Trainer, Power Control Unit, Hubble Space Telescope

Astronauts used this training unit to practice removing and replacing the Hubble Space Telescope's Power Control Unit (PCU) in orbit. The PCU is the telescope's power relay station; it distributes energy from the solar arrays to batteries, other electrical components, and scientific instruments and regulates the power for all operations.

The original PCU was replaced on Space Shuttle mission STS-109 in 2002. During replacement, the telescope was completely turned off for the first time. The work took place during the 6-hour 48-minute-long third spacewalk of this servicing mission. Astronaut Rick Linnehan methodically disconnected most of the 36 cables in a precisely timed order. Then crewmate John Grunsfeld finished removing the old unit and installed the new one, reconnecting the cables in reverse sequence. Use of the trainer prepared the crew to do this crucial task accurately and efficiently to restore power as quickly as possible.

NASA transferred this trainer to the Museum after the fifth and final Hubble Space Telescope servicing mission was completed in 2009.