Eyes and Ears

So, let’s now turn to the topic of sensors, and what exactly is in that Cilmínár Spaceworks AE-35 “standard navigational sensor suite” built into the majority of current-era starships. There are two primary groups of sensors incorporated into such a suite, referred to as “navigational” and “tactical” – even on civilian vessels – sensors, respectively, along with cross-feeds from the communications systems.


The first of these groups, the navigational sensors, are those primarily used to locate the starship itself in space and, to a lesser extent, time. Included in a standard suite are the following:

Orbital Positioning System

The Orbital Positioning System, considered the primary source of navigational data within settled space, makes use of beacons located on stargates, and orbiting in designated positions within the system, each broadcasting a unique identifying code and sequence signal. By correlating signals received from these satellites with the reference data published in astrogators’ ephemerides, or downloaded from the stargate navigation buoy on system entry, a starship’s position within the inner and the majority of the outer system can be determined precisely, although accuracy does fall off as the Shards are reached.

Star Tracker

As a backup to the Orbital Positioning System, and as the primary method of navigation in undeveloped star systems, the navigational suite includes a star tracker. This system maintains a sunlock, a continuous bearing to the local system primary, and a number of starlocks, continuous bearings to a number of well-known nearby stars, identified spectrometrically. Again, by correlating these bearings with ephemeris data, a starship’s position can be determined with considerable accuracy.

Pulsar Navigational Reference

A final backup is provided by the Pulsar Navigational Reference, which maintains continuous bearings to a number of pulsars located within the local galaxy, using the same principles as the star tracker. While unsuitable for fine navigation (due to the low available parallax of such distant reference points) it is of use in providing confirmatory gross position data.

Inertial Tracking Platform

The inertial tracking platform provides a continuous check on all other forms of navigation, a bridge during switches between beacons and starlocks, and a navigational reference for fine maneuvering; using a complex of accelerometers and gyroscopes linked to the starship’s drive systems, the ITP integrates angular velocity and linear acceleration into a continuous record of change of position and change of velocity. In the latter role, it operates alongside the timebase receiver to provide the relativistics officer with the information required to differentiate wall-clock time and empire time.

Imperial Timebase Receiver

The timebase receiver receives the continuous timebase reference signal transmitted by all stargates, based on their temporal consensus, which defines the empire time reference frame: i.e., the pseudo-absolute time frame without reference to the relativistic maneuvering of individual starships (or indeed celestial bodies); it provides an external temporal reference separate from the starship’s internal wall-clock time.


The second of these groups, the tactical sensors, are those which concern themselves rather with the environment around the starship than with the starship’s position. Those commonly included, which is to say ignoring specialized scientific sensors, include:

All-Sky Passive EM Array

The sensor with the most general utility is assuredly the all-sky passive EM array. The latest ASPEMA designs consist of a complex array of receptor elements woven through the outer layers of much of a starship’s hull surface, operating together to function as a single large sensor. An ASPEMA’s elements are designed to maintain a consistent watch across the majority of the EM spectrum, from low-frequency RF through infrared, visible light, and up to gamma-rays. A properly configured ASPEMA gives the sensor operator a clear, moderate-resolution view of everything radiating EM within the star system, which is everything worth speaking of.

Passive EM Telescope

When higher resolution is required for identification, or profiling of a target or its emissions, the sensor suite also incorporates one or more passive EM telescopes capable of significantly higher resolution and sensitivity which can be pointed at specific targets.

Active EM Radar

When precise ranging is called for, or the emissions of the target are insufficient to permit profiling with the passive EM telescope, it is possible to “go active”. The active EM radar usually makes use of the same reception hardware as the passive EM telescope; it merely transmits a directional RF pulse and receives its reflection from the target, the time of travel providing the ranging information. The disadvantage of this technique, of course, is that the use of the active EM radar announces one’s presence to all other starships in the system, even beyond typical passive detection ranges.


The gravitometer provides an effective and highly sensitive way to measure the local degree of space-time curvature, both absolute and differential. This can be used to provide a variety of information, including current depth with the gravity well (or altitude) when near objects of known mass, bearings to high-mass objects, and detection profiles of gravity waves, including those generated when a stargate is used by another starship in-system.

Neutrino Detector

The neutrino detector chiefly provides supplementary information. Nucleonic reactions are rich sources of neutrinos; as such, other than when swamped by stellar emissions, neutrino emissions can indicate the presence of operating fusion reactors, torch drives, or other nucleonic equipment commonly found aboard starships. While providing limited additional data on its own, although aiding in the profiling of starships by their power plant, it has the advantage over other sensors that neutrinos interact very little with other matter, and as such the neutrino detector can determine the presence of a signal otherwise occluded by a lunar or planetary body.

Docking Radar

A high-frequency omnidirectional radar system designed for use at short range, the docking radar is a specialized radar system intended to provide precise location and range information while docking, operating near habitats, or otherwise in crowded orbits.

Imaging Lidar Grid

Offering a significantly higher resolution than radar, a starship lidar grid is primarily used for two purposes: first, producing a surface map of asteroids or potential landing sites, or a hull map of an unidentified vessel or hulk to look up in the database; and second, since being hit with a high-intensity lidar pulse will overwhelm most EM-based sensors and can even trigger hull thermal alarms, as a very effective way to yell “Hey, stupid!” at starships which aren’t answering standard hails.

Communications (integrated)

Fed across from the communications subsystem are two other important sources of navigational data:


The first of these is transponder data received from other starships. A transponder broadcast must include that starship’s identity, the current time, and certain important parameters (safety distance from its drives, whether it’s carrying certain hazardous cargoes, registration, and so forth).  Ships currently operating under positive control include a subcode – a “squawk” – designated by space traffic control authorities for their reference, and a transponder can also signal various status codes, indicating distress situations in progress, communications failures, hijackings, and other such. The majority of transponders also transmit the ship’s own determination of its position.

IIP Interface

While an extranet feed may seem frivolous for astrogation purposes, it is an essential feature of…


The most notable common characteristics of all of these sensor systems is that they operate at the speed of light, or more slowly, and that they operate from a single point in space, which imposes a tremendous limitation on what information an astrogator may have available. The solution to this is longscan.

Using defined extranet protocols, cooperating starships broadcast their sensory gestalt to other starships in the system via the standard IIP communications relays, as do other sources of sensor data, such as habitats, stargates, and navigation satellites. Using this information, along with predictive AI and astrogator-assisted extrapolations of what each starship or other object visible has done or will do since the last update, the longscan system on each starship produces an overview of the current situation including that information which that ship could not itself sense, or which is still in transit to it, duly annotated with probability and reliability estimates for their future actions.

– Technarch Apt’s How-It-Works: Starships

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