Hubble Loses Another Gyro

WASHINGTON, D.C.--The failure of a gyroscope aboard the orbiting Hubble Space Telescope has astronomers worried about the instrument's future. A NASA official told a scientific advisory panel here today that a second of the telescope's six gyroscopes stopped operating on 22 October, leaving it with just a single spare. Researchers worry that more failures could cripple Hubble before a space shuttle maintenance mission reaches it sometime in 2000.

The $2 billion telescope, launched in 1990, has delivered a steady stream of spectacular images of the universe. Earlier this month, for instance, it detected the faintest galaxies ever seen, herds of stars located an estimated 12 billion light-years away from Earth (ScienceNOW 8 October). Astronomers hope to keep their treasured eye in the sky operating through at least 2010, but the failure-prone gyroscopes--which are key to aiming the telescope in the right direction--could imperil that plan. The latest breakdown, which follows an early 1997 failure of another gyroscope, "is disquieting," says NASA official Alan Bunner. "If [the gyros] continue to fail at this rate, we may not get as long a service life as we had hoped."

How soon NASA will be able to replace the flawed equipment depends, in part, on sorting out a shuttle launch schedule scrambled by the delay of a major new x-ray telescope called AXAF. Both AXAF and the Hubble repair mission can fly only aboard the shuttle Columbia, which is specially outfitted for the missions. But Columbia will be grounded for a lengthy overhaul later this year, putting off a repair flight until at least May 2000. In the meantime, astronomers are hoping that nothing else breaks. Said one: "We've got our fingers crossed."