Agency engineers, as a result, will pour over video of the massive wing unfurling before giving the shuttle crew a go-ahead to extend the second panel.

"We're going to do some analysis on the wing that's out, and when we're convinced we're ready, we'll deploy the second wing," Reeves said. "There's no reason to be in a big hurry and deploy the other blanket until we absolutely understand what we're looking at right now."

The extended solar wing is one of a pair attached to a $600 million electrical power tower that was mounted atop the International Space Station during a 7-hour, 33-minute spacewalk Sunday.

Covered with 32,800 shiny solar cells, the panel -- which converts sunlight into direct-current electricity -- slowly unfurled like a king-sized accordion in space during a 14-minute deployment sequence beamed back to Earth and broadcast live on SPACE.com.

"Ah, it looks beautiful," said Endeavour spacewalker Carlos Noriega, who was watching on from the shuttle's cargo bay at the time.

Added spacewalking partner Joe Tanner: "More power to the station."

NASA mission managers were just as impressed.

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"In one word, it's an awesome sight to see that array out there as big as it is, and then to imagine what it's going to look like with the second one out there as well," Reeves said. "It's quite a sight."

Endeavour spacewalkers Joe Tanner and Carlos Noriega work high atop the P6 power tower during the spacewalk on Sunday in this image from NASA TV.

The Alpha crew missed the spectacle. U.S. astronaut Bill Shepherd and his two Russian colleagues -- cosmonauts Yuri Gidzenko and Sergei Krikalev -- were in the midst of an eight-hour sleep period at the time.

Together, the two solar wings -- which are the largest ever to be hauled into orbit -- are designed to stretch some 240 feet (73 meters) from tip to tip, generating enough electricity to power 30 homes.

That power is critical to the $60 billion station construction project, which is a joint effort of 16 nations and 100,000 workers on four continents.

Existing electrical supplies are so sparse that one of the station's three pressurized work areas remains off limits to the Alpha crew, which took up residence at the complex in early November.

The extra electrical power also is a must before NASA and its international partners can expand the station during a series of almost 40 more U.S. shuttle and Russian rocket missions.

In fact, the station's first science lab -- now set for launch in mid-January -- would remain grounded if Endeavour's astronauts were unable to finish wiring the already deployed wing to the station during a spacewalk later this week.

NASA station flight director John Curry said that the single deployed panel is expected to generate enough electricity to press ahead with the lab launch.

"We could support the lab mission, I know that. Obviously there would be impacts on total power production. But we could survive with one (array) for a period of time," he said.

The solar wing deployment came after the successful mounting of the 17-ton power tower atop of the station, a job Canadian astronaut Marc Garneau deftly did with the shuttle's 50-foot (15-meter) robot arm.

With the arm acting as a construction crane, Garneau maneuvered the payload to within three feet (0.91 meters) of a rooftop truss mounted to the outpost by a visiting shuttle crew in October.

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Decked out in $12 million spacesuits, Tanner and Noriega then scaled the 13-story station and helped Garneau guide the power tower into a mechanical claw designed to secure it to the top of the outpost.

An example of a helmetcam view from Carlos Noriega as he works with a power tool while the Earth appears below in this image from NASA TV.

Both were outfitted with helmet-cams that provided unprecedented glimpses of the international outpost.

Similar to the lipstick-type cameras worn by National Football League referees and placed inside NASCAR racers, the helmet-cams are the heart of NASA's new Wireless Video System, or WVS.

The tiny cameras gave both the shuttle crew and NASA TV viewers close-up looks at work being done by the tool-toting astronauts, and long-range shots of Endeavour's floodlit cargo bay as the joined shuttle and station passed around the dark side of Earth.

"I have to tell you guys, this WVS is very cool," shuttle commander Brent Jett told the spacewalkers.

"I figured it would be," Noriega replied.

Tanner and Noriega will perform two more spacewalks during Endeavour's stay at the station.

A second sortie is scheduled to begin about 1 p.m. (18:00 GMT) Tuesday. The job at hand: Wiring the solar wings to the station and repositioning a key communications antenna.

The third spacewalk - which is set to begin just after noon EST (17:00 GMT) Thursday - will involve mounting a device designed to determine whether the solar wings might create a shock hazard to astronauts working outside the station.

Both of those spacewalks will be broadcast live on SPACE.com.

Endeavour and its crew -- which also includes pilot Mike Bloomfield -- are scheduled to land at Kennedy Space Center at 6:19 p.m. EST (23:19 GMT) Dec. 11.