This restraint harness is attached to the training unit that helped astronauts prepare to remove and replace the Hubble Space Telescope's Power Control Unit (PCU) in orbit. Their task entailed disconnecting 36 cables to remove the old unit and then reconnecting them to the new unit. During this task, the telescope was completely turned off, and it was necessary to restore power as quickly as possible. The restraint harness kept the loose cables arranged neatly and in order so the crew could work efficiently. The PCU replacement occurred on Space Shuttle mission STS-109 in 2002.
NASA transferred this training equipment to the Museum after the fifth and final Hubble Space Telescope servicing mission was completed in 2009.