Field propulsion

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Field propulsion is the concept of spacecraft propulsion where no propellant is necessary but instead momentum of the spacecraft is changed by an interaction of the spacecraft with external force fields, such as gravitational and magnetic fields from stars and planets. Proposed drives that use field propulsion are often called a reactionless or propellantless drive.

Contents

Types

Practical methods

Although not presently in wide use for space, there exist proven terrestrial examples of "Field Propulsion", in which electromagnetic fields act upon a conducting medium such as seawater or plasma for propulsion, is known as magnetohydrodynamics or MHD. MHD is similar in operation to electric motors, however rather than using moving parts or metal conductors, fluid or plasma conductors are employed. The EMS-1 and more recently the Yamato 1 [1] are examples of such electromagnetic Field propulsion systems, first described in 1994. [2] There is definitely potential to apply MHD to the space environment such as in experiments like NASA's electrodynamic tether, Lorentz Actuated Orbits, [3] the wingless electromagnetic air vehicle, and magnetoplasmadynamic thruster (which does use propellant).

Electrohydrodynamics is another method whereby electrically charged fluids are used for propulsion and boundary layer control such as ion propulsion [ citation needed ]

Other practical methods which could be loosely considered as field propulsion include: The gravity assist trajectory, which uses planetary gravity fields and orbital momentum; Solar sails and magnetic sails use respectively the radiation pressure and solar wind for spacecraft thrust; Aerobraking uses the atmosphere of a planet to change relative velocity of a spacecraft. The last two actually involve the exchange of momentum with physical particles and are not usually expressed as an interaction with fields, but they are sometimes included as examples of field propulsion since no spacecraft propellant is required. An example is the Magsail magnetic sail design. [4] :Sec. VIII

Speculative methods

Other concepts that have been proposed are speculative, using "frontier physics" and concepts from modern physics. So far none of these methods have been unambiguously demonstrated, much less proven practical.

The Woodward effect is based on a controversial concept of inertia and certain solutions to the equations for General Relativity. Experiments attempting to conclusively demonstrate this effect have been conducted since the 1990s.

In contrast, examples of proposals for field propulsion that rely on physics outside the present paradigms are various schemes for faster-than-light, warp drive and antigravity, and often amount to little more than catchy descriptive phrases, with no known physical basis[ citation needed ]. Until it is shown that the conservation of energy and momentum break down under certain conditions (or scales), any such schemes worthy of discussion must rely on energy and momentum transfer to the spacecraft from some external source such as a local force field, which in turn must obtain it from still other momentum and/or energy sources in the cosmos (in order to satisfy conservation of both energy and momentum).[ citation needed ]

Several people have speculated that the Casimir effect could be used to create a propellantless drive, often described as the "Casimir Sail", or a "Quantum Sail". [5] [6] [7] [8]

Field propulsion based on physical structure of space

This concept is based on the general relativity theory and the quantum field theory from which the idea that space has a physical structure can be proposed. The macroscopic structure is described by the general relativity theory and the microscopic structure by the quantum field theory. The idea is to deform space around the space craft. By deforming the space it would be possible to create a region with higher pressure behind the space craft than before it. Due to the pressure gradient a force would be exerted on the space craft which in turn creates thrust for propulsion. [9] Due to the purely theoretical nature of this propulsion concept it is hard to determine the amount of thrust and the maximum velocity that could be achieved. Currently there are two different concepts for such a field propulsion system one that is purely based on the general relativity theory and one based on the quantum field theory. [10]

In the general relativistic field propulsion system space is considered to be an elastic field similar to rubber which means that space itself can be treated as an infinite elastic body. If the space-time curves, a normal inwards surface stress is generated which serves as a pressure field. By creating a great number of those curve surfaces behind the space craft it is possible to achieve a unidirectional surface force which can be use for the acceleration of the space craft. [10]

For the quantum field theoretical propulsion system it is assumed, as stated by the quantum field theory and quantum Electrodynamics, that the quantum vacuum consists out of a zero-radiating electromagnetic field in a non-radiating mode and at a zero-point energy state, the lowest possible energy state. It is also theorized that matter is composed out of elementary primary charged entities, partons, which are bound together as elementary oscillators. By applying an electromagnetic zero point field a Lorentz force is applied on the partons. Using this on a dielectric material could affect the inertia of the mass and that way create an acceleration of the material without creating stress or strain inside the material. [10]

Conservation Laws

Conservation of momentum is a fundamental requirement of propulsion systems because in experiments momentum is always conserved. [11] This conservation law is implicit in the published work of Newton and Galileo, but arises on a fundamental level from the spatial translation symmetry of the laws of physics, as given by Noether's theorem. In each of the propulsion technologies, some form of energy exchange is required with momentum directed backward at the speed of light 'c' or some lesser velocity 'v' to balance the forward change of momentum. In absence of interaction with an external field, the power 'P' that is required to create a thrust force 'F' is given by when mass is ejected or if mass-free energy is ejected.

