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Stuck NASA astronauts depart ISS for 17-hour trip to Earth

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Crew's splashdown off Florida coast planned for 5:57 p.m.

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(2157 GMT)

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Homecoming of Butch Wilmore and Suni Williams caps end to

nine-month mission

By Joey Roulette

WASHINGTON, March 18 (Reuters) - NASA astronauts Butch

Wilmore and Suni Williams departed the International Space

Station early on Tuesday morning in a SpaceX capsule for a

long-awaited trip back to Earth, nine months after their faulty

Boeing Starliner craft upended what was to be a roughly

week-long test mission.

Wilmore and Williams, two veteran NASA astronauts and

retired U.S. Navy test pilots, strapped inside their Crew Dragon

spacecraft along with two other astronauts and undocked from the

orbiting laboratory at 1.05 a.m. ET (0505 GMT), embarking on a

17-hour trip to Earth.

The four-person crew, formally part of NASA's Crew-9

astronaut rotation mission, is scheduled for a splashdown off

Florida's coast later on Tuesday at 5:57 p.m. ET.

Wilmore and Williams' homecoming caps an end to an

unusual, drawn-out mission filled with uncertainty and technical

troubles that have turned a rare case of NASA's contingency

planning - as well as failures of Boeing's ( BA ) Starliner spacecraft

- into a global and political spectacle.

The astronaut pair had launched into space as Starliner's

first crew in June for what was expected to be an eight-day test

mission. But issues with Starliner's propulsion system led to

cascading delays in their return home, culminating in a NASA

decision last year to have them take a SpaceX craft back this

year as part of the agency's crew rotation schedule.

The mission has captured the attention of U.S. President

Donald Trump, who upon taking office in January called for a

quicker return of Wilmore and Williams and alleged without

evidence that former President Joe Biden "abandoned" them on the

ISS for political reasons.

SpaceX CEO Elon Musk, a close adviser to Trump, echoed

his call for an earlier return. SpaceX's Crew Dragon is the

United States' only orbital-class crew spacecraft, which Boeing ( BA )

had hoped its Starliner would compete with before the mission

with Wilmore and Williams threw its development future into

uncertainty.

The astronauts will be flown to their crew quarters at the

space agency's Johnson Space Center in Houston for several days

of health checks, per routine for astronaut returns, before NASA

flight surgeons approve they can go home to their families.

Living in space for months can affect the human body in

multiple ways, from muscle atrophy to possible vision

impairment.

Upon splashing down, Wilmore and Williams will have logged

286 days in space - longer than the average six-month ISS

mission length, but far short of U.S. record holder Frank Rubio.

His continuous 371 days in space ending in 2023 was the

unexpected result of a coolant leak on a Russian spacecraft.

Williams, capping her third spaceflight, will have tallied

608 cumulative days in space, the second most for any U.S.

astronaut after Peggy Whitson's 675 days. Russian cosmonaut Oleg

Kononenko set the world record last year at 878 cumulative days.

REPLACEMENT CREW

Swept up in NASA's routine astronaut rotation schedule,

Wilmore and Williams could not begin their return to Earth until

their replacement crew arrived, in order to maintain adequate

U.S. staffing levels, according to NASA.

Their replacements arrived on Friday night - four astronauts

as part of NASA's Crew-10 mission briefly put the station's

headcount at 11.

"We came prepared to stay long, even though we planned to

stay short," Wilmore told reporters from space earlier this

month, adding that he did not believe NASA's decision to keep

them on the ISS until Crew-10's arrival had been affected by

politics.

"That's what your nation's human spaceflight program's all

about," he said, "planning for unknown, unexpected

contingencies. And we did that."

Wilmore and Williams have been doing scientific research and

conducting routine maintenance with the station's other five

astronauts. Williams had performed two six-hour spacewalks for

maintenance outside the ISS, including one with Wilmore.

The ISS, about 254 miles (409 km) in altitude, is a football

field-sized research lab that has been housed continuously by

international crews of astronauts for nearly 25 years, a key

platform of science diplomacy managed primarily by the U.S. and

Russia.

Williams told reporters earlier this month that she was

looking forward to returning home to see her two dogs and

family. "It's been a roller coaster for them, probably a little

bit more so than for us," she said.