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An ion drive is a form of spacecraft propulsion that is currently being researched by NASA and the ESA. An ion drive is considered to be more efficient than traditional solid or liquid propellant rockets and in most cases provide more thrust. However they have not been used much beyond satellites and space probes. To understand the ion drive we need to know how it works and what are some of the challenges that engineers and scientist face in replacing traditional spacecraft propulsion with ion drives.
Ion drives like the name implies use ions as propellants. To be more specific they use gases like hydrogen and charge them until they become heated plasma. Since plasma is mostly composed of ions it allows for a unique form of propulsion that makes use of the Lorentz force or Coulomb Force. To be specific ion drives use either an electrostatic field or magnetic field to accelerate the charged particles of the propellant out the the engine creating thrust.
Ion drives have many advantages over traditional rocket engines. First, ion drives use fuel more efficiently. Energy is more clearly transferred to propellant and better directed. This allows for better management of fuel over long distances. There is also great thrust. Since the fuel is better managed an ion drive produces more thrust than a normal rocket engine this means greater velocities.
Ion Drives do have some challenges and drawbacks. First an Ion Drive can normally only work in the vaccum of space. This means there would need to be an alternative method for getting spacecraft of planet. This is a problems shared by theoretical ramjet aircraft. The other issue is acceleration. An ion drive can not at the moment produce the same propulsion as tradtional rockets so it seems unlikely that they can be effective for shorter missions like going to the Moon. However the do hold some promise for longer missions.
A big breakthrough was the successful testing of the VASIMR propulsion system in 2009. During the test scientists were able to have the system produce the full prototype capacity of 200kw. This opening some interesting possibilities for major missions in the future like a manned mission to mars. An engine based on this design could potentially cut a 6 month trip to Mars down to 39 days. This could help reduce the risk of overexposure to radiation and reduced gravity. It could also provide an out if the mission went wrong allowing astronauts to safely return to earth.
If you enjoyed this article there other interesting articles on Universe Today. There is a great article about the VASIMR tests. There is also an article on chemical propulsion.
You can also find great resources online. You can find some information on the NASA website on Deep Space 1 a probe powered by ion propulsion. You can also check out NASA’s ion propulsion website.