Teams Assessing Affected Systems

NASA says mission control teams are assessing systems affected by a power loss aboard the ISS over the weekend.

Early Sunday morning one of the power channels on the P4 solar array electrical system dropped out when a DC switching unit failed. The switch controls power from the solar array to batteries and other components on the station.

The lost power channel briefly cut ISS communication with mission control, and shut down control moment gyroscope #2, one of the station's three remaining attitude control gyros. Other ancillary equipment such as science facilities were also affected.

NASA says the crew and station were never in danger. The crew and controllers never lost orientation control of the station which continued operating on its #1 and #4 gyros -- #3 gyro was previously shut down awaiting repair.

Flight controller were able to restore power to nearly all affected systems by Monday morning and are currently investigating what the agency believes to be an isolated incident.

The crew of expedition 14 -- commander Michael Lopez-Alegria and flight engineers Sunita Williams and Mikhail Tyurin -- are preparing for the next spacewalk scheduled for February 22. Lopez-Alegria and Williams completed their third of three recent spacewalks last Thursday (Williams photographed herself in the picture below) prepping the station for further exterior work during missions STS-118 and STS-120 later this year.

During the next spacewalk -- for which the crew will use Russian procedures -- Lopez-Alegria and Tyurin will service an antenna on the Progress 23 cargo ship docked at the Zvezda service module.

After that spacewalk, the crew of expedition 14 will have completed five -- more than any other ISS crew.

FMI: www.nasa.gov