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Arthur Kantrowitz, Founding Father of Laser Propulsion

On November 29, 2009, in New York City, in age of 95 passed away Arthur Kantrowitz. Kantrowitz will be always remembered among most prominent American scientists of past century as a founder of Avco Everett Research Labs, professor of Dartmouth College, holder of numerous patents (from medicine to space) and supporter of Science Court. However, in this short note I would like to say a few words about one of his greatest contributions, which he made for us all and for future generations: the founding of laser propulsion.

Laser Propulsion is a part of rocket science, but dont be discouraged by a silly tag: the idea is simple. We pay on average $10,000 per every pound of payload delivered to low earth orbit. Why that much? Because, we use very inefficient carriers: chemical rockets. These hydrogen gluttons have to carry everything onboard: fuel, oxidizer, cryogenics, tanks, lines, you name it, leaving a small (and very expensive room) for the payload. If we could only find a way to separate the energy source from the vehicle, deliver that energy to the vehicle from some power station, the gain in efficiency of such vehicle will be tremendous.

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 Arthur Kantrowitz published in Astronautics and Aeronautics Propulsion to Orbit by Ground Based Lasers, a scientific paper which started a new field: laser propulsion. In this paper Kantrowitz proposed to change our very approach to space launches: instead of building larger (and even less energy-efficient rockets), start using high-power lasers for space launches of small satellites. Such satellites would literally straddle the tip of laser beam, focused on their propellant area. When high power laser beam is focused (even loosely) on a solid matter, such matter is evaporated and ionized almost instantaneously, i.e. the release of energy is much higher than one used from burning hydrogen in rockets. So, laser-driven vehicle will be still flying on the same rocket principle, but exhaust energy and structural lightness will be incomparably superior to hydrogen-burning rockets.

Driven by laser rocket will be composed of very light focusing mirrors, relatively small (energy efficient) solid propellant and, voila: the rest will be payload! Forget heavy liquefied gases (oxygen and hydrogen), cryogenics, fuel tanks and lines, combustion chambers, etc.: Payload, Propellant and Photons, Period! Arthur Kantrowitz called it 4P Rule. Bottom line: scientifically sound calculations have shown that the price of one pound of a payload delivered to low earth orbit will be drop to $100. Laser propulsion offers 100-fold, revolutionary savings on space deliveries.

The paper of Dr. Kantrowitz from 1972 marked the beginning of a new scientific quest. In early seventies Kantrowitz has initiated first research program on laser propulsion at Avco-Everett Research Labs, which for over a decade was the only research program in this field in the world. Later other projects ensued, first laser-propelled vehicles were launched (not into space yet, but high enough to prove the viability of an idea), other countries (Russia, Japan, Germany, China) and hundreds of scientists and engineers joined the quest for laser propulsion (and other forms of beamed-energy propulsion, such as microwave propulsion). However, we should always remember one man who started it all: Arthur Kantrowitz, the father of laser propulsion.

Tags: advanced space propulsion, beamed-energy propulsion, Computers & Technology, laser propulsion, science, space, space propuslion, space science, space technology, technology