ISS Expedition 55 (NASA) ISS Expedition 55 was a space mission to the International Space Station (ISS), managed by NASA as part of the ongoing program for human presence on the orbital laboratory. The expedition began on April 10, 2018, with the launch of Soyuz MS-09 from the Baikonur Cosmodrome in Kazakhstan, and concluded on December 3, 2018, following the return of the Soyuz MS-09 crew to Earth. During its tenure, the crew conducted numerous scientific experiments and maintenance tasks, furthering our understanding of life and physical science in microgravity environments and advancing technologies for long-duration space travel. The expedition was marked by a series of spacewalks and the arrival of the new Multipurpose Laboratory Module (MLM), named 'Baikonur'. The mission was led by American astronaut Alexander Gerst, with Russian cosmonauts Sergey Prokopyev and Serena Aun-Chancellor serving as flight engineers.