This story was updated at 12:25 a.m. EDT.
Two Russian cosmonauts have floated outside the International Space Station to begin a spacewalk aimed at changing out a broken camera and wiring up a new room so spaceships can park there on autopilot.
The spaceflyers ? flight engineers Fyodor Yurchikhin and Mikhail Kornienko of the station's Expedition 24 mission ? plan to be outside for about six hours. Their spacewalk began about half an hour late, officially starting on Tuesday at 12:11 a.m. EDT (0411 GMT).
While the Russian-led spacewalk is taking place, the cosmonauts' four crewmates ? three Americans and one Russian ? will work on science and maintenance activities inside the International Space Station.
Yurchikhin, a spaceflight veteran, will be making his fourth spacewalk, while Kornienko will be spacewalking for the first time.
The first task for the two spacewalkers, after exiting the station's Pirs docking compartment airlock, will be to remove a broken camera.
"The crew is going to replace a degraded video camera at the aft end of the Zvezda module and replace it with a new one that was recently delivered to the station," NASA's Expedition 24 spacewalk flight director Chris Edelen said during a briefing last week. "The video camera currently on orbit has numerous bad pixels resulting in degraded picture quality."
The camera is used to track incoming European Automated Transfer Vehicles (ATVs) ? unmanned cargo ships that ferry supplies to the station ? as they approach and dock at the Zvezda module.
Yurchikhin and Kornienko will use a ratchet to remove the old camera, then install its replacement. At the end of the spacewalk the cosmonauts will jettison the broken hardware into space, where it should slowly loose altitude and, after about 120 days, re-enter Earth's atmosphere and burn up.
The decision to add a new piece of space junk to orbit isn't made lightly, but in this case mission managers decided it was necessary.
"In this case with the ATV camera, it does present a hazard to the crew due to the insulation surrounding the camera," Edelen said. "The concern is that that insulation could flake loose inside the cabin [if brought back inside], resulting in fibers that the crew could breathe in. So once that determination was made then it was clear that jettisoning was the right thing to do."
After the camera work, Yurchikhin and Kornienko will transfer over to the station's new Rassvet research module. The $200 million room was delivered to the station in May by the visiting space shuttle Atlantis.
The spacewalkers will connect a series of cables to link the module with Russian Command and Data Handling computers. Another set of cords will connect Rassvet with the station's Kurs automated docking system to allow incoming vehicles to automatically connect with Rassvet's docking port.
The job will enable Rassvet to serve as a fourth fully-functioning docking port on the International Space Station. The new port will be used for arriving Russian vehicles.
The next spacewalk planned for the station crew is an American excursion scheduled for Aug. 5. Expedition 24 flight Engineers Tracy Caldwell Dyson and Doug Wheelock will conduct that trip.
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