AMS-02 with EVA astronauts in the background

The newly-installed Alpha Magnetic Spectrometer-2 (AMS-02) with astronauts Andrew Feustel (right) and Greg Chamitoff, both STS-134 mission specialists, on background. They participated in the mission's first session of extravehicular activity (EVA) on 20 May 2011. During the six-hour, 19-minute spacewalk, Feustel and Chamitoff retrieved long-duration materials exposure experiments and installed another, installed a light on one of the station's rail line handcarts, made preparations for adding ammonia to a cooling loop and installed an antenna for the External Wireless Communication system.