Discovery team wrap first ISS spacewalk

Mission specialists Clayton Anderson and Rick Mastracchio (seen below) earlier today ventured outside the International Space Station on the first of three planned spacewalks for space shuttle Discovery's STS-131 mission.

The pair exited the Quest airlock at 05:31 GMT, and during the six-hour, 27-minute EVA "disconnected ammonia and nitrogen fluid lines from a spent Ammonia Tank Assembly (ATA)".

They'll fit a replacement ATA on their second spacewalk, and today unbolted the tank from Discovery's cargo bay, allowing pilot James P Dutton Jr and mission specialist Stephanie Wilson to move it temporarily to the Quest Airlock External Stowage Platform 2 using the ISS's robotic arm.

Anderson and Mastracchio also "retrieved the Micro-Particles Capture/Space Environment Exposure Device experiment from the Japanese Exposed Facility", and "on the center-most portion of the International Space Station’s backbone, they replaced a Rate Gyro Assembly, part of the station’s navigation system".

Anderson and Mastracchio are old hands at extravehicular activity, and "performed two spacewalks together during the STS-118 mission in August 2007", NASA notes. On that occasion, they were tasked with adding "the third starboard truss segment, the S5 truss, to the station's backbone". ®