The United States and Russia have named the two astronauts who will spend one year aboard the International Space Station (ISS).
NASA's Michael Kelly and Russia's Mikhail Kornienko will fly to the ISS in spring 2015 and spend one year there to gather data on the effects on humans of long periods in outer space.
The aim is to determine how humans would react on long missions to the moon or Mars.
International crews have so far spent only some six months at a time aboard the ISS, although Russian cosmonauts were on longer missions aboard the Mir space station before it was discarded in 2001.
Russian cosmonaut Valery Polyakov holds the record for time in space, staying 437 days aboard Mir in 1994-95.
Based on reporting by ITAR-TASS and AP