Expedition 20/21 was a mission to the International Space Station (ISS) that took place from May 2009 to March 2010. It involved a crew of six astronauts and cosmonauts who conducted scientific research and maintenance tasks aboard the station. The mission aimed to enhance the ISS's capabilities and support ongoing experiments in various fields, including biology and physics. During Expedition 20/21, the crew included members from NASA, Roscosmos, and ESA. They performed spacewalks to upgrade the station's systems and installed new equipment. The mission contributed to the long-term goals of the ISS, fostering international collaboration in space exploration.