A SpaceX rocket ship has blasted off from Florida carrying a billionaire e-commerce executive and three less-wealthy private citizens he chose to join him in the first all-civilian crew ever launched into earth orbit.
The amateur astronauts, led by the American boss of financial services firm Shift4 Payments, Jared Isaacman, lifted off just before sunset on Wednesday from the Kennedy Space Center in Cape Canaveral.
A SpaceX webcast showed Isaacman, 38, and his crewmates - Sian Proctor, 51, Hayley Arceneaux, 29, and Chris Sembroski, 42 - strapped into the pressurised cabin of their SpaceX Crew Dragon capsule, dubbed Resilience.
Thumbs-up were on display as the capsule streaked into the Florida sky perched atop one of the company's reusable two-stage Falcon 9 rockets. The Crew Dragon, fitted with a special observation dome in place of its usual docking hatch, reached orbit almost 10 minutes after the 8.03pm (1003 AEST) blast-off.
The rocket's first-stage booster, after separating from the spacecraft's top half, descended back to earth and touched down safely on a landing platform floating in the Atlantic.
The flight, marking the first crewed mission to orbit with no professional astronauts along for the ride, is expected to last about three days from launch to splashdown in the Atlantic.
It marks the debut flight of SpaceX owner Elon Musk's new orbital tourism business, and a leap ahead of competitors offering paid rocket ship rides.
Isaacman paid an undisclosed sum to fellow billionaire Musk to send himself and his three crewmates aloft.
The mission, called Inspiration4, was conceived by Isaacman mainly to raise awareness and support for St Jude Children's Research Hospital, a pediatric cancer centre in Memphis, Tennessee.
Inspiration4 is aiming for an orbital altitude of 575 kilometres, higher than the International Space Station or Hubble Space Telescope, and the furthest any human will have flown from earth since the end of NASA's Apollo moon program in 1972, according to SpaceX.
At that height, the Crew Dragon will circle the globe once every 90 minutes at 27,360km/h.
Rival companies Virgin Galactic and Blue Origin inaugurated their own private-astronaut services in recent months, with their respective founding executives, billionaires Richard Branson and Jeff Bezos, each going along for the ride.
The Inspiration4 crew has no part to play in flying the spacecraft, which is operated by ground-based flight teams and onboard systems.
Isaacman, who is rated to fly commercial and military jets, is mission "commander", while Proctor, a geoscientist and former NASA astronaut candidate, is the "pilot".
Rounding out the crew are "chief medical officer" Arceneaux, a bone cancer survivor turned St Jude physician assistant, and mission "specialist" Sembroski, a US Air Force veteran and aerospace data engineer.
The crewmates have spent five months in rigorous preparations, including altitude fitness, simulator training and medical exams.
Once in orbit, the crew will perform medical experiments with "potential applications for human health on earth and during future spaceflights", according to media materials.
Australian Associated Press