In the absence of any significant gravitational or atmospheric forces, a bullet fired into space will continue to travel in a straight line unless acted upon by an external force. The distance it will travel depends on its initial velocity, the direction it is fired in, and any potential interactions it may have with celestial objects or interstellar matter.

While in space, the bullet will be in a state of perpetual motion, known as constant velocity. This means it will maintain its initial speed and trajectory unless acted upon by an external force, such as the gravitational pull of a nearby planet or other object.

Therefore, the distance the bullet travels will primarily be determined by the initial velocity it was given when fired and the amount of time it has been in space.