"With the stars shining through them," Parazynski added.

And they were equally impressed with the towering 17-story station, which now comprises four bus-sized segments as well as glimmering gold American solar arrays that have a wingspan greater than that of a 747 jumbo jet.

"When I was a little kid hoping to be an astronaut when I grew up, this is what I wanted to do," Hadfield told his spacewalking partner.

"This is the ultimate," Parazynski replied.

"Remember those scenes in [the movie] Star Wars where the camera flies along the spaceship and you see every little detail?" Hadfield asked. "Well, this is a spaceship. It's beautiful."

Keeping up a near-constant banter during their seven-hour, 10-minute sortie, Hadfield and Parazynski made fast work of a crucial job: erecting a 57.7-foot (17.5-meter) Canadian robot arm that is essential to finishing the outpost.

Flown up to the station aboard shuttle Endeavour, the huge boom sports snare-like "hands" at either extremity and will be able to move end-over-end to various work sites, creeping to places the shuttle's fixed robot arm cannot reach.

That capability will be vital as the United States and its 15 international partners add science labs, electrical power towers and skeletal truss segments to the growing complex, which ultimately will span an area nearly as large as two football fields.

Said NASA lead flight director Phil Engelauf: "We're now at a point in the assembly where components to be added to the station cannot be installed without the additional reach capability that's provided by this new arm."

The spacewalking construction work got underway after shuttle pilot Jeff Ashby plucked a crane carrier out of Endeavour's cargo bay and mounted it on a cradle on the outside of the station's U.S. Destiny science laboratory.

Too long to fit in the shuttle's bay, the so-called Space Station Remote Manipulator System -- also known as Canadarm2 -- was folded up and firmly latched to the pallet for the ride up to the station.

The tricky lift called for Ashby to twist and turn the pallet, snaking it around to the far side of the $1.4 billion lab without banging it into the station or a nearby outpost communications antenna.

~

Hadfield and Parazynski then ventured out of the shuttle's airlock and made their way up to the top of the lab, an excursion that took them three stories above the nose of Endeavour.

The spacewalkers waved to the station crew as they moved past the lab's picture window, clearly enjoying the view as the linked shuttle-station complex passed over the dark side of Earth.

"I'm not used to seeing the world below my feet," Hadfield said. "Look at that line of sun on the Earth over there, and the blackness below it. It's quite eerie out here at night, huh?"

"It's different," replied Parazynski.

The sunlit side of Earth also made for some dazzling sights as Parazynski took a moment to snap pictures of a gleaming black-and-white shuttle below them.

"Just got a beautiful shot," he said, "The sun-glint on the tail of the orbiter -- that's a beautiful thing."

"Yeah, I'll say," Hadfield replied.

The high-flying foray, however, was not all play and no work.

Acting as orbital electricians, the two spacewalkers hooked up power, data and video cables so that the new station arm could be brought to life electrically and controlled from computer workstations inside Destiny.

They also set out a new communications antenna and then unfurled the lengthy arm, a job that called for eight "superbolts" -- each four feet (1.2 meters) long -- to be unfastened so the arm could be unfolded and extended before its hinges were firmly locked in place.

"Time for the main event," Hadfield said.

"We're at the 'at-my-signal' point," Parazynski replied.

"Release the arm," Hadfield added. "Canadarm2 is staying in space."

An advanced version of the shuttle's Canadian-built robot arm, the new crane -- which has been in the works now for 15 years -- is considered the heart of Canada's $900 million station contribution.

Equipped with force sensors that give it an artificial sense of feel, the robot arm is four times stronger and more flexible than its shuttle predecessor. And since it will have to operate in orbit during the next two decades, the arm can be retrofitted with spare joints if necessary.

~

Canadian Space Agency officials were overjoyed with the arm's deployment, which marked a significant milestone in that nation's space exploration program.

"This is the biggest day, really, in the history of the Canadian Space Agency," said Ed Tabarah, chief robot arm instructor with the organization. "This is a moment that we've all anticipated."

Coincidentally, the day's work with the arm wrapped up as the shuttle and the station flew in tandem over Newfoundland. And in a special tribute to Hadfield and Parazynski, ground controllers beamed up a rousing version of "Oh Canada," the Canadian national anthem.

All in all, the work came off largely as planned. The only hitch: Hadfield was reduced to tears when a soap-like film inside his spacesuit helmet got in his eyes. The coating is designed to keep helmet faceplates from fogging up but also can be an eye irritant.

The problem cleared up after Hadfield opened a purge valve, increasing the flow of oxygen within his helmet. But the spacewalker was forced to close his eyes to ward off a burning sensation, a move that essentially blinded him for about 15 minutes.

"It burns sort of lightly when they're closed, and fairly heavily when I open them," Hadfield reported. "It's not a big deal when they're closed, but I'm not much use out here with my eyes closed."

With the new outpost crane up and operating, station flight engineer Susan Helms started putting the Canadian robot arm through initial orbital testing.

Working within Destiny, she and crewmate Jim Voss will "walk" the arm off its carrier pallet about 6:30 a.m. EDT (10:30 GMT) Monday, placing it on an anchor on the exterior of the lab. The so-called Power and Data Grapple Fixture will become the arm's base at that point. Its other end subsequently will be set free from the pallet.

Hadfield and Parazynski will carry out a second spacewalk starting at 9 a.m. EDT (13:00 GMT) Tuesday. The job at hand: Rewiring power cables between the station arm and the pallet so that the latter can be stowed back in the shuttle's cargo bay for a return trip to Earth.

Both the shuttle and station arms will be involved in that task. Voss plans to grab the pallet with the new outpost crane and then hand it off to Hadfield, who will be operating the shuttle's robot arm. It will be the first time two robotic arms -- and two robot arm operators -- have ever worked in concert in space.

Launched Thursday from Kennedy Space Center, Endeavour's astronauts are in the midst of a weeklong stay at the station. Later this week, the astronauts plan to deliver several tons of supplies and equipment to Voss, Helms and station commander Yuri Usachev.

Made up of astronauts from the U.S., Russia, Canada and Italy, the shuttle crew is scheduled to depart the station Saturday, heading off on a two-day trip back to Earth.

The 11-day shuttle mission is to be capped with a 10 a.m. EDT (14:00 GMT) April 30 landing here at NASA's coastal Florida spaceport.