On March 27, 2015, NASA astronaut Scott Kelly launched to the International Space Station. He surpassed the previous record for time spent in space by a U.S. astronaut on Oct. 16, 2015. After his return, he will have spent a total of 520 days in space across four space missions.
During the 340 days of this mission – which spanned four space station expeditions – Kelly and his one-year crewmate, Russian cosmonaut Mikhail Kornienko, have participated in a variety of research that will help scientists better understand how the human body reacts and adapts to long-duration spaceflight. That knowledge will play a critical role in future NASA missions deeper into the solar system and on the Journey to Mars, in which a round-trip mission is likely to last 500 days or longer.
NASA recently shared a 45-picture Flickr gallery entitled, Best Pics from #YearInSpace. You can find our favorite images below.