NASA Shuttle Atlantis: Era’s Final ISS EVA

Spacewalker Ron Garan rides on the International Space Station's robotic arm as he transfers a failed pump module to the cargo bay of space shuttle Atlantis. 

Garan and fellow Expedition 28 astronaut Mike Fossum wrapped up a six-hour, 31-minute spacewalk Tuesday afternoon, performing upgrades and maintenance on the orbiting outpost.

It's the final scheduled spacewalk during a NASA Shuttle mission.

Image Credit: NASA

The Astronauts bounced between the International Space Station and the payload bay of the shuttle Atlantis during a demanding July 12 spacewalk in which they exchanged a failed thermal control system coolant pump from the orbiting science laboratory for a robotic satellite refueling demonstrator.


Though the astronauts got off to a late start at 9:22 a.m. EDT, the two men drew on their experience gained over three station assembly spacewalks in 2008 to recover. Atlantis astronaut Rex Walheim choreographed the 6-hr. 31-min. excursion.

The balky pump’s retrieval was a high priority for the Atlantis crew, who docked at the space station July 10, two days after lifting off on the STS-135 supply mission, NASA’s final shuttle flight.

The device that circulates ammonia coolant through the station’s outstretched starboard radiators failed prematurely on July 31, 2010.

The shutdown prompted a dramatic power down of the station, from which station managers recovered with a series of hastily planned spacewalks over three weeks.

 The source of the pump loss, an internal short circuit, remains unexplained. Once the hardware is back on Earth, it will undergo a failure analysis that could lead to a design change for circulation hardware.

Next, the spacewalkers hauled the boxy refueling demonstrator from the orbiter to Dextre, the two-armed Canadian robot secured to the station’s exterior. The demonstrator, developed by the NASA Goddard Space Flight Center and the Canadian Space Agency, is tentatively scheduled for trials later this year.

In other activities, the spacewalkers activated the Optical Reflector Materials Experiment that was placed on the station’s starboard solar power truss in May. The collection of optical material samples is scheduled to be retrieved next year to evaluate how well they weathered vacuum, solar radiation and the effects of atomic oxygen. Each sample is a candidate for future spacecraft fabrication.