Mass driver
Overview

A mass driver or electromagnetic catapult is a proposed method of non-rocket spacelaunch
Non-rocket spacelaunch
Non-rocket space launch is a launch into space where some or all needed speed and altitude is provided by non-rocket means, rather than simply using conventional chemical rockets from the ground. A number of alternatives to rockets have been proposed...

which would use a linear motor
Linear motor
A linear motor is an electric motor that has had its stator and rotor "unrolled" so that instead of producing a torque it produces a linear force along its length...

to accelerate and catapult
Catapult
A catapult is a device used to throw or hurl a projectile a great distance without the aid of explosive devices—particularly various types of ancient and medieval siege engines. Although the catapult has been used since ancient times, it has proven to be one of the most effective mechanisms during...

Velocity
In physics, velocity is speed in a given direction. Speed describes only how fast an object is moving, whereas velocity gives both the speed and direction of the object's motion. To have a constant velocity, an object must have a constant speed and motion in a constant direction. Constant ...

. All existing and contemplated mass drivers use coil
Coil
A coil is a series of loops. A coiled coil is a structure in which the coil itself is in turn also looping.-Electromagnetic coils:An electromagnetic coil is formed when a conductor is wound around a core or form to create an inductor or electromagnet...

s of wire energized by electricity
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...

to make electromagnet
Electromagnet
An electromagnet is a type of magnet in which the magnetic field is produced by the flow of electric current. The magnetic field disappears when the current is turned off...

s. Sequential firing of a row of electromagnet
Electromagnet
An electromagnet is a type of magnet in which the magnetic field is produced by the flow of electric current. The magnetic field disappears when the current is turned off...

s accelerates the payload along a path. After leaving the path, the payload continues to move due to momentum
Momentum
In classical mechanics, linear momentum or translational momentum is the product of the mass and velocity of an object...

.

A mass driver is essentially a coilgun
Coilgun
A coilgun is a type of projectile accelerator that consists of one or more coils used as electromagnets in the configuration of a synchronous linear motor which accelerate a magnetic projectile to high velocity...

that magnetically accelerates a package consisting of a magnetizable holder containing a payload.
Encyclopedia
A mass driver or electromagnetic catapult is a proposed method of non-rocket spacelaunch
Non-rocket spacelaunch
Non-rocket space launch is a launch into space where some or all needed speed and altitude is provided by non-rocket means, rather than simply using conventional chemical rockets from the ground. A number of alternatives to rockets have been proposed...

which would use a linear motor
Linear motor
A linear motor is an electric motor that has had its stator and rotor "unrolled" so that instead of producing a torque it produces a linear force along its length...

to accelerate and catapult
Catapult
A catapult is a device used to throw or hurl a projectile a great distance without the aid of explosive devices—particularly various types of ancient and medieval siege engines. Although the catapult has been used since ancient times, it has proven to be one of the most effective mechanisms during...

Velocity
In physics, velocity is speed in a given direction. Speed describes only how fast an object is moving, whereas velocity gives both the speed and direction of the object's motion. To have a constant velocity, an object must have a constant speed and motion in a constant direction. Constant ...

. All existing and contemplated mass drivers use coil
Coil
A coil is a series of loops. A coiled coil is a structure in which the coil itself is in turn also looping.-Electromagnetic coils:An electromagnetic coil is formed when a conductor is wound around a core or form to create an inductor or electromagnet...

s of wire energized by electricity
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...

to make electromagnet
Electromagnet
An electromagnet is a type of magnet in which the magnetic field is produced by the flow of electric current. The magnetic field disappears when the current is turned off...

s. Sequential firing of a row of electromagnet
Electromagnet
An electromagnet is a type of magnet in which the magnetic field is produced by the flow of electric current. The magnetic field disappears when the current is turned off...

s accelerates the payload along a path. After leaving the path, the payload continues to move due to momentum
Momentum
In classical mechanics, linear momentum or translational momentum is the product of the mass and velocity of an object...

.

A mass driver is essentially a coilgun
Coilgun
A coilgun is a type of projectile accelerator that consists of one or more coils used as electromagnets in the configuration of a synchronous linear motor which accelerate a magnetic projectile to high velocity...

that magnetically accelerates a package consisting of a magnetizable holder containing a payload. Once the payload has been accelerated, the two separate, and the holder is slowed and recycled for another payload.

