Tractor Beam - Fiction

Fiction

Science fiction movies and telecasts normally depict tractor and repulsor beams as audible, narrow rays of visible light that cover a small area of a target. Tractor beams are most commonly used on spaceships and space stations. They are generally used in two ways:

1. As a device for securing or retrieving cargo, passengers, shuttlecraft, etc. This is analogous to cranes on modern ships.
2. As a means of preventing an enemy from escaping, analogous to grappling hooks.

In the latter case, there are usually countermeasures that can be employed against tractor beams. These may include pressor beams (a stronger pressor beam will counteract a weaker tractor beam) or plane shears aka shearing planes (a device to "cut" the tractor beam and render it ineffective). In some fictional realities, shields can block tractor beams, or the generators can be disabled by sending a large amount of energy back up the beam to its source.

Tractor beams and pressor beams can be used together as a weapon: by attracting one side of an enemy spaceship while repelling the other, one can create severely damaging shear effects in its hull. Another mode of destructive use of such beams is rapid alternating between pressing and pulling force in order to cause structural damage to the ship as well as inflicting lethal forces on its crew.

Two objects being brought together by a tractor beam are usually attracted toward their common centre of gravity. This means that if a small spaceship applies a tractor beam to a large object such as a planet, the ship will be drawn towards the planet, rather than vice versa.

In Star Trek, tractor beams are imagined to work by placing a target in the focus of a subspace/graviton interference pattern created by two beams from an emitter. When the beams are manipulated correctly the target is drawn along with the interference pattern. The target may be moved toward or away from the emitter by changing the polarity of the beams. Range of the beam affects the maximum mass that can be moved by the emitter, and the emitter subjects its anchoring structure to significant force.