Critical to the flight of any vehicle through interstellar space are the concepts of guidance and navigation. These involve the ability to control spacecraft motions, to determine the locations of specific points in three and four dimensions, and to allow the spacecraft to follow safe paths between those points. The theater of operation for the USS Victory takes it through both known and unknown regions of the Milky Way galaxy. While the problems of interstellar navigation have been well-defined for over two hundred years, navigating about this celestial whirlpool, especially at warp velocities, still requires the precise orchestration of computers, sensors, active high-energy deflecting devices, and crew decision making abilities.
Spacecraft Guidance[]
The attitude and translational control of the USS Victory relative to the surrounding space involves numerous systems aboard both the Saucer Module and Battle Section. As the starship maneuvers within the volume of the galaxy, the main computers attempt to calculate the location of the spacecraft to a precision of 10 kilometers at sublight, and 100 kilometers during warp flight. The subject of velocity is important in these discussions, as different sensing and computation methods are employed for each flight regime.
During extremely slow in-system maneuvering at sublight velocity, the main computers, coupled with the reaction control thrusters, are capable of resolving spacecraft motions to 0.05 seconds of arc in axial rotation, and 0.5 meters of single impulse translation. During terminal docking maneuvers, accuracies of up to 2.75 cm can be maintained. Changes in spacecraft direction of flight, relative to its own center of mass, is measured in bearings.
Internal sensing devices such as accelerometers, optical gyros, and velocity vector processors, are grouped within the inertial baseline input system, or IBIS. The IBIS is in real time contact with the structural integrity field and inertial damping systems, which provide compensating factors to adjust apparent internal sensor values, allowing them to be compared with externally derived readings. The IBIS also provides a continuous feedback loop used by the reaction control system to verify propulsion inputs.
External Sensors[]
The major external sensors employed at sublight include stellar graviton detectors, stellar pair coordinate imagers, pulsar/quasar counters, far infrared scanners, and Federation Timebase Beacon (FTB) receivers. These devices also communicate with the structural integrity field and inertial damping field processors, inertial sensors, and main computers to obtain an adjusted awareness of the ship's location.
The wide range of external sensors make it possible to obtain the greatest number of readings under many different conditions. The standard external sensor pallet has been designed to insure that coarse position calculations can be made under adverse operating conditions: e.g., magnetic fields, dense interstellar dust, and stellar flares. While the network of FTBs operate on subspace frequencies to facilitate position calculations at warp, vehicles at sublight speed can, in fact, obtain more precise positioning data than ships at warp. In the absence of clear FTB signals, onboard timebase processors continue computing distance and velocity for later synchronization when FTB pulses are once again detected.
Guidance of the USS Victory at higher sublight velocities couples the impulse engines with those systems already mentioned. External sensor readings, distorted by higher relativistic speeds, necessitate adjustment by the guidance and navigation (G&N) subprocessors in order to accurately compute ship location and provide proper control inputs to the impulse engines. Extended travel at high sublight speed is not a preferred mode of travel for Federation vessels, due to the undesired time-dilation effects, but may be required occasionally if warp systems are unavailable.
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The whole of the galactic environment must be taken into account in any discussion of guidance and navigation. The Milky Way galaxy, with its populations of stars, gas and dust concentrations, and numerous other exotic (and energetic) phenomena, encompasses a vast amount of low-density space through which Federation vessels travel. The continuing mission segments of the USS Victory will take it to various objects within this space, made possible by the onboard navigation systems.
The Milky Way Galaxy[]
The Milky Way galaxy would seem, by any scheme of mapping, to be a record-keeping nightmare created to thwart all who would attempt to traverse it. Not only is the entire mass rotating, but it is doing so at different rates, from its core to the outer spiral arms. Over time, even small-scale structures change enough to be a problem in navigation and mapping. A common frame of reference is necessary, however, in order to conduct exploration, establish trade routes, and perform various other Starfleet operations, from colony transfers to rescue missions.
Celestial objects become known by planetary deepspace instrument scans and starship surveys, and are recorded within Starfleet's central galactic condition database. Locations and proper motions of all major stars, nebulae, dust clouds, and other stable natural objects are stored and distributed throughout the Federation. New objects are catalogued as they are encountered, and updated databases are regularly transmitted by subspace radio to Starfleet and allied Federation vessels.
During stops at Federation outposts and starbases, all detailed recordings of a ship's previous flight time are downloaded and sent on to Starfleet. Most of the information in the database concerns the present condition of an object, with "present" defined as real clock time measured at Starfleet Headquarters, San Francisco, Earth. The overall visual appearance of the galaxy from Earth or any planet is, of course, unreliable due to the limitation of the speed of light; so many additional sources (such as faster subspace readings) are needed to keep the database current. Where realtime object information is unavailable, predicted conditions are listed.
The main computers of the USS Victory apply the galactic condition database to the task of plotting flight paths between points in the galaxy. Objects lying along the flight path, such as stellar systems or random large solid bodies, are avoided. At sublight as well as warp velocities, the external and internal sensors communicate with the computers and engine systems to perform constantly updated course corrections along the basic trajectory.
Deflection of Low-Mass Particles[]
Lighter mass materials such as interstellar gas and dust grains are translated away from the ship's flight path by the main navigational deflector. During low-sublight travel, a number of nested parabolic deflector shields are projected by the main emitter dish. These shields encounter distant oncoming particles, imparting a radial velocity component to them, effectively clearing the space ahead of the vehicle fora short time. Higher sublight velocities require the additional use of precision-aimed deflector beams directed at specific targets in the projected flight path.
Control of the deflector power output is available in a number of modes, from simple deflection to predictive-adaptive subspace/graviton; a series of high-speed algorithms analyzes the ship's velocity and the density of the interstellar medium, and commands changes in the navigational deflector system.