NASA Moves Space Station Repair Spacewalk To Friday, Sets Briefings

he first of two spacewalks by NASA astronauts to replace a failed ammonia pump on the International Space Station has been delayed by 24 hours to Friday, Aug. 6. A second spacewalk is planned for Monday, Aug. 9, to complete the repairs.

Flight controllers and station managers made the decision Monday night after reviewing proposed timelines, final procedures for the repair work, and the results from a spacewalk dress rehearsal conducted in the Neutral Buoyancy Laboratory near NASA's Johnson Space Center in Houston.

Expedition 24 Flight Engineers Doug Wheelock and Tracy Caldwell Dyson are scheduled to perform the spacewalks. The two NASA astronauts will replace an ammonia coolant pump that failed July 31.

NASA Television coverage of both spacewalks will begin at 5 a.m. CDT. Wheelock and Caldwell Dyson are expected to begin the spacewalks from the Quest airlock at 5:55 a.m. Friday's spacewalk will be the fourth for Wheelock and Caldwell Dyson's first.

Approximately two hours after the conclusion of each spacewalk, NASA TV will broadcast a briefing from Johnson. The briefing participants will be Mike Suffredini, International Space Station program manager; Courtenay McMillan, Expedition 24 spacewalk flight director; and David Beaver, Expedition 24 spacewalk officer.

Reporters may ask questions from participating NASA locations, and should contact their preferred NASA center to confirm participation. Johnson will operate a telephone bridge for reporters with valid media credentials issued by a NASA center. Journalists planning to use the service must contact the Johnson newsroom at 281-483-5111 no later than 15 minutes prior to the start of a briefing. Phone bridge capacity is limited and will be available on a first-come, first-serve basis.

Engineers and flight controllers continue to review data on the failure, which resulted in the loss of one of two cooling loops aboard the station. This caused a significant power down and required adjustments to provide the maximum redundancy possible for station systems. The systems are stable, and the six crew members aboard are not in any danger.

Wheelock and Caldwell Dyson originally were scheduled to perform a spacewalk to outfit the Russian Zarya module for future robotics work and prepare the station for the installation of a new U.S. permanent multipurpose module. However, because of the importance of restoring redundancy to the station's cooling and power systems, the two new spacewalks will be dedicated to the pump module replacement.

For more information visit http://www.nasa.gov/home/hqnews/2010/aug/HQ_M10-107_EVA_Changes.html