Initial tests made by a team of scientists from Colorado-based Escape Dynamics (ED) show that microwaves sent from the ground might be used to propel space-planes into space. If this is actually confirmed as a feasible and safe technique, the process of sending out satellites into orbit might become much less costly.
The current method of launching spacecrafts is based on filling each part of a multi-stage rocket with propellant that burns to project it into space. This process is extremely expensive since the propellant is exceedingly heavy. ED, therefore, wishes to make use of microwaves beamed from the ground to burn hydrogen. The latter would be carried by the space-plane to push the craft into space. This method is deemed to be more efficient. Testing done suggests that it might even be feasible.
For the testing, a thruster operating on the ground was built. The capacity of the thrust was tested: a specific impulse of 500 seconds when using helium was achieved; this might increase to 600 seconds if hydrogen were to be used.
On a real space-place, the microwaves would hit the heat shield found at the bottom of it. The electromagnetic motor would then be powered, thereby heating the hydrogen as it was emitted from a tank. This would ultimately result in a thrust. Electricity would be used to power the microwave array.
When in orbit, the space-plane would stay afloat for a sufficient amount of time to release a satellite and then it would return to the Earth.
More tests need to be done before the idea is confirmed. For instance, the microwave array will have to be strong enough. It will have to maintain tracking of the space-plane. Safety issues will also need to be tackled.