A technology that uses a magnetic balloon to sail ionized particles shed by the Sun could speed humans to the Jovian moons in less than two years and push a probe past Voyager 1 to become the first spacecraft beyond our Solar System. The low-cost Mini-Magnetosphere Plasma Propulsion, or M2P2, propels spacecraft at speeds far greater than today’s chemical and even ion propulsion systems, and its magnetic-field sail would even protect travelers from deadly solar and Jovian radiation.