The Space Shuttle Atlantis has performed a successful landing at Edwards Air Force Base in California, completing STS-117, a troubled but successful mission to upgrade the International Space Station (ISS). The mission had a total duration of 13 days, 20 hours and 11 minutes, much longer than originally intended due to a mission extension and a missed landing opportunity.

The landing in California is the result of the latest in a string of difficulties for the mission, as poor weather forced Atlantis first to postpone its landing at the Kennedy Space Center in Florida, then to cancel it altogether, opting instead to land in California. NASA had previously expressed their desire to avoid a landing in California if possible due to logistical difficulties that would be caused by the diversion.

Atlantis will now be flown back to Florida on the back of a modified Boeing 747 at a cost of around US$1 million. The flight is expected to begin next Thursday and will take at least a day or two from then. According to officials at the Kennedy Space Center, the delay is already accounted for as a previously identified possibility as part of plans for the next Atlantis mission, scheduled for departure on October 20, again for ISS construction work.

During this mission, the Atlantis crew added the 17.5 ton S3/S4 Truss, the second of the trusses on the starboard side, as well as adding its associated energy systems, including the unfurling a set of solar arrays with a 240 foot tip-to-tip length. The arrays will generate power for European and Japanese science laboratories set to be added to the ISS at a later date. During the same mission, another solar array was folded up to allow the truss it is mounted to to be relocated later this year. The shuttle also left crewmember Clay Anderson at the ISS and returned with ISS crewmember Sunita Williams, who earlier set the record for female space endurance during her latest ISS mission.

Although successful, there were numerous problems during the mission. A computer failure in the Russian segments of the ISS almost forced the shuttle's mission to be extended and left the ISS struggling to maintain thrusters, oxygen generation, carbon dioxide scrubber, and other environmental control systems, and relying on Atlantis to help. Officials even looked at the possibility of an unprecedented emergency evacuation of the ISS, although astronauts were ultimately able to repair the systems.

Other concerns included hail damage, which delayed the mission's launch; damage to the thermal blanket, which required a spacewalk to repair; and discovery of unidentified debris shortly after Atlantis docked with the ISS. The mission had to be extended by two days in order to give astronauts time to repair the damaged heat-protection equipment. NASA officials held an emergency meeting Wednesday while engineers confirmed that they thought the repair would withstand the rigors of re-entry with the Earth's atmosphere.