China's third manned spaceship Shenzhou-7 launched a small monitoring satellite about two hours after an astronaut accomplished the country's first spacewalk Saturday afternoon (Sep 27).

The satellite, less than 40 kilograms in weight, will orbit the orbital module and send back the spaceship's first full video images.

It is equipped with two cameras that can capture clear images in a distance between four meters and two km, according to Shen Xuemin, deputy director of the Shanghai Institute of Technical Physics under the Chinese Academy of Sciences, developer of the satellite.

The accompanying satellite will observe and assist the main spaceship and work for communication, scientific experiment, earth and astronomy observation, he said.

"The task will test our ability to observe and control two objects in relative motion in space. Through this, we will prepare for the future orbiter docking," said Zhao Guangheng, deputy chief designer of the country's manned space program's space application system.

China will seek a breakthrough in the orbiter docking technology in its next manned spaceship Shenzhou-8, a step for the ultimate goal of building a permanent space laboratory.

Although China has managed to launch more than one satellites with one carrier rocket, it was the first time to monitor and control a satellite launched from a spaceship, said Lu Lichang, a designer of the program's remote control and communication system.

"To make sure the accompanying satellite orbits around the moving spaceship, we need to accurately monitor both the objects. It is quite difficult to work out control parameters of its motion," he said.

In addition, as the satellite is moving in a near-earth orbit, the control work is more vulnerable to atmosphere changes, he said.

Two possible accidents might occur. The small satellite may fail to function or move away from the planned track. "We have contingency plans," he said.

Editor: 张莹