Matthew Lipinski
10/23/15
ESS 102
Research Paper Rough Draft
Electric Thrust Space is a vast entity; the distance between any two bodies is great. Even a journey to the moon - 3.84e8 meters, a relatively short trip - took the Apollo 11 mission 8 days to complete. More ambitious missions involve much greater distances; Europa is 6.28e11 meters away while the distance to Alpha Centauri, 4.13e16 meters, is better measured in parsecs. Conventional chemical rockets are unable to propel spacecraft that distance in a cost effective - or even practical - manner. The amount of fuel needed to reach an acceptable speed would be difficult to contain in a spacecraft and would cost an astronomical amount of money. There are alternatives to chemical rockets in space that are much more cost effective. One of the most promising methods of propulsion is the ion thruster. Ion thrusters, while not producing much thrust, are able to pull longer burns using a much smaller fuel mass than their chemical counterparts.
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The thrust created is relatively small, measured in milliNewtons; while this is a significant disadvantage to more conventional chemical rockets, the advantage to ion thrusters is that they are powered by electricity. Instead of being dependant on a fast-burning chemical reaction to generate thrust, an ion thruster only needs electricity to operate. This allows ion thrusters to burn for long periods of time, weeks or even years at a time, as opposed to minutes or hours for a chemical rocket. NASA has run an experiment on an ion engine in which it ran for 48,000 hours, about 5.5 years without stopping. A burn of this extended period would allow for a massive change in velocity, despite the low maximum