Spacewalkers Tanner and Noriega work sit back in their foot restraints as the solar arrays are tensioned. Photo: NASA TV/Spaceflight Now

In the end, it was a "no brainer."

Spacewalkers Joseph Tanner and Carlos Noriega successfully tightened up a loose solar blanket on the international space station's new $600 million solar power tower in half the time worried engineers had predicted.

Working 90 feet above the shuttle Endeavour's cargo bay, Tanner and Noriega re-threaded two sprung cables around spring-loaded take-up reels and pulleys, enabling their crewmates in the orbiter's cockpit to finally tighten up the slack solar cell blanket.

"That is absolutely outstanding work," astronaut Shannon Lucid radioed the crew from mission control when the repair was complete.

"Joe and Carlos are quite the team," said spacewalk coordinator Marc Garneau from Endeavour's flight deck. "And, we might add, all the hard work that's been done by the ground to come up with this procedure."

"Yeah, that procedure they gave us was fantastic, it was perfect," added Noriega.

"This was almost - I'm not going to say a no brainer because everyone would make fun of me for not having one - but it was perfect," Tanner agreed.

"Well Endeavour, the ground is ecstatic," Lucid replied.

With the P6 solar array now fully operational and in excellent health, the Endeavour astronauts will finally open all the hatches between the shuttle and the space station early Friday to greet the lab's on-board crew face to face for the first time.

A close up view from Noriega's "helmetcam" of the solar array blanket box. Tanner's legs are visible on the other side of the array. Photo: NASA TV/Spaceflight Now

"I'm almost speechless as to what to say about today's activities," said lead flight director William Reeves. "We've had a totally successful third EVA, we accomplished all of our objectives including the repair of the tensioning on the solar array wing.

"On our scorecard, in terms of mission priorities, we're rapidly closing in on a totally successful mission," he added. The spacewalk "went exactly as planned, we found the problem with the solar array just as we expected it to be and the repair went extremely well."

Today's spacewalk officially ended at 4:23 p.m. when Tanner and Noriega repressurized Endeavour's airlock. It was the 57th spacewalk in shuttle history, the 96th in the history of the U.S. space program and the 13th devoted to space station assembly and outfitting. Fourteen astronauts have now logged 88 hours and 54 minutes putting the outpost together.

In a reminder of the dangers faced by all spacewalkers - and nearly 200 excursions will be required to build the space station - Tanner and Noriega noticed minor damage from what appeared to be an impact by a micrometeoroid or a piece of orbital debris that apparently occurred sometime between Sunday and today.

"Wow... this cold plate has taken an MOD hit already," Tanner reported, using NASA's acronym for "micrometeoroid/orbital debris."

"Already?"

"Yeah. ... It's definitely an MOD because it was clean three EVA days ago."

The P6 truss towers over the payload bay of the shuttle during today's spacewalk. Photo: NASA TV/Spaceflight Now

The primary goal of the 101st shuttle mission was accomplished Sunday when the 17.5-ton P6 solar power tower was mounted to a structural truss attached to the station's Unity connecting module.

After a series of false starts, the starboard solar wing of the array was unfurled, extending in nonstop fashion to a full 110 or so feet. Panels making up the wing's two solar blankets initially stuck together and as they would suddenly pop open, the blankets would jerk back and forth in dynamic fashion.

As a result, two cables needed to keep tension on one of the blankets popped off their pulleys, leaving the blanket slacker than engineers wanted.

After studying the problem overnight, flight controllers cleared the crew to open the port-side array in a cautions start-and-stop fashion to give any stuck panels time to pull open in a more gentle fashion. It worked, and the port wing deployed normally.

Tanner and Noriega carried out a second spacewalk Tuesday to electrically connect the P6 array to the station's electrical system and then stood by while engineers on the ground developed a plan to tighten up the slack blanket on the starboard wing.

Finally, after four days of around-the-clock work to devise a repair plan, Tanner and Noriega began the mission's third and final spacewalk at 11:13 a.m. today and quickly made their way to the top of the P6 solar array nine stories above Endeavour's cargo bay .

A spectacular view of the spacewalkers at work on the Unity module high above the nose of shuttle Endeavour. Photo: NASA TV/Spaceflight Now

Before they got there, their crewmates in the shuttle's cockpit retracted the solar wing's central mast slightly to make the reels and pulleys in question more accessible to the spacewalkers.

Once set up and in position, it took about five minutes to re-thread the blanket's outboard reel and pulley.

"I think we've got a winner on that procedure," Tanner radioed less than 45 minutes after starting the third spacewalk. "Let's go do the other one."

"Hey, what a great start!" called Garneau. A few minutes later, he passed the news on to Houston.

"Houston, Endeavour, in the blind, Joe and Carlos completed the outer tension reel on the first go and it looks just like in the picture," he said."

The second tensioning cable then was re-threaded and the array was re-extended to its full length about an hour and a half after the spacewalk began. Flight planners on the ground had budgeted three hours for the job.

"We have completed the interior tensioning reel and it was just like the outer one and it looks nominal," Garneau told Houston after both cables had been put back on their reels.

"The tension wires look good and so do the guide wires," Tanner reported.

Shuttle commander Brent Jett then sent commands through a laptop computer on Endeavour's flight deck to close a set of latches, tightening up both cables and pulling the blanket taut.

"Houston, Endeavour, we're going to attitude control as per the cue card and we show the left blanket box tensioned," Garneau reported.

"We concur and it's fully repaired," Lucid called. "Great work!"

"We agree."

In keeping with construction industry tradition, a picture of an evergreen tree was fixed at the tip of the P6 truss to mark the topping out of the "building". Photo: NASA TV/Spaceflight Now

Tanner and Noriega then accomplished the second objective of the excursion, installation of a television cable that will give the next station assembly crew camera views that will help them dock the U.S. laboratory module, Destiny, in late January.

The next item on the agenda was installation of a device called a floating potential probe.

The instrument, which will be turned on Monday, will be used to measure how much electrical charge builds up on the new solar array wings as the station flies through the charged particle environment of the extreme upper atmosphere.

Two devices called plasma contactors spew a steady stream of xenon atoms into space to close a huge electrical circuit, preventing any potentially dangerous charges from building up. But the plasma contactors do not provide any telemetry to show how effectively they are working.

The floating potential probe, mounted to the top of the P6 tower between the two solar wing gimbal joints, should prove once and for all that spacewalkers can remove lightning bolts from the list of potential threats they face.

Appropriately enough, a thermal cover on the floating potential probe had an evergreen tree painted on one side, a construction tradition signaling a building's "topping off."

Tanner and Noriega fixed the solar arrays in half the time engineers had predicted based on tests at a Lockheed Martin facility in Sunnyvale, Calif., where the arrays were built.

"The Sunnyvale team would like to pass along to you their sincere congratulations, you did an absolutely outstanding job," Lucid radioed. "And just for your information, Flight (director Reeves) was the only one down here who had the prediction right on as to how long it would take you to put on that first cord. He had you doing it in under five minutes, which is what you did."

"Did he really?" Tanner marveled.

"All right! Thanks a lot, BIll!" Noriega chimed in.

"Bill Reeves... I tell you, he's all right."