(AP) -- Astronauts working inside and out installed a porch for experiments on Japan's enormous space station lab Saturday, accomplishing the major objective despite microphone static that often drowned out the spacewalkers' voices.
Veteran spaceman David Wolf and rookie Timothy Kopra could barely make themselves understood at times because of the loud static emanating from Kopra's helmet microphones.
"Dave, you're unreadable," astronaut Christopher Cassidy called from inside the shuttle-station complex.
Two hours later, it was no better. "It's hard to follow along with this comm," Cassidy said, looking for clarification on what the spacewalkers were doing. The trouble lasted the entire 5 1/2-hour spacewalk, the first of five planned during Endeavour's space station visit.
Mission Control officials said it was a challenge to monitor the 220-mile-high action, especially with so many people in orbit - a record crowd of 13. But they said the static never threatened safety.
The problem apparently was with the two microphone booms in the cap worn by Kopra under his helmet. The booms were too far from his mouth - he could not move them once his helmet was on - and the ventilation flow created all the static. The booms may have been bumped as he was putting on his helmet.
This was Kopra's only spacewalk for the mission, so the airwaves should be much quieter when astronauts step back outside Monday.
"Listening to the static throughout the whole (spacewalk) tends to wear you out more than you would expect," said Kieth Johnson, the lead spacewalk officer in Mission Control. "But I think we made it through."
Despite the nerve-racking racket, the spacewalkers managed to prep the Kibo lab - Hope in Japanese - and the new porch for their mechanical hookup. Wolf removed a cover from the lab and tossed it overboard; the white cover drifted away, flipping end over end.
The spacewalkers then moved on to other routine work at the international space station as their colleagues inside used the shuttle and station robot arms, one at a time, to lift the Japanese porch from Endeavour's payload bay and hoist it toward the Kibo lab. The spacewalk was over by the time the porch was finally latched in place.
It marked the completion of Japan's $1 billion lab, so big that it required three shuttle flights to launch everything. The first two sections of the lab flew up last year.
The veranda - about 16 feet square - will get its first outdoor experiments in five more days.
Mission Control's congratulations to Wolf and Kopra, as they headed back inside, could hardly be heard because of the static. In the end, the two fell behind and had to skip some chores. They managed to free a platform for spare parts that jammed months ago, using a specially designed tool. But they did not have time to release a similar platform on the opposite side of the outpost.
With Apollo 11 on the minds of many back on Earth, NASA noted that Saturday's spacewalk was the 201st by Americans since those first steps on the moon by Neil Armstrong and Buzz Aldrin 40 years ago this Monday.
Remaining inside the linked shuttle and station were 11 astronauts, a full house. The station population swelled to 13 when Endeavour arrived Friday for a 1 1/2-week stay. Kopra, the station's newest resident, will remain on board for another 1 1/2 months.
Earlier Saturday, Mission Control had both good and bad news for the spacefarers.
The good: Endeavour looks to be in fine shape for re-entry at the end of the month, although a review of shuttle photos and other data continues. A surprisingly large amount of foam insulation came off Endeavour's fuel tank during liftoff, but the shuttle ended up with just 16 minor scuff marks on its belly.
The bad: The astronauts were informed of Walter Cronkite's death. Mission Control relayed statements by Armstrong and NASA's new chief, ex-astronaut Charles Bolden, both of whom noted Cronkite's passion for human space exploration.
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