Full coverage: China Tiangong-2 Space Lab Launch

The launch of Tiangong-2 is a key step of China's space station program. And a third Tiangong is planned.  China plans to build the world's third multi-module space station around 2020.

The first space laboratory, Tiangong-1, was launched in 2011. It mainly served as a "target vehicle" for docking experiments. Tiangong-2 is a more advanced space lab complete with cargo ship. It was also designed with a month of life support resources for a crew of at least 2.

Tiangong-3 will continue to develop these technologies, with longer life support for more astronauts. The rest of this year will see multiple major space missions.  The manned space flight of the Shenzhou 11 will dock with the Tiangong-2 later in October.

And the first flight of Long March 5, the next-generation heavy lift rocket, is scheduled for November from the Wenchang Satellite Launch Center on Hainan island.