Stock Photo - Astronaut Robert L. Behnken, STS-123 mission specialist, participates in the mission's third scheduled session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the 6-hour, 53-minute spacewalk, Behnken and Rick Linnehan (out of frame), mission specialist, installed a spare-parts platform and tool-handling assembly for Dextre, also known as the Special Purpose Dextrous Manipulator (SPDM). Among other tasks, they also checked out and calibrated Dextre's end effector and attached critical spare parts to an external stowage platform. The new robotic system is scheduled to be activated on a power and data grapple fixture located on the Destiny laboratory on flight day nine. The blackness of space and Earth's horizon provide the backdrop for the scene.