Spacewalkers Help Deliver Space Station's Largest Lab

This story was updated at 9:10 p.m. EDT.

HOUSTON ? Two spacewalking astronauts help deliver a major new addition, the giant Japanese Kibo laboratory, to the International Space Station (ISS) Tuesday in the first of three excursions planned for their mission.

Spacewalkers Mike Fossum and Ron Garan also tested methods of cleaning the orbital lab's sticky solar wing joint and retrieved their shuttle's inspection boom during their nearly seven-hour venture outside the station.

The astronauts officially began their spacewalk about an hour late at 12:22 p.m. EDT (1622 GMT) because of a communications glitch in Fossum's spacesuit, which was emitting a loud squeal. The crew was able to reconnect a cable and fix the problem.

The fix delayed the start of the spacewalk about 50 minutes past its planned beginning, but otherwise had no effect on the six-hour, 48-minute excursion.

Fossum and Garan arrived at the station Monday along with the other members of the space shuttle Discovery's seven-person crew, led by commander Mark Kelly.

The whole crew had a role in the spacewalk, with pilot Ken Ham choreographing the venture from inside the station, and mission specialists Karen Nyberg, Akihiko Hoshide and Greg Chamitoff driving the shuttle and space station robotic arms.

While the spacewalkers were trampling around the outside of the station, Ham called out, "Watch your feet on my roof!"

The spacewalk began on the 43rd anniversary of the first-ever U.S. spacewalk, a 23-minute excursion by astronaut Ed White during the Gemini 4 mission on June 3, 1965.

Long-lost boom

The spacewalkers began their trip outside by retrieving Discovery's sensor-tipped heat shield inspection pole from the ISS.

"Alright, boys, it's time to rock and roll," Ham called out at the start of the spacewalk.

Usually, shuttles carry their own inspection poles, which attach to the shuttle's robotic arm and are used to scan heat tiles for signs of damage. In this case, however, Discovery couldn't fit the 50-foot (15-meter) boom in its payload bay, which was crowded by Kibo, so the previous shuttle mission, Endeavour's STS-123 flight last March, left the boom outside the station for Discovery.

After viewing photographs taken of the shuttle?s belly right before it docked at the space station, mission managers said they have cleared the shuttle for landing in the case of an emergency. They have also determined that no further focused inspection will required, Mission management chair LeRoy Cain said today after the spacewalk.

Once the two spacewalkers released the restraints holding the pole in place on the space station's truss, the inspection tool was picked up by the space station's robotic arm, steered by Hoshide, and passed off to the shuttle arm, driven by Nyberg. Then Nyberg safely stowed the boom away, where it will stay until Friday when it is due to be used to perform a detailed inspection of Discovery's heat shield.

Kibo Installation

After recovering their shuttle's inspection pole, the two spacewalkers set to work preparing the new Kibo module to be installed on the station. It was secured in tight in Discovery's payload bay, so the bolts and straps that held it in had to be removed before it could be unberthed.

Once the spacewalkers had freed up the Japanese lab, Japanese astronaut Hoshide picked it up with the station's robotic arm and carried it "carefully, methodically and glacially" over to its new, permanent perch on the ISS's Harmony node, said NASA commentator Rob Navias.

At about 6:15 p.m. EDT (2215 GMT) 'Hope' finally reached Harmony, and about half an hour later the two modules attached.

"You are go for first stage capture," astronaut Garrett Reisman told Hoshide, instructing him to move forward with the first steps of installing the new module.

"Sweet!" Hoshide replied.

By 7:01 p.m. EDT (2301 GMT), the lab was finally secured on its permanent roost.

Clogged joint cleaning

While the station arm was moving Kibo across the sky, the two spacewalkers moved on to their planned inspection of a troublesome joint on one of the space station's solar panel wings.

The joint, called the Solar Alpha Array Rotary Joint (SARJ), is a huge gear that serves to rotate the station's outboard solar wings like a paddlewheel to keep them facing the sun to draw in as much pressure. The starboard joint has been clogged by metallic grit lodged inside it, which has damaged its rotating ring and caused odd power spikes and vibrations that were first detected last October.

Fossum tested cleaning techniques, including scraping the area with a dentist's pick-like tool and using a grease gun to lubricate the gear and dislodge debris.

"The initial scraping probably did the most good," Fossum said.

He also helped determine that one area of interest, an apparent divot in the gear's metal ring, was actually etched into the surface rather than raised above it.

"That mark was actually an indentation," said Kirk Shireman, NASA's deputy station project manager, after the spacewalk. "So that was good data for us."

If NASA decides the cleanaing techniques are successful, they plan to send a later mission to use them on a spacewalk to perform a more thorough cleaning.

Meanwhile, Garan worked to reinstall a previously-removed set of bearings that the gear rings roll on.

With one spacewalk in the books, Discovery's STS-124 crew and the station's Expedition 17 astronauts are now looking ahead to officially opening the new Kibo laboratory on Wednesday. They are also set to fix the station's balky space toilet, a Russian-built commode that has been acting up lately.

• New Video: Liftoff! Discovery Launches Into Space
• Video: STS-124 Mission Preview ? Delivering Kibo
• Complete Space Shuttle Mission Coverage