Chang-Díaz and Perrin ventured outside the station's Quest airlock at 10:27 a.m. Central time. With the help of Endeavour Pilot Paul Lockhart, who guided the spacewalk from inside the shuttle, Chang-Díaz and Perrin first installed a Power and Data Grapple Fixture to the station's P6 truss. The fixture will be used to relocate the P6 truss structure to its final location on the station.
Attached to a foot restraint at the end of the station's robotic arm, Canadarm2, operated by Expedition Five Flight Engineer Peggy Whitson and ISS Commander Valery Korzun, Chang-Díaz gathered six micrometeoroid debris shields from the shuttle cargo bay and, with help from Perrin, temporarily stored them on Pressurized Mating Adapter-1 which links Unity to Zarya. Whitson and Korzun will install the shields on the Zvezda Service Module during a spacewalk set for late July.
Chang-Díaz then conducted a visual and photographic inspection of one of the station's four control moment gyroscopes on the station's Z1 truss, a task that was added to today's spacewalk after the gyroscope experienced a mechanical failure yesterday. The photos may help ground controllers better understand why the gyroscope failed.
Removal of thermal blankets from the Mobile Remote Servicer Base System or MBS was the final task of the spacewalk. At 5:21 p.m. Endeavour Commander Ken Cockrell commanded the release of latches that had secured the MBS to its carrier in the payload bay. Whitson and Carl Walz then latched onto the MBS with Canadarm2, removed it from its carrier, and maneuvered it to a position about three feet above the station's railcar, the Mobile Transporter. Canadarm2 will be left in a parked position overnight to thermally condition the MBS before it is mated to the railcar Monday.
Later, the Canadarm2 robotic arm will be commanded to "walk off" its position attached to the Destiny Laboratory onto a Power and Data Grapple Fixture atop the MBS. The arm will then be able to move up and down along the station truss for use in future assembly operations.
Following an inventory of the tools they used during the spacewalk, Perrin and Chang-Díaz re-entered Quest. Airlock repressurization began at 5:41 p.m. Central time, signaling the end of the spacewalk.