Less than two minutes after liftoff from a launchpad in Florida, SpaceX's Crew Dragon capsule will fire on-board thrusters to eject itself off a Falcon 9 rocket mid-air, simulating an emergency abort scenario that will prove it can return astronauts to safety.
"I will tell you tomorrow will be an exciting day," Kathy Lueders, Nasa's commercial crew program manager, told reporters on Friday.
The test is crucial to qualify SpaceX's astronaut capsule to fly humans to the International Space Station, a feat the National Aeronautics and Space Administration expects to come as soon as mid-2020. It follows years of development and delays as the United States has sought to revive its human spaceflight program through private partnerships.
The Falcon 9 rocket's boosters will shut down roughly 12 miles (19 km) above the ocean, a mock failure that will trigger Crew Dragon's so-called SuperDraco thrusters to jet itself away at supersonic speeds of up to 1,500 miles per hour (2,400 kph).
The capsule will deploy three parachutes to slow its descent to water, carrying aboard two human-shaped test dummies dressed in motion sensors to collect valuable data on the immense g-force the effect of acceleration on the body imposed during abort.
The booster will free-fall and tumble back uncontrollably toward the ocean, SpaceX's Crew Mission Management director Benji Reed said.
"At some point we expect that the Falcon will start to break up.