June 25, 2012
Credit: Credit: CMSEO
By last year, China's manned space program had launched its Shenzhou spacecraft eight times, three of them with astronauts aboard. Yet only now, with 13 years of cautiously accumulated experience behind the program, has a Shenzhou crew been given responsibility for controlling the movement of their spacecraft.
So while Shenzhou 8 last year showed that the Chinese manned space program had the technology for automatically bringing one spacecraft up to another and linking them, Shenzhou 9 has set out to prove that if the autonomous system were unavailable, then the crew could do the job manually. If they succeed, planned missions to assemble a space station around the end of the decade will not be hostage to the reliability of the automatic rendezvous and docking equipment.
Shenzhou 9, with three astronauts, has proved that equipment a third time, adding to the two docking maneuvers that the unmanned Shenzhou 8 executed. On June 18, the latest spacecraft brought itself toward the Tiangong 1 orbital laboratory, then stopped at a range of 5,000 meters (16,400 ft.) while controllers on the ground assessed its progress. A few minutes later, it began moving on its target again until it stopped once more at a range of 400 meters. With a microwave radar and laser rangefinder supplying data, the spacecraft repeated its procedure down to 140 meters, then 30 meters before finally moving right up to Tiangong 1 and docking with it.
In pushing ahead with their military-led program, the Chinese have had to reinvent such technologies because Western nations have been largely unwilling to cooperate (see p. 18).
All Shenzhou craft have been fitted with manual flight controls, but until Shenzhou 9 the commands to fire maneuvering thrusters were all issued from the ground. Astronauts on previous Chinese missions “just sat in the cabin,” says government spacecraft and rocket builder CAST. “They did not control the spacecraft.”
Another major task of Shenzhou 9 is to prove that Tiangong 1 can support life. The three astronauts are due to spend 10 days of the 13-day mission in the quarters provided by the linked craft. When they left the Jiuquan space base on June 16, they had supplies for 15 days. (Shenzhou, pronounced shen-jo, means “divine craft” and is a homonym of an old name for China. Tiangong, pronounced tian-gong, means “palace of the heavens.”)