Ion Engine Ready for Space

I was looking around online and came across an interesting article revealing that NASA is ready to use ion engines in their spacecraft.

Surpassing the longest operating duration of previous ion engines by 5,000 hours, NEXT has operated for more than 35,500 hours, more than four years of cumulative time. In addition, over 600 kilograms of xenon propellant have been expended, twice as much as originally required. These two measures are essential to accomplishing long-duration scientific space exploration missions.

Link to Article

I thought NASA was being torn down? Man, I really need to get back with the times.

This seems to be similar to VASIMR, which is also an ionized engine. Supposedly it was going to be tested in space later this year but I haven't heard much about it lately with the funding issues. I really think this has some potential, I hope it works and opens up some new doors in space exploration.

I thought Mythbusters said Ion Lifters wouldn't work in the vacuum of space?



Or is an ion engine something completely unrelated to this phenomenon?

Ive always wondered something, which I am sure has already been answered here but...
In an atmosphere jets/rockets or any other propellant based flying machine gains thrust from
the exhaust pushing against the air.
So, if theres nothing to push against, like in a vacuum, how is forward momentum initially created?

reply to post by TriForce


Wrong.....

In an atmosphere jets/rockets or any other propellant based flying machine gains thrust from
the exhaust pushing against the air.

NOT from "pushing against the air".

A "pure" jet engine accelerates a mass of air, and expels it.....this creates the thrust....the MASS being expelled (Newton's Third Law). Rockets, same thing. The effect is seen, also, in a simple balloon. Blow it up, and release it untied. Air escaping exerts the energy to propel the balloon opposite direction.

NOW.....for an aircraft that uses a propeller, or a modern high-bypass turbofan jet engine.....in those cases the propulsion is "using" the air too....."throwing" it backwards to propel forward. Great quantities, and thus mass.

British sometimes call a propeller an "airscrew". The propellers on ships and boats are called the "screw" also.


One more way to realize that it isn't "pushing against the air" is to do this: Sitting in your chair, try to push yourself out of it with your hands....just "pushing" against the air.....won't work, will it?

reply to post by weedwhacker

One more way to realize that it isn't "pushing against the air" is to do this: Sitting in your chair, try to push yourself out of it with your hands....just "pushing" against the air.....won't work, will it?

So, how does a bird fly? Small jet engines in each feather or do their wings "push" against the air to gain lift?

I say that because, if my hand was big enough and my muscles strong enough a person could move by "flapping their arms" maybe not fly but you get my point right?

reply to post by TriForce


With birds, it's a combination. When they flap, the wings behave similarly to airplane propellers, in the sense as described. "Grabbing" air, and forcing the mass of air in one direction....Newton's Third Law in action, propels the bird the other direction.

But, birds can soar too.....in those cases they are just like the wing (airfoil) of an airplane. Of course, birds have evolved to be able to do this, and are (usually) light in mass, in order to achieve flight, solely on their own muscle power alone. (Without the technology that we need....to fly).

How does a bird fly through the air?
When a bird flaps its wings, air is pushed downward. This produces an opposite force that “lifts” the bird into the air. Since a bird’s wing is in the shape of an airfoil, it produces some lift even when the bird is just gliding.

Ok well, ive strayed us off topic here.
Let me ask this, with an Ion engine, is its "top" speed solely based on the amount of fuel its able to burn across space?
Once the fuel burns out, there is only inertia to keep it going right?

reply to post by TriForce


The theoretical maximum velocity would ultimately be determined by the speed at which the exhaust leaves the engine, in a perfect vacuum. At some percentage of the exhaust speed the ship could no longer gain sufficient thrust to accelerate it's mass. I believe the theoretical max velocity of these ion engines is around 10% of the speed of light (18,600 miles per second). Ion engines don't exhert the same type of force as rockets though, so the craft would need accelerate for a very long time to approach that speed.