Shown is a computer graphic of what a Tiangong-Shenzhou space docking might look like. Tiangong is on the left, and Shenzhou is on the right.China National Space Administration

China is likely to launch its space laboratory Tiangong 2 by 2015 as part of the country's ongoing space station programme. Tiangong 2 will take over from the smaller Tiangong 1 which was launched in 2011 and is still in orbit.

Tiangong 1 has successfully docked two unmanned rockets and a manned one in 2013 carrying two astronauts who conducted a number of successful docking tests on the space lab.

The space programme originally included the launch of two space laboratories, Tiangong 1 and 2, and an additional space station module Tiangong 3. The entire Tiangong programme was meant to develop and test technologies to sustain a full-fledged space station to be launched in the early 2020s.

In addition, China is launching a cargo ship Tianzhou or "Heavenly vessel" by 2016 to supply goods and propellants to Tiangong 2, according to Xinhua news agency.

The design of Tianzhou is similar to Tiangong 1, but it will be much larger and bulkier. It will be delivered into space by the medium heavy Long March 7 (LM-7) rocket.

However, China has apparently abandoned a plan to launch Tiangong 3, a decision which triggered a wave of speculation over the design of Tiangong 2, according to Space Daily.

Experts are concerned that Tiangong 2 will be too large for the yet untested LM-7 to carry.

China also plans to put an experimental core module of its space station into orbit by 2018, so its first manned space station would be ready by the early 2020s.