Astronauts, for Starters, Bolt a Girder to Station

Two spacewalking astronauts bolted a 44-foot girder to the international space station on Thursday, completing the first step in one of the most complicated construction jobs yet at the orbiting outpost.

The 27,000-pound beam was first hoisted into place and clamped down by the space station’s 58-foot robot arm, operated by remote control from inside the spacecraft by two astronauts.

Then two other astronauts, Steven Smith and Rex Walheim, floated outside, unfolded two V-shaped struts on the girder and bolted them down. As he put the final twist on the last of eight bolts, Walheim shouted, “Hot dog!”

“We’re going to put in for your ironworker’s card,” NASA’s most experienced spacewalker, Jerry Ross, said from inside Atlantis.

Space shuttle Atlantis’ visiting astronauts will go out three more times to finish installing the $600-million girder, the first section of a framework that eventually will stretch 356 feet and hold a collection of solar wings, radiators and science experiments.

During Thursday’s outing, Smith and Walheim also hooked up power cables and fluid lines. Some of the hoses were stiff and twisted, and the tray containing them was hard to release. It took both of them to yank the tray loose.

That put the spacewalkers behind, so much so that Mission Control ordered Smith to briefly retreat to the station air lock Thursday afternoon and recharge his oxygen supply.

The spacewalk ended up lasting almost eight hours, more than an hour longer than planned. “You guys did a fantastic job today,” Mission Control said. “You’re probably ready to come on in.”

It was also a tiring day for the robot-arm operators, who put in 13 hours at the controls in the space station laboratory. “You set a new world record,” Mission Control told crane operators Ellen Ochoa and Daniel Bursch.

Walheim, making his first spaceflight, was exuberant as he gazed at Earth 240 miles below. “This is incredible,” he said. “Unbelievable.”

“Sounds like you’re having too much fun out there,” Ross said.

The aluminum girder contains more than 10 miles of wiring and 664 feet of plumbing. It has 475,000 parts, including four computers and four Global Positioning System satellite antennas.

Also attached to the structure is a track on which a $190-million rail car will move, hauling cargo from one end of the framework to the other. The spacewalkers hooked up a reeled cable system to the rail car and track, in their last chore outside.

Atlantis will remain docked at space station Alpha until Wednesday.