How Plasma Rockets Work

Plasma: The Fourth State of Matter
A man checks out the world's largest HD LCD TV at a convention in Berlin. Plasma TVs are now very common. snapshot-photography/ullstein bild via Getty Images

The world is usually broken down into three states of matter: solid, liquid and gas. When matter is cold, it is solid. As it heats up, it turns into a liquid. When more heat is applied, you get a gas. The story doesn't end there, however. As you add even more heat, you get — plasma! The extra energy and heat break apart the neutral atoms and molecules in the gas into typically positively charged ions and negatively charged electrons. The charged particles give plasma interesting conductive properties, so plasma technology is used to make all sorts of items we use every day. Computer chips, neon signs, even the metallic coating on the inside of a bag of potato chips are created using plasma technology. And of course, there is the plasma television which uses plasma to release light photons, giving you a color display of pixels on your screen. In fact, 99 percent of ordinary matter in the universe is in the plasma state [source: Charles].

Most stars, including our sun, are made of plasma. If it's so prevalent in the universe, why don't we see it much on Earth? Well, actually, we do. The northern and southern lights are created by solar winds. And what are solar winds? Plasma! OK, not everyone is lucky enough to see these spectacular light displays, but you can see plasma in action during another awesome light shows provide by nature: a thunderstorm. As the electricity in lightning flows through the air, it provides so much energy to the molecules in its path that the gases in the lightning trail are actually transformed into plasma.

Plasma technology has also been used in rockets to help us get around outer space, and it holds the most promise for getting humans to places we could only dream of before. These rockets need to be in the vacuum of outer space to work since the density of air near the earth's surface slows down the acceleration of the ions in the plasma needed to create thrust, so we can't actually use them for lift-off from earth. However, some of these plasma engines have been operating in space since 1971. NASA typically uses them for upkeep on the International Space Station and satellites, as well as the main source for propulsion into deep space [source: NASA].

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