Sergey Nikolayevich Ryazansky is a Russian cosmonaut. He was selected as commander of the IMBP-6 cosmonaut group in 2003, but later transferred to the TsPK Cosmonaut Group. Ryazansky made his first spaceflight aboard the Soyuz TMA-10M/Expedition 37/Expedition 38 mission from September 2013 until March 2014. In 2017, Ryazansky returned to space was the commander of Soyuz MS-05, and served as Flight Engineer for Expedition 52 / 53.