Spacewalkers Chris Cassidy and Tom Marshburn completed their final mission tasks July 27 as the Space Shuttle Endeavour prepares to leave the International Space Station July 28 for a return trip to Earth. Cassidy and Marshburn's spacewalk was the fifth and final spacewalk of the 16-day mission to work on the build-out of the ISS.
"Most shuttle crews are content with three or four [spacewalks]," Mission Control reportedly told crewmembers. "Today, you'll be joining a very select group by doing your fifth! Thanks for going the extra mile ... or the extra 125,000 miles, as the case may be."
The spacewalk ended at 12:27 p.m (EDT) after completing the primary objective of the day: installing two cameras on Japan's Kibo laboratory that will provide views to help with rendezvous and berthing of the H-II Transfer Vehicle. Japan's HTV is a space vehicle that will be used to transport up to 6 tons of food, clothing and equipment to the ISS.
After a delivery of supplies, the HTV will return to Earth carrying waste materials such as used clothing that are burned up in the atmosphere upon re-entry. The HTV is scheduled to make its first deliveries to the station in September.
The spacewalkers also performed a number of "get ahead" tasks, including tying down some cables and installing handrails and a portable foot restraint to aid future spacewalkers.
Inside the ISS, Endeavour Commander Mark Polansky and Mission Specialist Dave Wolf supported the spacewalkers while Pilot Doug Hurley worked on cargo transfers between the Endeavour and the ISS. Flight Engineers Mike Barratt and Tim Kopra worked on several scientific experiments, and departing station crew member Koichi Wakata continued handovers with Kopra, the newest station crew member.
The Endeavour blasted off from Cape Canaveral July 15 after stormy Florida weather forced NASA to postpone launches on July 11, 12 and 13. In June, NASA twice scratched the mission due a launch pad hydrogen gas leak that has since been fixed.
Over the course of the mission, the crew unloaded and installed Japan's Kibo outdoor laboratory, a literal "front porch" for the ISS allowing for space-exposed science experiments. The mission is the second longest in shuttle history.