1. - - Harnessing Propellant-Free Space Travel Through Electromagnetic Radiation Pressure Riley Burton and Bryan Konieczka Radiation Pressure An anomaly that occurs when electromagnetic radiation in the form of microwaves pass through a magnetic field into a reflecting waveguide assembly Deflecting off of surfaces of different cross- sectional areas, an imbalance of momentum is transferred to the assembly The difference in pressure exerted on the refractors produces a net force in one direction Fig 1: Waveguide assembly illustrating the variance in forces due to areal differences between the top and bottom reflecting surfaces EmDrive Theoretical engine proposed by Roger Shawyer of Satellite Propulsion Ltd in 2006 Drive utilizes the idea of radiation pressure to produce a net thrust without requiring matter as a fuel source Consists of a magnetron which emits microwaves into a trapezoidal resonating cavity Theorized to exert a net force in one direction due to the effect of radiation pressure Fig 2: Satellite Propulsion Ltd’s demonstration EmDrive, note the trapezoidal shape of the cavity which induces a net thrust in the direction of the larger surface Fig 3 (above): Derivation of EmDrive thrust production as a function of input energy and radiation wavelength Figure 4 (below): Theoretical specific thrust from unloaded energy Research/Testing Theoretical verification and EmDrive experimentation by several notable engineering organizations worldwide: Satellite Propulsion Ltd, NASA Eagleworks Laboratories, and Northwestern Polytechnical Institute in China ExperimentSpecificsThrust Production Satellite Propulsion Ltd (experimental engine) 450 tests, incomplete but evident transfer of electricity to mechanical thrust 16 mN from 850W (demonstration engine) 134 test runs, increased energy input to cavity by a factor of 10 214mN/kW as opposed to the predicted 333mN NASA Eagleworks Laboratories Series of tests solely to confirm thrust production, no intent to improve upon prior thrust results approximately 30-50μN from low input power Northwestern Polytechnical Institute Confirms an increase in thrust from higher levels of energy consumption 720mN from 2.5kW EmDrive testing has given physical evidence that radiation pressure is capable of producing a net thrust Theoretical Implications Anomalous thrust production violates the Newtonian law of conservation of momentum Change in velocity of a spacecraft requires a change in momentum of equal magnitude and opposite direction (expulsion of mass in the form of exhaust) EmDrive propulsion requires no fuel, mass is not ejected, so it should not create a change in momentum Physicists and engineers remain suspicious of the EmDrive’s workings because there is no explanation of this theoretical violation Future Application Bypasses limitations of current forms of propulsion EmDrive is dependent only on electrical input which is abundant in space Electricity needed can be harvested from the sun or generated via nuclear reactions No restrictions on range, mission length, and craft encumbrance due to independence from physical fuel source Makes space exploration more plausible by introducing a more efficient, convenience form of thrust production rsb61@pitt.edu bek57@pitt.edu www.engineering.pitt.edu