This brief note is about Beamed Energy Propulsion (BEP), which is, actually, a rocket science. However, you dont have to be a rocket scientist in order to understand what it is about, it is simple and I will explain it to you in next few paragraphs.
Rocket science is of course about rockets. What is so special about rockets? Motion on Earth is based on pushing from the environment, wherever the motion takes place. For example, cars use wheels to push from the pavement, birds use wings to push from air, and so on. Space is empty, so in order to fly in space every rocket has to use reaction principle, i.e. burn fuel, form exhaust gases and push from that exhaust in opposite direction. There is no air in space, so if you need to burn fuel, you have to carry burning agent together with the fuel onboard. Hence rockets has to carry onboard their fuel (hydrogen), oxidizer (oxygen) and everything that needed to burn hydrogen and keep the motion in desired direction (rocket engine).
So, the rockets are the only manmade vehicles that push away from their own exhaust and move that way. Rockets have to carry everything needed for motion in space onboard, is a heavy burden and it brings a great downside: price of cargo gets enormously high. If we can only separate the source of energy from a rocket, we will be rewarded with gigantic increase in efficiency!
Energy can be delivered to the rocket from remote external source using light or, say, laser, x-ray, microwave high-power beams. With its mirrors, rocket will collect and focus that beams on its "fuel". Any solid matter can be a fuel. When high-power beam of photons is focused on a solid material, the material evaporates and ionizes instantaneously. The energy density in focused high-power beam exceeds hundreds to millions times one in the heat of burning hydrogen. Thus, beam-driven rocket will remain a rocket, it will be pushing from its own exhaust, but the energy of this exhaust is much higher, and the rocket itself is much lighter, comparing to hydrogen burners.
Beam-driven rocket is equipped with beam-collecting optics (i.e. mirrors) and some relatively lightweight solid fuel. That is it: no more tanks, oxidizer, cryogenics, nozzles, lines, - the rest will be cargo. Such rocket will be a subject of 4P Principle, formulated by the founder of laser propulsion, Arthur Kantrowitz: Payload, Propellants and Photons, Period!
So, what is efficiency gain of beam-driven rocket vs. hydrogen burning rocket? Hydrogen burners cost us $10,000 per pound of a payload delivered to low earth orbit. Scientifically-proven calculations have shown that the price of space delivery per pound drops to minute $100 for laser-driven rockets: a hundredfold, revolutionary change in cost!
Laser propulsion, i.e. use of high-power lasers for satellite launches and in-space transportation is the most developed today branch of BEP. Various types of laser propulsion have been demonstrated in field and by many research groups in lab. Microwave propulsion is another relatively well explored part of BEP. Much less is known about potential of x-rays and particle beams for BEP. Overall, beamed-energy propulsion remains a field of future technology, where a lot of interesting development will happen in the next several decades. Still, it is quite clear, that in the future a great part of space transportation will be driven by high-power photonic beams.
About the Author:
Andrew Pakhomov is founder and president of American Institute of Beamed Energy Propulsion, a nonprofit scientific organization serving to development and popularization of this space technology of tomorrow AIBEP
He is also associate professor of physics at University of Alabama in Huntsville. To know more about current research on beamed energy propulsion, please visit official site of AIBEP
