Question: hi charlie! very fascinating job and very creative! Will you build one for humans next time, and how long would it take?

Charlie Ryan answered on 19 Mar 2011:

hi amblotte thanks for your question and your interest in what i do!
Will the rockets i test work for human spacecraft?? Nosadly they wouldn’t!
The type of rocket i make and test is called an ion thruster (as i may of mentioned). They create charged particles (ions, obviously!) and attract them to an oppositely charged grid, which the ions shoot through into space. This gives a small amount of thrust – but really small! It’s about 1 millionth of a Newton, so that’s like the weight of one millionth of a apple on your hand!! You would barely feel the force created!!
So if the force is so small why bother with these ino thruster?? Well for starters they are very small, so can fit on very small spacecraft where larger rockets can’t. And secondly the ions are much faster than the burnt chemicals thrown out of the exhaust of a normal rocket engine (like the space shuttle). This makes them more efficient.
So…..because humans, and the spacecraft needed to carry humans, are pretty big, the thrusters have to have quite a lot of thrust. The space shuttle main engine has a thrust of 2 million newtons, millions of times bigger than the thrust i get. So although the thruster i test would manage to push the human spacecraft a tiny amount, it would take a really REALLY long time to get anywhere!