Navigation Overview

Navigation involves management of the vessel’s movement in space, including superluminal travel between stellar systems and maneuvering the vessel around other vessels and objects at subluminal speeds.

All navigation requires knowledge of the vessel’s current location, speed and heading as well as the location and bearing of any vessels or objects in surrounding space. Movement over any distance necessitates establishing a heading that will get the vessel to the intended destination.

Navigation Modes

There are three main navigation modes.

Superluminal

Superluminal navigation involves relativistic faster-than-light travel, enabling transit between star systems within hours or days. The vessel’s superluminal engine utilises powerful fields which warp space-time, significantly reducing the effective distance the vessel needs to travel between two points.

Travelling in compressed space-time takes the vessel out of phase with surrounding space. This means the vessel is undetectable but also means that sensor readings or communication outside the warp field are not possible.

Impulse

The vessel’s main engines provide thrust using magnetoplasma impulse technology. This uses superheated plasma to create a base level of thrust, which is accelerated using magnetic fields arranged in a carefully configured impulse pattern. Referred to colloquially as impulse engines, they can accelerate the vessel to 0.2c – one-fifth of the speed of light.

The impulse engines are also capable of varying the direction of thrust so as to alter the vessel’s heading. This process of turning the vessel while underway is referred to as maneuvering. This makes the powerful thrust of the impulse engines available to alter the heading of the vessel’s considerable mass relatively quickly and efficiently but also requires the vessel to be under way.

Impulse navigation is where encounters with other vessels are most likely and most tactical operations will occur.

Reaction Control (RCS)

The Reaction Control System (RCS) uses a number of small chemical rocket engines located around the vessel to make small and precise position or heading changes. RCS is used for establishing orbit, rendezvousing with another vessel or for docking.

RCS can alter the vessel’s position from stationary, but is not powerful enough to maneuver the vessel at impulse speeds.

Vessel Position

Example of a Cartesian 3D grid. The blue dot has co-ordinates of X1, Y1, Z1The navigation system is based around Navigable Astronomical Objects (NAOs) – typically stars – whose position is fixed by stellar cartography. Navigators can provide a heading and range which allows any NAO to be reached via superluminal travel from any other point in the mapped galaxy.

Once a NAO has been reached, the navigation system utilises a three-dimensional Cartesian grid for tracking the position of all objects in the surrounding space.  Positions are expressed as a triple set of co-ordinates representing the X, Y and Z axes of the grid. The grid is anchored on the NAO (at grid co-ordinates X0, Y0, Z0) and radiates from that point.

The grid does not have a predetermined size and grows as required by the direction and range of vessel travel. As the distances between NAOs would take several years to traverse at impulse speeds, the grids around any two NAO’s would never meet.

Galactic Normal

The network of NAOs is also used establish galactic normal, which is a universally constant reference point for establishing direction, much like magnetic north is used by compasses on Earth. The navigation systems are able to use whatever combination of NAOs are detectable from the vessel's current location to calculate galactic normal.

Heading

Example of heading calculation. The blue dot has a heading of 60 degrees.The vessel’s direction of travel – or heading – is also managed by the navigation system. Headings are calculated against galactic normal, expressed as the number of degrees variation between travelling directly towards galactic normal (zero degrees) and the vessel’s actual direction of travel.

If an object can maneuver (change direction under its own power) then it is considered a Tactically Significant Maneuvering Object (TSMO) and its heading is also managed by the navigation system.

Bearing

Vessel orientation is determined using bearings. A bearing describes a direction relative to the bow of the vessel (instead of relative to galactic normal). It is used to express the orientation of an object in surrounding space relative to the vessel. This is often a more intuitive way of expressing a TSMO’s relative position rather than its grid co-ordinates.

Range

Range determines distance along a bearing to an object. Range is an important factor in determining the effectiveness of sesnors and weapons, for example.

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