Space Station astronauts

The Soyuz TMA-14M spacecraft is seen as it descends toward Earth, carrying NASA's Barry Wilmore and Russian flight engineers Alexander Samokutyaev and Elena Serova. Bill Ingalls/NASA hide caption

toggle caption Bill Ingalls/NASA

The Soyuz TMA-14M spacecraft is seen as it descends toward Earth, carrying NASA's Barry Wilmore and Russian flight engineers Alexander Samokutyaev and Elena Serova.

Bill Ingalls/NASA

After spending nearly six months on the International Space Station, an astronaut and two cosmonauts have landed safely back on Earth. While in orbit, they traveled almost 71 million miles, NASA says.

Cmdr. Barry Wilmore of NASA and flight engineers Alexander Samokutyaev and Elena Serova of the Russian Federal Space Agency (Roscosmos) touched down in Kazakhstan on Thursday morning, local time.

They began their trip home by undocking a Soyuz TMA-14M spacecraft from the space station and undergoing a 4-minute, 41-second deorbit burn, NASA says. A parachute later eased the Soyuz craft down to the recovery area near the town of Zhezkazgan, Kazakhstan.

In the 167 days they were aboard the space station, the crew of Expedition 42 researched "the effects of microgravity on cells, Earth observation, physical science and biological and molecular science, " NASA says.

The space agency adds that the space station now has an Electromagnetic Levitator, which will let scientists "observe fundamental physical processes as liquid metals cool, " possibly leading to the production of "lighter, higher-performing" alloys.

The space station now has a three-person crew. A new trio will launch to join them in late March.

In other NASA news, the agency on Wednesday successfully tested what it calls the "largest, most powerful rocket booster ever built, " producing some 3.6 million pounds of thrust during a two-minute burn at a test site in Utah. Temperatures inside the booster reached more than 5, 600 degrees, NASA says.

The agency says the booster rocket is being developed "to help propel NASA's Space Launch System (SLS) rocket and Orion spacecraft to deep space destinations, including an asteroid and Mars."

Expedition 42 Cosmonauts Elena Serova (left) and Alexander Samokutyaev (center) sit in chairs along with NASA astronaut Barry Wilmore minutes after they landed back on Earth. Bill Ingalls/NASA hide caption

toggle caption Bill Ingalls/NASA

Expedition 42 Cosmonauts Elena Serova (left) and Alexander Samokutyaev (center) sit in chairs along with NASA astronaut Barry Wilmore minutes after they landed back on Earth.