STS-109

The purpose of STS-109 was to service the Hubble Space Telescope (HST). It was Columbia's first flight following an extensive two and a half year modification period (its most recent mission being STS-93). During the mission the crew installed a new science instrument, the Advanced Camera for Surveys (ACS), new rigid solar arrays (SA3), a new Power Control Unit (PCU) and an experimental cryocooler for the Near Infrared Camera and Multi-Object Spectrometer (NICMOS). Columbia also reboosted HST to a higher orbit.