As the launch of China's next astronaut mission approaches, a major question remains unanswered. Will the Shenzhou 9 spacecraft carry two or three astronauts? Chinese officials have not answered this question in public, although the answer would have been known in private for months. Analysts have speculated on the possible options, but have not produced a conclusive case for either.

This author has endorsed the two-man option in previous articles. This was done out of consideration for the easier management of logistics (food, water, oxygen), as well as improved personal space for the crew on a long flight.

The Shenzhou 9 spacecraft is expected to spend roughly two weeks docked with the small Tiangong 1 space laboratory.

This theory is also supported by the flight of two, not three, astronaut dummies on the uncrewed Shenzhou 8 mission, which was seen as a dress rehearsal for Shenzhou 9.

Then again, Shenzhou spacecraft can carry three people. China has only staged three crewed space missions, and they've tried all possible crew sizes. The first mission carried one astronaut, the second had two and the third mission flew three.

There is nothing to stop them fitting three astronauts on the next flight, and the additional space provided by the Tiangong laboratory could make personal space less of an issue. The logistics would be stretched further, but careful planning could still make this feasible.

Having a third crew member could maximize the amount of experiment time performed on board the Tiangong laboratory. Two astronauts could live there while the third man took care of routine spacecraft management tasks.

On balance, there's a fairly even case to be made for both crew options. A crude averaging of the different plans could safely conclude that Shenzhou 9 will be crewed by "two and a half men". Your correspondent will now resist the temptation to make any more rude remarks about statistical analysts, and will try to avoid saying anything sardonic about Charlie Sheen, who seems to get high enough without rocketry.

Okay. I'll be good now. We cannot make any more informed conclusions without knowing more about the available logistics on both Shenzhou and Tiangong. We also don't know for sure how the workload of the astronauts will be distributed.

The amount of time that could be spent on experimental tasks is almost arbitrary. We also don't know how much attention is required to operate a production-model Shenzhou spacecraft when it's "parked" at Tiangong. Plus, we don't know how much attention Tiangong itself needs, although it seems to function very well in a ground-controlled mode.

This makes it difficult to answer such a fundamental question. We will simply have to wait until the Chinese themselves provide an official answer. But this author still feels confident about another prediction.

Regardless of the size, the entire crew will be comprised of unflown "rookie" astronauts from the original 1998 group of Shenzhou trainees. These men are fully trained and keen to fly. There are six unflown members of this group.

Even if Shenzhou 9 flies with a two-man crew, this will still leave the option of flying three people on the mission that follows. Shenzhou 10 is expected to dock with Tiangong 1 in the second half of 2012. There could be two men aboard this mission, but there will also be a woman on board.

The first female Chinese astronauts started training in 2010, and China has strongly hinted that one will be launched on this mission.

Dr Morris Jones is an Australian space analyst and writer. Email morrisjonesNOSPAMhotmail.com. Replace NOSPAM with @ to send email.