The next Chinese crewed space mission won't fly until 2016. China is expected to send a crew of three astronauts to the Tiangong 2 space laboratory, which is expected to launch in the same year.

Right now, nobody knows who will be aboard the Shenzhou 11 spacecraft, which will carry these astronauts to the laboratory. The Chinese themselves probably won't even have a rough idea for at least another year.

But other questions about China's astronaut corps need to be explored. A changing of the guard must happen at some point in the next few years. New astronauts must be selected. Old ones must also be retired, even if they remain officially listed as active.

So far, China has done an impressive job of preserving its small corps of astronauts. There has been no attrition, at least not officially. We can probably say with confidence that some of China's astronauts will never fly in space again, and are secretly forbidden from doing so. Stamp this on the files for Yang Liwei, China's first man in space, Liu Yang, China's first woman, and Zhai Zhigang, China's first spacewalker.

They are national treasures who will not be risked on any more dangerous missions. It's also possible that some of China's astronauts now have slim odds of flying again, or flying at all. That's probably true for much of the original astronaut class of 1998. Any unflown members of this group who don't make it aboard Shenzhou 11 will probably retire without a mission.

We can expect a clearing of the decks in the next two years, but China will also need to recruit more space travellers. It will be more than just replacing those who have been retired. China will need to expand and modify the structure of its astronaut corps for the next phase of its space program.

Around 2022, China is expected to complete the Chinese Space Station, a large multi-modular space complex. Crews of three astronauts will occupy the station, which could easily outlive the ageing International Space Station. The Chinese station itself will become international, with European astronauts already tipped as guests. Other nations could also join the party, but don't expect any to be American.

China's next cohort of astronauts will probably be selected as potential crews for the Chinese space station. Sustaining the space station will require a regular sequence of expeditions, even if the station is not permanently occupied. This will be a step up from the traditional pace of Chinese astronaut launches, which are frustratingly rare. More flights will require more astronauts.

We can also expect more diversity in the backgrounds for these astronauts. China's first group were all "right stuff" material, a small team of elite male fighter pilots. The second group were generally in the same mould, but two female air force pilots were included.

The third group will probably introduce astronauts with scientific and technical backgrounds, but no experience as military flyers. We have seen a similar evolution in the way space travellers were selected for the Russian and American programs.

China will probably wait at least a year longer, and probably more than two, until it introduces its next group of astronauts. The station is coming, but it's still years away. We also don't really know if China will launch a third Tiangong module as the final practice run for the space station.

Much of this could depend on how successful Tiangong 2 is, and how much progress China makes with the Tianzhou cargo ship and its new Long March boosters. China has been vague on the subject, probably because the intermediate planning is somewhat fluid.

In any case, the next group of Chinese astronauts will probably be a major step towards launching the world's next space station. At some point, they could be humanity's only representatives beyond the planet.

Dr Morris Jones is an Australian space analyst who has written for spacedaily.com since 1999. Email morrisjonesNOSPAMhotmail.com. Replace NOSPAM with @ to send email. Dr Jones will answer media inquiries.