PLANETARY SURFACE TRANSPORT SYSTEMS.

Much research work has been done on the development of levitated vehicles using electromagnetic propulsion for terrestrial transport applications. Apart from their high speed, other potential advantages in a lunar application would include high energy efficiency, high reliability, low system maintenance and operation from wholly electrical power sources. Of the known magnetic levitation techniques, the recently reported technology of Mixed-Mu Magnetic Levitation (which uses superconducting high-field magnets and screens of superconducting material to stabilise the magnetic lifting forces on a steel track) gives a number of important technical advantages over comparable systems. The track structure for a Mixed-Mu levitated vehicle could be built from ferromagnetic materials available on or near the lunar surface. The power requirements for the system are low and the levitation effect is available at all vehicle speeds, including at rest. The Mix-Mu Levitation principle is based on the diamagnetic property of superconducting materials, e. g. , their exclusion of magnetic fields (the Meissner effect). An important practical consequence of this is the existence of a repulsive force between a superconducting surface and a source of magnetic field nearby. This repulsive force can be used to stabilise the forces of attraction between a magnet and an iron body. Thus, by appropriate design, the magnetic force and the gravitational forces can be made to balance to produce free stable levitation.