STS-133 was a space shuttle mission that launched on February 24, 2011. The mission's primary objective was to deliver the Permanent Multipurpose Module (PMM) to the International Space Station (ISS). The shuttle Discovery carried a crew of six astronauts, including Michael Barratt and Steve Lindsey. During the mission, the crew conducted various tasks, including installing the PMM and performing maintenance on the ISS. STS-133 lasted 13 days, with the shuttle returning to Earth on March 9, 2011. This mission marked the second-to-last flight of the Space Shuttle Program.