Fourth spacewalk completed Sunday

WASHINGTON, May 17 (UPI) -- U.S. space officials said two astronauts completed a fourth spacewalk Sunday, finishing another repair project on the Hubble telescope.

STS-125 mission specialists Mike Massimino and Mike Good replaced a low-voltage power supply board, which contained a failed power converter. Because of the power supply problem, NASA said the Space Telescope Imaging Spectrograph system had been in "safe mode" since August 2004.

The National Aeronautics and Space Administration said the latest spacewalk lasted 8 hours and 2 minutes.

The mission specialists are making repairs and improvements to the Space Telescope Imaging Spectrograph system that will extend the Hubble's service into the next decade.

The fifth and final STS-125 spacewalk is set for Monday at 9:16 a.m. EDT.