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Article: Electric rockets.(Rocketry)
- Article from:
- Popular Mechanics
- Article date:
- March 1, 2004
- Author:
CopyrightCOPYRIGHT 2004 Hearst Communications, reprinted with permission of Hearst. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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Watching the fire and thunder that accompany a rocket launch, that pyrotechnics have little to do with moving spaceships. It is all about mass. Or, as Sir Isaac Newton's Third Law of Motion so aptly puts it: For every action there is an equal and opposite reaction. A rocker is a reaction engine--if moves forward when mass is thrown backward. Air has mass, which is why a party balloon that slips from your fingers loops across the room. Lifting more substantial payloads into space requires ejecting tons of mass per second. One very efficient way to release a large amount of mass quickly is to turn it into a high-pressure gas--hence, the fireball that engulfs the launchpad ...