SPACE CENTER, Houston (AP) _ Two astronauts demonstrated the international space station's newfound spacewalking independence Saturday when they floated out of its new $164 million front door.
Space shuttle Atlantis astronauts Michael Gernhardt and James Reilly II spent four hours in space, adding the last of four gas tanks needed to pressurize the new air lock.
``On this historic anniversary of the first moonwalk, it's a real honor for the integrated shuttle and station crews, along with the flight control teams, to usher in a new era of spacewalking for the international space station,'' Gernhardt said.
In two earlier spacewalks, Gernhardt and Reilly had floated out of the docked shuttle, with Atlantis' cargo bay below them. The air lock's door instead opened directly over Earth as space station Alpha passed 240 miles above India.
``It's quite a view coming out,'' Reilly said.
``Yeah, really, it's straight down,'' Gernhardt said. ``You get a sense of falling, don't you?''
Saturday's outing was the last spacewalk of Atlantis' visit. The astronauts hooked up the 6 1/2-ton air lock on Sunday after the station's 58-foot robot arm hoisted it from the shuttle's cargo bay. On Wednesday, the arm handed off three of the 1,200-pound gas tanks to the astronauts, who attached them to the air lock.
``Thanks to everybody, thanks to our families, and it was a great flight,'' Reilly said as the astronauts headed back to the air lock after completing their work.
The new air lock gives space station residents more freedom as they continue building the outpost because it allows them to wear U.S.-made spacesuits during spacewalks without relying on a shuttle. Until now, they have had to use Russian spacesuits because the U.S.-made suits are incompatible with the Russian systems.
``We really couldn't get past where the station had grown to without adding this air lock and adding the station arm,'' shuttle flight director Paul Hill said. ``Now that we have those, the gate is wide open for us to keep right on building.''
The last spacewalk was postponed one day as the station and shuttle crews contended with several air leaks and water spills in the new passageway. NASA added a day to Atlantis' visit to make up for time lost to repairs.
NASA said two small air leaks that remained in the air lock before Saturday's spacewalk were inconsequential, and Hill declared the portal ready to go.
The portion of the air lock from which the astronauts exited took longer than planned to depressurize Saturday. Station flight director Mark Kirasich said that a valve, not leaks, was responsible and that the valve could be replaced during a future shuttle mission.
Late Friday night before the spacewalk began, Mission Control and the astronauts remembered the anniversary of the first moonwalk, conducted July 20, 1969.
``In about five minutes ... we will mark the 32nd anniversary of Neil Armstrong and Buzz Aldrin's spacewalk on the moon, which represented one of the most significant moments in human history,'' Mission Control said. ``Tonight, as you prepare to take your first steps out of the Quest air lock of international space station Alpha, we can take pride in the fact that we continue to step boldly into the future.''
Atlantis is due to undock from the space station Sunday and return to Earth early Tuesday.