Advertisement

Indian American astronaut Sunita Williams and her two colleagues at her home in space faced a day-long blackout, but US space agency NASA said it posed no danger to the crew or their complex.

An unexpected circuit breaker trip early on Sunday caused a power failure on the International Space Station. All systems were back up by Monday morning with no impact to operations on board.

However, the safety of the expedition crew and the station complex was never an issue, the National Aeronautics and Space Administration said.

The first indications of a problem came with the loss of communications between the station and mission control just after 10.30 pm IST on Sunday. This happened when an electrical switching unit experienced a brief malfunction that caused a breaker to trip, protecting the electrical system of the station much like a circuit breaker protects electrical systems and equipment in a home.

Commander Mike Lopez-Alegria and Flight Engineers Williams and Mikhail Tyurin - awake since mid-evening Saturday - took immediate action and followed procedures on board to recover the communications link with mission control, Houston, at about 12.35 am IST on Monday.

Restoration of systems continued through early on Monday. The systems affected included one of two redundant communications systems and one of four gyroscopes used to maintain the station's position, or orientation.

Also affected were several scientific facilities, including the freezer containing experiment samples, the Ku Band high data rate and television system, several smoke detectors and various heaters that maintain a thermal balance of external components, including the robotic arm and its mobile base.

None of these systems was permanently affected, and the equipment's temporary shut down did not impact research work or upcoming planned activities, NASA said.

In addition to the recovery from the power failure, the crew also began early preparations for the next spacewalk by Tyurin and Lopez-Alegria on February 22.

During that spacewalk, the two will free a stuck antenna on the ISS Progress 23 supply craft and survey navigation systems for the European Automated Transfer Vehicle's docking capability to the Zvezda Service Module.

They will try to secure or remove the antenna to preclude any interference during undocking in April. The spacewalk will be the 10th for Lopez-Alegria, which will be a US astronaut record. The two will wear Russian Orlan suits for the excursion out of the Pirs docking compartment.