Peggy Whitson clocks in 665 days in space

— -- Astronaut Peggy Whitson is approaching an astronomical landmark: 665 days in orbit over three missions, giving her the record for the most time in space of any American.

Whitson will complete her current mission -- having spent a year in space -- when she lands Saturday in Kazakhstan, at 9:22 p.m. ET. She has circumnavigated 122 million miles of the globe -- the equivalent of traveling to Mars and back nearly twice.

Over her career, she has made 10 spacewalks totaling 60 hours and 21 minutes -- ranking third on the all-time list for spacewalks.

ABC News’ David Kerley recently interviewed Whitson before she returns to Earth, and they spoke about whether she misses home while in orbit.

“You know, I think it was best not to think about going home, for the most part, during the mission,” she said.

On average, an astronaut’s tour includes 6 months spent on the International Space Station. The second longest flight -- by American astronaut Mike Lopez-Algeria -- took 215 days. Whitson bested that record by over a 100 days.

Being up in space for so long, Whitson has witnessed numerous cosmic events -- including this summer’s solar eclipse.

While Whitson does not have a plan to return to space, she would like to see humans explore more of the cosmos.

“I think that it benefits all of us on the planet,” Whitson said. “I think just philosophically we’re made to explore.”