Beamed Energy Propulsion (BEP) is rocket science, but you don’t have to be a rocket scientist to understand the concept. Because it’s as simple as any ingenious idea. In the next four paragraphs and in simple terms I will explain it to you.
It’s about rockets. What does everyone know about them? On Earth, movement is based on pushing from the environment, wherever movement takes place: cars pushing off the pavement with their wheels, swimmers pushing up from the water with their limbs, etc. Rockets fly in space and space is mostly a vacuum, it’s empty. Rockets move in space using the reactive principle, that is, expelling hot gases (backwards) and moving away from exhaust gases in the opposite direction (forwards). Rockets have to carry all of their fuel and combustion agent on board, because there is nothing in space that can be used to burn fuel (like air is used to burn gasoline in cars on Earth).
Rocket cargo space is very expensive. Because? Because with so many items on board: fuel, oxidizer, cryogenics, tanks, lines, you name it, there is little (and very expensive) space for payload. If we could find a way to separate the heavy power source from the rocket, the rocket efficiency gain would be tremendous.
This can be done if instead of bringing the power source on board, we transmit that power from a remote power station. What kind of beam can it be? The laser beam, the microwave beam, even the X-ray, in all cases, the energy will be sent to the rocket at the speed of light. When a large number of photons are focused (even weakly) on a solid matter, such matter evaporates and ionizes almost instantly, that is, the energy release is much greater than that used when burning hydrogen. Thus, the laser-powered vehicle will still fly on the same rocket principle (flying away from its exhaust), but the exhaust energy and structural lightness will be incomparably superior to hydrogen-burning rockets.
The beam-propelled rocket is equipped with beam-collecting optics (ie mirrors) and some relatively light solid fuel. That’s all – no more tanks, oxidizers, cryogenics, nozzles, lines, the rest will be cargo. Said rocket will be a subject of Principle 4P, formulated by the founder of laser propulsion, Arthur Kantrowitz: Payload, propellants and photons, period!
How much emitted energy is more efficient than traditional hydrogen burning? About a hundred times! Currently, for the reasons stated above, we are paying $10,000 per pound for payload delivered from the ground to Low Earth Orbit only. If space launches are done with high powered lasers, the price per pound of payload will drop to $100! This is a 100 times profit!
In addition to laser beams, other types of energy transfers using microwaves, X-rays, and even particle beams are being explored for BEP. The number of laboratory demonstrations of BEP principles is growing every year, and the day when we will achieve the BEP demonstration in space becomes inevitable. Of course, there are still many scientific and engineering problems that need to be solved before BEP will deliver its benefits to us. However, the days for the first practical use of energy beam propulsion are near.