ion engines?

Question

during a recent show I watched, they were talking about using ION Engines instead of the ordinary chemical mixture that NASA uses now.
My question is, will it make the craft faster using these new ion engines? will it make it quieter? How much difference will there be besides the chemical mixture?

Answer 1

Ion engines are not powerful enough to lift an object from earth to orbit. They are only used in space, and only when you don't need any sudden changes in velocity. They are very low thrust, though the exhaust is very high speed, because they electromagnetically accelerate charged atoms (ions). Because they exhaust only a rather narrow stream of ions, they don't use a great deal of fuel, so with a fairly small fuel tank, they can accelerate continuously for extended periods. This continuous acceleration can result in extremely high speeds after a while, which is why ion engines are desirable for interplanetary missions.

Answer 2

Current ion engines use xenon gas. The gas is ionised and then accelerated by electric fields. The idea is that you get a greater exhaust velocity. However the thrust is very small. In principle you could make the spacecraft go faster than with a current kerosene/oxygen or hydrogen/oxygen system but it would take a long time and at this point you still need the combustion rocket to get the spacecraft off the planet and into space in the first place.

Answer 3

Ion propulsion is electric. It used electricity to shoot a beam of ionized gas out the back instead of using the heat of burning fuel to shoot a jet of hot gas out the back. This is much more fuel efficient, but the thrust is extremely low, so the engine has to run for months to cause the same velocity change that a chemical engine can cause if a few minutes. This is no problem if you are going to Jupiter but you don't have time to wait for the speed to build up on short trips. And the thrust is too low to launch from the ground, it can only be used once you are in orbit.

Answer 4

Two of newton's equations can help us understand why ion engines are so attractive for space flight:

Mo = mv (momentum)

Ke = 1/2 * m * v^2 (kinetic energy)

The first equation shows that even if the exhaust mass is small if the exhaust velocity can be very large, and we can keep it up for long periods we can indeed provide a substantial momentum to the rocket. The second equation makes it clear that velocity is more important --in some sense-- than mass, especially where we do not have access to large amounts of mass for long periods.

If we can take a reasonable amount of mass and expel it at high velocity for long periods of time, then we can achieve high travel velocity. This makes something like an ion engine attractive for deep-space travel, but not for lifting mass from the surface of a planet.

HTH

Charles

Answer 5

For every action there is an equal and opposite reaction. The space craft will go at the speed equal and opposite to the speed of the thrust but duration has to be long enough to overcome it's mass; a small fast thrust needs more time than a large thrust of the same speed for that mass. Ion thrusters have an incredibly fast thrust but it is weak and needs time to push that mass. It is quiet as in space everything is; it won't work against gravity as it does not have that power, yet. Given time, they will really push.

Answer 6

Ion engines at this point are for deep space only. They cannot make enough power yet to launch a vehicle and they can only accelerate in space because of the non existence of drag. The space vehicle deepspace 1 is the first craft of its kind to use an ion engine.

Answer 7

RE.... Watch the PROGRAM..... or Email......NASA!

Thanks, RR