The International Space Station (ISS) lost some weight and gained a new camera eye Monday during a spacewalk conducted by its two-astronaut crew.
ISS Expedition 12 commander Bill McArthur and flight engineer Valery Tokarev moved swiftly through the five-hour and 22-minute spacewalk - the first of their six-month mission - attaching a new television camera and retrieving broken equipment from the space station exterior.
"It's a good day in space," said McArthur, who racked up his third career spacewalk with the extravehicular activity (EVA). "I like it."
McArthur even created a new small satellite of sorts when he tossed a defunct floating potential probe (FPP) - which measured static electricity buildup around the station's solar arrays - into space.
"How's that for a Hail Mary pass?" McArthur asked after hurling the 60-pound (27-kilogram) probe up and aft from the top of the ISS.
McArthur and Tokarev - in his EVA debut - wore U.S.-built spacesuits and left from the station's Quest airlock during their spacewalk, the first time an ISS crew has done so since April 2003 due to equipment cooling and contamination problems.
A false start
McArthur and Tokarev breezed through their spacewalk despite a false start early on that pushed them one hour behind schedule.
The two astronauts had already depressurized the airlock's outer compartment and checked their spacesuits for leaks when a closed vent valve forced them to repressurize the airlock, renter the Quest's inner compartment and open the valve. The valve is required to be open to empty the airlock of remaining atmosphere, and aid in an emergency repressurization if needed, NASA officials said.
By 10:32 a.m. EST (1532 GMT), McArthur and Tokarev officially began the EVA and were promptly captivated by the view of Earth.
"That is beautiful, oh man," McArthur said of the Earth as he and Tokarev made their way toward their first worksite.
"Oh, look at the planet," Tokarev added.
McArthur and Tokarev left the space station empty during their spacewalk, marking the ninth time the orbital lab has been devoid of human crew during an EVA. Normally, a third crewmember watches over spacewalks from within the ISS, but station crews have been limited to two astronauts since the 2003 Columbia accident. All eight of the previous two-person spacewalks were conducted in Russian-built Orlan spacesuits, while ISS flight controllers watched over many of the station's systems.
Despite their late start, McArthur and Tokarev managed to work quickly and make up the time they lost.
The astronauts swiftly installed a new camera the end of the station's portside truss - which will provide vital views during future construction spacewalks - then hauled themselves, hand-over-hand, to the station's starboard truss. There they removed a faulty electronics box, dubbed a rotary joint motor controller (RJMC), for one of the space station's radiators.
The box is due to return to Earth aboard the space shuttle Discovery's STS-121 flight so engineers can determine why it failed and improve later versions.
The Expedition 12 crew also scaled to the space station's highest point - its solar array-laden P6 truss - where McArthur removed the floating potential probe and cast it into space.
Spacewalking astronauts during the recent STS-114 shuttle mission to the ISS found that parts of the probe had backed out, prompting concerns the device might separate entirely and become a debris hazard. The probe was already slated for removal, since ISS engineers doubted it could withstand the strain during a future construction project to move the entire P6 truss.
"It does look kind of gnarly," McArthur said after examining the probe, which should burn up in the Earth's atmosphere after about 100 days.
McArthur and Tokarev also spotted a loose metal washer floating in near formation with the ISS, presumably shaken loose during their 50-foot (15-meter) ascent up the P6 truss.
"It does not appear to be a threat," McArthur said.
The two spacewalkers concluded their day by replacing a failed circuit breaker used to power a redundant heater aboard the space station's railcar-like Mobile Transporter. The circuit breaker and electronics box retrieval were bonus tasks added to the spacewalk only if time allowed. The camera installation and RJMC tasks were also pick-up procedures left incomplete during the final STS-114 spacewalk.
"It is possible to do more work," Tokarev said, referring to the bonus tasks.
By the numbers
With the conclusion of today's spacewalk, McArthur has accrued 18 hours and 38 minutes of EVA work, while Tokarev has five hours and 22 minutes under his belt.
"Valery's good," McArthur said during the spacewalk as Tokarev swapped out his tethers. "It's like he's done this forever."
The two astronauts are scheduled to again step outside the space station's Russian-built Pirs docking compartment - this time clad in Russian Orlan spacesuits - on Dec. 7. However, McArthur and Tokarev will also leave the ISS on Nov. 18 aboard their Russian Soyuz TMA-7 spacecraft, during a relocation flight from the Pirs compartment. The astronauts are slated to move the vehicle to a docking berth at the Zarya control module to free up Pirs for the upcoming spacewalk.
The successful spacewalk marked the 63rd EVA dedicated to the maintenance or construction of the ISS, the 35th to be staged from the station itself, and the 18th to begin at the Quest airlock. Astronauts have spent a total of 378 hours and 40 minutes working out the space station's exterior, which McArthur said was a sight to behold.
"You know, from the outside, this is a darn impressive spacecraft," McArthur said during the spacewalk.
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