The collision appears to have happened on January 22 when when it is thought that a piece of the 'Feng Yun 1C' weather satellite, which was destroyed in the 2007 Chinese missile test, accidentally hit the Russian satellite, said T S Kelso, a senior research astrodynamicist at the Colorado-based Center for Space Standards & Innovation.
The collision changed the orientation and orbit of the Russian satellite, which was being used in scientific experiments, Kelso said. It may have also damaged it.
"That would suggest that at least a part of the satellite broke off because of the collision," CNN quoted Kelso as saying.
It was February 4 when two scientists with the Institute for Precision Instrument Engineering in Moscow noticed a change in the orbit of the satellite, known as BLITS, Kelso said.
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The scientists estimated the change happened January 22. They contacted Kelso because CSSI operates a service that looks for close satellite approaches, he said.
CSSI looked for objects that may have had a nearby approach with the BLITS satellite around the time of the collision. The Chinese debris was the only object they found.
CSSI is now working with the Russian scientists to find out more about the collision.
BLITS is a small glass sphere that reflected laser beams for research. Because of the collision, the satellite now faces the wrong way and cannot be used, Kelso said.
The collision also sped up the satellite's spin period from 5.6 seconds to 2.1 seconds, Kelso said.
US tracking sensors determined the missile collision created hundreds of pieces of space debris, according to an American official at the time. The test prompted formal protests from the United States and several US allies including Canada and Australia.