For a photon rocket the efficiency is too small to be competitive. [12] Other technologies may have better efficiency if the ejection velocity is less than speed of light, or a local field can interact with another large scale field of the same type residing in space, which is the intent of field effect propulsion.

Advantages

The main advantage of a field propulsion systems is that no propellant is needed, only an energy source. This means that no propellant has to be stored and transported with the space craft which makes it attractive for long term interplanetary or even interstellar crewed missions. [10] With current technology a large amount of fuel meant for the way back has to be brought to the destination which increases the payload of the overall space craft significantly. The increased payload of fuel, thus requires more force to accelerate it, requiring even more fuel which is the primary drawback of current rocket technology. Approximately 83% of a Hydrogen-Oxygen powered rocket, which can achieve orbit, is fuel. [13]

Limits

The idea that with field propulsion no fuel tank would be required is technically inaccurate. The energy required to reach the high speeds involved begins to be non-neglectable for interstellar travel. For example, a 1-tonne spaceship traveling at 1/10 of the speed of light carries a kinetic energy of 4.5 × 1017 joules, equal to 5 kg according to the mass–energy equivalence. This means that for accelerating to such speed, no matter how this is achieved, the spaceship must have converted at least 5 kg of mass/energy into momentum, imagining 100% efficiency. Although such mass has not been "expelled" it has still been "disposed".

See also

Related Research Articles

<span class="mw-page-title-main">Interstellar travel</span> Hypothetical travel between stars or planetary systems

Interstellar travel is the hypothetical travel of spacecraft from one star system, solitary star, or planetary system to another. Interstellar travel is expected to prove much more difficult than interplanetary spaceflight due to the vast difference in the scale of the involved distances. Whereas the distance between any two planets in the Solar System is less than 55 astronomical units (AU), stars are typically separated by hundreds of thousands of AU, causing these distances to typically be expressed instead in light-years. Because of the vastness of these distances, non-generational interstellar travel based on known physics would need to occur at a high percentage of the speed of light; even so, travel times would be long, at least decades and perhaps millennia or longer.

<span class="mw-page-title-main">Spacecraft propulsion</span> Method used to accelerate spacecraft

Spacecraft propulsion is any method used to accelerate spacecraft and artificial satellites. In-space propulsion exclusively deals with propulsion systems used in the vacuum of space and should not be confused with space launch or atmospheric entry.

<span class="mw-page-title-main">Solar sail</span> Space propulsion method using Sun radiation

Solar sails are a method of spacecraft propulsion using radiation pressure exerted by sunlight on large surfaces. A number of spaceflight missions to test solar propulsion and navigation have been proposed since the 1980s. The first spacecraft to make use of the technology was IKAROS, launched in 2010.

<span class="mw-page-title-main">Mass driver</span> Proposed spacelaunch method

A mass driver or electromagnetic catapult is a proposed method of non-rocket spacelaunch which would use a linear motor to accelerate and catapult payloads up to high speeds. Existing and contemplated mass drivers use coils of wire energized by electricity to make electromagnets, though a rotary mass driver has also been proposed. Sequential firing of a row of electromagnets accelerates the payload along a path. After leaving the path, the payload continues to move due to momentum.

Beam-powered propulsion, also known as directed energy propulsion, is a class of aircraft or spacecraft propulsion that uses energy beamed to the spacecraft from a remote power plant to provide energy. The beam is typically either a microwave or a laser beam and it is either pulsed or continuous. A continuous beam lends itself to thermal rockets, photonic thrusters and light sails, whereas a pulsed beam lends itself to ablative thrusters and pulse detonation engines.

<span class="mw-page-title-main">Antimatter rocket</span> Rockets using antimatter as their power source

An antimatter rocket is a proposed class of rockets that use antimatter as their power source. There are several designs that attempt to accomplish this goal. The advantage to this class of rocket is that a large fraction of the rest mass of a matter/antimatter mixture may be converted to energy, allowing antimatter rockets to have a far higher energy density and specific impulse than any other proposed class of rocket.

