Astronauts start fourth spacewalk for daunting Hubble Telescope repair

SPACE.com: Atlantis astronauts headed out to the Hubble Space Telescope Sunday to attempt the second daunting repair of their mission: resurrecting a long-broken instrument that can sample the atmosphere of distant alien planets. It is their fourth spacewalk out of the five scheduled for the repair mission.

Spacewalkers Michael Massimino and Michael Good left the space shuttle at 9:45 a.m. EDT (1345 GMT) to resuscitate the Space Telescope Imaging Spectrograph, which failed after a power failure in 2004.