CAPE CANAVERAL, Fla. -- Two International Space Station residents ventured outside their orbital home Friday, mounting thruster exhaust shields, an amateur radio antenna, a science experiment and other gear on the hull of their crew quarters.
Outpost commander Yuri Onufrienko and flight engineer Daniel Bursch spent the better part of the day crawling hand-over-hand across the station's Russian-built "Zvezda," or "Star" module, methodically carrying out their work.
The veteran cosmonaut, however, did pause long enough to admire the view, at one point noting the shimmering curtain of colorful light extending up from the limb of the Earth as the station passed from the dark to the sunlit side of the planet.
"The sunrise is beautiful," Onufrienko said.
And Bursch, who was making his first foray into open space, also expressed a bit of amazement as the outpost flew high over the bright tan desert sands in eastern Africa.
"Wow! What a picture," he said. "Where are we right now?"
"Saudia Arabia," said fellow flight engineer Carl Walz, who was keeping track of his crewmates from inside the station.
Both spacewalkers, meanwhile, sounded tired but satisfied as they wrapped up their five-hour, 59-minute sortie. Letting out a breathy exhale, Onufrienko said, "Sheeeewwww! That was a good day."
Bursch's reply: "Excellent."
Coming 51 days after the trio launched into orbit, the spacewalk got off to an early start as Onufrienko and Busch floated out of the station's Russian airlock at 10:19 a.m. EST (1519 GMT).
Whizzing around Earth at 25 times the speed of sound, the pair traversed a small ladder and then began to make their way to the rear end of the station's crew quarters with two large bundles of tools, hardware and equipment.
Among the paraphernalia: six exhaust shields that Onufrienko and Bursch placed over steering thrusters that help keep the station properly positioned as it cruises through orbit.
Power by toxic rocket fuel, the thrusters spew out exhaust when fired, leaving behind hazardous residues that could foul sensitive external science experiments, stain windows and tarnish the hull of the spacecraft.
Another concern is that exhaust residue could stick to the spacesuits of spacewalking assembly and maintenance workers, only to be inadvertently brought back into the station. The solid substance, in that event, could turn into a gas, potentially exposing crews to noxious fumes.
Working side-by-side at the aft end of the crew module, Onufrienko and Bursch installed the custom-made plume deflectors, which are designed to either contain exhaust residue or direct the soot into open space.
A veteran of seven previous spacewalks, Onufrienko cleaned up the thrusters with towels and then tossed the towels overboard. He and Bursch also wiped down their spacesuit gloves and boots to make certain they wouldn't track any residue back into the station.
The duo handled a related job, too: Replacing a Russian contamination monitor that had been collecting thruster exhaust residue since November.
About the size of a laptop computer, the old "witness plate" will be ferried back to Earth by a visiting Soyuz crew in late April so that Russian specialists can examine it. The new monitor was put in place to help gauge how well the exhaust shields work.
While his crewmates toiled outside, Walz was busy positioning the station's $600 million Canadian robot arm so that a camera on its tip could be used to beam down live video of the spacewalk as it unfolded.
The video showed the two spacewalkers, clad in Russian spacesuits, carting their two equipment bundles around outside the Zvezda module, carefully avoiding solar wings that jut out from the side of the 21-ton craft.
In addition to the plume deflectors, the packing crates also contained:
- An external science experiment package that was mounted to the exterior of the crew module, where it will gather evidence of natural low-energy heavy nuclei of solar or galactic origin.
- Small guides that will be used by future spacewalkers to route retractable U.S. safety tethers, which can be reeled out as far as 55 feet (16.7 meters). The guides are designed to keep the braided steel tethers from getting tangled up in equipment attached to the Zvezda module.
- The second of four antennas that will enable astronauts and cosmonauts to chat with family, friends and amateur radio enthusiasts from inside the station's crew quarters rather than a Russian space tug attached to it.
Onufrienko and Walz set up the first of those antennas during a Jan. 14 spacewalk. The last two will be mounted later this year.
Bursch and Walz are scheduled to make one more spacewalk during the crew's planned five-and-a-half-month tour of duty on the station.
Tentatively set for Feb. 20, that excursion will be staged out of the station's $164 million U.S. Quest airlock and will serve as a dress rehearsal of sorts for spacewalks to be carried out from that same orbital portal by a visiting shuttle crew in April.
Launched Dec. 5, Onufrienko, Bursch and Walz make up the fourth full-time crew of the station. The three remain scheduled to return to Earth aboard shuttle Endeavour in mid-May.
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