Benefit of Constant Momentum Propulsion for Large Delta V Missions -- Applications in Laser Propulsion

Abstract : The authors show that perfect propulsion requires a constant momentum mission as a consequence of Newton's second law. Perfect propulsion occurs when the velocity of the propelled mass in the inertial frame of reference matches the velocity of the propellant jet in the rocket frame of reference. They compare constant momentum propulsion to constant specific impulse propulsion, which, for a given specification of the mission Delta V, has an optimum specific impulse that maximizes the propelled mass per unit jet kinetic energy investment. They also describe findings of more than 50% efficiency for conversion of laser energy into jet kinetic energy by ablation of solids.