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Security sensor display 2369

A sensor reading of Deep Space 9 with real-time output on a Cardassian terminal

The term sensor, also referred to aboard starships as subspace sensors or sensor probes, was used to refer to any device that was used to scan, record, or otherwise observe any aspect of an environment surrounding a starship, space station, or person. This could be as simple a device as a manual camera or light sensor, or as complicated as the myriad devices designed to scan many aspects of the matter and energies of subspace, space, time, and stellar bodies that make up all of existence.

Sensor probe[]

The term "sensor probe" was used to indicate sensors used for probing. (TOS: "The Corbomite Maneuver", "Mudd's Women", "For the World is Hollow and I Have Touched the Sky"; TNG: "Code of Honor") Lieutenant junior grade Worf conducted a routine deep sensor probe while the USS Enterprise-D traversed the Zed Lapis sector, which indicated "no obstacles or vessels within a range of three light years." (TNG: "Skin Of Evil")

However, the term also referred to a specific type of automated probe, used by Starfleet. Such a probe was launched by the USS Enterprise to scan Delphi Ardu IV in 2364 and to monitor a convoy used as bait for the Maquis in 2370. (TNG: "The Last Outpost", "Preemptive Strike") The USS Valiant also used such a probe to study the Jem'Hadar battleship in 2374. (DS9: "Valiant")


Sensors of various types played roles in almost every aspect of space travel. Every type of sensor, from navigational sensors to ARA sensors, created data to be interpreted by the vessels' computers and operators. In most situations, the sensor data revealed information that was not apparent through other data-collecting means, such as visual observations. (TNG: "Justice", "Timescape"; DS9: "Emissary"; VOY: "Parallax", "Ex Post Facto", "Basics, Part I") Galaxy-class starships were equipped with high-resolution, multi-spectral sensors. (TNG: "Encounter at Farpoint")

There were two basic types of sensor arrays employed: passive and active. A passive scan was less obtrusive than an active scan, and might not be detected by the subject being sensed. Sensors were divided further into short- and long-range types, and low- and high-energy types. (Star Trek: The Motion Picture; TNG: "Conspiracy")

The exact dividing point between short- and long-range sensors was not clearly established on screen. Long-range sensors picked up information about targets that were, on occasion, several hours' travel time distant from the sensing ship. Short-range sensors seemed to be restricted to a range consistent with the immediate environment of the sensing ship (the term "immediate" being relative), and were most often mentioned being used to scan the surface of planets from orbit or to target weapons fire. This uncertainty extends to the difference between low- and high-energy scans.

While there are many ways to mask a sensor scan, sensor screens were the most commonly used method. (TOS: "The Mark of Gideon") One could also mask a sensor scan with certain materials, or radiation. (TNG: "Who Watches The Watchers", "The Pegasus") Sensors can be disrupted by overloading them with information. (ENT: "Detained") Sensors and communications can also be disrupted by interference from a planet's troposphere and ionosphere. (Star Trek II: The Wrath of Khan; TNG: "The Dauphin"; Star Trek Generations) One could also move to a position in orbit at a planet's magnetic pole to confuse sensors. (TNG: "The Hunted") But to truly hide from a sensor scan, one would actually have to change one's molecular structure. (TOS: "Obsession")

For more information about the different variations of scans, see "types of scans".

Use on vessels[]

The Starfleet vessel Enterprise was equipped with a lateral sensor array. When Captain Jonathan Archer and Commander Charles Tucker III were inspecting the new prototype NX-class ship in an inspection pod during 2151, one of the components that Archer wanted to view was the lateral sensor array. (ENT: "Broken Bow")

Sensors were meanwhile used by the Vahklas, a Vahklas-type ship, which had left the planet Vulcan in approximately 2143. When Sub-Commander T'Pol was studying the Arachnid Nebula aboard the Vahklas in 2151, she was temporarily unable to scan the nebula's disodium layer, due to the fact that the transport ship's lateral sensors were out of alignment. (ENT: "Fusion")

Less than a year later, all sensors at Tandaran Detention Complex 26 were overly "occupied" by Hoshi Sato aboard Enterprise, who transmitted loads of data to the facility, thereby jamming the internment camp's frequencies. This disruption allowed Enterprise to conceal a transporter beam from the ship to the facility. (ENT: "Detained")

In the final draft script of "Detained", the disruption of the sensors at Detention Complex 26 was attributed, by Lieutenant Malcolm Reed, to Hoshi having "dumped" Enterprise's "entire movie database" to the facility's computer (though the particular documents that were contained in the influx of data, as established in the episode, were also largely referred to in the script, the only exception being the Vulcan database).

The final draft script of ENT: "Desert Crossing" established that Enterprise's sensors were used in an unsuccessful effort to localize the bio-signs of Archer and Tucker during a widespread assault in the Cygniai Expanse, in preparation for beaming them to the ship. In the script, after the attempt failed, Malcolm Reed exclaimed, "To hell with the sensors," before hatching a new plan. However, sensors are not referred to in the final version of this scene.

In 2364, prior to stardate 41775, the Federation starships USS Puget Sound and USS Ganymede were ordered, by a Starfleet admiral, not to scan a particular subsector with a high energy scan. (TNG: "Conspiracy")

In early 2368, when investigating the Phoenix Cluster, the lateral sensors of the USS Enterprise-D were booked solid for planetary observation. (TNG: "The Game")

In 2370, the Romulan warbird Terix performed a sensor scan of asteroid Gamma-601 in the Devolin system with its lateral sensor array in hope to locate the USS Pegasus. (TNG: "The Pegasus")

Voyagers Sensor logs

USS Voyager's sensor readings at various time indexes

An example of the accuracy of sensors was in the sensor data of the USS Voyager during one encounter with the Borg. Sensor readings from the ship's active scans recorded "random subspace energy fluctuations" at various time indexes in the sensor logs. Closer examination of this data revealed the detections were not random fluctuations but communications to Seven of Nine, one of Voyager's crew. (VOY: "Dark Frontier")

The enormous capability of the USS Voyager's sensors was demonstrated on one occasion when Captain Janeway requested that Harry Kim scan space for sporocystian life-forms. Moments later, Harry reported finding a "sporocystian energy burst, approximately ten light years distant." This implies that the sensors were able to scan and analyze a volume of more than 4,100 cubic light years in about six seconds. (VOY: "Cold Fire")

Types of scans[]

Background information[]

In a section of ultimately unused dialogue from the first draft script of ENT: "Fortunate Son", Vulcan sensors were established as being more technologically advanced than Starfleet sensors at the time of the episode's setting (in 2151). One function that Vulcan sensors were said to be capable of was detecting a Nausicaan bio-sign whereas Starfleet sensors were notoriously incapable of that.

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