NAVIGATIONAL SENSORS

	A terrestrial bird, a living organism, is aware of its surroundings and 
uses its senses to find its way from one point to another, frequently guided 
by stars in the night sky. The comparison of the USS Enterprise to the bird 
here is an apt one. In much the same way, the Enterprise system constantly 
processes incoming sensor data and routinely performs billions of 
calculations each second, in an effort to mimic the biological solution to the 
problem of navigation. While an equivalent number of Enterprise sensors and 
simulated neurons (and their interconnections) within the main computers 
are still many orders of magnitude less efficently designed than the avian 
brain, nonetheless the Enterprise system is more than adequate to the task 
of traversing the galaxy.

	Sensors provide the input;  the navigational processors within the 
main computers reduce the incessant stream of impulses into usable 
position and velocity data. The specific navigational sensors being polled at 
any instant will depend on the current flight situation. If the starship is in 
orbit about a known celestial object, such as a planet in a charted star 
system, many long-range sensors will be inhibited, and short-range devices 
will be favored. If the ship is cruising in interstellar space, the long-range 
sensors are selected and a majority of the short-range sensors are powered 
down. As with an organic system, the computers are not overwhelmed by a 
barrage of sensory information.

	The 350 navigational sensor assemblies are, by design, isolated from 
extraneous cross-links with other general sensor arrays. This isolation 
provides more direct impulse pathways to the computers for rapid 
processing, especially during high warp factors, where minute directional 
errors, in hundredths of an arc-second per light year, could result in impact 
with a star, planet, or asteroid. In certain situations, selected cross-links may 
be created in order to filter out system discrepancies flagged by the main 
computer.

	Each standard suite of navigational sensore includes:

¥Quasar Telescope
¥Wide-Angle IR Source Tracker
¥Narrow-Angle IR-UV-Gamma Ray Imager
¥Passive Subspace Multibeacon Receiver
¥Stellar Graviton Detectors
¥High-Energy Charged Particle Detectors
¥Galactic Plasma Wave Cartographic Processor
¥Federation Timebase Beacon Receiver
¥Stellar Pair Coordinate Imager

	The navigational system within the main computers accepts sensor 
input at adaptive data rates, mainly tied to the shipÕs true velocity within the 
galaxy. The subspace fields within the computers, which maintain faster-
than-light (FTL) processing, attempt to provide at least 30% higher 
proportional energies than those required to drive the spacecraft, in order to 
maintain a safe collision-avoidance margin. If the FTL processing power 
drops below 20% over propulsion, general mission rules dictate a 
commensurate drop in warp motive power to bring the safety level back up. 
Specific situations and resulting courses of action within the computer will 
determine the actual procedures, and special navigation operating rules are 
followed during emergency and combat conditions.

	Sensor input processing algorithms take two distinct forms, baseline 
code and rewritable code. The baseline code consists of the latest version of 
3D and 4D position and flight motion software, as installed during starbase 
overhauls. This code resides within the protected archival computer core 
segments and allows the starship to perform all general flight tasks. The 
Enterprise has undergone three complete reinstallations of its baseline code 
since its first dock departure. The rewritable code can take the form of 
multiple revisions and translations of the baseline code into symbolic 
language to fit new scenarios and allow the main computers to create their 
own procedure solutions, or add to an existing database of proven solutions.

	These solutions are considered to be learned behaviors and 
experiences, and are easily shared with other Starfleet ships as part of an 
overall spacecraft species maturing process. They normally include a large 
number of predictive routines for high warp flight, which the computers use 
to compare predicted interstellar positions against realtime observations, 
and from which they can derive new mathematical formulae. A maximum of 
1,024 complete switchable rewrite versions can reside in main memory at 
one time, or a maximum of 12,665 switchable code segments. Rewritable 
navigation code is routinely downloaded during major starbase layovers and 
transmitted or physically transferred to Starfleet for analysis.

	Sensor pallets dedicated to navigation, as with certain tactical and 
propulsion systems, undergo preventative maintenance (PM) and swapout 
on a more frequent schedule than other science-related equipment, owing to 
the critical nature of their operation. Healthy components are normally 
removed after 65Ñ0% of their established lifetimes. This allows additional 
time for component refurbishment, and a larger performance margin if 
swapout is delayed by mission conditions or periodic spares unavailability. 
Rare detector materials, or those hardware components requiring long 
manufacturing lead times, are found in the quasar telescope (shifted 
frequency aperture window and beam combiner focus array), wide angle IR 
source tracker (cryogenic thin-film fluid recirculator), and galactic plasma 
wave cartographic processor (fast Fourier transform subnet). A 6% spares 
supply exists for these devices, deemed acceptable for the foreseeable 
future, compared to a 15% spares supply for other sensors.  Æ