Mission Control assigned two more jobs, which the astronauts also completed.
Williams and Reiter wrapped up their productive 5-hour, 54-minute excursion and began repressurizing the Quest airlock at 3:58 p.m. EDT. The astronauts left the airlock in U.S. spacesuits at 9:04 a.m. EDT. Station Commander Pavel Vinogradov helped them with spacewalk preparations and getting into their suits. It was the first time in more than three years a third crewmember had been available for those tasks on the orbiting laboratory.
Williams, designated lead spacewalker, or EV1, wore the U.S. spacesuit with red stripes. Reiter, EV2, wore the all-white suit.
Astronaut Steve Bowen acted as spacewalk intravehicular officer and coached the astronauts from the International Space Station Flight Control Room in Houston's Mission Control Center. Williams and Reiter quickly got ahead of their timeline. First, they installed the Floating Potential Measurement Unit. The device measures the electrical potential of the station so procedures can be devised to minimize arcing hazards, or the jumping of current from a conductor to a ground, as the station grows.
Their second job was to install two containers for MISSE, the Materials on International Space Station Experiment. The suitcase-like containers are left open to evaluate the long-term effects of space exposure on a variety of materials. The idea is to identify optimal materials for use in future spacecraft. MISSE 3 went on one of the high-pressure tanks around the crew lock, while MISSE 4 was installed on Quest's outboard end.
The two astronauts then went on to separate jobs. Williams installed a controller for a thermal radiator rotary joint on the S1 truss, while Reiter replaced a computer on the truss.
Williams then began installing a starboard jumper and spool positioning device (SPD) on the S1 truss. Reiter inspected a radiator beam valve module SPD site where one device was already installed and installed an additional one. He then moved on to install a SPD on a port cooling line jumper. The jumpers are designed to improve the flow of ammonia through the radiators once that coolant is installed.
Williams began setup for the final major scheduled task, a test of an infrared camera designed to detect damage in a shuttle's reinforced carbon carbon (RCC) thermal protection. The camera highlights damage by showing variations in temperature between clean and damaged RCC test sections. Reiter operated the experiment while Williams went on to one of the additional tasks.
The first task was installation of a light on the truss railway handcart to help future spacewalkers. Williams then removed a malfunctioning GPS antenna. After Reiter finished the infrared camera experiment, he installed a vacuum system valve on the U.S. laboratory Destiny for future scientific experiments.
Mission control came up with additional tasks. Williams moved two articulating portable foot restraints to prepare for STS-115 spacewalks and then photographed a scratch on the airlock hatch. Reiter went to PMA1, a pressurized "corridor," to retrieve and inspect a ball stack, which holds hardware during spacewalks. The crew also had additional time throughout the spacewalk to photograph the worksites after their tasks were complete and then snap pictures of each other at the end. With no more quick tasks to add, the spacewalkers re-entered the airlock and closed the hatch early.