Today's spacewalk by astronauts Michael Lopez-Alegria and John Herrington was a complete success, NASA managers said tonight, and the new P1 solar array truss is operating flawlessly after being wired into the space station's electrical system.

"Things went very, very well," said flight director Robert Castle. "We activated P1, all those systems came up, everything came up beautifully, all the hardware is working, there are no anomalies to talk about.

"With the activation of the P1 truss, we now have completed what I think of as the central part of the (station's main solar array) truss. We now have the entire cooling system, all the radiators, all the cooling lines are all there, the ammonia is there. The air conditioning system, if you will, is now fully constructed and is ready to be turned on (next year)."

The new $390 million P1 solar array truss segment, a 45-foot-long, 14.5-ton beam packed with computers, a complex ammonia cooling system and other equipment, was attached to the station at 1:48 p.m. EST.

Like a massive baton in some cosmic relay, the beam was pulled from Endeavour's cargo bay by the shuttle's robot arm and then handed off to the station's Canadarm2 space crane for installation on the lab complex.

Astronaut Peggy Whitson, operating Canadarm2 from inside the Destiny laboratory module, moved P1 into position near the port end of the station's growing solar array truss so a mechanical claw could pull it into place. Four motorized bolts completed the job, firmly locking the two components together.

The addition of P1 boosts the station's total mass to nearly 200 tons.

Floating in the Quest airlock module, Lopez-Alegria and Herrington switched their spacesuits to internal battery power at 2:49 p.m. to officially begin the first of three spacewalks to outfit and activate the new truss.

Lopez-Alegria completed one set of electrical connections and installed six spool positioning devices, or SPDs, on ammonia quick-disconnect fittings between the body of the P1 truss and three sets of radiator panels. Herrington, meanwhile, released a set of launch locks that held a new astronaut rail car in place on the forward face of P1. The cart will be repositioned during a spacewalk Thanksgiving day.

With that work done, Lopez-Alegria and Herrington turned their attention to removing structural supports called drag links that helped hold the 14.5-ton truss in place in the shuttle's cargo bay. The massive keel pins themselves will be removed Thursday.

Lopez-Alegria later made one more set of electrical connections as Herrington wrapped up work with the CETA cart. The final activity planned was the installation of a "helmet cam" antenna stanchion, part of a system to give station crews helmet cam views during spacewalks between shuttle visits.

The spacewalkers even managed to take a few moments to enjoy the view from 245 miles up.

"How do you like the view?" EVA-veteran Lopez-Alegria asked his rookie crewmate as the two began the spacewalk.

"The view is just phenomenal!" Herrington replied, with feeling.

After completing the initial set of electrical connections, Lopez-Alegria asked Herrington to pause for a picture.

"John I have to get a picture of you down there. ... if you could just hold tight," Lopez-Alegria radioed. "Paco, do we have time for this frivolity?"

"You can take one picture," spacewalk coordinator Paul "Paco" Lockhart replied from Endeavour's flight deck.

"That sounded pretty (much) like a no," Herrington observed.

"OK, one picture coming up," Lopez-Alegria said. "John, try to get away as far as you can from the CETA cart. And get that crew lock bag out of the sun... there you go."

"How's that?"

"Great, thank you."

"Thanks, Paco," Herrington radioed.

"No sweat."

"First it's, 'out the door, out the door, don't be taking any pictures!'"

"That's so we can get you in the door, in the door," Lockhart joked.

Today's spacewalk began at 2:49 p.m. and ended at 9:35 p.m. EST for a duration of six hours and 45 minutes. Some readers might think that adds up to six hours and 46 minutes, but they would be wrong. The actual duration of the excursion was six hours, 45 minutes and 53 seconds but NASA's EVA office rounds down because of occasional lags in telemetry indicating when airlock repressurization - which marks the end of a spacewalk - actually began.

So at NASA, it would seem, 53 seconds is no time at all.

"The reason why we started rounding down the times is our EVA clock technical stops when we start repress," said lead spacewalk officer Dana Weigel. "And it's difficult to tell exactly when the crew starts repressing the airlock. The data on the ground doesn't always respond right away. So what we do is, we watch the data and as soon as we think it starts to change and it's indeed the repress, we stop our clock. And often times, that's 30 seconds or so off. So we tend to round down."

Asked why NASA didn't simply change the official ending time to 9:34 p.m. so the hours and minutes would at least add up, Castle said that was a question best left to the agency's public affairs office.

Go figure.

This was the 47th spacewalk devoted to assembly and maintenance of the international space station, the 16th this year and the 22nd staged from one of the station's two airlocks.

As of today, 35 NASA astronauts, one Canadian, one Frenchman and seven Russian cosmonauts have logged 292 hours and 11 minutes of space station assembly time since construction began in 1998. Herrington and Lopez-Alegria plan to stage two more spacewalks Thursday and Saturday to complete the outfitting of the P1 truss.