The “Lightcraft” is a laser-propelled spacecraft, flying saucer concept that could ultimately run on other beamed energies, such as microwave.
Video includes NASA concept of propelling craft using helium for initial liftoff, then power is supplied by a beam of microwaves generated by solar power collected by satellite.
This method of propulsion would greatly reduce the size of spacecraft.
It could also provide a cost effective environmental friendly way of air transport around the world based on solar power.
A video worth watching