Blue Origin’s Jeff Bezos and Virgin Galactic’s Richard Branson both made history this summer by becoming the first billionaire space tourists to blast off on their respective rocket ships, New Shepard and Unity22. On Wednesday, a third billionaire on Wednesday is scheduled to do the same with the help of Elon Musk’s SpaceX. Called Inspiration4, the mission will be a much more ambitious undertaking than the earlier flights in July.

Unlike Bezos and Branson, who spent about 10 minutes in their suborbital craft, Jared Isaacman, founder of the e-commerce firm Shift4 Payments, and three other novice astronauts will spend three days orbiting the Earth. Inspiration4 is comprised of a crew capsule that will be atop a reusable Falcon 9 rocket.

The mission will have a 24-hour weather window beginning at 8 pm ET on Wednesday. Once in space, it will orbit the Earth every 90 minutes at more than 17,000 miles per hour, or about 22 times the speed of sound. The target altitude of 360 miles is higher than the International Space Station.