At least three orbiting satellites have been malfunctioning but all were salvaged by experts, aerospace scientists said here Monday. The experts from the Xi'an Satellite Monitor and Control Center said that an orbiter lost its position and repeated rollovers in space in October 2006. "The ground center temporarily lost control over the malfunctioning satellite," said Dong Deyi, head of the center.
After carefully studying previous orbiting statistics collected about the uncontrollable satellite and analyzing computer simulations, experts decided to try rescues in December, when they judged was the best opportunity for the rescuing work.
They tried to compile complicated orders into a short period of eight seconds and repeatedly sent those orders into space. After continuous tests, the almost lost satellite started to respond and the Xi'an center finally controlled the orbiter.
Shortly after the incident, Dong said, another satellite lost its position and was, again, salvaged by the experts based in Xi'an.
In February 2007, the solar cells on a satellite were troubled. Principal investigator Yu Peijun and his team in the Xi'an center calculated different gestures of the troubled satellite and worked out contingency plans accordingly. After adjusting angles of the solar panel, the Xi'an center regained control over the satellite.
The Xi'an center, established on June 23, 1967, in mountains of northwest China, has monitored and controlled more than 100 satellites and the six Shenzhou spaceships. Official record said China now has at least 19 satellites orbiting the earth.
Source: Xinhua News Agency
