STS-125, or HST-SM4 (Hubble Space Telescope Servicing Mission 4), was the fifth and final space shuttle mission to the Hubble Space Telescope. The mission lasted a total of just under 13 days.

Space Shuttle Atlantis carried two new instruments to the Hubble Space Telescope, the Cosmic Origins Spectrograph and the Wide Field Camera 3. The mission also replaced a Fine Guidance Sensor, six gyroscopes, and two battery unit modules to allow the telescope to continue to function at least through 2014, a date which was later updated to "possibly until 2018" - a prediction which has fortunately been realized.

The STS-125 crew also installed new thermal blanket insulating panels to provide improved thermal protection to Hubble, and a soft-capture mechanism that would aid in the safe de-orbiting of the telescope by an unmanned spacecraft at the end of its operational lifespan. Additionally, the mission carried an IMAX camera with which the crew documented the progress of the mission for the Hubble IMAX movie.

The crew of STS-125 included three astronauts who had previous experience servicing Hubble. Scott "Scooter" Altman visited Hubble in 2002 as commander of STS-109, the fourth Hubble servicing mission. John Grunsfeld, an astronomer, had serviced Hubble twice, performing a total of five spacewalks on STS-103 in 1999 and STS-109. Michael Massimino had served with both Altman and Grunsfeld on STS-109, and had performed two spacewalks to service the telescope.

After landing, NASA managers and engineers declared the mission a complete success. The completion of all the major objectives, as well as some that were not considered vital, upgraded the Hubble telescope to its most technologically advanced state since its launch nineteen years prior and made it more powerful than ever.

STS-125 was the only visit to the Hubble Space Telescope for Atlantis; the telescope had been previously serviced twice by Discovery and once each by Columbia and Endeavor. The mission was the 30th flight of Space Shuttle Atlantis and also the first by Atlantis in over 14 years not to visit a space station, the last one being STS-66.

Note: the description of this video originally contained an incorrect figure for the runway length.