Mass drivers can be used to propel spacecraft in three different ways: A large, ground-based mass driver could be used to launch spacecraft away from Earth, the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

, or another body. A small mass driver could be on board a spacecraft, flinging pieces of material into space to propel itself. Another variation would have a massive facility on a moon or asteroid send projectiles to assist a distant craft.

Miniaturized mass drivers can also be used as weapons in a similar manner as classic firearms or cannon using chemical combustion. Hybrids between coilgun
Coilgun
A coilgun is a type of projectile accelerator that consists of one or more coils used as electromagnets in the configuration of a synchronous linear motor which accelerate a magnetic projectile to high velocity...

s and railgun
Railgun
A railgun is an entirely electrical gun that accelerates a conductive projectile along a pair of metal rails using the same principles as the homopolar motor. Railguns use two sliding or rolling contacts that permit a large electric current to pass through the projectile. This current interacts...

s such as helical railgun
Helical railgun
Helical railguns are multi-turn railguns that reduce rail and brush current by a factor equal to the number of turns. Two rails are surrounded by a helical barrel and the projectile or re-usable carrier is also helical...

s are also possible.

## Fixed mass drivers

Mass drivers can have no physical contact between moving parts due to the projectile being guided by dynamic magnetic levitation, allowing extreme reusability in the case of solid-state power switching, a life of theoretically up to millions of launches. While marginal costs tend to be accordingly low, initial development and construction costs are highly dependent on performance, especially the intended mass, acceleration, and velocity of projectiles. For instance, while Gerard O'Neill built his first mass driver in 1976–77 with a $2000 budget, a short test model Mass Driver 1 Constructed in 1976 and 1977, Mass Driver 1 was an early demonstration of the concept of the mass driver, a form of electromagnetic launcher, which in principle could also be configured as a rocket motor, using asteroidal materials for reaction mass and energized by solar or other electric power.As... firing a projectile at 40 m/s and 33 g G-force The g-force associated with an object is its acceleration relative to free-fall. This acceleration experienced by an object is due to the vector sum of non-gravitational forces acting on an object free to move. The accelerations that are not produced by gravity are termed proper accelerations, and... , his next model was an order of magnitude greater acceleration after a comparable increase in funding, and, a few years later, the University of Texas estimated that a mass driver firing a 10 kilogram projectile at 6000 m/s would cost$47 million.

For a given amount of energy involved, heavier objects go proportionally more slowly. Light objects may be projected at 20 km/s or more. The limits are generally the expense of energy storage able to be discharged quickly enough and the cost of power switching, which may be by semiconductors or by gas-phase switches (having often a niche still in extreme pulse power applications). However, energy can be stored inductively in superconducting coils. A 1 km long mass driver made of superconducting coils can accelerate a 20 kg vehicle to 10.5 km/s at a conversion efficiency of 80%, and average acceleration of 5,600 g.

Earth-based mass drivers for propelling vehicles to orbit, such as the StarTram
StarTram
StarTram is a proposal for a maglev space launch system. The initial Generation 1 facility would be cargo only, launching from a mountain peak at 3 km to 7 km altitude with an evacuated tube staying at local surface level, raising ≈150,000 tons to orbit annually...

concept, would require large capital investment.

The Earth's strong gravity and thick atmosphere make such an installation difficult, so many proposals have been put forward to install mass drivers on the moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

where the lower gravity and lack of atmosphere
Atmosphere of the Moon
For most practical purposes, the Moon is considered to be surrounded by vacuum. The elevated presence of atomic and molecular particles in its vicinity , referred to as 'lunar atmosphere' for scientific objectives, is negligible in comparison with the gaseous envelope surrounding Earth and most...

much reduce the required velocity to reach lunar orbit.

Most serious mass driver designs use superconducting coils to achieve reasonable energetic efficiency (often 50% to 90+%, depending on design). Methods include a superconducting bucket or aluminum coil as the payload. The coils of a mass-driver can induce eddy-currents in a payload's aluminum coil, and then act on the resulting magnetic field
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...

. There are two sections of a mass-driver. The maximum acceleration
Acceleration
In physics, acceleration is the rate of change of velocity with time. In one dimension, acceleration is the rate at which something speeds up or slows down. However, since velocity is a vector, acceleration describes the rate of change of both the magnitude and the direction of velocity. ...

part spaces the coils at constant distances, and synchronize the coil currents to the bucket. In this section, the acceleration increases as the velocity increases, up to the maximum that the bucket can take. After that, the constant acceleration region begins. This region spaces the coils at increasing distances to give a fixed amount of velocity increase per unit of time.

