The tactical deflector system is the primary defensive system of the Galaxy class starship. It is a series of powerful deflector shields that protect both the spacecraft and its crew from both natural and artificial hazards.

Like most force field devices, the deflector system creates a localized zone of highly focused spatial distortion within which an energetic graviton field is maintained. The deflector field itself is emitted and shaped by a series of conformal transmission grids on the spacecraft exterior, resulting in a field that closely follows the form of the vehicle itself. This field is highly resistive to impact due to mechanical incursions ranging from relativistic subatomic particles to more massive objects at lesser relative velocities. When such an intrusion occurs, field energy is concentrated at the point of impact, creating an intense, localized spatial distortion.

To an observer aboard the starship, it appears that the intruding object has "bounced off" the shield. A zero-dimensional observer on the intruding object would, however, perceive that his/her trajectory is unaffected, but that the location of the starship has suddenly changed. This is somewhat analogous to the spatial distortion created by a natural gravity well, and is typically accompanied by a momentary discharge of Cerenkov radiation, often perceived as a brief blue flash. The deflector is also effective against a wide range of electro- magnetic, nuclear, and other radiated and field energies.

Field Generators

The deflector system utilizes one or more graviton polarity source generators whose output is phase-synchronized through a series of subspace field distortion amplifiers. Flux energy for the Primary Hull is generated by five field generators located on Deck 10. Three additional generators are located on Deck31 in the Secondary Hull. Two additional field generators are located in each of the warp nacelles, although the output of the Saucer Module grid can be boosted to include the nacelles if necessary. Each generator consists of a cluster of twelve 32 MW graviton polarity sources feeding a pair of 625 millicochrane subspace field distortion amplifiers. Cruise Mode operating rules require one generator in each major section to be operational at all times, with at least one additional unit available for activation should an Alert condition be invoked. During Alert situations, all operational deflector generators are normally brought to full standby.

Nominal system output (Cruise Mode) of the deflector system is 1152 MW graviton load. Peak momentary load of a single generator can approach 473,000 MW for periods approaching 170 milliseconds. During Alert status, up to seven generators can be operated in parallel phase-lock, providing a continuous output of 2688 MW, with a maximum primary energy dissipation rate in excess of 7.3 x 105 kW.

Heat dissipation on each generator is provided by a pair~ of liquid helium coolant loops with a continuous-duty rating of 750,000 MJ. Four backup generators are located in each hull providing up to twenty-four hours of service at 65% of nominal rated power. Normal duty cycle on primary generators is twelve hours on-line, with nominal twelve hours degauss and scheduled maintenance time. Graviton polarity sources are rated for 1,250 operating hours between routine servicing of superconductive elements.

Shield Operating Frequencies

Providing shielding against the entire spectrum of electromagnetic radiation would prove far too energy-costly for normal Cruise Mode use. Additionally, a full-spectrum shielding system would prevent onboard sensors from gathering~ many types of scientific and tactical data. Instead, Cruise Mode operating rules allow for deflectors to operate at the relatively low level (approximately 5% of rated output) and at the specific frequency bands necessary to protect the spacecraft's habitable volume to SFRA-standard 347.3(a) levels for EM and nuclear radiation.

During Alert situations, shields are raised to defensive configuration by increasing generator power to at least 85% of rated output. Shield modulation frequencies and bandwidths are randomly varied to prevent a Threat force from adjusting the frequency of a directed energy weapon (such a phaser) to penetrate shields by matching frequency and phase. Conversely, when the frequency characteristics of a directed energy weapon are known, it is possible to dramatically increase deflector efficiency by adjusting the shielding frequencies to match those of the incoming weapon. Similar techniques are used to protect the vehicle against various natural hazards, as when shielding is increased in the 10^-10 meter band to protect against X rays generated by a supernova.

Raising shields to defensive configuration also triggers a number of special operating rules. First, active sensor scans are operated according to special protocols that are intended to minimize the interference due to the shielding effects. For certain types of scans, sensors are continually recalibrated to take advantage of any EM "windows" left open by rotation of shield frequencies. In other cases, the random variation of shield frequencies is modified slightly to allow a specific EM window at specific intervals necessary for data collection. Such sensor operation techniques generally result in substantially reduced data collection rates, so sensor usage is strictly prioritized during Alert situations. Further, most defensive scenarios require sensors to be operated in "silent running" mode during which the usage of active scan sensors is not permitted and only passive sensors may be used.

            Also affected by deflector shield usage is operation of the transporter system. The annular confinement beam that serves as the transmission medium for the transporter beam requires such a wide EM and subspace bandwidth that it is normally impossible to transport through shields. Additionally, the shields' spatial distortion effects can be severely disruptive of the transporter beam's pattern integrity.

            Shield operation also has a significant impact on warp drive operation. Because of the spatial distortion inherent in the shielding generation process, there is a measurable effect on the geometry of the warp fields that propel the ship. Warp drive control software therefore includes a number of routines designed to compensate for the presence of deflector shields, which would otherwise cause (at maximum rated output) a 32% degradation in force coupling energy transfer. Simultaneously, shield generator output must be upshifted by approximately 147 kilohertz to compensate for translational field interaction.