# Ion engines

I was in a very heated debate with one of my friends last night and we agreed to let the straight dope community decide who is right.

The problem is very simple: If you put the same type of ionic drive that we currently have on some (Two maybe?) deep space probes, would it be strong enough to move a Ford Festive down the highway?

I guess the real question is how much thrust does an ion engine produce.

Thanks for giving me a few seconds of your gray matter

I don’t think so. I think they usually compare ion drive engines to the weight of a small rock or brick pushing down on your hand. I think the idea is that while their thrust is weak, it doesn’t have to be very strong in outer space, and the effect is cumulative.

So while the push is weak, it keeps building and building and eventually you’re going damned fast with just a little push.

–Tim

O.k. thanks that makes sense.

Do Ion engines produce thrust? My friend says that they produce inertia, but no thrust. That sounds kinda weird to me. I thought that if some thing moves there is thrust behind it. Am I wrong?

Not to mention the fact that here on the ground, cars have friction to deal with. That weak, steady force is probably no more effective at accelerating your Ford than you leaning on it.

This site indicates that the thrust produced by the ion drive on Deep Space 1 is about 0.1 N (0.022 lb) of force.

Inertia is a property of matter. It is the resistance of an object to acceleration, and is measured by the mass of an object. Thrust is force, and yes, if an object is to be acclerated, it must have a net force acting on it. If an object is moving at constant velocity, however, there must be no net force acting on it. (The converse is also true.) This is Newton’s 1st Law.

You cannot “produce” inertia (in the context that your friend is using the term).