NASA and SpaceX on Friday launched a long-awaited crew to the International Space Station that will let them bring home U.S. astronauts Butch Wilmore and Suni Williams, who have been stuck on the orbital lab for nine months.

SpaceX's Falcon 9 rocket lifted off at 7:03 p.m. from NASA's Kennedy Space Center in Florida carrying four astronauts who will replace Wilmore and Williams, both of whom are veteran NASA astronauts and retired U.S. Navy test pilots and were the first to fly Boeing's faulty Starliner capsule to the ISS in June.

Otherwise a routine crew rotation flight, Friday's Crew-10 mission is a long-awaited first step to bring the astronaut duo back to Earth - part of a plan set by NASA last year that more recently has been given greater urgency by President Donald Trump.

After the Crew-10 astronauts' ISS arrival on Saturday at 11:30 p.m. ET, Wilmore and Williams are scheduled to depart on March 19, along with NASA astronaut Nick Hague and Russian cosmonaut Aleksandr Gorbunov. Hague and Gorbunov flew to the ISS in September on a Crew Dragon craft with two empty seats for Wilmore and Williams.

The Crew-10 crew, which will stay on the station for roughly six months, includes NASA astronauts Anne McClain and Nichole Ayers, Japanese astronaut Takuya Onishi and Russian cosmonaut Kirill Peskov.

Minutes after reaching orbit, McClain, part of NASA's astronaut corps since 2013, introduced the mission's microgravity indicator - per tradition in American spaceflight to signal the crew safely reached space - as a plush origami crane, "the international symbol for peace, hope and healing."

"It is far easier to be enemies than it is to be friends, it's easier to break partnerships and relationships than it is to build them," McClain said from the Crew Dragon capsule, her communications live-streamed by NASA.

"Spaceflight is hard, and success depends on leaders of character who choose a harder right over the easier wrong, and who build programs, partnerships and relationships. We explore for the benefit of all," she said.

The mission became entangled in politics as Trump and his adviser Elon Musk, who is also SpaceX's CEO, urged for a quicker Crew-10 launch and claimed without evidence that former President Joe Biden had abandoned Wilmore and Williams on the station for political reasons.

"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."

NASA officials have said the two astronauts have had to remain on the ISS to maintain adequate staffing levels, and that it did not have the budget or the operational need to send a dedicated rescue spacecraft.

Having seen their mission turn into a normal NASA rotation to the ISS, Wilmore and Williams have been doing scientific research and conducting routine maintenance with the other astronauts.

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.

Trump and Musk's demand for an earlier return for Wilmore and Williams was an unusual intervention into NASA operations. The agency later brought forward the Crew-10 mission from March 26, swapping a delayed SpaceX capsule for one that would be ready sooner.

The pressure from Musk and Trump has hung over a NASA preparation and safety process that normally follows a well-defined course.

NASA's Commercial Crew Program manager, Steve Stich, said preparing for the mission had been an "unusual flow in many respects."

The agency had to address some "late-breaking" issues, NASA space operations chief Ken Bowersox told reporters, including investigating a fuel leak on a recent SpaceX Falcon 9 launch and deterioration of a coating on some of the Dragon crew capsule's thrusters.

Bowersox said it was hard for NASA to keep up with SpaceX: "We're not quite as agile as they are, but we're working well together."