In this mode, a major proposal for use of mass-drivers was to transport lunar surface material to space habitats so that it could be processed using solar energy. The Space Studies Institute showed that this application was reasonably practical.

In some designs, the payload would be held in a bucket and then released, so that the bucket can be decelerated and reused. A disposable bucket, on the other hand, would avail acceleration along the whole track.

### On Earth

In contrast to cargo-only chemical space gun
Space gun
A space gun is a method of launching an object into outer space using a large gun, or cannon. It provides a method of non-rocket spacelaunch‎.In the HARP Project a U.S...

concepts, a mass driver could be any length affordable, with relatively smooth acceleration throughout, optionally even lengthy enough to reach target velocity without excessive g forces
G-force
The g-force associated with an object is its acceleration relative to free-fall. This acceleration experienced by an object is due to the vector sum of non-gravitational forces acting on an object free to move. The accelerations that are not produced by gravity are termed proper accelerations, and...

for passengers. It can be constructed as a very long and mainly horizontally aligned launch track
Launch track
The launch track is the section of a launched roller coaster in which the train is accelerated to its full speed in a matter of seconds. A launch track is always straight and is usually banked upwards slightly, so that a train would roll backwards to the station in the event of a loss of power.A...

for spacelaunch, targeted upwards at the end, partly by bending of the track upwards and partly by Earth's curvature in the other direction.

Natural elevations, such as mountains, may facilitate the construction of the distant, upwardly targeted part. The higher up the track terminates, the less resistance from the atmosphere the launched object will receive.

The 40 megajoules per kilogram or less kinetic energy
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...

of projectiles launched at up to 9000 m/s velocity (if including extra for drag losses) towards Low Earth Orbit
Low Earth orbit
A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...

is a few kilowatt-hours per kilogram if efficiencies are relatively high, which accordingly has been hypothesized to be under \$1 of electrical energy cost per kilogram shipped to LEO
Low Earth orbit
A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...

, though total costs would be far more than electricity alone. By being mainly located slightly above, on or beneath the ground, a mass driver may be easier to maintain compared with many other structures of non-rocket spacelaunch
Non-rocket spacelaunch
Non-rocket space launch is a launch into space where some or all needed speed and altitude is provided by non-rocket means, rather than simply using conventional chemical rockets from the ground. A number of alternatives to rockets have been proposed...

. Whether or not underground, it needs to be housed in a pipe that is vacuum pump
Vacuum pump
A vacuum pump is a device that removes gas molecules from a sealed volume in order to leave behind a partial vacuum. The first vacuum pump was invented in 1650 by Otto von Guericke.- Types :Pumps can be broadly categorized according to three techniques:...

ed in order to prevent internal air drag
Drag (physics)
In fluid dynamics, drag refers to forces which act on a solid object in the direction of the relative fluid flow velocity...

, such as with a mechanical shutter kept closed most of the time but a plasma window
Plasma window
The plasma window is a technology that fills a volume of space with plasma confined by a magnetic field...

used during the moments of firing to prevent loss of vacuum.

A mass driver on Earth would usually be a compromise system. A mass driver would accelerate a payload up to some high speed which would not be enough for orbit. It would then release the payload, which would complete the launch with rockets. This would drastically reduce the amount of velocity needed to be provided by rockets to reach orbit. Well under a tenth of orbital velocity from a small rocket thruster is enough to raise perigee
Perigee
Perigee is the point at which an object makes its closest approach to the Earth.. Often the term is used in a broader sense to define the point in an orbit where the orbiting body is closest to the body it orbits. The opposite is the apogee, the farthest or highest point.The Greek prefix "peri"...

if a design prioritizes minimizing such, but hybrid proposals optionally reduce requirements for the mass driver itself by having a greater portion of delta-v
Delta-v
In astrodynamics a Δv or delta-v is a scalar which takes units of speed. It is a measure of the amount of "effort" that is needed to change from one trajectory to another by making an orbital maneuver....

by a rocket burn (or orbital momentum exchange tether
Momentum exchange tether
Momentum Exchange Tethers is one of many applications for space tethers. This sub-set represents an entire area of research using a spinning conductive and/or non-conductive tether to throw spacecraft up or down in orbit , thereby transferring its momentum.Due to the centrifugal acceleration, the...

