U.S. astronaut Peggy Whitson on Monday broke the record for most accumulated time spent in orbit by an American.
Commander Whitson, who is aboard the International Space Station, was congratulated by U.S. President Donald Trump, who spoke to space station astronauts via video.
"Five-hundred thirty-four days and counting. That's an incredible record to break," Trump said from the Oval Office. "On behalf of our nation, and frankly on behalf of the world, I'd like to congratulate you."
WATCH: Trump congratulates Whitson
The 57-year-old Whitson is the most experienced U.S. spacewoman. She is scheduled to return to Earth in September, at which time she will have spent 666 days in space over the course of three flights.
"It's actually a huge honor to break a record like this," Whitson told Trump.
The two also discussed the potential for further space travel, including to Mars, which NASA has said it wants to accomplish by the 2030s. However, Trump moved that deadline up, telling Whitson that he'd like to see a Mars trip "at worst, during my second term."
It wasn't immediately clear whether the president's comments were meant to be taken literally.
Whitson also explained to Trump how technology in the space station allows astronauts to convert their urine to drinking water. "It's really not as bad as it sounds," she said.
"Well that's good, I'm glad to hear that," Trump responded. "Better you than me."
Trump also spoke with U.S. astronaut Jack Fischer, who arrived at the space station for the first time last week. Asked by Trump how his flight went, Fischer, an Air Force pilot, responded: "Sir, it was awesome. It made even my beloved F-22 feel a bit underpowered."
Trump, who was speaking alongside his daughter Ivanka Trump, said he was honored to speak with the astronauts.
"I've been dealing with politicians so much. I'm so much more impressed with these people, you have no idea," he said.