Expedition 20 was a mission to the International Space Station (ISS) that took place from May to November 2009. It involved a crew of six astronauts, including Michael Barratt, Gennady Padalka, and Koichi Wakata. The mission focused on scientific research, technology demonstrations, and maintenance of the ISS. During Expedition 20, the crew conducted various experiments in fields such as biology, physics, and Earth sciences. They also worked on upgrading the station's systems and preparing for future missions, including the arrival of the European Space Agency's Johannes Kepler spacecraft.