Inspiration4: SpaceX and Elon Musk’s all-civilian space tourism mission about to launch

The craft will orbit Earth for three days before crashing into the Atlantic Ocean as part of another billionaire’s private mission to space

Private Spaceflight Explainer (John Kraus)

SpaceX’s all-civilian launch of its Inspiration4 craft is set to take place today, the latest in a line of billionaires taking to high altitudes on private craft.

The quartet of amateur space travellers, led by the American founder and chief executive of e-commerce firm Shift4, Jared Isaacman, will leave the planet at midnight GMT from the Kennedy Space Center in Cape Canaveral, Florida.

SpaceX's senior director of human spaceflight, Benji Reed, has said that the weather forecast “looked great” following a final "static" test-firing of the rocket engines on Monday morning.

The flight, with no professional astronauts accompanying SpaceX's paying customers, is expected to last about three days from liftoff to splashdown in the Atlantic.

They will fly aboard a gleaming white SpaceX Crew Dragon capsule, dubbed Resilience, perched atop one of the company's reusable Falcon 9 rockets and fitted with a special observation dome in place of the usual docking hatch.

Isaacman has forked over an undisclosed but presumably hefty sum to fellow billionaire and SpaceX owner Elon Musk to send himself and his three crewmates aloft. Time magazine has put the ticket price for all four seats at $200 million.

The so-called Inspiration4 mission was conceived by Isaacman mainly to raise awareness and support for St. Jude Children's Research Hospital, a leading paediatric cancer centre in Memphis, Tennessee.

It marks the debut flight of Musk's new orbital tourism business, and a leap ahead of competitors likewise offering rides on rocket ships to well-heeled customers willing to pay a small fortune for the exhilaration, and bragging rights, of spaceflight.

Inspiration4 is aiming for an orbital altitude of 360 miles (575 km) above Earth, higher than the International Space Station or Hubble Space Telescope. At that height, the Crew Dragon will circle the globe once every 90 minutes at a speed of some 17,000 miles per hour (27,360 kph), or roughly 22 times the speed of sound.

Rival companies Virgin Galactic and Blue Origin inaugurated their own private-astronaut services this summer, with their respective founding executives, billionaires Richard Branson and Jeff Bezos each going along for the ride.

But those suborbital flights, lasting a matter of minutes, were short hops compared with Inspiration4's spaceflight profile.

SpaceX already ranks as the most well-established player in the burgeoning constellation of commercial rocket ventures, having launched numerous cargo payloads and astronauts to the International Space Station for Nasa. Two of its Dragon capsules are docked there already.

Despite some largely honorary titles, the Inspiration4 crew will have no part to play in flying the spacecraft, which will be operated by ground-based flight teams and onboard guidance systems, even though two crew members are licensed pilots.

Isaacman, who is rated to fly commercial and military jets, has assumed the role of mission "commander," while geoscientist Sian Proctor, a former Nasa astronaut candidate, has been designated as the mission "pilot."

Rounding out the crew are "chief medical officer" Hayley Arceneaux, a bone cancer survivor turned St. Jude physicians' assistant, and mission "specialist" Chris Sembroski a US Air Force veteran and aerospace data engineer.

The four crewmates have spent five months in rigorous preparations, including altitude fitness, centrifuge (G-force), microgravity and simulator training, emergency drills, classroom work and medical exams.

Inspiration4 officials stress that the mission is more than a joyride.

Once in orbit, the crew will perform a series of medical experiments with "potential applications for human health on Earth and during future spaceflights," the group said in media materials.

Biomedical data and biological samples, including ultrasound scans, will also be collected from crew members before, during and after the flight.

"The crew of Inspiration4 is eager to use our mission to help make a better future for those who will launch in the years and decades to come," Isaacman said in a statement.

Due to the low-Earth orbit of the craft, it is likely that Insspiration4 will be visible with the naked eye as it makes its three-day trip around the Earth - however astronomers will not be able to predict when it will be visible until the mission has started.

Additional reporting by Reuters