WASHINGTON, United States (AFP) — Four astronauts are set to dock at the International Space Station on Saturday for a months-long research mission, replacing a crew forced to return to Earth early over a medical issue.

The United States (US)  space agency’s international Crew-12 blasted off early Friday aboard a SpaceX Falcon 9 rocket from the Cape Canaveral launch site in Florida.

After more than 30 hours in flight, the astronauts are expected to arrive at the ISS and dock by about 3:15 pm Eastern (2015 GMT).

Crew-12 is composed of Americans Jessica Meir and Jack Hathaway, along with French astronaut Sophie Adenot and Russian cosmonaut Andrey Fedyaev.

“We have left the Earth, but the Earth has not left us,” Meir said as the astronauts ventured into space. “When we gaze on our planet from above, it is immediately clear that everything is interconnected.”

“We are one humankind.”

The travelers are replacing Crew-11, which returned to Earth in January a month earlier than planned in the first medical evacuation in the space station’s history.

The ISS, which orbits 250 miles (400 kilometers) above Earth, has since been staffed by a skeleton crew of three.

NASA declined to disclose any details about the health issue that cut the previous mission short.

Once the astronauts arrive, they will be one of the last crews to live aboard the football field-sized space station.

Continuously inhabited for the last quarter-century, the aging ISS is scheduled to be pushed into Earth’s orbit before crashing into an isolated spot in the Pacific Ocean in 2030.

– Microgravity and the human body –

During their eight months on the outpost, the astronauts will conduct many experiments, including research into the effects of microgravity on their bodies.

Meir, who previously worked as a marine biologist studying animals in extreme environments, will serve as the crew’s commander.

Adenot has become the second French woman to fly into space, following in the footsteps of Claudie Haignere, who spent time on the Mir space station.

Among other research, she will test a system that uses artificial intelligence and augmented reality to allow astronauts to carry out their own medical ultrasounds.

The ISS, once a symbol of warming post-Cold War relations, has been a rare area of continued cooperation between the West and Russia since Moscow invaded Ukraine in 2022.

However, the space station has not entirely avoided the tensions back on Earth.

In November, Russian cosmonaut Oleg Artemyev — who had long been planned to be a member of Crew-12 — was suddenly taken off the mission.

Reports from independent media in Russia suggested he had been photographing and sending classified information with his phone while training at a SpaceX facility. Russian space agency Roscosmos merely said he had been transferred to a different job.

His replacement, Fedyaev, has already spent some time on the ISS as part of Crew-6 in 2023.

Roscosmos cosmonaut Andrey Fedyaev says goodbye as he prepares to travel to the SpaceX Falcon 9 rocket with the company’s Dragon spacecraft at Space Launch Complex 40 for the Crew-12 mission launch at Cape Canaveral Space Force Station, Florida, on February 13, 2026. (Photo by Jim WATSON / AFP)