Provided are various spacecraft propulsion systems, and associated methods of operation. A spacecraft comprises an ion propulsion system and an ion blocker suspended from the spacecraft via one or more electrically insulated tethers. The ion propulsion system is configured to generate a first propulsive force by emitting a charged ion beam in a direction with an ion velocity vector comprising an ion vector component that is perpendicular to a magnetic field of a planet, such as Earth. The magnetic field causes the ion beam to curve toward the ion blocker at a trajectory such that ions within the ion beam are blocked by the ion blocker to generate a second propulsive force on the ion blocker. The ion blocker blocks the ions by contacting or deflecting the ions. The ion blocker is positioned approximately twice the gyroradius of the ion beam trajectory.