An airlock module for the Shenzhou VII spaceship and an extravehicular spacesuit - key elements of China's first spacewalk mission scheduled for later this year - have passed initial ground tests, a top scientist said Wednesday.

This virtual image from China Academy of Space Technology shows an astronaut spacewalking outside the Shenzhou VII spaceship. [China Daily]

"Both the airlock module and the extravehicular spacesuit passed the tests, which simulated the zero-gravity environment of space," Yang Baohua, head of the China Academy of Space Technology, said.

"This boosts our confidence in the spacewalk," he said on the sidelines of an event to celebrate the academy's 40th anniversary.

The academy designed all previous Shenzhou spaceships and the moon probe Chang'e I, launched last year.

Although an exact date has yet to be set for the spacewalk, the Shenzhou VII will be launched from Jiuquan, Gansu province, with three astronauts on board. It will be the latest milestone in China's manned flight history.

The airlock module and extravehicular spacesuit are essential elements of the mission and their design provided tough challenges for the country's scientists.

The airlock is a pressure chamber linking the main body of the spacecraft to the outside. It is a complex piece of equipment but was not required on the previous six Shenzhou space flights, Yang said.

Similarly, the extravehicular spacesuit, developed by other scientific institutes, is also technologically much more demanding, compared with the intra-vehicular spacesuits worn by astronauts on earlier missions. It must protect astronauts from dramatic temperature changes and radiation in space, as well as provide them with food, oxygen and equipment to communicate with the spaceship, experts said.

Fourteen candidates have been undergoing training for the Shenzhou VII mission, including Yang Liwei, China's first astronaut, who was aboard Shenzhou V in 2003.

But the final three have yet to be named.

The spacewalk mission is expected to be broadcast live on television.

Yang Baohua said the spaceship's re-entry module is the largest in the world in terms of its available space. Once it returns to Earth, the orbital module will remain in space to carry out experiments.

A successful spacewalk mission will lay the foundation for a space laboratory and space station, he said.