NASA carried out five Space Shuttle servicing missions for Hubble. These missions repaired failures, corrected the telescope’s optical problem, replaced aging hardware, and installed newer scientific instruments that extended Hubble’s usefulness for decades.
The missions were Servicing Mission 1 in 1993, Servicing Mission 2 in 1997, Servicing Mission 3A in 1999, Servicing Mission 3B in 2002, and Servicing Mission 4 in 2009. They involved astronaut spacewalks, robotic-arm operations, equipment replacement, and upgrades to Hubble’s instruments and power systems.
The first servicing mission was especially important because Hubble’s primary mirror had been manufactured with a flawed shape. Astronauts installed corrective hardware that restored the telescope’s intended sharp vision. The fifth mission was nearly canceled after the 2003 Columbia disaster, but NASA later approved it after additional safety planning. The number five refers to dedicated servicing missions, not every shuttle flight that carried Hubble-related equipment or observations.