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.