<span class="mw-page-title-main">Warp drive</span> Fictional superluminal spacecraft propulsion system

A warp drive or a drive enabling space warp is a fictional superluminal spacecraft propulsion system in many science fiction works, most notably Star Trek, and a subject of ongoing physics research. The general concept of "warp drive" was introduced by John W. Campbell in his 1957 novel Islands of Space and was popularized by the Star Trek series. Its closest real-life equivalent is the Alcubierre drive, a theoretical solution of the field equations of general relativity.

<span class="mw-page-title-main">Starship</span> Spacecraft designed for interstellar travel

A starship, starcraft, or interstellar spacecraft is a theoretical spacecraft designed for traveling between planetary systems. The term is mostly found in science fiction. Reference to a "star-ship" appears as early as 1882 in Oahspe: A New Bible.

<span class="mw-page-title-main">Zero-point energy</span> Lowest possible energy of a quantum system or field

Zero-point energy (ZPE) is the lowest possible energy that a quantum mechanical system may have. Unlike in classical mechanics, quantum systems constantly fluctuate in their lowest energy state as described by the Heisenberg uncertainty principle. Therefore, even at absolute zero, atoms and molecules retain some vibrational motion. Apart from atoms and molecules, the empty space of the vacuum also has these properties. According to quantum field theory, the universe can be thought of not as isolated particles but continuous fluctuating fields: matter fields, whose quanta are fermions, and force fields, whose quanta are bosons. All these fields have zero-point energy. These fluctuating zero-point fields lead to a kind of reintroduction of an aether in physics since some systems can detect the existence of this energy. However, this aether cannot be thought of as a physical medium if it is to be Lorentz invariant such that there is no contradiction with Einstein's theory of special relativity.

The Breakthrough Propulsion Physics Project (BPP) was a research project funded by NASA from 1996 to 2002 to study various proposals for revolutionary methods of spacecraft propulsion that would require breakthroughs in physics before they could be realized. The project ended in 2002, when the Advanced Space Transportation Program was reorganized and all speculative research was cancelled. During its six years of operational funding, this program received a total investment of $1.2 million.

<span class="mw-page-title-main">Laser propulsion</span> Form of beam-powered propulsion

Laser propulsion is a form of beam-powered propulsion where the energy source is a remote laser system and separate from the reaction mass. This form of propulsion differs from a conventional chemical rocket where both energy and reaction mass come from the solid or liquid propellants carried on board the vehicle.

<span class="mw-page-title-main">Interstellar probe</span> Space probe that can travel out of the Solar System

An interstellar probe is a space probe that has left—or is expected to leave—the Solar System and enter interstellar space, which is typically defined as the region beyond the heliopause. It also refers to probes capable of reaching other star systems.

This is an alphabetical list of articles pertaining specifically to aerospace engineering. For a broad overview of engineering, see List of engineering topics. For biographies, see List of engineers.

A reactionless drive is a hypothetical device producing motion without the exhaust of a propellant. A propellantless drive is not necessarily reactionless when it constitutes an open system interacting with external fields; but a reactionless drive is a particular case of a propellantless drive that is a closed system, presumably in contradiction with the law of conservation of momentum. Reactionless drives are often considered similar to a perpetual motion machine. The name comes from Newton's third law, often expressed as: "For every action, there is an equal and opposite reaction."

<span class="mw-page-title-main">Spacecraft electric propulsion</span> Type of space propulsion using electrostatic and electromagnetic fields for acceleration

Spacecraft electric propulsion is a type of spacecraft propulsion technique that uses electrostatic or electromagnetic fields to accelerate mass to high speed and thus generate thrust to modify the velocity of a spacecraft in orbit. The propulsion system is controlled by power electronics.

<span class="mw-page-title-main">EmDrive</span> Device claimed to be a propellantless spacecraft thruster

The EmDrive is a concept for a thruster for spacecraft, first written about in 2001. It is purported to generate thrust by reflecting microwaves inside the device, in a way that would violate the law of conservation of momentum and other laws of physics. The concept has at times been referred to as a resonant cavity thruster.

Advanced Space Propulsion Investigation Committee (ASPIC) was a research group of specialists, including Y.Minami, and T.Musha, which was organized under the Japan Society for Aeronautical and Space Sciences in 1994. Its purpose was to study various non-chemical space propulsion systems instead of the conventional rocket for the use of space missions to near-Earth, the Moon, and the outer solar system, including plasma propulsion, laser propulsion, nuclear propulsion, solar sail and field propulsion systems which utilize a strain on space, zero-point energy in a vacuum, electro-gravitic effect, non-Newtonian gravitic effect predicted by Einstein's general theory of relativity, and the terrestrial magnetism. The research report was published by the Japan Society for Aeronautical and Space Sciences in March 1996.

