This flight of a Falcon 9 rocket with a Crew Dragon capsule on top is known as an in-flight abort test. It will not have any astronauts aboard, and it will not be like most launches where “we’re really hoping for it not to be exciting,” said Kathy Lueders, manager of the commercial crew program for NASA.

About 84 seconds after launch, the Falcon 9 rocket will shut off its nine engines, simulating a failure, and powerful thrusters on the Crew Dragon will ignite to propel the capsule away. The force of that sudden departure will destroy the rocket, possibly even causing it to explode.

“Probably a fireball of some kind,” Mr. Reed said.

After reaching an altitude of about 25 miles, the Dragon will then drop off the “trunk,” or bottom half of the spacecraft, and small thrusters will push the capsule into the correct vertical orientation before parachutes deploy. It is to splash down in the Atlantic Ocean just 10 minutes after launch.

While weather on Saturday looked favorable at the launchpad, waves and winds were high at the splashdown site.