The Soyuz TMA-14M spacecraft is seen as it lands with Expedition 42 commander Barry Wilmore of NASA, Alexander Samokutyaev of the Russian Federal Space Agency (Roscosmos) and Elena Serova of Roscosmos near the town of Zhezkazgan, Kazakhstan on Thursday. Photo: AFP

Two Russian cosmonauts and an American astronaut on Thursday returned to Earth aboard a Soyuz space capsule after six months at the International Space Station (ISS).

Yelena Serova - the first female Russian cosmonaut to have spent time on the ISS - landed along with Alexander Samokutyaev and Barry Wilmore in snowy Kazakhstan just after sunrise.

"The Expedition 42 crew is back on Earth," said NASA commentator Rob Navias on the US space agency's live broadcast of the event.

"They have landed in a vertical position, upright," he added, citing Russian search and recovery units which pick up returning space-farers after they touch down on the remote steppe southeast of Dzhezkazgan.

The trio left Earth on September 26. They spent 167 days in space and travelled more than 70 million miles (112 million kilometers) during that time, NASA said.

Russian Deputy Prime Minister Dmitry Rogozin, who oversees the space industry, said that the crew had been picked up and were all in good health. During their time in orbit the Russian cosmonauts conducted some 50 experiments and did repair work on the space station, Roscosmos said

A scare over a possible ammonia leak onboard the craft in January forced astronauts in the US side to shelter briefly in the Russian section but that later appeared to have been a false alarm. 

The next crew launches from Baikonur, Kazakhstan on March 27, Roscosmos has said.

The men on board will be US astronaut Scott Kelly and Russian cosmonauts Mikhail Kornienko and Gennady Padalka.

Kelly and Kornienko will stay at the research outpost for an entire year instead of the usual six months, "collecting valuable biomedical data that will inform future deep space, long-duration missions," NASA said.

Meanwhile, three crew members - Russian Anton Shkaplerov, Italian Samantha Cristoforetti and American Terry Virts - remain onboard the space station.

Russia last month confirmed that it will continue using the ISS in partnership with NASA until 2024.