Working in orbital darkness to minimize the risk of electric shock, astronauts Peggy Whitson and Dan Tani removed a faulty solar array positioning motor today so it can be replaced by a spare unit. The new motor is needed to boost the station's electrical generation enough to support the planned launches of European and Japanese research modules in February, March and April.

The first of five cables plugged into the bearing motor roll ring module, or BMRRM - pronounced "broom" - was disconnected a few minutes before 7 a.m. just after the station sailed into Earth's shadow. The solar array connected to the BMRRM produces some 160 volts of electricity when in full sunlight at up to 210 amps. Working in shadow, the array's output no longer poses a shock hazard and the cable disconnections today went smoothly.

"No discoloration, no arcing," Tani observed as Whitson carefully pulled the faulty motor out of its housing.

Along with passing power from the array to the station, the BMRRM also provides the structural support for the solar array it turns. Whitson and Tani paid special attention to making sure two clamps were securely latched to hold the array in place during the swap out.

Earlier in the spacewalk, flight controllers at the Johnson Space Center in Houston ran into a communications problem that briefly prevented them from talking directly to Whitson and Tani.

Relaying instructions through station flight engineer Yuri Malenchenko, flight controllers told the astronauts to continue preparations for replacing the BMRRM, but said the actual swap-out would not proceed unless normal communications were restored. A few minutes later, after switching to a backup communications channel, controllers re-established normal two-way voice traffic with Whitson and Tani.