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Memory Alpha
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(covers information from several alternate timelines)
For the Starfleet agency, please see Planetary Defense Systems.

A planetary defense system, also called an orbital defense system or planetary defense battery was a network of space-based and/or ground-based defenses intended to protect a planet from attack.

Federation examples[]


The Mars Defense Perimeter

In the 23rd century, Earth was protected by the Earth Defense Network. (Star Trek: The Motion Picture)

In 2258 of the alternate reality, Earth's border protection grids had several access codes which were known to Starfleet captains. Nero captured Christopher Pike and tortured him to learn the codes. (Star Trek)

The inner Sol system was defended by the Mars Defense Perimeter, which was breached in early 2367 by a Borg cube en route to Earth. (TNG: "The Best of Both Worlds, Part II")

USS Defiant and Yeager at DS9

Starbase Deep Space 9

In 2369, when Starfleet assumed operational control of Deep Space 9, the station became a planetary defense system for Bajor as one of its main duties was to protect the planet from hostile attack. (DS9: "Emissary")

In 2372, the sabotage of Earth's power relay grid left Earth "defenseless" as sensors, transporters, and surface-based defense installations were taken offline. (DS9: "Homefront")

During the Dominion War, Betazed had antiquated and undermanned planetary defense systems, which proved little match for an invading Dominion force in 2374. (DS9: "In the Pale Moonlight")

Martian planetary defense system satellite

Defense satellites in orbit of Mars

By 2385, Mars was protected by a deflector shield and a defense net that included orbiting satellites. These systems were deactivated or compromised by rogue synths during the Attack on Mars. (PIC: "Remembrance", "Maps and Legends")

In 2401, Earth was protected by a collection of planetary defenses which included orbital weapon platforms, Sol Station and planetary shields, which fell under the attack of the Borg-assimilated fleet of Federation starships that had gathered for Frontier Day. (PIC: "The Last Generation")


Earth Planetary Defense System Engaging

In the 32nd century, when USS Discovery arrived at Earth, It encountered a heavily advanced planetary forcefield along with United Earth Defense Force Ships. (DIS: "People of Earth")

Non-Federation examples[]

Apollo's hand grips the Enterprise, remastered

Apollo's hand

The Romulan Star Empire used cloaked mines to defend recently annexed planets in the 22nd century. (ENT: "Minefield")

In 2267, the USS Enterprise encountered Apollo's hand near the planet Pollux IV. This enormously-powerful force field was capable of stopping the ship from approaching the planet, preventing it from firing its weapons, and also preventing escape. (TOS: "Who Mourns for Adonais?")

The Aldeans, until 2364, used a high-powered repulsor beam to repel any unwanted ships from Aldea's orbit, as well as a powerful shield and a cloaking device. (TNG: "When The Bough Breaks")

Echo papa 607 under fire

Minosian Echo Papa 607 drone

The Echo Papa 607 weapon system of Minos could act as an effective planetary defense system, repelling attackers in space and on land. (TNG: "The Arsenal of Freedom")

A moon in the Gamma Quadrant, home of the Ennis and the Nol-Ennis, had a sophisticated array of orbiting satellites which inhibited transporter functions, and also actively sought out and attacked orbiting vessels. (DS9: "Battle Lines")

After the Klingon invasion of the Cardassian Union in 2372, the Klingon Empire deployed orbital defense systems around the planets they had captured. (DS9: "The Way of the Warrior")

The planetary defense systems of Korma included system-5 disruptors. They were overwhelmed by Klingon forces in 2372. (DS9: "Return to Grace")

A planet of the Mokra Order visited by USS Voyager in 2372 was defended by numerous surface-based phased ion cannons. (VOY: "Resistance")


Klingon defenses around Ty'Gokor

Chancellor Gowron moved the Klingon military headquarters from Qo'noS to Ty'Gokor in 2373. Ty'Gokor was protected by a powerful defensive shield and a tachyon detection grid, along with a large number of warships and space stations. (DS9: "Apocalypse Rising")

Cardassian orbital weapon platform

Cardassian orbital defense platforms

In late 2374, during the Dominion War, the Cardassians developed unmanned Cardassian orbital weapon platforms to protect planets. The platforms were deployed in the Chin'toka system and around Cardassia Prime. (DS9: "Tears of the Prophets", "What You Leave Behind")

As of 2399, Vashti possessed a standard Romulan planetary defense system comprised of orbital killer drones, described as "primitive but effective". It had been bought secondhand and installed with the help of the Fenris Rangers. (PIC: "Absolute Candor")

Ni'Var satellite

Ni'Var with defense satellites in 3189

As of 3189, Ni'Var had a network of defense satellites. (DIS: "Unification III")


See also[]

Background information[]

A cut bit of dialogue in the script of Star Trek: First Contact would have established that in 2063 Earth did not have planetary defense systems.

External links[]