Ax-2 private astronauts can't wait for their May 21 SpaceX launch to the space station

The crewof Axiom Space's Ax-2 mission on SpaceX's crew access arm at Launch Pad 39A at NASA's Kennedy Space Center in Florida. From left: Saudi astronaut Ali Alqarni, Axiom Space's Peggy Whitson, paying customer John Shoffner and Saudi astronaut Rayyanah Barnawi.

The four crewmembers of the second-ever private astronaut mission to the International Space Station (ISS) are eager to leave their home planet behind, at least for a little while.

That mission, known as Ax-2, is scheduled to launch toward the ISS atop a SpaceX Falcon 9 rocket on Sunday afternoon (May 21) — and the four astronauts who will fly it are counting down the days.