NASA may have solved Hubble power problem

December 13, 1991|By Douglas Birch

NASA thinks it has found and fixed a power problem aboard the Hubble Space Telescope that began in late July and by mid-September halted observations with one of the telescope's five stargazing electronic instruments.

Joseph H. Rothenberg, associate director of flight projects for Hubble, said that the National Aeronautics and Space Administration plans to permit the Baltimore-based Space Telescope Science Institute to resume its regular schedule of observations next month with the spacecraft's Goddard High-Resolution Spectrograph.

The Goddard spectrograph is the hardware least affected by a )) flaw in the telescope's 94.5-inch mirror that has limited its performance.

Astronomers have used the telephone booth-sized unit to study ultraviolet light from stellar objects, most of which is blocked by the Earth's atmosphere.

Mr. Rothenberg said NASA technicians think the instrument's intermittent power problem probably was caused by a brittle solder joint that was opening and closing when the spacecraft vibrated.

Vibration occurs as Hubble rapidly heats and cools as it moves in and out of the Earth's shadow.

NASA found that by leaving the power supply units for both ultraviolet detectors on all the time, the instrument heated from about 32 degrees Fahrenheit to about 40 degrees. That seemed to keep the faulty electrical connection from opening and closing. Normally, power to the telescope's instruments is turned on only when they are in use.

"We couldn't get it to fail through the test if we kept it warm," Mr. Rothenberg said.

Ray P. Villard, a spokesman for the telescope institute, said spectrograph observations are expected to resume in mid-January.

The apparent repair of the spectrograph is unrelated to the Hubble's shutdown four days ago after it received a faulty computer command from the ground.

Mr. Villard said the three-day shutdown, the fourth in the past year, was wrongly interpreted as a new glitch in the troubled telescope.

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