Yet another billionaire entrepreneur is set to ride into space this week, strapped inside the capsule of a SpaceX rocketship, as part of an Astro-tourist team, poised to make history as the first all-civilian crew launched into Earth orbit.

Jared Isaacman, the American founder and chief executive of e-commerce firm Shift4 Payments, will lead three fellow spaceflight novices on a trip expected to last three days from blastoff at Cape Canaveral, Florida, to splashdown in the Atlantic.

The 38-year-old tech mogul has plunked down an unspecified but presumably exorbitant sum to fellow billionaire and SpaceX owner Elon Musk to fly Isaacman and three specially selected travel mates into orbit aboard a SpaceX Crew Dragon capsule.

The crew vehicle is set for blastoff from NASA’s Kennedy Space Center atop one of Musk’s reusable Falcon 9 rockets, with a 24-hour targeted launch window that opens at 8 p.m. EDT (0000 GMT) on Wednesday. That window will be narrowed or possibly altered a few days before, depending on the weather.

Dubbed Inspiration4, the orbital outing was conceived by Isaacman primarily to raise awareness and support for one of his favorite causes, St. Jude Children’s Research Hospital, a leading pediatric cancer center. He has pledged $100 million personally to the institute.

But a successful mission would also help usher in a new era of commercial space tourism, with several companies vying for wealthy customers willing to pay a small fortune to experience the exhilaration of supersonic flight, weightlessness and the visual spectacle of space.

Setting acceptable levels of consumer risk in the inherently dangerous endeavor of rocket travel is also key and raises a pointed question.

“Do you have to be both rich and brave to get on these flights right now?” said Sridhar Tayur, a professor of operations management and new business models at Carnegie Mellon University in Pittsburgh, in an interview with Reuters on Friday (September 10).

Inspiration4 officials stress that the mission is more than a joyride. Once in orbit, the crew will perform medical experiments with “potential applications for human health on Earth and during future spaceflights,” the group said in its press materials.

“There is a certain amount of frivolousness and ego in it. But I also believe that we have moved in our understanding of science and our capability and technologies because people have taken these kinds of extraordinary risks. I mean, that is the human endeavor to push the limits,” Tayur said.

The SpaceX flight is designed to carry its four passengers where no all-civilian crew has gone before – into Earth orbit.

There, they will circle the globe once every 90 minutes at more than 17,000 miles per hour, or roughly 22 times the speed of sound. The target altitude is 575 kilometers, or nearly 360 miles high, beyond the orbits of the International Space Station or even the Hubble Space Telescope.

The Inspiration4 crew will have no part to play in operating their spacecraft, despite some largely honorary titles, though two members – Isaacman and geoscientist Sian Proctor – are licensed pilots.

Rounding out the crew are “chief medical officer” Hayley Arceneaux, 29, a bone cancer survivor turned St. Jude physicians’ assistant, and mission “specialist” Chris Sembroski, 42, a U.S. Air Force veteran and aerospace data engineer.