The new science data computer that astronauts installed on the Hubble Space Telescope five weeks ago has malfunctioned.
The science instruments that rely on the computer to transfer Hubble's discoveries to the ground have been shut down and placed in "safe" mode, NASA officials said Thursday. The space agency has named an anomaly review board to study the problem.
The faulty computer, the Science Instrument Command and Data Handler, is not really new. It was a spare built before the Hubble was launched in 1990.
After the space telescope's original unit suffered a partial failure in September, NASA delayed the planned October launch of the fifth and final servicing mission until the replacement could be refurbished and tested. It was launched with the repair crew and installed May 14 by astronauts Drew Feustel and Johns Grunsfeld.
But on Monday, NASA said, the new unit began sending erroneous signals to the observatory's main computer. It then sent commands to put the science instruments in safe mode, but the instruments did not respond.
Engineers concluded that the science data computer was neither receiving nor forwarding commands. They tried turning it off and then on again. That seemed to work, and enabled operators on the ground to order the science instruments into safe mode.
By late Monday, NASA said, the balky computer appeared to be back to normal, and engineers began working to understand the malfunction. In the meantime, the science instruments remain shut down and the checkout of repairs and upgrades performed during the servicing mission has been put on hold for at least a week.
"The observatory as a whole, including the new and repaired instruments, is in excellent shape," officials said, "and activities not requiring the use of the SI C&DH ... are proceeding."
