Three steps

"China has now reached the second phase of a three-step plan drafted in 1992 for implementing a manned space program," said Zhang Jianqi, former deputy chief of China's Manned Space Program.

During the first stage of the program, unmanned and manned spacecraft were sent into near-Earth orbit to conduct Earth observation and scientific experiments.

Work began on developing Shenzhou series of spacecraft in the early 1990s. In November 1999, Shenzhou 1, China's first unmanned spacecraft, successfully blasted into space. Three more successful unmanned missions followed, with Shenzhou 2 in 2001, and Shenzhou 3 and Shenzhou 4 in 2002.

This first stage culminated with the successful implementation of China's inaugural manned space mission on October 15, 2003. Shenzhou 5 carried astronaut Yang Liwei into space, and he remained in orbit for 21 hours.

China then began the second stage of its manned space program. The goals of this phase include: the launch of spacecraft with more than one astronaut, spacewalks, docking between spacecraft and space modules, and the establishment of short-term manned space laboratories.

In the medium term, China plans to launch Tiangong-2 and Tiangong-3 space modules around 2015, according to CNSA.

Tiangong-2 will primarily be used for Earth observation and Earth science research. It will also be home for research into aerospace medicine and other research programs.

Tiangong-3 will focus on research into regenerative environmental control and life support systems.

 The final aim of China's space program is to establish a permanent space station.

"A spacecraft usually remains in space for a week or so. Therefore it has limited time to conduct scientific research," said Peking University Professor Jiao. "A functioning space station, however, can stay in orbit for a long time and scientists can run various experiments and develop space products."

In late April, the China Manned Space Engineering Office announced its plans to build a 60-ton space station and asked the public to help come up with a name and logo for the space station.

The office also said China will develop a cargo spaceship, with a launch weight of less than 13 tons, to transport supplies and lab facilities, including water, food, air and other necessities, to the space station.

At present, the Shenzhou spaceships will only be able to carry a 300-kg payload when three astronauts are on board. CNSA spokesman Wang said developing cargo supply technology would be among the tasks to be met in the 2011-15 period.