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Name: Teodor
Status: student
Grade: 9-12
Country: Macedonia
Date: Summer 2013


Question:
I am very interested in space travel and I just found out that we can also travel with ion propulsion. So my question is can we travel on earth with ion propulsion or only in space?



Replies:
Hi Teodor,

The reason why an ion engine is not suitable for propulsion on earth is simple. Ion engines produce only a very tiny amount of thrust. In space where there is no resistance to motion, this is no problem. Although a large ion engine may only produce a few newtons of thrust, the engine can easily operate for weeks or months. Even though the resulting small thrust results in an extremely small acceleration, in space where there is no friction, weeks or months of this acceleration will eventually result in very high spacecraft speeds.

But down on earth, where a moving body must overcome friction, a thrust of a few Newtons wouldn't even start a vehicle moving!

Regards, Bob Wilson


Hi Teodor,

Thanks for the question. In principle, you can travel on Earth using ion propulsion. However, when ions are exposed to air, they become neutralized and charge on them becomes zero. This results in a substantial decrease in propulsion and the propulsion energy is wasted as heat. Furthermore, the ion source (containing a red hot wire which generates ions) will be destroyed when it is exposed to air. It is much like a light bulb burning out. Ion propulsion works in space since there is no air to interfere.

Thanks Jeff Grell



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