NASA had to adjust the orbit of The Fermi Telescope to avoid the Soviet Cosmos 1805 1.5-ton satellite piece of junk that would have otherwise collided.
Source Russia Today News
“These are objects of several tons each, as wide as a small airplane, traveling 20 times faster than a bullet. The Fermi mission would be over,” the statement on NASA’s official website quotes engineer Eric Stoneking, who controls Fermi’s orientation in the sky.
On March 29, 2012. Primary calculations showed that the two space objects would miss each other by just more than 200 meters. But later it became clear that their orbits would cross through the same point in space within 30 milliseconds of one another.
Since the launch of the first satellite in 1957, space junk has been a growing threat to all spacecraft, as occasional collisions occur. NASA tracks 17,000 objects larger than 10cm across in orbit above the Earth daily. Only 10 per cent of those tracked objects are actually active satellites.