Air lock installed on space station

(CNN) -- Astronauts successfully installed a new $164 million air lock on the international space station.

Sunday's Extravehicular Activity (EVA), or space walk, started an hour late after Mike Gernhardt and Jim Reilly took longer than anticipated to complete pre-walk checks but finished on time when it took only six hours, rather than the predicted seven.

Astronauts from the space shuttle Atlantis, which is docked on the space station, worked with some of the station's crew to complete installation of the air lock named Quest.

At one point while preparing the airlock for lifting from the shuttle's cargo bay, Gernhardt said: "it was like wrestling a 12- foot alligator and tying it up with a 20-foot snake."

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The heavy lifting was then left to space station resident astronaut Susan Helms who used the station's new robot arm to pluck the Quest from the shuttle's cargo bay.

For the next three hours, Helms slowly moved the Quest into position. Gernhardt and Reilly then began attaching power and heater cables to bring Quest to life.

At one point they were asked, "you guys about ready for a cup of coffee?" "Getting close man, getting close." was the response.

The air lock installation is the primary objective of the Atlantis mission, with the two-room chamber allowing space station crews to venture from the station in NASA spacesuits without the assistance of visiting shuttles. Currently, crews must exit from the Russian segment of the outpost wearing Russian spacesuits.

Atlantis launched from the Kennedy Space Center in Florida on Thursday.

The orbiter was originally expected to fly in June, but technical problems with the new robotic arm on the space station forced NASA to postpone the mission.

The five Atlantis astronauts are the space station's first visitors in more than two months. The one Russian and two Americans expect to be relieved by another three-person crew in August.

The shuttle docked with the space station on Friday night as the two spacecraft soared about 200 miles (320 kilometers) just as it passed the southern coast of Chile.