They had spent more than four months aboard the International Space Station (ISS).
NASA`s Rubins, a molecular biologist, was the first person to sequence DNA in space.
Rubins, Roscosmos` Anatoly Ivanishin and Takuya Onishi of the Japan Aerospace Exploration Agency landed southeast of the Kazakh steppe town of Zhezkazgan in frosty conditions following a 115-day mission on board the ISS.
As they were brought out of the capsule, live television images showed them happy and enjoying the fresh air.
The ISS space laboratory has been orbiting Earth at about 28,000 kilometres per hour (17,000 miles per hour) since 1998.
All three Expedition 49 crew members exit Soyuz spacecraft. https://t.co/C7LVQGQ6Xn pic.twitter.com/40QqxpBIcj
— Intl. Space Station (@Space_Station) October 30, 2016
