STS-61 was NASA's first Hubble Space Telescope servicing mission, and the fifth flight of the Space Shuttle Endeavour. The mission launched on December 2, 1993, from Kennedy Space Center (KSC) in Florida. The mission restored the spaceborne observatory's vision (marred by spherical aberration in its mirror) with the installation of a new main camera and a corrective optics package (COSTAR). This correction occurred more than three and a half years after the Hubble was launched aboard STS-31 in April 1990. The flight also brought instrument upgrades and new solar arrays to the telescope. With its very heavy workload, the STS-61 mission was one of the most complex in the Shuttle's history.
STS-61 lasted almost 11 days, and crew members made five spacewalks (extravehicular activities (EVAs)), an all-time record; even the re-positioning of Intelsat VI on STS-49 in May 1992 required only four. The flight plan allowed for two additional EVAs, which could have raised the total number to seven; the final two contingency EVAs were not made. In order to complete the mission without too much fatigue, the five EVAs were shared between two pairs of different astronauts alternating their shifts. During the flight, mission specialist Jeffrey A. Hoffman also spun a dreidel for the holiday of Hanukkah to a live audience watching via satellite.