Meet Astronaut Jeff Williams, on Track to Beat Scott Kelly's Record for Days in Space

— -- An American astronaut who is set to launch on the Russian Soyuz spacecraft on Friday is on track to break Scott Kelly's record to become the American who has spent the most cumulative days in space.

When Jeff Williams finishes his six-month mission, the veteran astronaut will have racked up 534 career days in space -- beating Kelly's lifetime total of 520 days, according to NASA.

Williams, 58, was selected for NASA's class of astronauts in 1996. This will be his fourth trip to space and his third six-month stay at the International Space Station.

The Wisconsin native has two children and three grandchildren, according to his NASA profile. He also has a pretty cool distinction: NASA said Williams was the first astronaut to interact live with the agency's social media followers during Expedition 22 in 2010.

Williams will hitch a ride in Russia's Soyuz on Friday at 5:26 p.m. ET alongside Roscosmos cosmonauts Oleg Skripochka and Alexey Ovchinin.

The Soyuz is set to dock at the International Space Station six hours after launch, where the trio will be welcomed by American astronaut Tim Kopra, who is the current commander, along with British astronaut Tim Peake and Russian Yuri Malenchenko.

NASA has been purchasing seats for American astronauts on board the Soyuz since the 2011 retirement of the shuttle program. The agreement helps the United States maintain its presence in space as Boeing and SpaceX work on vehicles expected to be ready near the end of 2017.