Two Russian spacewalkers ran into a problem shortly after beginning their planned five-hour 39-minute spacewalk Thursday morning outside the International Space Station.
were initially unable to attach a platform carrying a camera aiming system to the hull of the Zvezda command module, one of the primary goals of today's excursion.
The mounting plate needed to secure the work platform to Zvezda apparently was bolted on in the wrong orientation.
"They reported that when they got the base plate, the attach point, into the bracket where it would be secure, it was their impression that the work station was not oriented properly," NASA commentator Pat Ryan reported from NASA's mission control center.
However, after first ordering Yurchikhin and Misurkin to stop and haul the work platform and camera aiming system back to the Pirs airlock, Russian flight controllers later told them to retrieve the hardware from the airlock and to press ahead with its installation.
Ryan said Russian engineers believe they can compensate for the misalignment by re-orienting the motorized camera aiming system, known as the bi-axial pointing platform, on command from the ground.
"It is believed that it is misaligned, but it is only out of alignment in the yaw axis," Ryan explained. "That ... can be corrected mechanically after it is installed by maneuvering the bi-axial pointing platform. So the decision was made and the Russian spacewalkers have installed the EVA workstation ... on the starboard side of Zvezda."
The experiment in question is a commercial venture by a Canadian company -- Urthecast (pronounced Earth-cast) -- that plans to launch a pair of cameras to the station later this year that will provide near real-time views of Earth to cell phones and other devices. The cameras were to be attached to the platform during a December spacewalk.
Yurchikhin and Misurkin, meanwhile, pressed on with an inspection of the covers protecting six low-gain antennas, three at each end of Zvezda, that are used by the navigation system of approaching European Space Agency ATV cargo ships.
During a spacewalk last week, one cover somehow came loose and floated away and Russian engineers asked Yurchikhin and Misurkin to check the status of all the antennas.
The remaining covers were seen to be in place, but several appeared to be loosely attached and at least one of them was missing two of four screws needed to hold the cover in place. The two cosmonauts worked together at the aft end of Zvezda to tighten up the covers.
Both cosmonauts are wearing Russian spacesuits with blue markings. Yurchikhin wore a suit with red stripes during last Friday's spacewalk, but an apparent problem with that suit's primary coolant pump prompted mission managers to put that outfit on standby, pending additional troubleshooting, and to use a different suit today.
For identification, Yurchikhin, call sign EV-1, is using NASA helmet cam No. 20 while Misurkin, EV-2, uses camera No. 17.
This is the 173rd spacewalk devoted to station assembly and maintenance since construction began in 1998, the seventh so far this year, the eighth for Yurchikhin and the third for Misurkin. Assuming a full-duration EVA, Yurchikhin will move from 12th to 5th on the list of most experienced spacewalkers.
Going into today's excursion, 112 astronauts and cosmonauts representing nine nations had logged 1,082 hours and 51 minutes of station EVA time, or 45.1 days.