The Boeing CST-100 Starliner Crew Flight Test will launch two NASA veteran astronauts atop a United Launch Alliance Atlas V rocket from Cape Canaveral Space Force Station’s Space Launch Complex 41 targeting liftoff Monday, May 6, at 10:34 p.m. headed for the International Space Station.

Butch Wilmore and Suni Williams will stay on board for eight days before returning the Starliner to Earth with a land touchdown in the western United States sometime in mid-May. The mission looks to pave the way for certification of the spacecraft as part of NASA’s Commercial Crew Program so that Boeing can join SpaceX with rotational astronaut missions to the ISS.

The CFT flight comes about four years after SpaceX managed its first crewed test flight because of a series of delays in Boeing’s program. In those four years, SpaceX has managed 13 flights of its fleet of Crew Dragons taking 50 people into space including eight rotational missions to the ISS during which astronauts stay for around six months.

Boeing’s first shot at a rotational flight would be Starliner-1 that would come no earlier than February 2025. Boeing has six contracted flights to the ISS through its planned decommissioning in 2030. Once Starliner is approved, Boeing and SpaceX will share one flight each per year with crew rotations every six months.