Attitude-control systems have failed on Japanese and NASA science satellites. Japan's Institute of Space and Astronautical Science solar X-ray satellite, Yohkoh, which was launched in 1991, may be beyond recovery. Meanwhile, NASA's Far Ultraviolet Spectroscopic Explorer, launched in January 1999, is now certain to fall short of its projected three-year lifetime after losing a second of its four three-axis stabilisation reaction wheels.
Source: Flight International