). On Earth, a mass driver design could possibly use well-tested maglev
Maglev train
Maglev , is a system of transportation that uses magnetic levitation to suspend, guide and propel vehicles from magnets rather than using mechanical methods, such as friction-reliant wheels, axles and bearings...

components.

If launching humans, it would need to be several hundreds of kilometers long if providing almost all the velocity to Low Earth Orbit
Low Earth orbit
A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...

, though lesser length can provide major launch assist. Required length, if accelerating mainly at near a constant maximum acceptable g-force
G-force
The g-force associated with an object is its acceleration relative to free-fall. This acceleration experienced by an object is due to the vector sum of non-gravitational forces acting on an object free to move. The accelerations that are not produced by gravity are termed proper accelerations, and...

for passengers, is proportional to velocity squared. For instance, half of the velocity goal could correspond to a quarter as long of a tunnel needing to be constructed, for the same acceleration. For rugged objects, much higher accelerations may suffice, allowing a far shorter track, potentially circular.

Mass drivers have been proposed for space disposal of nuclear waste, where a projectile launched at much above Earth's escape velocity
Escape velocity
In physics, escape velocity is the speed at which the kinetic energy plus the gravitational potential energy of an object is zero gravitational potential energy is negative since gravity is an attractive force and the potential is defined to be zero at infinity...

would escape the Solar System, with atmospheric passage at such speed calculated as survivable through an elongated projectile and very substantial heatshield.

## Spacecraft-based mass drivers

A spacecraft
Spacecraft
A spacecraft or spaceship is a craft or machine designed for spaceflight. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, planetary exploration and transportation of humans and cargo....

could carry a mass driver as its primary engine. With a suitable source of electrical power (probably a nuclear reactor
Nuclear reactor
A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Most commonly they are used for generating electricity and for the propulsion of ships. Usually heat from nuclear fission is passed to a working fluid , which runs through turbines that power either ship's...

) the spaceship could then use the mass driver to accelerate pieces of matter of almost any sort, boosting itself in the opposite direction. At the smallest scale of reaction mass, this type of drive is called an ion drive.

No absolute theoretical limit is known for the size, acceleration or muzzle energy of linear motors. However, practical engineering constraints apply for such as the power to mass ratio, waste heat dissipation, and the energy intake able to be supplied and handled. Exhaust velocity is best neither too low nor too high.

There is a mission-dependent limited optimal exhaust velocity and specific impulse for any thruster constrained by a limited amount of onboard spacecraft power. Thrust and momentum from exhaust, per unit mass expelled, scales up linearly with its velocity (momentum
Momentum
In classical mechanics, linear momentum or translational momentum is the product of the mass and velocity of an object...

= mv), yet kinetic energy and energy input requirements scale up faster with velocity squared (kinetic energy
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...

= ½ mv2). Too low exhaust velocity would excessively increase propellant mass needed under the rocket equation, with too high a fraction of energy going into accelerating propellant not used yet. Higher exhaust velocity has both benefit and tradeoff, increasing propellant usage efficiency (more momentum per unit mass of propellant expelled) but decreasing thrust and the current rate of spacecraft acceleration if available input power is constant (less momentum per unit of energy given to propellant).

Electric propulsion methods like mass drivers are systems where energy does not come from the propellant itself. (Such contrasts to chemical rockets where propulsive efficiency
Propulsive efficiency
In aircraft and rocket design, overall propulsive efficiency \eta is the efficiency, in percent, with which the energy contained in a vehicle's propellant is converted into useful energy, to replace losses due to air drag, gravity, and acceleration. It can also be stated as the proportion of the...

varies with the ratio of exhaust velocity to vehicle velocity at the time, but near maximum obtainable specific impulse tends to be a design goal when corresponding to the most energy released from reacting propellants). Although the specific impulse of an electric thruster itself optionally could range up to where mass drivers merge into particle accelerator
Particle accelerator
A particle accelerator is a device that uses electromagnetic fields to propel charged particles to high speeds and to contain them in well-defined beams. An ordinary CRT television set is a simple form of accelerator. There are two basic types: electrostatic and oscillating field accelerators.In...

s with fractional-lightspeed exhaust velocity for tiny particles, trying to use extreme exhaust velocity to accelerate a far slower spacecraft could be suboptimally low thrust when the energy available from a spacecraft's reactor or power source is limited (a lesser analogue of feeding onboard power to a row of spotlights, photons being an example of an extremely low momentum to energy ratio).

