- Associated Press - Tuesday, July 12, 2011

CAPE CANAVERAL, Fla. (AP) Astronauts making the last spacewalk of NASA’s space-shuttle era on Tuesday retrieved a broken pump from the International Space Station and installed a fill-er-up experiment for a robot.

The space station’s two-armed robot Dextre won’t tackle the $22.6 million playset - a fancy Fisher-Price toy as one astronaut describes it - until long after Atlantis departs and the shuttle program ends.

But perhaps more than anything else on this final journey by a shuttle, the robotic demonstration illustrates the possibilities ahead for NASA: satellite-refueling stations in space run by robots.

In a departure from previous shuttle visits, the spacewalking job fell to space-station astronauts, Michael Fossum and Ronald Garan Jr., who teamed up for three spacewalks in 2008. The four-person Atlantis crew is the smallest in decades, and so the lone spacewalk of the mission was handed over to the full-time station residents.

It was the 160th spacewalk in the 12 1/2-year life of the orbiting outpost, and the last one planned for Americans for nearly a year.

Mr. Fossum and Mr. Garan paused to admire the view 245 miles below, the Kennedy Space Center, before heading to a storage platform holding the old, broken pump.

“Hello Kennedy, beautiful launch,” Mr. Fossum called out. Atlantis departed Kennedy on Friday on the very last shuttle launch.

They completed the two major chores - the pump removal and robotic test hookup - inside of 3 1/2 hours.

The ammonia coolant pump stopped working last July and, for more than two weeks, left the space station with only half its cooling capability. Space station residents had to perform three emergency spacewalks last summer to replace the pump and restore full cooling to all the on-board equipment.

NASA wants the pump brought back to Earth so engineers can figure out why it failed to help them keep the on-board station pumps running. The space station is intended to operate until at least 2020.

Mr. Garan gripped the pump as the space station’s robot arm maneuvered him over to Atlantis. The pump was anchored onto a platform in the shuttle’s payload bay, ready for next week’s ride home.

As they turned their attention to the robotic experiment, the spacewalkers thanked all the thousands of people who worked on the shuttle. “It is really beautiful,” Mr. Garan said.

The robotic workbench, which the astronauts attached to a shelf on Dextre’s base, consists of a 3 1/2-foot box holding four customized tools, including a wire cutter and a safety cap removal device, as well as an assortment of knobs, caps, valves and a half gallon of ethanol.

Dextre, a hulking metal robot with 11-foot arms, will release locks on the tools in August but won’t try out the workbench until January.

The designers of the experiment, based at Goddard Space Flight Center in Greenbelt, Md., envision robots one day using these methods to fill the fuel tanks of satellites orbiting as high as 22,300 miles. That would keep the spacecraft operating longer, instead of becoming expensive pieces of space junk. What’s more, spacecraft bound for distant worlds could fill up after launch, thereby flying more payloads because of the savings in fuel weight.

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