Record-holding US astronaut and 2 Russians return to Earth

An American astronaut who set the US record for cumulative time in orbit safely returned to Earth early Wednesday along with two Russian cosmonauts after a six-month mission aboard the International Space Station.

NASA's Jeff Williams, 58, logged 534 days in space over four missions. The ISS commander landed at 7:13 local time (0113 GMT) on the steppes of central Kazakhstan aboard a Russian-made Soyuz capsule along with Alexey Ovchinin and Oleg Skripochka.

"Touchdown! Welcome home @Astro_Jeff, officially back on Earth after 172-day mission & total 534 days on 4 missions," NASA tweeted.

A NASA live video feed showed Williams on the ground smiling and waving while talking on a satellite phone before being carried away for medical tests.

The three men undocked from the ISS nearly three and a half hours earlier after spending their mission largely conducting scientific experiments.

Williams performed five space walks, including one along with NASA astronaut Kate Rubins to install a docking adapter for future commercial Boeing and SpaceX crew capsules to visit the space station.

"Williams was instrumental in preparing the station for the future arrival of US commercial crew spacecraft," NASA said in a statement.

He also helped set up an experimental temporary inflatable module designed by Bigelow Aerospace to test expandable habitats astronauts might use on the Moon or Mars in the coming decades.

The retired Army colonel beat the previous US record set by astronaut Scott Kelly during his year in orbit. 

Kelly has 520 days in space over his career.

Williams, a grandfather, is also the oldest American to spend live on the space station. 

Williams first blasted to space aboard the shuttle Atlantis in 2000.

He returned to the International Space Station in 2006 when the space station was far smaller -- with just two modules and three crew members -- and again in 2009.

Today, the ISS is staffed by six astronauts and cosmonauts and spans the size of a football field.

Williams may hold the US record for time in orbit, but Russia's Gennady Padalka still holds the record for the person with the most cumulative days in space at 879.