Spacecraft, Shenzou-8 and Tiangong-1 will dock again in a week's time. Unlike the first docking, this is likely to occur in harsh conditions in order to test the design and capabilities of the two modules.

A poor light and orbit environment have been chosen on purpose to test whether the docking system can withstand use under differing conditions. Uncertainties surround the second docking between Shenzhou-8 and Tiangong-1, which have flown together now for more than one hundred hours.

Wang Xiang, deputy chief designer of Manned Spacecraft System, said, "We never did this before; to make the second docking possible, the two modules need to be first disconnected, and then they will have to be reconnected perfectly."

Sensors and radars are installed in Shenzhou-8 to aid docking. Under different conditions, the challenge is how to minimize the disturbance of solar light on the sensors.

Wang Xiang said, "The sensors have different reactions under different conditions. All space engineers will meet this problem. The only way to overcome the problem is to test the sensors in a different orbit in the second docking. "

Shenzhou-8 and Tiangong-1 will orbit together for a total of 12 days. The second docking will be followed by two days' flight. Shenzhou-8 is scheduled to return to Earth on November 17th.