This door positioner is part of the training unit that helped astronauts prepare to remove and replace the Hubble Space Telescope's Power Control Unit (PCU) in orbit. This device propped open the door of the electronics bay where the PCU was located while the astronauts worked from a mobile work station attached to the robotic arm. This task 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.