The magnetohydrodynamic microwave propulsion drive is every bit as complicated as it sounds. It bears a resemblance to laser light craft, in that it uses a microwave beam which is directed onto a reflective surface, which creates an explosion, and thrust. The complicated part comes in at the time of the first part of the name, the magnetohydrodynamic part. This means, in highly abridged form, that the microwave beam's energy is somewhat taken, and used to reduce air friction. The energy is used to ionize the atmosphere's gases, and then they are expelled forward. They create a drag-less vacuum which dramatically reduces the air friction. Think of it as the ionized gas being a snow plow moving the 3 ft. deep snow out of your path on the way to your work, you could do it without the snow plow, but it would be very slow. This propulsion would either take craft into orbit (where the ionized gas would be useless and nonexistant), or it could move things around on earth.

The solar thermal propulsion uses a very big magnifying glass, which focuses the sun's light onto a small block of graphite. This heats the graphite to many thousands of degrees. Then hydrogen is pumped over it, and it expands and is focused with nozzles. Basically it works like a standard chemical engine, and could be used to take satellites into higher or lower orbits.

The last, light sails, would be used to position stationary craft which would observe the sun. The solar winds, and the sun's light itself, would bounce off of an enormous, and light, sail which would produce enough "propulsion" to resist the sun's gravity. This would cause it to be stationary.

These propulsions all have their roles, but they are either far fetched, or not very glamorous.