Astronauts back home after six months

Three astronauts have completed a return trip to Earth after nearly six months aboard the International Space Station.

Three astronauts have completed a return trip to Earth after nearly six months aboard the ISS. (AAP)

Three astronauts are back on Earth after a five-and-a-half-month space station mission.

The two Americans and one Russian landed in their Soyuz capsule shortly after sunrise on Wednesday, local time, in Kazakhstan. It was a frigid homecoming. Despite snow and temperatures below freezing, recovery teams got to where they needed to be.

NASA's Joe Acaba and Mark Vande Hei and Russia's Alexander Misurkin checked out of the International Space Station just a few hours earlier.

Acaba, Vande Hei and Misurkin flew to the orbiting lab last September. Their mission was highlighted by robot-arm renovations, schoolteacher pep talks and heavenly greetings from Pope Francis.

A replacement crew will launch to the space station in three weeks.

The trio had spent five-and-a-half months at the ISS, a $US100 billion ($A140 billion) lab that flies about 400km above Earth.

The are due to be replaced by NASA's Andrew Feustel and Richard Arnold, and Oleg Artemyev of Roscosmos, whose spacecraft will blast off from the Baikonur cosmodrome, also in Kazakhstan, on March 21.