Forrester and Swanson working on the S3 Truss during EVA 4

S117-E-07772 (17 June 2007) --- Astronauts Patrick Forrester (right) and Steven Swanson, both STS-117 mission specialists, participate in the mission's fourth and final session of extravehicular activity (EVA), as construction continues on the International Space Station. Among other tasks, Forrester and Swanson continued activation of the station's new starboard 3 and 4 (S3/S4) truss segment; checked out the Drive Lock Assembly 2, one of two mechanisms that will drive rotation of the S3/S4 Truss Solar Alpha Rotary Joint (SARJ); and removed the final launch restraints on the SARJ.