Reactionless propulsion

Inertial propulsion, support-less propulsion, or reactionless propulsion are all names of the technological concept of a an engine that moves a spacecraft without using any external body to push from, and without jettisoning any of its parts. In other words, it does not use the Newtonian principle of action and reaction. Some theoretical and fictional approaches involve "folding space" or other non-Newtonian principles, especially for faster-than-light travel. Some of those approaches, however, have aspects of perpetual motion machines.

E. E. "Doc" Smith, a popular "space opera" writer of the 1930s and 1940s, indeed used the idea of "intertia cancellation" as the basis for his high-speed and faster-than-light propulsion. He called ships subject to Newtonian inertia as "inert", and the others "free". His principles worked well in the fiction of the time, but correspond to no generally accepted modern physical principles.

Inertial propulsion is not to be confused with the well-established technique of inertial navigation.

History

(PD) Illustration: Theodor Hosemann
Baron Munchausen uses support-less propulsion to get out from the swamp by pulling himself up by his hair.

The need to push anything in order to cause any movement was recognized well before Christ. The sentence "Give me a place to stand and I will move the Earth" is attributed to Archimedes. Since that time, there was not so many documents about the inertial propulsion.

The most famous (and, according to the story, successful) intent of the support-less propulsion is attributed to Baron Münchhausen. Some proposals offer detailed schemes of inertial propulsion engines.

Not many researchers consider support-less propulsion seriously, if at all. Indeed, such propulsion contradicts the First law of Newton: there exist reference frames (so-called Inertial frame of reference) in which all bodies that are far from other bodies, move straight with constant speed or rest immobile. Traditionally, support-less propulsion was considered as nonsense, as some equivalent of perpetual motion which contradicts the fundamental concepts of physics. Exploring the principle of equivalence of the gravitation and the inertial force, support-less propulsion can also be called antigravity; the claims for which were considered to be science-fiction, circus illusions and a subject for jokes.

Interest in inertial propulsion

The interest in Inertial propulsion arose in Russia during the early years of the 21st century as documented by reports such as this by the Russian Information Agency Novosti (RIA Novosti):

The Scientific Research Institute for Space Systems (SRISS) is busy developing a perpetual-motion engine of sorts. This engine that will have a virtually unlimited service life that could be used on Earth and in outer space. Valery Menshikov, who heads the Institute, said in mid-March "Our Institute's staffers have been developing a non-jet propulsion unit for several years. A liquid or solid-state propulsive mass moves along a preset tornado-shaped trajectory inside this engine, thereby ensuring sustainable propulsion. Quite possibly, we are witnessing a hitherto unknown interaction between the propulsive mass and little-studied fields, including the gravitation field." This unique solar-powered engine will have a service life of at least 15 years, developers claim. And it can be switched on 300,000 times or so.

and this by Pravda, the Russian newspaper:

Specialists of the Scientific Research Institute for Space Systems conducted successful tests of a perpetual motion machine in space. Valery Menshikov, the director of the institute, said that the machine was installed in the Jubilee satellite which was launched into orbit almost a year ago. The satellite can now move from one orbit to another with the help of the engine, which discharges no reaction mass. The first tests were conducted in June and July of 2008. The tests revealed some problems that need further developments of the machine, but the orbital experiment was conducted successfully in general.

Criticism

The research, development and testing of inertial propulsion in Russia has been funded by the Russian government. There have been a number of publications and reports within Russia criticizing the inertial propulsion program, most of which has been based on the fact that inertial propulsion violates the classical laws of physics. For more information about that criticism, see the list of Russian language publications and reports in the Bibliography subpage for this article.