Two NASA astronauts completed their mission's third and last spacewalk Monday, installing a new science experiment and an oxygen tank outside the International Space Station.

The spacewalkers, STS-129 mission specialists Robert "Bobby" Satcher, Jr. and Randy Bresnik, got a late start this morning after dealing with an issue on Satcher's pressurized spacesuit. The valve on his drink bag, which allows him to sip water during the spacewalk, came loose and the astronauts had to replace it. The fix caused a delay, and the spacewalkers officially began the excursion at 8:24 a.m. EST, about an hour behind schedule.

Once outside the station, Satcher and Bresnik quickly made up for lost time, and managed to accomplish all of their planned tasks and still finish just shortly after the original planned ending time, at 2:06 p.m. EST.

• SLIDESHOW: Atlantis astronauts go for a spacewalk

• SLIDESHOW: Space Shuttle Atlantis mission in pictures

The spacewalk was the second for both Satcher and Bresnik, who are each making their first spaceflights on this mission. The two launched Nov. 16 on an 11-day trip to deliver about 15 tons of spare supplies to the orbiting laboratory.

Satcher recently became the father of a baby daughter Abigail, who was born to his wife Rebecca back in Houston on Saturday.

"I got to see [via video] my little girl for the first time yesterday," Bresnik said at the end of his spacewalk. "Thank you to my wonderful wife for bringing her into the world. That is the most beautiful thing I've seen since I left Earth."

The couple already has a son, Wyatt, who is three years old.

"Hey, Wyatt, I look just like Spiderman," Bresnik called while climbing across the space station's railing today to attach a science experiment.

The equipment is a test to see how materials, including a new type of Teflon, hold up to the ultraviolet radiation, atomic oxygen, and extreme temperatures of space.

In addition to that project, the spacewalkers installed a new oxygen gas tank on the station's Quest airlock that will be used to help pressurize and depressurize the compartment where astronauts enter and exit for spacewalks. After that work was done, the two astronauts even had time to take on some other "get-ahead" chores at the station.

"You guys are working great together out there," said mission specialist Mike Foreman, who was helping coordinate the excursion from inside the space station.

"We've got a good big team with you and everybody else on the ground too," Bresnik replied.

At one point, things were going so smoothly the astronauts stopped to wish for lunch.

"I don't know about you Bobby, but if we happen to pass a burger joint in the next few thousand miles, I wouldn't mind stopping and getting something to drag up," Bresnik said.

"That sounds good to me," Satcher replied. "Although for some reason I was thinking about nacho cheese tortilla chips."

"Mmm, mmm, mmm," Bresnik said.

With this second spacewalk under their his belt, Bresnik has now clocked a total of 11 hours and 50 minutes outside of a spacecraft, while Satcher has spent 12 hours and 19 minutes spacewalking.

Today's work marks the last spacewalk of this mission and the completion of a large chunk of the remaining objectives for Atlantis' docked mission at the station. The astronauts, led by commander Charlie Hobaugh, are set to undock from the outpost early Wednesday and return to Earth on Friday.