Space Shuttle Atlantis’s STS-125 mission completed the final repair and upgrade of the Hubble Space Telescope. There were five repair or upgrade missions to the Hubble Space Telescope: Servicing Mission 1 (SM1): December 2–13, 1993, astronauts installed new instruments, including equipment adapted to correct a defect in Hubble’s main mirror; Servicing Mission 2 (SM2): February 11–21, 1997, installation of new instruments extended Hubble’s near-infrared wavelength range for imaging and spectroscopy, allowing scientists to probe the farthest reaches of the universe; replacement of failed or degraded spacecraft components increased efficiency and performance; Servicing Mission 3A (SM3A): December 19–27, 1999: What was originally intended as a preventative maintenance mission became more urgent on November 13, 1999, when the fourth of Hubble’s six gyroscopes failed. Hubble requires at least three of its stabilizing gyroscopes to conduct science. Hubble entered a hibernation state called Safe Mode while the telescope awaited repairs. NASA split the third servicing mission into two parts to get Hubble back up and running more quickly. Servicing Mission 3B (SM3B): March 1–12, 2002: During SM3B, astronauts replaced Hubble’s solar panels and installed the Advanced Camera for Surveys, which replaced Hubble’s Faint Object Camera, the telescope’s last original instrument. Servicing Mission 4 (SM4): May 11–24, 2009: The Hubble Space Telescope was reborn with Servicing Mission 4 (SM4). The orbiting observatory’s fifth and final servicing mission flew aboard the space shuttle Atlantis (STS-125) from May 11–24, 2009.
