(photo credit: REUTERS/NASA/Handout)
CAPE CANAVERAL, Fla. - Two of NASA's most experienced spacewalkers floated outside the International Space Station on Sunday for some preventive maintenance to help get the station ready to operate after the shuttle program ends this summer.
Shuttle Endeavour astronauts Drew Feustel and Mike Fincke left the station's Quest airlock at about 2:15 a.m. EDT to begin the second of four spacewalks planned during Endeavour's 16-day mission, the next-to-last in the US space shuttle program.
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It was the fifth outing for Feustel, a former Hubble Space Telescope repairman making his first trip to the space station, and the seventh for Fincke, who previously served as a flight engineer and then as commander of the orbital outpost.
Fincke's previous spacewalks were done Russian-style, in stiff Orlon spacesuit.
"The American spacesuit is called the Extravehicular Mobility Unit -- 'mobility' is the key word for me," Fincke said in a preflight interview.
"When I put on the American spacesuit it's only running about four pounds per square inch (27.57 kilopascals) (of pressure) and all of a sudden, I got a lot more mobility.
When we're building the complex parts of the space station, we needed an EMU, whereas Orlan is good for routine maintenance on the outside where you don't need to have such dexterity."
Nimble hands will be useful for the jobs facing Fincke and Feustel on Sunday. First on the astronauts' to-do list is the potentially messy job of topping off a tank of ammonia, used in the station's cooling system.
Feustel and astronaut Greg Chamitoff set up the spare ammonia line during the mission's first spacewalk on Friday. Tapping the new line should fix a slow leak somewhere in the original plumbing.
"This isn't your household cleaner ammonia," Fincke said before flight.
"This is high-grade industrial ammonia so we have to be super careful not to get it on us or to spill it because it's quite dangerous if we brought it back inside."
NASA has a procedure to decontaminate the astronauts' spacesuits if they do get any ammonia on them.
Feustel and Fincke also plan to lubricate the massive joint that keeps the station's left-side power-generating solar arrays rotating to track the sun.
"We found the original design had some extra friction that we weren't expecting and it started to grind our joint, so we've, every couple years, started to add some grease on it and it rotates great," Fincke said.
The four spacewalks planned during Endeavour's mission are the last in
the 30-year-old shuttle program. NASA has one last flight, a cargo run
aboard shuttle Atlantis scheduled to launch July 8, planned before the
three-ship fleet is grounded.
NASA wants to use US commercial companies to deliver cargo, and
eventually transport crew, to the station. The United States will rely
on partner countries' Russia, Europe and Japan for transport in the
The shuttles are being retired due to high operating costs and to save
funds to develop new spaceships that can travel beyond the station's
220-mile (354-km) high orbit.
The station, a $100-billion project of 16 nations, has been under construction since 1998.
Endeavour, which carried the $2 billion Alpha Magnetic Spectrometer
particle detector and spare parts to the station, is due back at the
Kennedy Space Center in Florida on June 1.