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.
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 beamed to the rocket with powerful lasers! The original idea on beaming energy to a space rocket was invented by Konstantin Tsiolkovsky in 1924. Genius and visionary, Tsiolkovsky could not know about lasers (the first laser was demonstrated in 1960), so he was talking about tight beams of light, beamed to a rocket and hence providing it with necessary energy or, in other words, making the rocket much more energy efficient. In 1924 all this was just a dream, a few decades later Arthur Kantrowitz presented the world with scientifically sound plan for turning this dream into reality.
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.
Laser-propelled rocket will be made of light focusing optics (mirrors), modest amount of ablative solid fuel, and the rest is a payload. No more need for heavy fuel/oxidizer, tanks, lines, chambers, nozzles! Kantrowitz called it 4P Principle: Payload, Propellant and Photons, Period! Scientifically proven (and repeated in different ways for many times) calculations show that with the laser propulsion space delivery price will be reduced to $100 per pound of a payload! It is hundredfold savings!
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.
Tags: advanced space propulsion, beamed-energy propulsion, laser propulsion, Science, space propuslion, space science, space technology, technology