Memory Beta, non-canon Star Trek Wiki

A friendly reminder regarding spoilers! At present the expanded Trek universe is in a period of major upheaval with the finale of Year Five, the Coda miniseries and the continuations of Discovery, Picard and Lower Decks; and the premieres of Prodigy and Strange New Worlds, the advent of new eras in Star Trek Online gaming, as well as other post-55th Anniversary publications. Therefore, please be courteous to other users who may not be aware of current developments by using the {{spoiler}}, {{spoilers}} or {{majorspoiler}} tags when adding new information from sources less than six months old. Also, please do not include details in the summary bar when editing pages and do not anticipate making additions relating to sources not yet in release. 'Thank You


Memory Beta, non-canon Star Trek Wiki

Diagram of an impulse engine.

An impulse engine (a colloquialization of internally metered pulse drive) was a nuclear fusion-based propulsion system used primarily for sub-light travel.

History and specifics

Impulse engines were first used by Humans in the 21st century aboard the Nomad unmanned probe and on the manned USS Lewis & Clark, the first ship to visit Saturn. (TOS novel: The Rings of Time)

Impulse engines were used by the United Earth, and later, the Federation. (TOS novel: Final Frontier; ENT novelization: Broken Bow)

A new impulse engine design was created in 2169; Starfleet vessels were the first to use the new design. (Last Unicorn RPG module: Starfleet Academy Handbook)

The Last Unicorn RPG module: Starfleet Academy Handbook implies that the first impulse designs were created in 2169, but the phrasing leaves it open to interpretation as to whether they were a new design put into use. Canon sources place the discovery of the impulse engine in the 21st century.

In the early-to-mid 23rd century, Starfleet would test new impulse engine designs at their Impulse Engine Testing Grounds located in the city of El Paso, Texas. (TOS - Who's Who in Star Trek comic: "Issue 1")

Following the discovery of the Bajoran wormhole in 2369, any starship crew that required access to the wormhole had to drydock their vessel at Deep Space 9 to have impulse energy buffers mounted around their impulse engines. (DS9 novel: Bloodletter)

The components of the Vorl-tak could be used to construct an impulse engine. (EV - Cloak and Dagger comic: "Part 2 of 2")


Each impulse engine consisted of one or more nuclear fusion reactors, a series of subspace field coils, and a vectored thrust nozzle to direct the plasma exhaust. The engine produced a high energy plasma that was vented out of the thrust nozzles to propel the starship. In the event of an emergency while at warp, the impulse engines could also be utilized to temporarily generate a Warp field to maintain warp speed for the vessel or the primary hull in the event of Saucer separation. (ST reference: USS Enterprise Owners' Workshop Manual)

The deuterium-based fusion reaction of the impulse drive also served as a secondary power system for a starship, and was utilized for powering internal systems. (TNG reference: Star Trek: The Next Generation Technical Manual)

Design variants

In addition to a standard impulse drive, several subgroups of impulse engine existed. A hyperimpulse engine, such as the drive system utilized by the Timeship Aeon, had exceptional speed, but high power requirements. (ST video game: Star Trek Online; VOY episode: "Future's End")

Another form of impulse drive was a combat impulse engine, which offered an edge in maneuverability, but had low top speed. (ST video game: Star Trek Online)

Additional impulse engines were available through modifications; however, the traditional impulse engine underwent little change since the 23rd century. (TNG episode: "Relics")

Impulse engine types

Earth and Federation impulse drive types

FIB-3 type

FIC-2 type

FIC-3 type


Related topics


External link