The problem with traditional rockets is that they’re terribly inefficient. About 90% of a mission’s initial weight is fuel, most of which is burned up escaping earth’s gravitational pull. After that, a traditional rocket could only slowly coast to Mars. Very slowly. Scientists describe rocket efficiency in terms of specific impulse, which is a rough measure of how fast fuel is ejected out of the back of the rocket. A chemical rocket has a relatively low specific impulse of 450 seconds - in other words, it gets one pound of thrust from one pound of fuel for 450 seconds.
Chang-Diaz’s prototype, however, promises specific impulses as high as 15,000 seconds. How? Well, his rocket doesn’t achieve propulsion by combusting fuel but, rather, by superheating atoms to create and expel a plasma plume. |
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