Four astronauts have returned safely to Earth from the International Space Station in a SpaceX Crew Dragon capsule, parachuting to splash-down in the Gulf of Mexico.

NASA's SpaceX Crew-1 mission with astronauts Michael Hopkins, Victor Glover, and Shannon Walker, and Soichi Noguchi of the Japan Aerospace Exploration Agency (JAXA) returned to Earth after almost six months on the orbiting outpost.

The Crew Dragon spacecraft, named Resilience, landed at 7.56am (Irish time) this morning off the coast of Panama City, Florida where recovery vessels recovered the spacecraft and the four astronauts.

The astronauts will fly to Houston after arriving on shore, NASA said.

"It's not very often you get to wake up on the Space Station and go to sleep in Houston," Holly Ridings, NASA's chief flight director said at a news conference.

"The orbital mechanics and the weather don't always work out, but today they did. And so so that's pretty remarkable."

The astronauts' return marked the end of the first crew rotation mission to the station by the Crew Dragon spacecraft, developed in partnership between NASA and Elon Musk's rocket company SpaceX, the agency said in a statement.

The mission was part of NASA's fledgling public-private partnership with SpaceX, the rocket company founded in 2002 by Musk, who is also CEO of electric car maker Tesla Inc.