The two module simulators weren’t the only training rigs for the astronauts. Perhaps the least favorite apparatus of the group was the Centrifuge, also known as the “G Machine,” used to simulate the forces of acceleration a body would have to withstand while traveling by spacecraft. Astronauts strapped into the steel ball, which would then spin around on its 50-foot arm like some sort of intense amusement park ride. This tested how the forces would impact a body, for instance, whether a person can breathe (they can, but with great difficulty), as well as how much the astronauts can maneuver under the physical pressure.