Mass Driver 1
Encyclopedia
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 originally envisioned, the mass driver was intended to launch payloads from a lunar base to L5, the fifth Lagrange point in which a stable orbit can be maintained. This is where Gerard K. O'Neill proposed building a space colony
(of the five Lagrange points, only L4 and L5 are truly stable, both for the real physical Earth/Moon system as well as for the ideal restricted 3-body case).
The model consisted of a series of some 20 drive coils through which a small armature (called the bucket) traveled, pushed by the pulsed magnetic fields of the drive coils.
The bucket rode on four rails made from copper plumbing tubes, through which was fed direct current from several car batteries connected in series. It was an epoxy glass cylinder, roughly 10 cm in diameter by 20 cm long, wrapped with a coil of aluminium wire, energized by the batteries. The copper rails were mounted onto the interior of the drive coils, and the bucket was held onto the copper rails by spring-loaded beryllium copper strips with automotive carbon brushes
mounted on the ends.
The passage of the bucket depressed microswitches which triggered the discharge of capacitors through the drive coils.
The current in the bucket coil interacted, by the Lorentz force
, with the pulsed magnetic fields from the drive coils to accelerate the bucket. When the bucket coil was cooled by liquid nitrogen
to reduce its electrical resistance, it was able to achieve an acceleration of around 30 g
(300 m/s²
).
The mass driver was inspired and designed by Gerard K. O'Neill of Princeton University
(who was on sabbatical at MIT during the 1976-77 academic year) and Henry Kolm
of MIT. It was built under their direction by students at MIT, largely using material scavenged from the scrap heap at the Bitter Magnet Lab
at MIT. A demonstration at the May 1977 Princeton University Space Manufacturing Facilities Conference was covered by Nova
.
Ultimately O'Neill and Kolm hoped to launch payloads to escape velocity from Earth, thus reducing the cost of space launch to only about ten dollars a pound, the cost of electric energy, by eliminating the need to launch rocket fuel. Further development awaits the day when the space launch market off-Earth is large enough to justify the cost.
The idea for the mass driver did not come from the 1966 Robert A. Heinlein
book The Moon Is a Harsh Mistress
. Heinlein referred to a similar device as an "induction catapult".
Mass driver
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. All existing and contemplated mass drivers use coils of wire energized by electricity to make electromagnets. Sequential...
, 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 originally envisioned, the mass driver was intended to launch payloads from a lunar base to L5, the fifth Lagrange point in which a stable orbit can be maintained. This is where Gerard K. O'Neill proposed building a space colony
Space colonization
Space colonization is the concept of permanent human habitation outside of Earth. Although hypothetical at the present time, there are many proposals and speculations about the first space colony...
(of the five Lagrange points, only L4 and L5 are truly stable, both for the real physical Earth/Moon system as well as for the ideal restricted 3-body case).
The model consisted of a series of some 20 drive coils through which a small armature (called the bucket) traveled, pushed by the pulsed magnetic fields of the drive coils.
The bucket rode on four rails made from copper plumbing tubes, through which was fed direct current from several car batteries connected in series. It was an epoxy glass cylinder, roughly 10 cm in diameter by 20 cm long, wrapped with a coil of aluminium wire, energized by the batteries. The copper rails were mounted onto the interior of the drive coils, and the bucket was held onto the copper rails by spring-loaded beryllium copper strips with automotive carbon brushes
Brush (electric)
A brush is a device which conducts current between stationary wires and moving parts, most commonly in a rotating shaft. Typical applications include electric motors, alternators and electric generators.-Etymology:...
mounted on the ends.
The passage of the bucket depressed microswitches which triggered the discharge of capacitors through the drive coils.
The current in the bucket coil interacted, by the Lorentz force
Lorentz force
In physics, the Lorentz force is the force on a point charge due to electromagnetic fields. It is given by the following equation in terms of the electric and magnetic fields:...
, with the pulsed magnetic fields from the drive coils to accelerate the bucket. When the bucket coil was cooled by liquid nitrogen
Liquid nitrogen
Liquid nitrogen is nitrogen in a liquid state at a very low temperature. It is produced industrially by fractional distillation of liquid air. Liquid nitrogen is a colourless clear liquid with density of 0.807 g/mL at its boiling point and a dielectric constant of 1.4...
to reduce its electrical resistance, it was able to achieve an acceleration of around 30 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...
(300 m/s²
Metre per second squared
The metre per second squared is the unit of acceleration in the International System of Units . As a derived unit it is composed from the SI base units of length, the metre, and the standard unit of time, the second...
).
The mass driver was inspired and designed by Gerard K. O'Neill of Princeton University
Princeton University
Princeton University is a private research university located in Princeton, New Jersey, United States. The school is one of the eight universities of the Ivy League, and is one of the nine Colonial Colleges founded before the American Revolution....
(who was on sabbatical at MIT during the 1976-77 academic year) and 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:...
of MIT. It was built under their direction by students at MIT, largely using material scavenged from the scrap heap at the Bitter Magnet Lab
Francis Bitter
Francis Bitter was an American physicist.Bitter invented the Bitter plate used in resistive magnets . He is the one who thought of using dust to visualize a magnetic field...
at MIT. A demonstration at the May 1977 Princeton University Space Manufacturing Facilities Conference was covered by Nova
NOVA (TV series)
Nova is a popular science television series from the U.S. produced by WGBH Boston. It can be seen on the Public Broadcasting Service in the United States, and in more than 100 other countries...
.
Ultimately O'Neill and Kolm hoped to launch payloads to escape velocity from Earth, thus reducing the cost of space launch to only about ten dollars a pound, the cost of electric energy, by eliminating the need to launch rocket fuel. Further development awaits the day when the space launch market off-Earth is large enough to justify the cost.
The idea for the mass driver did not come from the 1966 Robert A. Heinlein
Robert A. Heinlein
Robert Anson Heinlein was an American science fiction writer. Often called the "dean of science fiction writers", he was one of the most influential and controversial authors of the genre. He set a standard for science and engineering plausibility and helped to raise the genre's standards of...
book The Moon Is a Harsh Mistress
The Moon Is a Harsh Mistress
The Moon Is a Harsh Mistress is a 1966 science fiction novel by American writer Robert A. Heinlein, about a lunar colony's revolt against rule from Earth....
. Heinlein referred to a similar device as an "induction catapult".