Johnson-Tanaka Drive

A spacecraft drive system that works without reaction mass. This means it doesn't need to throw gas out the back of the craft to accelerate like a rocket, which makes it possible to accelerate for years at a time. This technology, combined with cryptosleep, is what made interstellar travel at all feasible for living humans. The drive doesn’t violate conservation laws; it works by transferring momentum to nearby stars along precisely-aligned “beams” of momentum waves instantiated in exotic virtual particles.

Regular interstellar space travel is possible because of JT drive. Without one, the trip between stars would take thousands if not millions of years.

Because of its complexity, researching these drives is simply beyond most if not all RimWorld colonies, and the only way to acquire one is steal one from a shipyard, trade for it with a glitterworld civilization, or find one wrecked on your planet.