Space travel under constant acceleration is a hypothetical method of space travel that involves the use of a propulsion system that generates a constant acceleration rather than the short, impulsive thrusts produced by traditional chemical rockets. For the first half of the journey the propulsion system would constantly accelerate the spacecraft toward its destination, and for the second half of the journey it would constantly decelerate the spaceship. Constant acceleration could be used to achieve relativistic speeds, making it a potential means of achieving human interstellar travel. This mode of travel has yet to be used in practice.

<span class="mw-page-title-main">Interstellar Probe (1999)</span> 1999 NASA space probe concept

Interstellar Probe is the name of a 1999 space probe concept by NASA intended to travel out 200 AU in 15 years. This 1999 study by Jet Propulsion Laboratory is noted for its circular 400-meter-diameter solar sail as a propulsion method combined with a 0.25 AU flyby of the Sun to achieve higher solar light pressure, after which the sail is jettisoned at 5 AU distance from the Sun.

A plasma magnet is a proposed spacecraft propulsion device that uses a dipole magnetic field to capture energy from the solar wind. The field acts as a sail, using the captured energy to propel the spacecraft analogously to how the wind propels a sailing vessel. It could accelerate a vessel moving away from the sun and decelerate it when approaching a distant star at the end of an interstellar journey. Thrust vectoring and steering could be achieved by manipulating the dipole tilt for any type of magnetic sail.

References

  1. AKAGI, Shinsuke; FUJITA, Kikuo; SOGA, Kazuo (May 27, 1994). "Optimal Design of Thruster System for Superconducting Electromagnetic Propulsion Ship" (PDF). Proceedings of the 5th International Marine Design Conference. Retrieved November 30, 2022.
  2. US 5333444,Meng, James C. S.,"Superconducting electromagnetic thruster",published 1994-08-02, assigned to United States Secretary of the Navy
  3. Peck, Mason A. "Lorentz-Actuated Orbits: Electrodynamic Propulsion without a Tether" (PDF). Retrieved November 30, 2022.
  4. Zubrin, Robert M.; Andrews, Dana G. (March 1991). "Magnetic sails and interplanetary travel". Journal of Spacecraft and Rockets. 28 (2): 197–203. doi:10.2514/3.26230. ISSN   0022-4650.
  5. "Running on empty". New Scientist. Retrieved 2023-08-06.
  6. DeBiase, R. L. (2010-01-28). "A Light Sail Inspired Model to Harness Casimir Forces for Propellantless Propulsion". AIP Conference Proceedings. 1208 (1): 153–167. Bibcode:2010AIPC.1208..153D. doi:10.1063/1.3326244. ISSN   0094-243X. OSTI   21370934.
  7. DeBiase, R. L. (2010-01-01). "A Light Sail Inspired Model to Harness Casimir Forces for Propellantless Propulsion". Space. AIP Conference Proceedings. 1208 (1): 153–167. Bibcode:2010AIPC.1208..153D. doi:10.1063/1.3326244.
  8. Seife, Charles, ed. (2000). Zero: the biography of a dangerous idea. A New York Times Notable Book (1. publ ed.). New York: Viking. pp. 187–188. ISBN   978-0-14-029647-1.
  9. Musha, Takaaki (15 February 2018). Field Propulsion System for Space Travel: Physics of Non-Conventional Propulsion Methods for Interstellar Travel. Bentham Books. pp. 20–37. ISBN   978-1-60805-566-1.
  10. 1 2 3 4 Minami, Yoshinari; Musha, Takaaki (February 2013). "Field propulsion systems for space travel". Acta Astronautica. 82 (2): 215–20. Bibcode:2013AcAau..82..215M. doi:10.1016/j.actaastro.2012.02.027.
  11. Ho-Kim, Quang; Kumar, Narendra; Lam, Harry C. S. (2004). Invitation to Contemporary Physics (illustrated ed.). World Scientific. p. 19. ISBN   978-981-238-303-7. Extract of page 19
  12. There will be no photon rocket, by V. Smilga http://www.dtic.mil/dtic/tr/fulltext/u2/611872.pdf Archived 2017-05-17 at the Wayback Machine
  13. Pettit, Don. "The Tyranny of the Rocket Equation". NASA.