Spacewalkers Leroy Chiao and Bill McArthur attach the 78-inch Ku-band antenna to its boom on the Z1 truss. Photo: NASA TV/Spaceflight Now

Astronauts Leroy Chiao and William McArthur pulled off a near perfect spacewalk today, wiring up the international space station's new truss, deploying its main antenna and stowing tools for use by future assembly teams.

"You guys have set the bar pretty high for tomorrow," crewmate Peter "Jeff" Wisoff radioed from the shuttle Discovery's flight deck.

Wisoff and astronaut Michael Lopez-Alegria are scheduled to carry out the second of four back-to-back spacewalks Monday to attach a new $20 million shuttle docking port to the space station and to continue hooking up the $273 million Z1 truss installed Saturday.

In the meantime, NASA managers were elated with the success of the first spacewalk, or EVA, today, especially given a steady stream of problems and glitches earlier in the flight.

"We had a very, very - very - successful (day) today," said lead flight director Chuck Shaw. "We were able to go out and accomplish all the tasks. The crew and the EVA team in the control center worked absolutely perfectly together."

Said EVA trainer Daryl Schuck: "It doesn't get any better than this when you're in the spacewalk business."

The 51st spacewalk in shuttle history began at 10:27 a.m. when Chiao and McArthur switched their spacesuits to internal battery power before floating out of Discovery's airlock. The spectacular view that greeted them stunned first-time spacewalker McArthur.

A sequence of images shows the international space station's Ku-band antenna being deployed by the spacewalkers. Photo: NASA TV/Spaceflight Now

"Oh, sweet Jesus," he said slowly, as he floated out of the shuttle's airlock. Then he quickly exclaimed: "Whoo whoo!" a cheer he uttered repeatedly as the spacewalk progressed.

The first item on the agenda was to connect four electrical cables between the new Z1 truss and NASA's Unity module. With his feet anchored to clamps on the shuttle's robot arm, McArthur was lifted high above Discovery's cargo bay to make the critical connections.

He obviously found the bird's eye view stunning.

"Being out on the end of the arm, not being able to see the shuttle, it is a strange feeling," he commented. "My toes are curling right up. Oh, good God! In a second, I might not be able to see any spaceship... ahhh... ahhh... OK, this makes five years (of training) worthwhile." He and Chiao had no problems connecting the four primary cables between the truss and the Unity module and, after repositioning the station's S-band antenna system, they hooked up four backup cables to provide full redundancy.

The Z1 truss houses four massive gyroscopes to stabilize the space station, as well as its main communications antennas. It also will serve as the mounting point for a huge set of solar arrays scheduled for attachment in December.

The cables connected today will permit electricity from the arrays to reach other station components, including the U.S. laboratory module, Destiny, scheduled for delivery in late January.

They also allowed flight controllers to turn on internal heaters to keep the gyroscopes from getting too cold. Ammonia coolant lines from the lab's electronics ultimately will be routed to radiators on the P6/Z1 truss solar array.

"We have a very healthy spacecraft today, especially the Z1," said Sally Davis, the lead space station flight director. "All the connections that were made were good connections, we were able to verify those as we went along, good data connections across the board, good electrical connections.

"Through the night we'll be checking out individual loads on each of the connections to the best we can given the telemetry that's available," she said. "So far, everything's looking really good."

After the Z1 electrical and data connections were completed, McArthur and Chiao unstowed the station's main Ku-band communications antenna, which was launched flush against the side of the Z1 truss.

After carefully attaching the fragile antenna dish, the spacewalkers successfully deployed the boom.

During a pass over a U.S. ground station, the astronauts were able to downlink videotape showing the massive boom as it slowly rotated open against the black backdrop of space.

Bill McArthur carries a toolbox for installation to the station's hull. Photo: NASA TV/Spaceflight Now

"I've got to admit, that was one of the scariest tasks we've been presented with in a long time," Schuck said. "It's a delicate piece of hardware, it's thermally sensitive. It required a precision mate and connections to keep it safe. And all of these thins came together and worked perfectly."

But the S-band and Ku-band antennas, like the control moment gyroscopes, will not be activated until after the Destiny module is attached and they are all tied into the station's main computer system.

The final item on the agenda for Chiao and McArthur today was to mount a large toolbox on the station's hull for use by future assembly crews.

Throughout it all, West Point graduate McArthur provided lively commentary - including a hearty rendition of the Army fight song for Naval Academy graduate Lopez-Alegria - clearly enjoying his first spacewalk and the views it afforded.

When all was said and done, the outing lasted six hours and 28 minutes, coming to an end at 4:55 p.m. when the astronauts began repressurizing Discovery's airlock.

"It was quite an adventure," McArthur reflected as the crew downlinked videotape of the spacewalk. "It's always nice when you know something's going to be a lot of fun and it really is."

"And we enjoyed your commentary," astronaut Ellen Ochoa replied from Houston.

"Mike said it kept everyone here entertained as well," McArthur laughed. "Really, it certainly seemed to us the training we had was right on the money."

"We were impressed at how closely the timeline worked out to the pre-flight predicts," Ochoa said.