In the Star Trek universe, the impulse drive is the method of propulsion that starships and other spacecraft use when they are travelling below the speed of light.

In the Star Trek universe, the impulse drive is the method of propulsion that starships and other spacecraft use when they are travelling below the speed of light. Typically powered by deuterium fusion reactors, impulse engines let ships travel interplanetary distances readily. For example, Starfleet Academy cadets use impulse engines when flying from Earth to Saturn and back.