China counted down on Thursday to its third manned space mission Shenzhou-7 which will include the country's first ever space walk.

The Jiuquan Satellite Launch Centre started an eight-hour countdown at 1:10 PM on Thursday (Beijing Time).

The Shenzhou-7 spaceship, carrying three Chinese astronauts Zhai Zhigang, Liu Boming and Jing Haipeng, is due to blast off between 9:07 PM and 10:27 PM on a Long March II-F rocket.

At 2:10 PM on Thursday, technicians have switched on ground facilities for another round of self-check, a source with the launch centre said.

The trio taikonauts are also making preparations to enter the Shenzhou-7 spaceship.

"The weather is very likely to be infected by cold air as the season is shifting to autumn in late September. Statistics show that the most favorable weather condition for the launch appears at around 9:00 PM tonight," said Liu Hantao, chief weather forecaster of the launch center.

He has been leading a team to study the historical weather data in the recent 30 years.

"To ensure a precise forecast, we have adopted the most advanced facilities including satellite cloud imagery receivers, radars for estimation of rain and wind, as well as digital forecasting systems," he said.

The space environment will be "fine" for the launch of the spacecraft and extravehicular activity (EVA), or space walk, according to the latest report by the Center for Space Environment Research and Forecast (CSERF) under the Chinese Academy of Sciences.

"Within the next three days, solar activities are expected to be low. The geomagnetic field is expected to be quiet," the CSERF report said on Thursday.

(Xinhua News Agency September 25, 2008)