Spacewalkers Mike Foreman and Bobby Satcher have successfully completed their planned work outside the space station today, at times 2 hours ahead of schedule.

After unloading a spare antenna from the cargo bay and installing it on the station, the team had enuogh extra time for an extra chore, the deployment of a payload attachement system — a sort of orbital shelf for more spare parts.

The astronauts spent about 6 and a half hours on the 228th spacewalk conducted by U.S. astronauts — the 134th in support of space station assembly and maintenance. Today’s spacewalk began at 9:24 a.m. EST and ended at 3:51 p.m

"To go outside — and it's a great view from inside the shuttle — but outside with just your helmet and that visor in front of you, and panoramic view of the Earth and the heavens, it's just amazing," Foreman said of spacewalking, during a preflight interview.

• SLIDESHOW: Atlantis astronauts go for a spacewalk

• SLIDESHOW: Space Shuttle Atlantis mission in pictures

Foreman and Satcher arrived at the orbiting laboratory Wednesday along with four other crewmembers flying aboard the space shuttle Atlantis' STS-129 mission, led by commander Charlie Hobaugh. The shuttle launched Monday to begin the 11-day spaceflight.

The spacewalkers' first task will be to unload a spare communications antenna from the shuttle's cargo bay and install it on the station. The new element will serve as backup in case the antenna currently in use breaks and a replacement is needed.

After that, Satcher plans to add some grease to the end of the station's Japanese robotic arm and an attachment point on the outpost's railcar. Both devices have grabbing mechanisms called snares that can get stuck if not properly lubricated. Meanwhile, Foreman will attach a set of cables and a new handrail to be used during a future mission when a new node is installed on the station.

"I'll spend most of the spacewalk actually flying on the robotic arm, so it'll be a pretty incredible view because the arm kind of takes you away from [the] structure and you're kind of hovering above everything," Satcher said.

The spacewalk is crucial for the mission's overall goal of outfitting the station to prepare for the era after the retirement of the space shuttles and their large cargo-carrying ability. NASA's three-orbiter shuttle fleet is due to stop flying in about a year.

Atlantis arrived bearing two large platforms full of extra parts to have on hand in case something breaks. One of them was installed on the station's main truss late Wednesday.

"Having these already there is going to make things much easier down the road for long term of the International Space Station to 2015 or beyond," said lead STS-129 flight director Mike Sarafin.

Thursday's spacewalk will mark Satcher's orbital debut, an experience he's expecting to relish.

"That's going to be the highlight, I think, of the flight for me," Satcher said in a preflight interview. "Really stepping out and seeing the vastness of the view of the Earth and the space station and the shuttle and then, of course out beyond. That is going to be spectacular... I hear people describe it and they all say that it has a significant impact on their perspective overall and it's a life-changing event."

Mission specialist Randy Bresnik, who is expecting his wife to give birth to a baby girl Friday, will help orchestrate the spacewalk from inside the station. Shuttle pilot Barry "Butch" Wilmore and mission specialist Leland Melvin will also assist by controlling the shuttle's robotic arm from inside the station.