More details of the Shenzhou 7 space mission have now emerged from Chinese media sources. Reports carried by China Daily and China.org.cn have identified the crew as Zhai Zhigang, who is tipped to become China's first spacewalker, Liu Boming and Jing Haipeng.

The names of all these men have circulated in rumours in recent weeks. There has been no release of the identities of the back-up crew, and we will probably not know them until after the mission.

Shenzhou 7 is still on course for a liftoff on the night of September 25. The spacewalk was previously tipped to begin a few hours later, which would place it on September 26. This is still the case according to one report, but another suggests the EVA could take place on September 27.

Presumably, this gives the crew a window of time to prepare their gear, and also themselves. If the crew experiences spacesickness on the first day of flight, it would be wise to delay the spacewalk.

There's one other revelation. China.org.cn claims that the mission will return to Earth on September 28. This means that Shenzhou 7 will fly in space for roughly three days. That's a surprisingly short mission. It suggests that China is interested in carrying out the spacewalk, and almost nothing else.

In a previous article, I wondered what else the crew would be doing on the flight, assuming, as others did, that the flight would last for five days. Now we know that they will probably do little else apart from preparing for the spacewalk, conducting the spacewalk, and preparing to return to Earth.

The short flight probably has its advantages. It allows the crew to focus on the core task. It also probably avoids straining the logistics of the spacecraft. There will be three crewmembers on Shenzhou 7, more than have ever flown before.

There will also be fewer solar panels, and thus less power. Food, water and oxygen will also be used at a greater rate. The spacewalk will also require a lot of gas to repressurize the orbital module at the end of the task.

Shenzhou 6 carried two astronauts for roughly five days, making a total logistical demand of roughly ten man-days. Shenzhou 7 will match this with roughly nine man-days and reduced power generation. Have we finally discovered the endurance capacity of the Shenzhou spacecraft?

Dr Morris Jones is the author of "The Adventure of Mars" and "When Men Walked on the Moon". Email morrisjonesNOSPAMhotmail.com. Replace NOSPAM with @ to send email.