Guidance and Navigation

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 Solstice 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.

### Flight Information Input

There are five standard input modes available for specification of spacecraft flight paths. Any of these options may be entered either by keyboard or by vocal command. In each case, Flight Control software will automatically determine an optimal flight path conforming to Starfleet flight and safety rules. Conn then has the option of executing this flight plan or modifying any parameters to meet specific mission needs.

Normal input modes include:

* **Destination planet or star system**. Any celestial object within the navigational database is acceptable as a destination, although the system will inform Conn in the event that a destination exceeds the operating range of the spacecraft. Specific facilities (such as orbital space stations) within the database are also acceptable destinations.
* **Destination sector**. A sector identification number or sector common name is a valid destination. In the absence of a specific destination within a sector, the flight path will default to the geometric center of the specified sector.
* **Spacecraft intercept**. This requires Conn to specify a target spacecraft on which a tactical sensor lock has been established. This also requires Conn to specify either a relative closing speed or an intercept time so that a speed can be determined. An absolute warp velocity can also be specified.Navigational software will determine an optimal flight path based on specified speed and tactical projection of target vehicle's flight path. Several variations of this mode are available for use during combat situations.
* **Relative bearing**. A flight vector can be specified as an azimuth/elevation relative to the current orientation of the spacecraft. In such cases, 000-mark-0 represents a flight vector straight ahead.
* Absolute heading. A flight vector can also be specified as an azimuth/elevation relative to the center of the galaxy. In such cases, 000-mark-0 represents a flight vector from the ship to the center of the galaxy.
* **Galactic coordinates**. Standard galactic XYZ coordinates are also acceptable as a valid input, although most ship's personnel find this cumbersome.

### Spacecraft Guidance

The attitude and translational control of the USS Solstice relative to the surrounding space involves numerous systems aboard both the Saucer and Engineering Sections. 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 realtime 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.

### Navigation

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 Solstice 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 Solstice apply the galactic condition database to the task of plotting flight paths between points in the galaxy. Objects lying along the flight 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.