The first step to creating a space station

Zhai Zhigang's mission will be a zero-gravity walk 'with Chinese characteristics'

Chinese astronauts will attempt their first step into the void this afternoon to acquire the experience that will play a central role in the future assembly of China's space station.

As the 29th orbit begins, flight commander Zhai Zhigang and Liu Boming will enter the orbit module, close the hatch behind them and put on their spacesuits for the walk, technically called an extravehicular activity (EVA). Jing Haipeng will remain in the re-entry module to guide the spacecraft.

Colonel Zhai will put on a made-in-China suit called Feitian ('flying to the sky'), and Colonel Liu will get into a Russian-made Orlan. Putting on spacesuits in a confined zero-gravity environment is an arduous task. As astronauts wrestle with their suits, they must be careful not to step on each other's suit or hit one another.

Once in their suits, the astronauts will probably be sweating profusely, and their visors may fog. The life- support backpacks should be working, but the suits' air conditioners are not designed to work until they are in a non-pressurised environment.

After the final check on the spacecraft's status, the crew will be given the all-clear to depressurise the orbit module. The oxygen pressure in the cabin will gradually decrease from 33 pascals - one-third of the pressure on Earth - to about 20. The spacesuits will inflate, and the astronauts will check their suits' systems to make sure the lock rings and seals are maintaining air pressure.

Then they will gradually reduce the cabin pressure to zero pascals. If the suit springs a leak or a glove is blown off, they have to respond quickly to repressurise.

If all goes well, they will open the hatch, and the Chinese astronauts will have equalled the Russians and Americans in the ability to walk into space.

The Chinese space authority said there was no real plan for a sequence of the EVA, so Colonel Zhai, the only astronaut expected to leave the cabin, will have to improvise. He will probably use the handrails to manoeuvre around the spacecraft, from the middle section to the nose, trailed by his 'umbilical cord', reporting on what he sees.

Sources vary on his assignment. Some say the first EVA would involve only simple tasks such as floating and tumbling, twisting his body for balance, waving a hand, doing some rolling and pitching.

Others say it will be more complex, involving retrieval of experimental samples, fastening rings and hooks, tightening bolts and wiping a window.

'The Russians' and Americans' first EVAs were very simple,' said a space industry source. 'They did little more than drift around a bit and take photos. Even that proved to be difficult for first-timers.

'China is 40 years late but the walk will be more technically advanced and sophisticated. It will be a walk with Chinese characteristics.'

The single space walk is scheduled to last about 30 minutes.

Colonel Liu's only role is to watch on a monitor. He will also have an 'umbilical cord', and if something goes wrong, he will have to fetch Colonel Zhai, being careful that the cords do not become tangled.

On March 18, 1964, Russian Alexey Leonov had a suicide pill ready for the first space walk in human history and almost used it when he found that his spacesuit inflated so much that he could not squeeze back into the airlock. Instead, he let some of the air out and returned at the brink of heatstroke with his clothes drenched in sweat.

Three months later, Ed White became the first American to walk in space and encountered no less daunting challenges fighting with a jammed latch and a stiff spacecraft hatch.

Colonel Zhai will have to end his first EVA before it gets dark. Maybe he will utter the same words that White used when the order to return was issued: 'It's the saddest moment in my life.'