US astronaut Frank Rubio, who broke the record for the longest continuous spaceflight by an American, and two Russian cosmonauts began their journey back to Earth on Wednesday when their space capsule undocked from the International Space Station.

"The undocking has taken place," Moscow mission control said.

The capsule will shoot towards Earth and is due to enter the Earth's atmosphere at 10:55 GMT. It will then unfurl a parachute and is due to land in the grassland steppe of Kazakhstan at 11:17 GMT, according to Russia's space corporation, Roscosmos.

Rubio is traveling back to earth with Russian cosmonauts Sergey Prokopyev, 48, and Dmitry Petelin, 40.