Anyone who has seen a rocket launch in person (I have!) has also felt its surreal rumbles despite being several kilometers away. A spacecraft sitting on top of a rocket needs to avoid damage to its structure by surviving the jolt from rocket engines turning on and the intense vibrations they generate during flight. For this, all spacecraft—and sometimes even their individual components—are tested pre-launch on electric or hydraulic shaker tables, which simulate a rocket’s intense vibrations. The European Space Agency’s HYDRA facility can generate vibrations equivalent to an earthquake of 7.5 on the Richter scale.