Home at last: After an unexpected nine-month stay in space, a pair of NASA astronauts finally returned to Earth on Tuesday, concluding a mission that gripped global attention and became a political flashpoint.

A SpaceX Crew Dragon spaceship carrying Butch Wilmore and Suni Williams — alongside fellow American Nick Hague and Russian cosmonaut Aleksandr Gorbunov — streaked through the atmosphere before deploying parachutes for a gentle splashdown off the Florida coast at 5:57 pm (2157 GMT).

Ground teams erupted in cheers as the gumdrop-shaped spacecraft named Freedom, charred from withstanding scorching temperatures of 3,500 degrees Fahrenheit (2,000 degrees Celsius) during re-entry, bobbed steadily on the waves beneath a clear, sunny sky.

Fast boats raced to the capsule for initial safety checks, soon to be followed by a recovery vessel that will retrieve the crew before they are flown to Houston to begin a 45-day rehabilitation program.

"What a ride — I see a capsule full of friends here," Hague said.

The quartet left the International Space Station roughly 17 hours earlier after exchanging final farewells and hugs with remaining crew members.

Wilmore and Williams, both ex-Navy pilots and veterans of two prior space missions, flew to the orbital lab in June last year, on what was supposed to be a days-long roundtrip to test out Boeing's Starliner on its first crewed flight.

But the spaceship developed propulsion problems and was deemed unfit to fly them back, instead returning empty.

They were subsequently reassigned to NASA's SpaceX Crew-9 mission, which arrived at the ISS last September with a reduced crew of two — rather than the usual four — to accommodate the pair, who had become widely referred to as the "stranded" astronauts.

Early Sunday, a relief team called Crew-10 docked with the station, paving the way for the Crew-9 team to depart.

'Unbelievable resilience'

Wilmore and Williams' 286-day stay exceeds the usual six-month ISS rotation but ranks only sixth among US records for single-mission duration.

Frank Rubio holds the top spot at 371 days in 2023, while the world record remains with Russian cosmonaut Valeri Polyakov, who spent 437 consecutive days aboard the Mir station.

That makes it "par for the course" in terms of health risks, according to Rihana Bokhari of the Center for Space Medicine at Baylor College of Medicine.

Challenges such as muscle and bone loss, fluid shifts that can lead to kidney stones and vision issues, and the readjustment of balance upon returning to a gravity environment are well understood and effectively managed.

"Folks like Suni Williams are actually known for their interest in exercise, and so I believe she exercises beyond what is even her normal prescription," Bokhari told AFP.

Still, the unexpected nature of their extended stay — away from their families and initially without enough packed supplies — has drawn public interest and sympathy.

"If you found out you went to work today and were going to be stuck in your office for the next nine months, you might have a panic attack," Joseph Keebler, a psychologist at Embry-Riddle Aeronautical University, told AFP.

"These individuals have shown unbelievable resilience."

Trump weighs in

Their unexpected stint also became a political lightning rod, with President Donald Trump and his close advisor, Elon Musk — who leads SpaceX — repeatedly suggesting former president Joe Biden abandoned the astronauts and refused an earlier rescue plan.

Such accusations have prompted an outcry in the space community, especially as Musk offered no specifics and NASA's plan for the astronauts' return has remained largely unchanged since their Crew-9 reassignment.

Trump has also drawn attention for his bizarre remarks, referring to Williams, a former Navy captain who holds the US record for the second-longest cumulative time in space, as "the woman with the wild hair" and speculating about the personal dynamic between the two.

"They've been left up there — I hope they like each other, maybe they love each other, I don't know," he said during a recent White House press conference.