STS-128

STS-128 (ISS assembly flight 17A) was a NASA Space Shuttle mission to the International Space Station (ISS) that launched on August 28, 2009. Space Shuttle Discovery carried the Multi-Purpose Logistics Module Leonardo as its primary payload. It was Discovery's 37th flight. Leonardo contained a collection of experiments for studying the physics and chemistry of microgravity. Three spacewalks were carried out during the mission, which removed and replaced a materials processing experiment outside ESA's Columbus module, and returned an empty ammonia tank assembly. The mission's first launch attempt was delayed due to weather concerns, including multiple weather violations in NASA's launch rules, beginning over two hours before the scheduled launch. The second launch attempt, scheduled for August 26, 2009, at 01:10:22 EDT, was called off the previous evening due to an anomaly in one of the orbiter's fuel valves. The launch finally took place on August 28, 2009, at 23:59 EDT. Discovery landed on September 11, 2009, at Edwards Air Force Base, which was the last landing of a shuttle to occur at the California site.