TRACTOR BEAMS

	Starfleet missions sometimes require direct manipulation of relatively 
large objects in proximity to a starship. Such operations can take the form of 
towing another ship, modifying the speed or trajectory of a small asteroid, or 
holding a piece of instrumentation at a fixed position relative to the ship. The 
execution of such missions generally requires the use of tractor beam 
remote manipulators.
	Tractor emitters employ superimposed subspace/graviton force 
beams whose interference patterns are focused on a remote target, 
resulting in significant spatial stress being applied on the target. By 
controlling the focal point and interference patterns, it is possible to use this 
stress pattern to draw an object toward the ship. Conversely, it is also 
possible to invert the interference patterns and move the focal point to 
actually push an object.

EMITTERS

	Tractor beam emitters are located at key positions on the shipÕs 
exterior hull, permitting objects at almost any relative bearing to be 
manipulated. Key among these are the two main tractor beam emitters, 
located fore and aft along the keel of the Engineering Hull as well as a third 
main emitter located on the forward surface of the interconnecting dorsal. 
Additional emitters are located near each shuttlebay for use in shuttle 
landing maneuvers. Mooring tractor beam emitters, used when the ship is in 
dock, are located at each reaction control thruster quad.
	The main tractor beam emitters are built around two variable phase 
16 MW graviton polarity sources, each feeding two 450 millicochrane 
subspace field amplifiers. Phase accuracy is within 2.7 arc-seconds per 
millisecond, necessary for precise interference pattern control. Secondary 
tractor beam emitters have lesser performance ratings. Main tractor beam 
emitters are directly mounted to primary structural members of the shipÕs 
framework. This is because of the significant mechanical stress and inertial 
potential imbalance created by tractor beam usage. Additional structural 
reinforcement and inertial potential cancellation is provided by tying the 
tractor emitter into the structural integrity field (SIF) network by means of 
molybdenum-jacketed waveguides.
	Effective tractor beam range varies with payload mass and desired 
delta-v (change in relative velocity). Assuming a nominal 5 m/sec® delta-v, 
the primary tractor emitters can be used with a payload approaching 
7,500,000 metric tonnes at less than 1,000 meters. Conversely, that same 
delta-v can be imparted to an object massing about one metric tonne at 
ranges approaching 20,000 kilometers.  Æ