Scientists want to better understand the effects of long-term spaceflight. In order to know the same, astronauts need to stay at the International Space Station for a long time.

This week, two astronauts, US astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko, will move to the ISS to stay there for a year. Both of them will stay at the ISS for a year. It would not be for the first time that astronauts will spend a year or more in space.

Russia's Valeri Polyakov has the record of staying on the Mir space station for 437 days. On March 27, Kelly and Kornienko will take off for the ISS. They will be accompanied by Russian cosmonaut Gennady Padalka.