MAGNETOBRAKING FOR MARS RETURN VEHICLES

It is proposed that magnetobraking may be used to dissipate hyperbolic excess velocity from a spacecraft returning from Mars to Earth orbit. In magnetobraking, an electrodynamic tether is deployed from the spac ecraft. The Earth's magnetic field produces a force on electrical curr ent in the tether, which can be used to either brake or accelerate the spacecraft without expenditure of reaction mass. The peak acceleratio n on the Mars return is 0.007 m/s(2), and the amount of braking possib le is dependent on the density and current-carrying capacity of the te ther, but is independent of length. Since energy is produced as the sp acecraft velocity decreases, no on-board power source is required. As the spacecraft approaches the Earth, the magnetic field increases and the power produced by the tether increases, reaching a maximum of abou t 800 W per kg of spacecraft mass at closest approach.