NASA engineers have a plan to build a magnetic railway system on the moon that would use floating robots to carry supplies and materials around a lunar base so astronauts can eventually reach Mars. The plan calls for laying flexible film tracks that would use embedded electrical circuitry to levitate and propel the unpowered cargo robots. Unlike conventional lunar robots with legs, wheels and tank-style treads, those planned for the magnetic railway would have no moving parts to prevent abrasion and wear from lunar dust. The project — called FLOAT, for Flexible Levitation on a Track — was unve…