scientists, headquartered in Cambridge, Massachusetts. "That battle is effectively over now, however, and the funds for the space station seem to have been allocated, which is why more concrete details are finally beginning to emerge."

Significantly smaller in mass than the ISS and Russia's Mir space station (see 'Rooms with a view'), which was deorbited in 2001, the station will consist of an 18.1-metre-long core module and two 14.4-metre experimental modules, plus a manned spaceship and a cargo craft. The three-person station will host scientific experiments, but Kulacki says it also shares the broader goals of China's human space program, including boosting national pride and China's international standing.

The space-station project will unfold in a series of planned launches over the next ten years. Last Friday, official state media confirmed that the Tiangong 1 and Shenzhou 8 unmanned space modules will attempt a docking in orbit later this year, a maneuver that will be crucial for assembling a station in orbit. If that goes well, two manned Shenzhou craft will dock with Tiangong 1 in 2012. China will then move on to proving its space laboratory capabilities, launching Tiangong 2 and Tiangong 3, which are designed for 20-day and 40-day missions, respectively, over the next 3 years. Finally, it will launch the modules that make up the station.

Observers describe the program as slow, systematic and cautious. According to the Chinese media, engineers have made more than 170 technical modifications to China's Long March rocket in preparation for the next series of launches. "As China is now really venturing into terra incognita with this stage of its manned space program, the unknowns and risks are greater," says Eric Hagt, director of the China program at the Center for Defense Information in Washington DC.

Hagt says that the station's small size is partly the result of advances in miniaturization since Mir and the ISS were designed and partly because China "needs to be economical and has stressed that all along. China has studiously avoided the impression that it is in a race, particularly with the United States."

China has said that its space technology will be compatible with that used in the ISS so that modules from other countries could dock with its station, and it promises that its facility will be able to host experiments from non-Chinese researchers. But the US Congress, fearing industrial espionage, has long opposed any role for China in the ISS. As a result, the Chinese space program has had no alternative but to "go it alone", says Joan Johnson-Freese, an expert on national security and on China at the US Naval War College in Newport, Rhode Island.

Last week's announcement came just two weeks after the passage of a 2011 US federal spending bill that explicitly prohibits NASA from collaborating with China.

This article is reproduced with permission from the magazine Nature. The article was first published on May 4, 2011.