Four astronauts are scheduled to return to Earth from the International Space Station early Monday after spending more than six months in space, NASA announced.

The four members of the Crew-2 mission, including a French and a Japanese astronaut, will therefore return to Earth before the arrival of a replacement crew, whose take-off was delayed several times due to unfavorable weather conditions.

NASA said in a statement late Friday that Crew-2 members are due to return to Earth "no earlier than 7:14 am EST (1214 GMT) Monday, Nov. 8, with a splashdown off the coast of Florida."

"As we're preparing to leave, it's kind of a bittersweet feeling, we might never come back to see the ISS, and it's really a magical place," French astronaut Thomas Pesquet said earlier Friday during a press conference from the space station.

"I'm very thankful that people dreamt the ISS some time ago and then went ahead and worked hard to make it happen and to build it for the benefit of everyone," Pesquet added. 

Endeavour, the Crew Dragon spacecraft, is scheduled to undock from the International Space Station at 1805 GMT Sunday to begin the journey home.

Once detached from the ISS, the capsule will begin a journey of several hours, the duration of which can vary greatly depending on the trajectory, and will then land off the coast of Florida.

A backup undocking and splashdown opportunity is available Monday, if weather conditions are not favorable, NASA said.

The two missions are being carried out by NASA in collaboration with SpaceX, which now provides regular launches to the ISS from the United States.

Crew-3 is scheduled to take off for the ISS aboard a SpaceX Falcon 9 rocket from Kennedy Space Center in Florida, where astronauts have been in quarantine for days.

US astronaut Megan McArthur was confident that not getting the replacement crew to ISS before the current crew departs was just a temporary setback.

"Of course that's not optimal," McArthur told reporters during the Friday press conference. "But we are prepared to manage that. Spaceflight is full of lots of little challenges."