SpaceX is expected to launch another billionaire into space on Wednesday in what will become the first time ever that humans are blasted into Earth's orbit with only civilians aboard.

The group of four is being led by Jared Isaacman, the chief executive of an e-commerce company called Shift4 Payments.

Professor Sridhar Tayur teaches about new business models at Carnegie Mellon University.

"I think it's exciting. I think they need to get the safety numbers in, I would think, better than one in 100 for this to go beyond a few brave people. And then I believe they could get a thousand people to try it a year or something like that at good safety levels, at about $250,000 an orbital flight, because that is the kind of money people are spending on expensive cars and things of that type."

"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 kind of extraordinary risks. I mean, that is the human endeavor to push the limits."

Virgin Galactic and Blue Origin have also recently blasted civilian tourists into space, but both of those were suborbital - meaning they didn't circle the Earth and only lasted a few minutes. This new trip will take three days, circling the Earth every 90 minutes.

Isaacman says they'll conduct experiments and is using the event to raise support for St. Jude's Children's Research Hospital. One of his fellow crew members, Hayley Arceneaux, is a physician's assistant at the institution.

The other two members are Sian Proctor, a geoscientist and Chris Sembroski, a U.S. Air Force vet and engineer. They were the winners of an online contest and sweepstakes respectively.