article_snippet: Two cosmonauts are riding up with Scott Kelly: Mikhail Kornienko and Gennady Padalka.
article_snippet: Mikhail Kornienko also will stay up for a year.
article_snippet: Padalka will only stay up for six months.
article_snippet: The trio will join three crew members already on the International Space Station: U.S. astronaut Terry Virts, Russian cosmonaut Anton Shkaplerov and Italian astronaut Samantha Cristoforetti.
article_snippet: Other crew members also will rotate in and out during Other crew members year in orbit so it will never be just Scott Kelly and Mikhail Kornienko on Space station.
article_snippet: He is expected to spend 342 days off the planet on this mission.
article_snippet: So Mark will be on Earth getting poked and prodded by researchers -- while Scott makes history in orbit.
article_snippet: Final candidates announced for one-way trip to Mars .