It is expected that the flying vehicle will have a positive charge, which, when interacting with a positively charged lunar surface, will allow it to lift and hover above the surface of an Earth satellite.
Scientists have proposed using a variety of ion engines as a source of charge generation. In this case, the voltage will be applied to the ionic liquid in the form of molten salt.
Note that similar engines are already being used in small satellites. How soon the project will get to the final stage has not yet been announced.