STS-109

The fourth servicing call on the Hubble Space Telescope, flown by Columbia. Over five spacewalks the crew installed the Advanced Camera for Surveys, which sharply increased Hubble's imaging power, replaced the telescope's flexible solar arrays with sturdier rigid ones, and fitted a cryocooler to revive its infrared instrument. It was Columbia's next-to-last flight before the orbiter was lost on STS-107.