Science / Medicine : Hubble Sensor Suffers Intermittent Power Loss

NASA engineers are trying to circumvent a new glitch in the star-crossed Hubble Space Telescope, an intermittent power failure that afflicts one of the most productive of the telescope’s five scientific instruments. Because of the problem, the National Aeronautics and Space Administration has stopped using one of two ultraviolet detectors housed in the telescope’s Goddard high-resolution spectrograph, postponing indefinitely about 30% of the research planned for the spectrograph.

The power problem has not affected the Hubble’s four other instruments, including its two cameras, its faint-object spectrograph and its sensitive light meter, the high-speed photometer. Joe Rothenberg, NASA’s associate director of flight projects for Hubble, said last week that there was still a chance that NASA experts would be able to fix the telephone-booth-sized Goddard spectrograph, located behind the Hubble’s main mirror, with commands radioed from the ground.

But if they cannot, he said, repairs will probably have to wait until a scheduled 1997 shuttle mission. A replacement instrument, he said, could not be built in time for the shuttle’s first Hubble repair flight, in November or December, 1993.

The telescope, launched in April, 1990, is also plagued by vision-jarring “jitters” that occur as its solar power panels heat up and cool down. Two of the six gyroscopes that keep Hubble pointed at celestial objects have malfunctioned, and a third has threatened to do so--although so far the telescope is still able to lock on its targets.