By Ed Stoddard HOUSTON, June 15 (Reuters) - Spacewalking astronauts aim to repair a damaged thermal blanket on the space shuttle Atlantis on Friday as U.S. and Russian controllers struggle with a worrying computer failure on the International Space Station. James Reilly and John "Danny" Olivas are scheduled to begin the third spacewalk of the current mission of the shuttle to the space station at 1:38 p.m. EDT. The spacewalkers' first scheduled task will be to repair a bit of protruding insulation near the rear of the shuttle. A corner of the thermal blanket tore loose during Atlantis' launch last Friday, potentially exposing inner layers of the shuttle's surface to superheated gases on re-entry. Another pressing issue is the failure of the Russian computers aboard the $100 billion space station, which emerged on Wednesday shortly after the installation of a solar wing panel that was brought to the station by the space shuttle. The Russian computers control a critical part of the space station's navigation system. "The new power feed to the Russian segment could be the problem," International Space Station program manager Mike Suffredini told a news briefing at the Johnson Space Center late on Thursday. Suffredini said the Russians would try to reboot the system when the station passed over Russian ground stations on Friday during its orbits around the Earth. The two Russian cosmonauts aboard will work on the problem with their controllers on the ground through the wee hours of the morning. NASA has said a failure to resolve the problem could see it temporarily evacuate the space station but that worst-case scenario is deemed highly unlikely. Dealing with unexpected problems was "part of the challenge" of such missions, shuttle commander Rick Sturckow said in a televised interview from space late on Thursday. Among the challenges on Friday will be finishing the retraction of the old solar wing panel. It must be moved before the new array can rotate and track the sun for full power. NASA said it will resume the retraction activities on Friday with the help of the spacewalkers if needed. NASA has extended Atlantis' mission from 11 to 13 days and added a fourth spacewalk to make sure there was enough time to fix the blanket and retract the old solar wing. (Additional reporting by Irene Klotz in Cape Canaveral)
