No Blight

Artur Kantrowitz, a prominent American scientist of late twentieth century, died in age of 95 in New York City on November 29, 2008. Founder of Avco Everett Research Labs, professor of Dartmouth College, champion of Science Court and versatile inventor, he will be always remembered. In this short note I just like to say a word about one of his greatest ideas and contributions to society, which will benefit future generations of our planet. I am talking about his role in founding of laser propulsion.

It is rocket science, but forget the silly clich: the idea of laser propulsion is simple. Modern space rockets are too heavy, inefficient, and dangerous, because they have to carry their fuel and oxidizer onboard. On average they cost us $10,000 per pound of a payload delivered to low earth orbit. If someone could find a way to separate the energy source from a rocket, which will eliminate all fuel-related burden, the gain in rocket efficiency will be enormous.

The energy can be delivered with powerful laser beams! Believe it or not, the original idea was published in 1924 by Konstantin Tsiolkovsky, the space scientist and great visionary, who preceded his own times for at least on half-century. Tsiolkovsky pointed out that energy can be delivered to a space rocket by means of tight light beams (laser was invented 35 years later). The idea of light-beaming energy to a rocket that could be just a dream in 1924, was refined, formulated and delivered by Arthur Kantrowitz as a precise scientific concept of laser propuslion.

In 1972 Kantrowitz published a paper Propulsion to orbit by ground based lasers, with a genius idea: to launch light satellites right from the ground to space with high-power laser beams. In this the vehicle will be just straddling the tip of the beam. When laser beam is focused on a solid surface, it has enough power to vaporize and ionize almost anything with energy release much higher than hydrogen burning, used in modern space rockets. So, comparing to chemical rockets, laser propulsion uses the same rocket principle, excepting much more energetic exhaust and much lighter vehicle structure: no tanks, fuel lines, etc. leaving a lot of room for a payload.

Payload, Propellant, Photons, Period! ” 4P Principle introduced by Kantrowitz was an essence of laser propulsion. Laser-driven vehicles will consist of lightweight focusing optics (mirrors), modest amount of solid ablative propellant and the rest: the rest will be payload! No more fuel, cryogenics, tanks, combustion chambers. As a result, scientifically-proven calculations have shown that the price of space delivery per pound will drop from $10,000 (hydrogen “burning rockets) to a modest $100 (laser-driven rockets): a hundredfold, revolutionary change in price!

The paper of Kantrowitz was like a manifesto, an opening to a new technological paradigm, well thought, clearly formulated and delivered. For those who never worked in science, this can be compared to a person who says, hey, here is a diamond field, and I am showing you exactly how to get there. He was a real forerunner, so he started at Avco Everett Research Labs the first in the world research program on laser propulsion. Ten years later other research groups joined the cause, ten more years first laser-driven demo missions were launched (not into space yet, but into air). New studies were opened in Russia, Japan, Germany, China, new forms of beamed-energy propulsion were discovered and explored (microwave propulsion). It is amazing how the field that involved hundreds and yet attracts new hundreds of scientists and engineers was once just a pure immaterial thought of a visionary. So he was a visionary, Arthur Kantrowitz, the founding father of laser propulsion, and he will be always remembered.