STS-131 spacewalkers Rick Mastracchio and Clayton Anderson disconnected ammonia and nitrogen fluid lines from a spent Ammonia Tank Assembly (ATA). The old ATA will be removed from the International Space Station’s starboard truss during the mission’s second spacewalk. Mastracchio and Anderson also removed bolts that held the replacement ATA in Discovery’s payload bay, then handed the new assembly to the space station robotic arm, operated by Pilot James P. Dutton Jr. and Mission Specialist Stephanie Wilson. The arm is moving the new ATA to a temporary location on the Quest Airlock External Stowage Platform 2. The spacewalkers also retrieved the Micro-Particles Capture/Space Environment Exposure Device experiment from the Japanese Exposed Facility and will bring it back to Earth. The spacewalk has been under way for two hours, 55 minutes.