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They sat, and sat, strapped in tight, while a voice kept telling them their launch was being delayed. Finally, the pod doors swung open, and the tourists, who were called trainees, were told they would be moved to a different simulator.

Asked what was wrong, a Disney World staffer said only, “One of our trainees didn’t enjoy the training,” which is Disney-speak for “somebody’s lunch achieved liftoff.”

It happens from time to time on the new thrill ride Mission: Space at Epcot, a simulator so intense that it induces a brief feeling of weightlessness similar to what NASA astronauts undergo in training.

Open since October and costing a reported $100 million–the most expensive amusement park ride ever built–Mission: Space doesn’t really move like a traditional roller coaster, but makes you feel like you’re moving, actually pulling G-forces as the simulator induces the feeling that you’re in a real rocket.

It’s already one of the most popular rides at Disney World, but sometimes not as popular afterward.

“After you get off, you see these parents that are green in the face, looking for a trash can,” said Kevin Moen, 17, who recently rode it twice.

“The first time I got some nausea for a second, but not like I was going to get sick. The second time I rode it I was fine,” he added.

Overall, though, Moen decided the ride was “flat out boring” and “overhyped” compared to his favorites, which include Disney’s Tower of Terror and Universal Orlando’s Spiderman ride and Incredible Hulk roller coaster.

“It was brilliant,” countered Dave Barron, 44, a factory manager visiting from Preston, England, with his family. “I felt my head really go from the pressure of the G-forces.”

Barron’s son Dan, 12, loved it, but daughter Carrie, 20, looked a little pale and shaky as she exited. His wife, Hilary, had been in line, but the more she heard the warnings about claustrophobia, another hazard of the ride, the more nervous she became, and she bailed out seconds before getting on, as plenty of other tourists do.

After waiting in line and receiving repeated warnings about claustrophobia and motion sickness from actor Gary Sinise (playing an astronaut trainer), riders enter a pod that seats four. (With 40 pods, the ride moves 160 at a time when at full capacity.) A video screen gives the illusion you’re tilting toward the sky, and then the centrifuge technology makes it feel as if the rocket is blasting off.

You orbit the moon once, to get a slingshot effect from its gravity, then head to Mars, where you must dodge through an asteroid field. Finally, you pilot the ship to a rough landing, using a dummy joystick that makes it feel as if you’re really piloting the ship. It all lasts about four minutes (not counting the wait time, which can be extensive), close to the average for thrill rides at Disney World and Universal Orlando.