Space Travel

Okay, I'm going to make this short and sweet before I forget about it.

Spaceships (can) travel by expelling an ion jet into an ion cloud (I like ions because they are small). The same way a rocket works, more or less, only rockets push off from the cloud formed by their own jet, which already has a negative vector (with respect to the vector of the rocket). By producing a cloud at the same velocity as the body you are moving, you can increase thrust (or so my limited knowledge of high school level physics and logic would suggest).

Does this matter? Not really. Maybe a little for engine design.

The important thing is the ion trail that is produced which can obviously be tracked. If someone picks up your ion trail, they can determine how long ago you were there (or somewhere. the trail will obviously move in the opposite direction of the spaceship) based on the dispersion of the ions and, I'm sure, a number of other technical criteria.

How does one avoid being tracked? Simple. Use your main ion thrusters to get you going in a direction that isn't exactly where you are going (most useful if it appears to be headed somewhere else) then dart using standard gas thrusters in very short bursts. Your pursuer will track your ion trail in a straight vector. Meanwhile, while moving in roughly the same direction (your forward vector will be constant in space unless you add a counter force which simply cancels all the energy you put into firing your ion thrusters) you are now on your way to a destination that becomes increasingly different the longer you drift. More darting means a harder track to follow. However, a trained gas dynamic physicist/astro-navigator/three-dimension trigonometric analyst may be able to detect the unusual small gas pocket that you have expelled in the opposite direction and deduce from dispersion pattern the age and origin of the gas and, when compared with the vector given by the ion trail, the new vector of the ship.

Ohh sweet science, how I missed you!

Funny, I thought of this while I was thinking about relationships...