The first all-private astronaut team ever to fly aboard the International Space Station (ISS) has safely splashed down off the coast of Florida, capping a two-week science mission hailed as a milestone in commercial spaceflight.

A SpaceX Crew Dragon capsule carrying the four-man team from the Houston-based startup company Axiom Space undocked from the ISS at about 2.10am Irish time and embarked on a 16-hour return flight, a live NASA webcast showed.

The Axiom astronauts, dressed in their helmeted white-and-black spacesuits, were seen strapped into the crew cabin shortly before the spacecraft separated from the station, orbiting some 420km above Earth.

A couple of brief rocket thrusts then pushed the capsule safely clear of the ISS.

The Dragon capsule, dubbed Endeavour, parachuted into the Atlantic off the coast of Florida around 6pm Irish time.

The flight home was postponed for several days due to unfavorable weather at the splashdown zone, extending the Axiom crew's stay in orbit well beyond its original departure date early last week.

The multinational team was led by Spanish-born retired NASA astronaut Michael Lopez-Alegria, 63, Axiom's vice president for business development.

Larry Connor, 72, a real estate-technology entrepreneur and aerobatics aviator from Ohio, was the second in command.

Rounding out the Ax-1 crew were investor-philanthropist and former Israeli fighter pilot Eytan Stibbe, 64, and Canadian businessman and philanthropist Mark Pathy, 52, who both served as mission specialists.

Axiom paid SpaceX for transport services and NASA for use of the ISS, and also charged between $50 million to $60 million per seat (€47m-€56m), according to Mo Islam, head of research for the investment firm Republic Capital.

Launched from NASA's Kennedy Space Center on 8 April, they spent two weeks aboard ISS with the seven regular, government-paid crew of the space station: three American astronauts, a German astronaut and three Russian cosmonauts.

The Axiom quartet became the first all-commercial astronaut team ever launched to the space station, taking with them equipment for two dozen science experiments, biomedical research and technology demonstrations to conduct in orbit.