The National Aeronautics and Space Administration said astronauts John Grunsfeld and Drew Feustel stepped into space at 8:52 a.m. EDT and ended their spacewalk at 4:12 p.m. In addition to other actions, they removed and replaced the telescope's Wide Field Planetary Camera 2. That, said NASA, will allow Hubble to capture a wider range of images from ultraviolet to near-infrared wavelengths.
Also during the 7-hour and 20-minute spacewalk they replaced a failed science data processing computer and installed a "soft capture" mechanism that will allow a remote-controlled spacecraft to capture Hubble for a de-orbit burn at the end of its life.
The astronauts were to install three latch-over-center lock kits, designed to allow faster opening and closing of the telescope's doors, keeping stray light entering the telescope at a minimum. One such system was installed, but the astronauts ran into technical problems with the other two. They will revisit those problems during the third spacewalk.
Spacewalk No. 2 was scheduled to begin at 8:16 a.m. EDT Friday, but it will be preceded by an unscheduled re-inspection of approximately 40 heat shield tiles that might have been damaged during Monday's launch of space shuttle Atlantis.