A record-shattering NASA astronaut is set to return to Earth on Saturday, finishing a 288-day mission that put her over the top as the American who has spent the most cumulative amount of time in space.

A record-shattering NASA astronaut is set to return to Earth on Saturday, finishing a 288-day mission that put her over the top as the American who has spent the most cumulative amount of time in space.

Peggy Whitson, 57, is also the oldest female astronaut in the history of space exploration, was the first female International Space Station commander, and holds the record for number of spacewalks by a woman.

Whitson wrapped up a record-breaking flight that catapulted her to first place for US space endurance. Whitson's 665 days off the planet — 288 days on this mission alone — exceeds that of any other American and any other woman worldwide.

Upon her return, Whitson will have racked up 665 days in space in her career, more than any other American astronaut. She is eighth on the all-time space endurance list, NASA said.

The biochemist is completing a mission at the International Space Station that began in November 2016, covering 122.2 million miles (196.7 million kilometers) and 4,623 orbits of Earth.

She and crewmates Jack Fischer of NASA and Fyodor Yurchikhin of Russian space agency Roscosmos were expected to land in Kazakhstan at 9:22 pm (0122 GMT Sunday) in a Soyuz MS-04 spacecraft.

She checked out of the International Space Station just hours earlier, along with another American and a Russian. Their Soyuz capsule landed in Kazakhstan shortly after sunrise Sunday — Saturday night back in the US.

Whitson was the last one carried from the Soyuz. She immediately received a pair of sunglasses to put on, as she rested in a chair on the barren, wind-swept Kazak steppes. Medical personnel took her pulse, standard practice. She then received a bouquet of flowers with the greeting, "Welcome back, Peggy."

Besides duration, Whitson set multiple other records while in orbit: world's oldest spacewoman, at age 57, and most experienced female spacewalker, with 10. She also became the first woman to command the space station twice following her launch last November.

Returning cosmonaut Fyodor Yurchikhin logged even more time in space: 673 days over five missions. NASA astronaut Jack Fischer returned after 136 days aloft. The men flew up in April.

All three briefly held hands for a photo op, before being carried one by one in their chairs to the medical tent.

It was an emotional farewell to the space station for Whitson, Yurchikhin and Fischer. Before retreating into their Soyuz, they embraced the three colleagues they were leaving behind at the 250-mile-high complex. Yurchikhin patted the inside of the station before floating into his Soyuz for the final time. The station's newest commander, Randy Bresnik, noted the outpost was losing 1,474 days of spaceflight experience with the departure of Whitson, Yurchikhin and Fischer.

Four years and two weeks, he pointed out.

"We are in your debt for the supreme dedication that you guys have to the human mission of exploration," Bresnik told them on the eve of their departure. He offered up special praise for Whitson— "American space ninja" — and wished them all Godspeed.

Yurchikhin is now No. 7 on the world's all-time endurance list, followed by Whitson at No. 8. The top spot belongs to Russian Gennady Padalka, with 879 days in space over five flights.

After earning a doctorate in biochemistry in 1985, Whitson worked as a NASA scientist for seven years before starting as an astronaut in 1997.

On this most recent mission, Whitson conducted experiments with human stem cells, blood samples and grew several crops of Chinese cabbage, according to posts on her Facebook page.

"The best part, was that after we harvested for the science, we got to eat the rest!" she said of her greens.

In an interview before departing the space station, Whitson said she was looking forward to flush toilets ("Trust me, you don't want to know the details") and pizza.

But, "I will miss seeing the enchantingly peaceful limb of our Earth from this vantage point. Until the end of my days, my eyes will search the horizon to see that curve," she said, according to a transcript of the interview posted on the NASA website.

She noted that she's not totally comfortable with the attention she receives for her various records and her status as a role model.

"I honestly do think that it is critical that we are continuously breaking records, because that represents us moving forward in exploration," Whitson said.

The scientist also has a silly side. To celebrate the July Fourth holiday, she posted photos and a video of herself and Fischer wearing loud red, white and blue outfits, striking poses in zero gravity.

"I am not sure what the future holds for me personally, but I envision myself continuing to work on spaceflight programs. My desire to contribute to the spaceflight team as we move forward in our exploration of space has only increased over the years," she said of her plans.

The astronauts' return comes as the Texas city of Houston, home to NASA's Johnson Space Center, has been struggling to get back to normalcy after a week of deadly flooding triggered by Hurricane Harvey.

"As a result of the impacts of Hurricane Harvey, NASA is reviewing return plans to Houston of Whitson, Fischer and the science samples landing in the Soyuz spacecraft," the space agency said.

Whitson, a biochemist, set a breakneck pace on all three of her space station expeditions, continually asking for more — and still more — scientific research to do. Scientists on the ground said it often was hard to keep up with her. She even experimented on food up there, trying to add some pizazz to the standard freeze-dried meals. Tortillas transformed into apple pies on her watch.

Whitson was supposed to fly back in June after a half-year in space. But when an extra seat opened up on this Soyuz, she jumped at the chance to stay in orbit an extra three months. Only one other American — yearlong spaceman Scott Kelly — has spent longer in space on a single mission.

Except for the past week, Whitson said her mission hurried by. She's hungry for pizza and can't wait to use a regular flush toilet again. She's also eager to reunite with her husband, Clarence Sams, a biochemist who also works at Johnson Space Center in Houston.

Because of the effects of Hurricane Harvey, NASA could not get its plane from Houston to Kazakhstan in time for the crew's landing. Instead, the European Space Agency offered to transport Whitson and Fischer to Cologne, Germany, where they will meet up with the NASA plane for the final leg of their journey. They should be back in Houston on Sunday night.

Three men remain at the space station: Bresnik, a Russian and an Italian. They will be joined by two Americans and a Russian following liftoff from Kazakhstan on 12 September.

With inputs from AP and AFP