Scott Kelly has officially spent more time in space on a single mission than any American astronaut in history.
On Thursday, he passed the 215-day record set by Michael Lopez-Alegria in 2007. When his mission ends, Kelly will have spent a grand total of 342 days orbiting Earth on the International Space Station.
The 51-year-old astronaut started his year-long journey back in March 2015. NASA hopes to gain insights on how long-term space travel affects the human body before launching a potential mission to Mars.
Kelly's twin brother, Mark, who's on Earth, celebrated the milestone on Twitter.
Scott had another reason to be happy. He completed the first spacewalk of his career on Wednesday, performing maintenance tasks on the ISS with fellow astronaut Kjell Lindgren.
Kelly already owns the record for the most cumulative time in space of any American astronaut, thanks to three previous missions to the ISS. In March 2016, when he finally touches down on Earth, he should have 522 days of living in space under his belt.