Spacewalkers Tom Marshburn and Chris Cassidy head outside to begin STS-127’s final spacewalk at 8:28 a.m. EDT. They first will secure multi-layer insulation around the Special Purpose Dexterous Manipulator known as DEXTRE. On the Zenith 1 patch panel, they will split out power channels for two of the four space station Control Moment Gyroscopes, which provide non-propulsive attitude control for the station. Currently two of the gyros are fed from the same power channel, and this activity will prevent a failure on one channel from disabling both of the gyros. Next, Marshburn and Cassidy will install video cameras on the front and back of the new Japanese Exposed Facility. And their final task will be to deploy a Payload Attach System on the Starboard 3 truss that will provide storage capability for spare space station hardware. The spacewalk is planned to last no more than six hours, 30 minutes.
Astronauts Set for Final Spacewalk of STS-127 Mission
The final full day of activities for the joint crew of Endeavour and the International Space Station will focus on the fifth and final spacewalk of the mission.
Spacewalkers Chris Cassidy and Tom Marshburn spent the night camped out in the Quest airlock. The primary objective of the spacewalk is to install two cameras on Japan’s Kibo laboratory that will provide views to help with rendezvous and berthing of the H-II Transfer Vehicle (HTV). The HTV is scheduled to make its first deliveries to the station in September.
The six-and-a-half-hour spacewalk also includes an electrical cable swap and adjustment of insulation blankets on the Special Purpose Dexterous Manipulator. If time permits, the pair also will deploy a Payload Attachment System on the Starboard 3 truss structure that will allow an external spare parts stowage platform to be installed on a future shuttle mission.
Inside the complex, Polansky and Mission Specialist Dave Wolf will support the spacewalkers, and Pilot Doug Hurley will continue cargo transfers, which are more than 80 percent complete.