CAPE CANAVERAL, Fla. -- Two U.S. spacewalkers ambled through a series of odd jobs outside the International Space Station Wednesday, taking time to mark the 40th anniversary of John Glenn's groundbreaking flight into space.
With the station circling 240 miles (384 kilometers) above Earth, NASA astronauts Carl Walz and Daniel Bursch prepped the exterior of the station for the upcoming delivery of a metal girder that will serve as the central segment of a 356-foot (108-meter) outpost truss.
And in doing so, the astronauts paid tribute to Glenn, the former Mercury astronaut and U.S. senator who became the first American to orbit Earth on Feb. 20, 1962.
"We are certainly indebted to John Glenn," Walz told fellow astronauts and engineers gathered in NASA's Mission Control Center at Johnson Space Center in Houston. "We saw him in growing up as a tremendous role model -- a hero."
"It was a great mission, by a great man," astronaut Joe Tanner replied from Mission Control.
"Absolutely," said Walz. "And we're proud to be following in his footsteps."
Glenn, now 80, set sail 40 years ago Wednesday in a cramped Mercury capsule that was mounted atop an Atlas rocket -- a vehicle well known for explosive failures.
At the time, the U.S. and the former Soviet Union were locked in a Cold War battle for technological and ideological supremacy, one that spawned a "Space Race" the Americans were clearly losing.The tide, however, turned quickly after Glenn lapped the planet three times during his historic flight. Simply stated, the 4-hour, 55-minute mission propelled America's fledgling space program on to the Apollo lunar landings.
"From that moment on, there was no obstacle too great, no task too difficult," said NASA Administrator Sean O'Keefe. "America was going to pioneer the future, and NASA was going to lead that quest. We owe Senator Glenn and those early space explorers our deepest and most sincere appreciation."
Walz and Bursch made a little history of their own Wednesday, staging the first spacewalk out of the station's new U.S. Quest airlock without a visiting shuttle present.
Crawling hand-over-hand across the outer hull of the outpost, the two spacewalkers performed some advance work for a visiting shuttle crew that aims to deliver and install the station's central truss segment in early April.
The girder-like truss will serve as the hub of the station's metallic backbone, which in turn will provide a mounting point for Japanese and European science laboratories to be launched to the orbital complex around 2005.
Set for launch April 4, the truss will be attached to the U.S. Destiny lab and then connected to outpost power supplies during the first of four spacewalks to be staged from Quest by the visiting shuttle crew.
To speed up the time-critical work -- which must be completed in about eight hours to avoid thermal damage to sensitive truss electronics and fluid lines -- Walz and Bursch:
- Tested airlock systems as well as a new medical protocol aimed at helping spacewalkers avoid decompression sickness during suited sorties into the deadly vacuum of space.
- Gathered up tools stowed outside the station that the shuttle crew will need to carry out the installation job. Packed within a bag the size and shape of a square backpack, the tools were moved inside the station by the two spacewalkers.
- Tested a pair of spare cables that would be used to plug the truss into station electricity if prime power lines for some reason fail to work properly. The cables were hooked up so ground controllers could make sure station electricity flowed through them properly. The engineers found that current coursing through associated power converters was not quite what they expected. The electrical lines, consequently, were left in place so that further analysis can be conducted prior to the truss installation work.
- Packed away four thermal blankets that had been tabbed for removal prior to the arrival of the shuttle crew. The new truss will shadow areas where the shrouds were located. Engineers, consequently, asked the astronauts to remove the insulation blankets so that station components in those areas will remain at the proper temperatures after the truss segment is installed.
During their five-hour, 47-minute excursion, Walz and Bursch also snapped pictures of small micrometeorite "hits" on station radiations and windows, and they photographed an external experiment package designed to expose paints, coatings and other materials to the harsh space environment.In addition, Walz and Bursch tightened up latches that secure four gaseous oxygen and nitrogen tanks to the outer hull of the $164 million Quest airlock. The latches were found to be looser than expected after the gas tanks -- which are the size and shape of doghouses -- were installed when the airlock was delivered to the station last July.
Tanner, a veteran spacewalker himself, judged their work a "perfect 10."
Russian station commander Yuri Onufrienko watched the spacewalk from inside the outpost and the wives of Walz and Bursch kept tabs on the work at Mission Control.
"Gentleman, for both of you, your better halves are watching, and having a good time doing it," Tanner told the astronauts at one point.
"Hope I haven't scared them too much," Bursch joked.
The two astronauts, meanwhile, also took a moment to note how much human space exploration has changed since the day John Glenn first flew into orbit.
"You know, the world certainly has changed since 40 years ago," Bursch said.
"I would have never believed even 10 or 15 years ago that I would be flying on a space station, be outside, and we'd have a Russian commander inside taking care of things," he added. "So I really think that the next big step is worldwide cooperation, and I think that's the only way that we're going to continue with human exploration."
Bursch, Walz and Onufrienko are in the midst of a five-and-a-half-month tour of duty aboard the international station, which is being erected in orbit by space agencies from the U.S., Russia, Europe, Canada, Japan and Brazil.
Launched into space Dec. 5, the fourth full-time crew of the outpost remains scheduled to return to Earth aboard shuttle Endeavour in mid-May.
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