The third spacewalk of the mission with astronauts Michael Good and Garrett Reisman is expected to begin at 6:45 a.m. EDT Friday. The spacewalkers will replace the final two batteries on the Port 6 truss. They also will install an ammonia jumper on the Port 4/Port 5 truss and retrieve a power and data grapple fixture from the shuttle’s payload bay. The grapple fixture will be installed later on the Zarya module.