THE MICROWAVE THERMAL ROCKET

In 1924, K.E. Tsiolkovsky wrote "there is a third and most attractive method of acquiring velocity. This consists in the transmission of energy from the outside, from Earth." He envisaged a "parallel beam of shortwave electromagnetic rays" directed from the ground to power spaceships into orbit at a future time when the problems of beam generation, tracking and refractory materials had been solved. Over the past 60 years, the power output of microwave sources in the key millimeter wavelength range has increased by over six orders of magnitude, for the first time putting Tsiolkovsky's vision within economic reach.

This presentation introduces The Microwave Thermal Rocket, a vehicle which uses a beam-absorbing heat exchanger in place of a combustion chamber to bypass the fundamental energy density limit of chemical reactants. It is shown how this implies a 1-2 stage rocket with a 5-15% payload fraction, as opposed to a 3-4 stage rocket with a 1-4% payload fraction.

Key simplifying approaches to refractory materials, trajectories, tracking, beam combining and millimeter wave telescopes are reviewed, particularly near-term (sometimes bordering on garage-ready) solutions that can be demonstrated in the next few years. Finally, the R&D now underway is discussed in the context of current technical uncertainties and future 1-100 meter altitude tests planned using NASA's 1.2 MW gyrotron beam facility, which is anticipated to be available for academic and industrial teams starting in 2012.

Speaker: Dr. Kevin Parkin, Carnegie Mellon Silicon Valley