After 143 days in space, astronauts set to return

(CNN) -- Nearly five months of cramped living in zero gravity will come to an end Thursday for one American astronaut and two Russian cosmonauts aboard the International Space Station.

Their Soyuz capsule is set to undock at 8:30 p.m. ET, and land less than three and a half hours later in Kazakhstan.

Soyuz modules are vital to the Russian space program.

They are launched into space as capsules atop a rocket, and are capable of landing on land, not requiring a body of water to splash down in.

Kevin Ford on space mission with Russia

Three return from space station

A Soyuz carried the first ever crew to the ISS in November 2000, according to NASA. One is docked there at all times, in case the crew needs to leave in an emergency.

It became the standard mode of transportation to the station after the deadly 2003 Columbia space shuttle accident.

The modern version, the Soyuz TMA, is made of three parts. Two of them jettison then burn upon reentry into Earth's atmosphere, according to NASA. Only the Descent Module will land on Earth, carrying Commander Kevin Ford of NASA, Russian Soyuz Commander Oleg Novitskiy and Russian Flight Engineer Evgeny Tarelkin.

NASA TV will broadcast the undocking and landing live.

The undocking of the Soyuz will mark the beginning of the 35th ISS mission, which awaits the arrival of two more Russian cosmonauts and an American astronaut in two weeks.

The journey up to the station takes longer than the return trip to Earth, NASA said. The Soyuz needs a total of two days to catch up with the ISS in its orbit.

More space and science news on CNN's Light Years blog