Randy “Komrade” Bresnik has amassed more than 149 days in space. Most recently, he returned in December 2017 from a long-duration mission onboard the International Space Station, in which he served as Flight Engineer for Expedition 52 and Commander for Expedition 53. Selected as a NASA astronaut in 2004, Bresnik’s first spaceflight was on space shuttle mission STS-129. His work in extreme environments has also included research conducted as a Cave-a-naut with the European Space Agency to test living and working deep beneath the Earth’s surface. Hehasalso served as an Aquanaut on Aquarius for NASA’s Extreme Environment Mission Operation 19. Aquarius is an underwater research laboratory where aquanauts live and work for up to three weeks at a time in preparation for future space exploration.