HOUSTON — Two spacewalking astronauts primed the International Space Station's (ISS) new European lab for orbital science Friday by adding new experiments to its gleaming hull.

Atlantis shuttle astronauts Rex Walheim and Stanley Love attached two science experiments to platforms on the outboard edge of the European Space Agency's (ESA) Columbus lab in the final spacewalk of their STS-122 mission.

"Nice module we have here, huh?" Walheim said of newly arrived Columbus, which the two spacewalkers helped install on Monday.

"It is!" Love replied.

Clad in bulky NASA spacesuits, the two astronauts began their orbital work at 8:07 a.m. EST (1307 GMT) as the space station and docked Atlantis flew high above the southern Pacific Ocean.

"Oh wow, what a picture," Love said as he snapped photographs of Walheim while the sun dipped behind the Earth's horizon. "I'm snapping like mad."

Friday's spacewalk ran seven hours and 25 minutes and marked the third excursion of Atlantis' 13-day mission to deliver the 1.4 billion euro ($2 billion) Columbus lab and a new crewmember to the ISS. The shuttle is due to land Feb. 20.

Walheim and Love attached the ESA's sun-watching SOLAR experiment the top of Columbus' research porch, where it will spend two years studying Earth's nearest star. They added a nine-instrument exposure facility to monitor the space environment and test new materials to Columbus' second experiment slot.

The astronauts also retrieved a massive, but broken, space station gyroscope and manhandled it into Atlantis' cargo bay to be returned to Earth for repair. The gyroscope, one of four used to maintain the space station's orientation in space without firing Russian thrusters, was replaced last year and awaiting a ride home.

"You guys did a great job bolting that down," Atlantis commander Stephen Frick told the spacewalkers. 

Exploring 'Love Crater"

After completing their primary tasks, Walheim and Love took a close look at a ding on a handrail near the space station's airlock. Love spotted the 2-millimeter divot during a Monday spacewalk, prompting Mission Control to nickname it the "Love Crater."

Love photographed the tiny ding while Walheim prodded it with his spacesuit gloved-finger before using an collectSPACE.com">improvised metal tool wrapped in spare spacesuit material to determine whether it posed a tear hazard for future spacewalkers. 

NASA engineers have been hunting for any sharp edges outside the ISS after finding damage to spacesuit gloves — ending one spacewalk early last year due to a small rip in spacewalker's outer glove layer — since it can pose a serious safety hazard to astronauts working in the vacuum of space.

Walheim and Love were unable to squeeze in a second extra task to inspect a damaged gear that rotates the station's starboard solar wings like a paddlewheel to track the sun. 

The large gear has been moved only sparingly since astronauts discovered the damage last fall, with any major repair slated for late this year. Atlantis carried some spare parts and grease guns that may be used in those repairs, NASA officials said.

Friday's spacewalk was the 104th dedicated to space station construction and the fifth career excursion for Walheim, who finished with 36 hours and 23 minutes of spacewalking time under his belt.

The spacewalk marked the second for Love, who is making his first spaceflight aboard Atlantis and concluded the excursion with 15 hours and 23 minutes. Altogether, Walheim, Love and German astronaut Hans Schlegel of the ESA spent 22 hours and eight minutes working outside the ISS during their mission's three spacewalks. 

Mission Control roused the astronauts early Friday with the German song by Drafi Deutscher, whose title translates to "Marble, Breaks and Iron Bends" in English, for Schlegel and wished ISS robotic arm operator Leland Melvin a happy 44th birthday during the spacewalk.

As they passed the seven-hour mark, Mission Control told the spacewalkers it was time to head back in. 

"Do we have to?" Walheim asked.

Love spent the bulk of the spacewalk perched at the tip of the station's Canadarm2 robotic arm while crewmates inside the ISS moved him between to and from Atlantis' cargo bay to retrieve the Columbus experiments and stow the broken gyroscope.

"Flying's been wonderful," he said. 

NASA is broadcasting Atlantis' STS-122 mission live on NASA TV. Click here for SPACE.com's shuttle mission coverage and NASA TV feed.