UPDATE 1-Astronauts revive Hubble imaging device

*Glitches mire fourth spacewalk to fix spectograph

*Final key Hubble fix planned for Monday (Updates with spacewalk problems, repair complete)

By Irene Klotz

HOUSTON, May 17 (Reuters) - Space shuttle Atlantis astronauts on Sunday repaired a failed instrument on the Hubble Space Telescope used to discover black holes and other galactic phenomena following a tedious spacewalk mired by equipment glitches.

Like Hubble's advanced camera, which was rewired during a spacewalk on Saturday, the Space Telescope Imaging Spectrograph was not designed to be overhauled in space.

The device, known by the acronym STIS, splits light into its component wavelengths. It was shut down in 2004 after electronics problems cut off its power.

It was the fourth of five back-to-back spacewalks planned for shuttle Atlantis' 11-day servicing mission, NASA's fifth and final visit to the observatory before the shuttles are retired next year.

NASA hopes the improvements will keep Hubble operational until at least 2014 so it can work in tandem with its replacement, the James Webb Space Telescope.

Spacewalkers Michael Massimino and Michael Good had expected problems unscrewing 111 fasteners on the STIS cover plate, which had to be removed to access its faulty circuit board. But what frustrated the astronauts was a stripped bolt on a handrail that needed to be removed before they could reach STIS.