The sudden inclusion of a woman in the crew, which will also probably include veteran astronauts Jing Haipeng and Liu Wang , surprised some overseas observers, who say such a decision could only have been made at the highest levels, and for political reasons.

Analysts closely monitoring the Tiangong-I programme, as the unmanned space lab orbits the earth following its launch in September last year, say the decision to send a woman delayed the Shenzhou-IX launch.

Some experts close to the astronauts' training programme confirmed there had been a 'rush' to get a woman astronaut prepared in time. Joining the mission at such a late stage meant they had to undergo expedited training, which added to the pressure on the other crew members and support staff.

Though officially a civilian project, the manned space programme is controlled by the People's Liberation Army and most of its decision-making, operations and overall goals are strictly guarded as military secrets, fuelling suspicion overseas that China's expansion into space is for aggressive purposes.

But all experts agreed having a woman on board would be a boost for the space programme, sending a powerful message to the nation about the equality between the sexes. It would also offer insight into how women operate in space and what adjustments the programme would need to make to accommodate them on future missions.

A successful docking with the space lab will also be a significant step along China's path to completing its own space station by 2020, when the International Space Station is due to be retired. With no countries having announced any plans to replace the ISS, this will leave China as the operator of the only full-scale space station in less than a decade.

Docking the Shenzhou-IX with Tiangong-I will be difficult. The two craft will be flying at more than seven kilometres per second, and at such a high speed a small error could lead to disaster. The astronauts will line up the two spacecraft using manual controls similar to joysticks. After docking, the crew will stay on board the orbiting craft for 10 days, the longest stay in space by Chinese astronauts. The entire mission will last about two weeks, according to reports in mainland media.

Morris Jones, Australian space expert and author, noted that today's planned launch had been subject to some strange delays. The international space community had been expecting China to launch the spacecraft earlier this year, when the Tiangong-I's orbit was lowered to a level suitable for docking, Jones wrote in an article on spacedaily.com. However, it was later returned to its higher orbit, aborting the process.

Jones is among those who believe that the delay was caused by a sudden decision to include a woman astronaut. Reshuffling the original crew would affect training and planning schedules, forcing authorities to pull back the launch.

In an e-mail to the South China Morning Post, Jones wrote that he believed Liu and Wang underwent accelerated training.

'China reported that the female astronauts were receiving 'pointed training'. This is code for saying that they are being rushed through with basic training,' he wrote.

Women will also need to deal with issues such as sex discrimination. A Chinese male astronaut expressed concern to the Post that the men would feel uncomfortable in the presence of a woman in confined quarters. The Tiangong-I space lab was smaller than a standard module of the ISS and living in such a small space for more than a week would cause 'unnecessary body contact', he said.

Jones, however, did not think that this would be a problem. 'I think the astronauts are all highly disciplined professionals. They can deal with even greater challenges than privacy and gender issues.'

Politics might have played a big role in the rush, Jones said.

'It's possible that the inclusion of a female astronaut ahead of the original mission schedule was made for political reasons, and on the orders of high-level cadres in Beijing,' he wrote.

'It is no secret that China's Communist Party is struggling to preserve its public image in the face of some high-profile political scandals. A woman in space, courtesy of China's state-run space programme, would provide some much-needed good news. It is a move to boost the credibility of the space programme and of the political masters behind it.'

The Chinese government has often used its rocket launches for political goals. In recent years, almost every one of the national holidays that fall in October was followed by a launch. The launch of China's first lunar probe took place on the final day of the 17th party congress, on October 15, 2003.

A senior Chinese expert on the space programme confirmed that there had been a rush to find a woman candidate. The expert, a researcher with the China Aerospace Science and Technology Corporation familiar with the screening, selection and training of the astronauts, said that a woman astronaut had also been scheduled for the launch of Shenzhou-X and the decision to advance women's participation had disrupted some preparations.

The women astronauts, including Liu, had been trained for two years but they had less than a year to practice manual docking, the expert said. 'The rush to meet the deadline has put tremendous pressure on everyone,' he said, adding that the decision was made by scientists, not political leaders.

Space expert Professor Jiao Weixin said that the final choice of crew had remained uncertain until late last year and that the eventual decision to include a woman astronaut had come as a surprise.

Before the launch of Shenzhou-VIII in July last year, the authorities had been hesitating about whether to send anyone on board Shenzhou-IX. The success of the Shenzhou-VIII mission had probably given them the confidence to proceed with the mission to put a crew on board the Tiangong-I.

Liu and Wang would nevertheless have to have passed the strictest requirements, Jiao said. 'They must learn every detail by heart and achieve a high level of proficiency that can only be gained by intensive, repetitive training,' he said.

State media reported that Liu and Wang's training had been intensive. Liu, for example, was unable to return home to attend her grandfather's funeral because of the training. She also had no time to have a child even though there is medical concern that her trip into space would expose her to high radiation and affect her fertility.

The former Soviet Union and United States treated the first flights of their women astronauts and cosmonauts differently. The Soviets sent Valentina Tereshkova into space in 1963, only two years after their first male cosmonaut, Yuri Gagarin. Since then Russia has sent only a few women into space. The US did not send its first woman, Sally Ride, into space until 1983. But out of 54 women who have been part of space missions, 48 have gone with Nasa.