STS-117 was a Space Shuttle mission flown by Space Shuttle Atlantis, launched from pad 39A of the Kennedy Space Center on June 8, 2007. Damage from a hail storm on February 26, 2007 had previously caused the launch to be postponed from an originally-planned launch date of March 15, 2007.

The mission, also referred to as ISS-13A by the ISS program, delivered to the International Space Station (ISS) the second starboard truss segment (the S3/S4 Truss) and its associated energy systems, including a set of solar arrays. During the course of the mission the crew installed the new truss segment, retracted one set of solar arrays, and unfolded the new set on the starboard side of the station. STS-117 also brought Expedition 15 crewmember Clayton Anderson to the station, and returned with ISS crewmember Sunita Williams.

This mission was the 118th Space Shuttle flight, the 28th flight for Atlantis and the 21st U.S. flight to the ISS. The launch of STS-117 marks the 250th orbital human spaceflight.The completion of the mission leaves thirteen flights remaining in the Space Shuttle program until its end in 2010, excluding two as-yet-unconfirmed Contingency Logistic Flights.

On June 11, NASA mission managers announced a two-day extension of the mission, adding a fourth extra-vehicular activity (EVA). These two days were inserted into the mission timeline after flight day 8. This possibility had been discussed prior to launch. Because of launch day and thus rendezvous day uncertainty the decision to extend was deferred until after launch. The repair of the gap in the Orbital Maneuvering System (OMS) thermal blanket (heat shielding) was conducted during EVA 3.

Because of the cancellation of landing opportunities on June 21st because of weather, STS-117 is the longest mission for Atlantis, landing at Edwards Air Force Base on June 22nd.