SpaceX's Axiom Mission 2 set for May 21 launch.

The Ax-2 mission, the second-ever private astronaut mission to the International Space Station (ISS), has been given the green light for a May 21 launch. The mission will spend eight days docked to the ISS, with a crew of four people riding a SpaceX Dragon capsule to the orbiting lab. If the mission misses its backup opportunity on May 22, it will have to wait for the next best opportunity as NASA and SpaceX shift toward preparing for the launch of CRS-28, SpaceX's 28th robotic cargo mission to the ISS, on June 3.