For instance, if limited onboard power fed to its engine was the dominant limitation on how much payload a hypothetical spacecraft could shuttle (such as if intrinsic propellant economic cost was minor from usage of extraterrestrial soil or ice), ideal exhaust velocity would rather be around 62.75% of total mission delta v
Delta-v
In astrodynamics a Δv or delta-v is a scalar which takes units of speed. It is a measure of the amount of "effort" that is needed to change from one trajectory to another by making an orbital maneuver....

if operating at constant specific impulse, except greater optimization could come from varying exhaust velocity during the mission profile (as possible with some thruster types, including mass drivers and variable specific impulse magnetoplasma rockets).

Since a mass driver could use any type of mass for reaction mass to move the spacecraft, a mass driver or some variation seems ideal for deep-space vehicles that scavenge reaction mass from found resources.

One possible drawback of the mass driver is that it has the potential to send solid reaction mass travelling at dangerously high relative speeds into useful orbits and traffic lanes. To overcome this problem, most schemes plan to throw finely-divided dust
Dust
Dust consists of particles in the atmosphere that arise from various sources such as soil dust lifted up by wind , volcanic eruptions, and pollution...

. Alternatively, liquid oxygen could be used as reaction mass, which upon release would boil down to its molecular state. Propelling the reaction mass to solar escape velocity
Escape velocity
In physics, escape velocity is the speed at which the kinetic energy plus the gravitational potential energy of an object is zero gravitational potential energy is negative since gravity is an attractive force and the potential is defined to be zero at infinity...

is another way to ensure that it will not remain a hazard.

## Hybrid mass drivers

A mass driver on a spacecraft
Spacecraft
A spacecraft or spaceship is a craft or machine designed for spaceflight. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, planetary exploration and transportation of humans and cargo....

could be used to "reflect" masses from a stationary mass driver. Each deceleration and acceleration of the mass contributes to the momentum
Momentum
In classical mechanics, linear momentum or translational momentum is the product of the mass and velocity of an object...

of the spacecraft. The lightweight, fast spacecraft need not carry reaction mass, and does not need much electricity beyond the amount needed to replace losses in the electronics, while the immobile support facility can run off power plants able to be much larger than the spacecraft if needed. This could be considered a form of beam-powered propulsion
Beam-powered propulsion
Beam-powered propulsion is a class of aircraft or spacecraft propulsion mechanisms that use energy beamed to the spacecraft from a remote power plant to provide energy...

(a macroscopic-scale analogue of a particle beam
Particle beam
A particle beam is a stream of charged or neutral particles which may be directed by magnets and focused by electrostatic lenses, although they may also be self-focusing ....

propelled magsail). A similar system could also deliver pellets of fuel to a spacecraft to power another propulsion system.

Another theoretical use for this concept of propulsion can be found in space fountain
Space fountain
A space fountain is a proposed form of space elevator that does not require the structure to be in geostationary orbit, and does not rely on tensile strength for support. In contrast to the original space elevator design , a space fountain is a tremendously tall tower extending up from the ground...

s, a system in which a continuous stream of pellets in a circular track holds up a tall structure.

## Mass drivers as weapons

Small to moderate size high-acceleration electromagnetic projectile launchers are currently undergoing active research by the military for use as ground-based or ship-based weapons (most often railgun
Railgun
A railgun is an entirely electrical gun that accelerates a conductive projectile along a pair of metal rails using the same principles as the homopolar motor. Railguns use two sliding or rolling contacts that permit a large electric current to pass through the projectile. This current interacts...

s but coilgun
Coilgun
A coilgun is a type of projectile accelerator that consists of one or more coils used as electromagnets in the configuration of a synchronous linear motor which accelerate a magnetic projectile to high velocity...

s in some cases). On larger scale than weapons currently near deployment but sometimes suggested in long-range future projections, a sufficiently high velocity linear motor
Linear motor
A linear motor is an electric motor that has had its stator and rotor "unrolled" so that instead of producing a torque it produces a linear force along its length...

, a mass driver, could in principle be used as intercontinental artillery (or, if built on the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

or in orbit, used to attack a location on Earth's surface). As the mass driver would be located further up the gravity well than the theoretical targets, it would enjoy a significant energy imbalance in terms of counter-attack.

