Where There’s No Smoke, There’s Rockets?

Quick. What’s the best part about a rocket launch, any rocket launch? If you ask me, it’s seeing something like this.

Right? So, would someone please explain to me what’s the point of a smokeless rocket launch?

James Woodward, a history professor at California State University in Fullerton, presented his research into Mach-Lorentz thrusters Wednesday at the Future in Review conference here. Mach-Lorentz thrusters (MLTs), assuming they can be scaled up from lab tests, could provide a new source of propulsion that "puts out thrust without blowing stuff out the tailpipe," Woodward said.

MLTs are based on Mach’s principle, which suggests that all particles in the universe have an effect on each other, and the work of Hendrik Lorentz, who conducted research into the movement of charged particles in a magnetic field. Woodward has constructed an engine that takes advantage of the fact that objects produce energy when their mass changes slightly, he said.

Woodward used capacitors to change the mass of an object and then applied a current to that mass. That produces a small amount of thrust. Increasing the voltage and frequency of the current increases the strength of the thrust, to the point where the engine could be used to adjust the orbit of a satellite, or push a rocket into space.

Is there a downside to "blowing stuff out the tailpipe"? Is there an upside to not doing so?