The company’s Falcon 9 rocket has a five-hour launch window that opens just after 8:00 p.m. EST.
The Inspiration4 crew, all private citizens, will ride into space in the Dragon spacecraft atop the rocket.
It will be the 23rd launch of a Falcon 9 rocket so far this year.
The mission is also part of a fundraising effort to raise $200 million for St. Jude Children’s Research Hospital.
The four members of the crew are billionaire Jared Isaacman, Hayley Arceneaux—who is a cancer survivor and physician’s assistant at St. Jude—Chris Sembroski—a data engineer—and Sian Proctor—a geoscientist and the mission pilot.