Rocket Static Fire Test

An important part of designing and building any spaceship is making sure the engines work.  Rockets are complex pieces of machinery that depend on detailed timing.  So, they are tested on a mount.  If it explodes, then you aren't damaging the rest of the spaceship.  Rockets will test like this several times in a design cycle, and even after design to make sure it was built correctly.  Most of the time, they don't explode, even if they aren't working quite right.  However, it is the exploding tests that become popular videos to watch!