Space Shuttle Atlantis is launched on the final mission to service the Hubble Space Telescope.

Space Shuttle Atlantis is a retired Space Shuttle orbiter vehicle which belongs to NASA, the spaceflight and space exploration agency of the United States. Atlantis was manufactured by the Rockwell International company in Southern California and was delivered to the Kennedy Space Center in Eastern Florida in April 1985. Atlantis is the fourth operational and the second-to-last Space Shuttle built. Its maiden flight was STS-51-J made from October 3 to 7, 1985.

STS-125, or HST-SM4, was the fifth and final Space Shuttle mission to the Hubble Space Telescope (HST). The launch of the Space Shuttle Atlantis occurred on May 11, 2009, at 2:01 pm EDT. Landing occurred on May 24 at 11:39 am EDT, with the mission lasting a total of just under 13 days.

The Hubble Space Telescope is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versatile, renowned as a vital research tool and as a public relations boon for astronomy. The Hubble Space Telescope is named after astronomer Edwin Hubble and is one of NASA's Great Observatories. The Space Telescope Science Institute (STScI) selects Hubble's targets and processes the resulting data, while the Goddard Space Flight Center (GSFC) controls the spacecraft.

May 11 is the 131st day of the year in the Gregorian calendar; 234 days remain until the end of the year.