Spacewalkers christen station's Quest airlock
BY WILLIAM HARWOOD
Posted: July 20, 2001
At a post-spacewalk briefing, flight director Paul Hill reflected that one year ago, the space station was composed of the Russian FGB propulsion module and NASA's Unity connecting node. "It was 76 feet long and weighed 35 tons," he said. "We'll leave an ISS that's as long as a 17-story building is tall and weighs 131 tons.
"Measured in total tonnage, we're about halfway finished building ISS and we're now ready to build out the truss," he said. "With its now fully operational (robot) arm and airlock, ISS will now be an equal partner with shuttle in continuing that construction."
Today's spacewalk, the third and final outing planned during the shuttle Atlantis' mission, began at 12:35 a.m. and ended at 4:37 a.m. for a duration of four hours and two minutes. It was the 107th by U.S. astronauts and the 24th devoted to space station assembly. Twenty-three U.S. astronauts, one Canadian and two Russian cosmonauts have now logged 155 hours and 39 minutes in space station assembly spacewalks, or EVAs.
If all goes well, Atlantis will undock from the station around 12:54 a.m. Sunday and land back at the Kennedy Space Center around 12:34 a.m. Tuesday.
The Quest airlock module was attached to the station last Sunday during the first spacewalk by Gernhardt and Reilly. Station astronaut Susan Helms, using the lab's Canadarm2 space crane, moved the module from Atlantis' cargo bay to its attachment point on the Unity module's starboard hatch. Gernhardt and Reilly then made critical external electrical connections.
After two days of internal outfitting, Gernhardt and Reilly staged a second spacewalk overnight Tuesday to attach three high-pressure gas tanks to the airlock's hull, two containing oxygen and one loaded with nitrogen.
During today's spacewalk, a final nitrogen tank was installed. The astronauts also stowed a no-longer needed lab module power cable and floated to the top of the P6 solar array to inspect a suspect bearing assembly. They did not see any obvious problems.
While at the top of the P6 truss, they inspected a device called the Floating Potential Probe, designed to measure the station's electrical charge. The device has worked erratically since its installation and Gernhardt and Reilly reported today its status lights were not illuminated.
Before re-entering the airlock module, Gernhardt took congratulate flight controllers and engineers on the successful operation of the new compartment.
"Before we conclude this EVA, JIm and I would both like to say thanks to the thousands of people who worked so hard to make this mission come together and be the success that it is," Gernhardt said. "I'd like to tell those people they have built a very excellent airlock, everything worked great. The spaces are much bigger than the shuttle's, it's going to add a great capability for crews to do space station maintenance."
"Those were some great words," astronaut Daniel Burbank replied from Houston. "And from all of us down here, we'd like to thank you guys. You did a great job on the first space station-based EVA, you inaugurated the airlock in great fashion. It was just a joy to watch from down here."
The only anomaly occurred during the airlock's initial depressurization, when it took about 40 minutes to go from five pounds per square inch to vacuum. Engineers expected it to take six to seven minutes.
Station flight director Mark Kirasich said an external inspection of the airlock's main vent revealed no obvious signs of blockage "so we're scratching our head and we have a little bit more work to do on figuring out why that happened." Hill said engineers may opt to have a future crew replace the valve.
With attachment of the station's robot arm in April and the airlock during Atlantis' mission, what NASA calls Phase Two of space station assembly is now complete. "Now that we have those." Hill said, "the gate is wide open for us to keep right on building,"
"You know, some of us felt like we weren't ever going to get here, that it just seemed like something that we were always going to keep working towards that was in the future," he told reporters early today. "And now we're going away and station's this huge thing. It almost boggles the mind when you see it in the video or the crew sees it out the window how big this thing's gotten.
"And to think that in a couple of years, after we've built out to the alpha joints and added the rest of the solar modules, when this thing flies over - during the daylight - you'll be able to look up for the first time and see a man-made object flying through the sky with the naked eye. That's pretty significant. We're halfway there and this opens the door up for that becoming reality."
The Canadarm2 space crane and the new airlock will not be used again until March when a shuttle crew delivers the first segment of a huge truss assembly that ultimately will carry the station's solar arrays.
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