China will take another giant step into space on Thursday night, with the launch of its second space laboratory, Tiangong-2, into low-earth orbit from its Jiuquan Satellite Launch Center in the Gobi desert in the country's northwestern region.
You can watch the live webcast, starting 7.30 pm IST, here: http://www.cctv-america.com/2016/09/14/countdown-to-tiangong-2
The Tiangong-2 is the second of a series of three launches that began in 2011, with the Tiangong-1, that will culminate in the building of a manned space station by around 2022 with Tiangong-3.
China National Space Agency (CNSA) engineers on Wednesday began fuelling the Long March-2F T2 rocket that will carry Tiangong-2 into space.
"All systems are ready for lift-off," the Xinhua news agency quoted Wu Ping, deputy director of the agency's manned space engineering office, as saying on Wednesday afternoon.
"The launch of Tiangong-2 will lay a solid foundation for the building and operation of a permanent space station in the future," she said, adding that China's manned space program had entered a "new phase of application and development."
Once launched into space, the 8.6-tonne Tiangong-2 will fire its own rockets and maneuver itself initially into an orbit about 380 kilometers above Earth and later into an orbit 393 kilometers above, the height at which the future Chinese space station will operate.
Sometime in October, China will launch two male astronauts aboard a Shenzhou-11 spaceship, which will dock with the Tiangong-2. The two astronauts will work in the space laboratory for 30 days and then return to Earth.
In April 2017, the Chinese space agency will launch its first cargo ship, Tianzhou-1, which, too, will dock with the Tiangong-2 and replenish it with fuel and other supplies.
The launching and docking of the Shenzhou crew module and the cargo ship will help the CNSA evaluate technologies involved in on-orbit propellant re-supply, equipment repairs and long-term stays in space by astronauts, Xinhua quoted Wu as saying.
The Tiangong-2 space lab itself will operate in space for at least two years, with astronauts launched into it by multiple missions through the period conduct over 40 space science and application experiments onboard, including in aerospace medicine, space physics and biology, quantum key transmission, space atomic clock and solar storm studies.
The Tiangong-2, a bigger version of its 2011 predecessor Tiangong-1, measures 10.4 meters in length and 3.35 meters in maximum diameter, and allows for two astronauts to live in space for up to 30 days and can receive manned and cargo spaceships.
China is pulling out all the stops with the Tiangong-2, not just with the large number of experiments and their sophistication but also by the way it has gone about it. There are foreign collaborations and experiments onboard -- one payload, called POLAR, for instance, is a collaboration between Swiss, Polish and Chinese institutions to study gamma ray bursts; the space atomic clock, which experts claim loses only one second every 30 million years, is meant to make future navigation more accurate; three of the experiments onboard were designed by winners of a Hong Kong middle school contest. And, there's even a micro-satellite sharing the ride with the Tiangong-2, which will orbit close to the space lab.
China will "share the fruits of its development in its manned space program with all countries, especially developing countries", Xinhua quoted Wu as saying.
China began its ambitious space station plan as far back as 1992, when Project 921-2 received initial approvals. The final approvals came just as India was giving approvals to ISRO's Chandrayaan mission.
In 2001, Chinese engineers publicised the three-step process by which China would realise the space station ambition. The original target date was 2010, but now, the project will see fruition only sometime in the 2020s.
The first phase was to be manned space flight, which China achieved in 2003, with the Shenzhou crew modules.
The second phase was the orbiting of a space laboratory, which began with the Tiangong-1 in 2011.
The third phase will be the launch of a large space laboratory that will be permanently crewed and will be China's first true space station, rivalling the US-Russia-EU-Canada International Space Station, which will begin to be dismantled by about 2025, around the time China puts its station in place.
China is now somewhere between Phase 2 and Phase 3.
Tiangong means 'Heavenly Palace'.
With Tiangong-1, China mastered space docking as well as performing a limited number of experiments.
The 8.5-tonne laboratory was visited by the Shenzhou 8 unmanned and the Shenzhou 9 and 10 manned spacecraft during its two-year operational life. The Shenzhou 10 carried China's first female astronauts, Liu Yang and Wang Yaping. But given its size, though, it was not meant for astronauts to stay on it long.
Tiangong-1 is now in an orbit about 370 kilometres above Earth and descending 100 metres every day. It is expected to burn up in the Earth's atmosphere in the second half of 2017.
Tiangong-2 is a 20-tonne space lab that will support two astronauts for 30 days at a time. The Shenzhou 11 spacecraft will dock with it in October and bring the lab its first crew.
The lab is 14.4 meters in length and 4.2 meters in maximum diameter. A third-generation space lab, comparable to the Russian Mir, it has two docking points, to receive both manned spacecraft and unmanned cargo ships.
Tiangong-3 will be a 22-metric-ton core module, 18 meters in length, 4.2 meters in diameter, on which three astronauts can live for 40 days at a stretch.
It will help China develop regenerative life-support technology and methods of orbital replenishment of propellant and air.
It will also provide a multi-docking berthing mechanism, allowing four spacecraft to dock with it simultaneously.
It is expected to be launched in the 2020-2022 timeframe.
Following these, sometime in the mid-to-late 2020s, China will begin to build its large modular space station, expected to be a 60-tonne 'Heavenly Palace'.