Replacement of the Power Control Unit

The Power Control Unit (PCU) controls and distributes electricity from the solar arrays and batteries to other parts of the telescope. The original PCU has been on the job for 11 years and to replace it Hubble was completely powered down for the first time since its launch in 1990. Hubble's new Power Control Unit allows astronomers to take full advantage of the extra power generated by the new solar arrays.

Astronauts preparing for the challenging tasks to be performed during Servicing Mission 3B.