Two spacewalking grandfathers have finished bolting a massive girder to the international space station. Astronauts from the U.S. space shuttle Atlantis are now halfway through the four spacewalks needed to mount the truss and string cables through it.
Fifty-four-year old Jerry Ross and 49-year-old Lee Morin spent more than seven hours outside the station Saturday tightening the last bolts to fasten the 13-ton, 13-meter girder to the U.S. laboratory.
With four grandchildren between them, they are the first pair of grandfathers to walk in space.
In addition to bolting the truss, the 'silver team,' as their colleagues call them, also ran a set of power, data, and video cables to a small railway flatcar that will haul heavy cargo along the girder when it is extended to its full 100-meter length on future shuttle visits.
The truss, which NASA has designated S-0, will be the longest structure in space. It eventually will support massive solar power arrays and cooling radiators for European and Japanese labs to come.
Mission official Ben Sellari says that Saturday's spacewalk has made the girder stable enough to accept the forthcoming loads.
"For long term, S-0 is now permanently a fixture aboard the international space station and we couldn't be happier," he said. "It meets all the structural requirements necessary to continue phase three of assembly. So I guess in a short word, S-0 open for business," said Mr. Sellari.
Another mission official, Wayne Hale, says the timing of the work is also noteworthy, coming 41 years after Soviet cosmonaut Yuri Gargarin's historic voyage into space and 21 years after a U.S. space landmark.
"I think it's significant as we think about yesterday being the anniversary of the first human in space and the anniversary of the first shuttle launch that today we watched an international crew of nine Americans and a Russian station commander put together a symbol of the next element of the station so that it became truly a skyscraper in space," said Mr. Hale.
But the work on the new girder is not finished. On Sunday, Steve Smith and Rex Walheim, the alternate spacewalking team, venture outside the station for the third of four mission spacewalks. They will do more work setting up the girder's trolley, the first space railway.
Then on Tuesday, astronauts Ross and Morin go out again to complete the work. That will be the ninth spacewalk for Mr. Ross, a U.S. space agency record. In addition, this is his seventh mission in orbit, a world record.