## Practical attempts

One of the first engineering descriptions of an "Electric Gun" appears in the technical supplement of "Zero to Eighty" by "Akkad Pseudoman", a pen name for the Princeton physicist and electrical entrepreneur Edwin Fitch Northrup
Edwin Fitch Northrup
Edwin Fitch Northrup was a professor of physics at Princeton University from 1910 to 1920. He was affiliated with the "Leeds & Northrup Company" for about seven years....

. Dr. Northrup built prototype coil guns powered by kHz-frequency three phase electrical generators, and the book contains photographs of some of these prototypes. The book describes a fictional circumnavigation of the moon by a two-person vehicle launched by a Northrup electric gun.

Later prototype mass drivers have been built since 1976 (Mass Driver 1
Mass Driver 1
Constructed in 1976 and 1977, Mass Driver 1 was an early demonstration of the concept of the mass driver, a form of electromagnetic launcher, which in principle could also be configured as a rocket motor, using asteroidal materials for reaction mass and energized by solar or other electric power.As...

), some constructed by the U.S. Space Studies Institute
Space Studies Institute
Space Studies Institute is a non-profit organization that was founded in 1977 by the late Princeton University Professor Dr. Gerard K. O'Neill. The stated mission is to "open the energy and material resources of space for human benefit within our lifetime"...

in order to prove their properties and practicality. Military R&D on coilguns is related, as are also maglev trains
Maglev
Maglev is a form of rail transport using magnetic levitation.Maglev may also refer to:* Magnetic levitation, a method by which an object is suspended using magnetic fields* MagLev , a virtual machine for the Ruby programming language...

.

## In fiction

Various types of devices resembling mass drivers have been a staple of science fiction for decades. Mass drivers are very often used in Gundam
Gundam
The is a metaseries of anime created by Sunrise studios that features giant robots called "Mobile Suits" ; usually the protagonist's MS will carry the name Gundam....

.

• Electromagnetic Aircraft Launch System
• Helical railgun
Helical railgun
Helical railguns are multi-turn railguns that reduce rail and brush current by a factor equal to the number of turns. Two rails are surrounded by a helical barrel and the projectile or re-usable carrier is also helical...

• Railgun
Railgun
A railgun is an entirely electrical gun that accelerates a conductive projectile along a pair of metal rails using the same principles as the homopolar motor. Railguns use two sliding or rolling contacts that permit a large electric current to pass through the projectile. This current interacts...

• Coilgun
Coilgun
A coilgun is a type of projectile accelerator that consists of one or more coils used as electromagnets in the configuration of a synchronous linear motor which accelerate a magnetic projectile to high velocity...

• Linear motor
Linear motor
A linear motor is an electric motor that has had its stator and rotor "unrolled" so that instead of producing a torque it produces a linear force along its length...

• StarTram
StarTram
StarTram is a proposal for a maglev space launch system. The initial Generation 1 facility would be cargo only, launching from a mountain peak at 3 km to 7 km altitude with an evacuated tube staying at local surface level, raising ≈150,000 tons to orbit annually...

• Launch loop
Launch loop
A launch loop or Lofstrom loop is a proposed system for launching objects into space orbit using a moving cable-like system attached to the earth at two ends and suspended above the atmosphere in the middle...

• Space fountain
Space fountain
A space fountain is a proposed form of space elevator that does not require the structure to be in geostationary orbit, and does not rely on tensile strength for support. In contrast to the original space elevator design , a space fountain is a tremendously tall tower extending up from the ground...

• Spacecraft propulsion
Spacecraft propulsion
Spacecraft propulsion is any method used to accelerate spacecraft and artificial satellites. There are many different methods. Each method has drawbacks and advantages, and spacecraft propulsion is an active area of research. However, most spacecraft today are propelled by forcing a gas from the...

### People

• Eric Laithwaite
Eric Laithwaite
Eric Roberts Laithwaite was a British electrical engineer, known as the "Father of Maglev" for his development of the linear induction motor and maglev rail system.- Biography :...

and the Maglifter project
• Gerard K. O'Neill
• Henry Kolm
Henry Kolm
Henry Herbert Kolm was an American physicist associated with MIT for many years, with extensive expertise in high-power magnets and strong magnetic fields.-Visiting Scientist at MIT:...