(covers information from several alternate timelines)
An environmental suit, also known as an EV suit, pressure suit, exo-suit or environmental unit, is a special form of clothing designed to be used for protection or life support in inhospitable environments.
For Humans, with the advent of space travel came the need to perform tasks outside the controlled atmosphere of space vessels. Consequently, the EV suit was developed. As planets and other stellar objects came within the reach of Human space explorers, their EV suits became necessary for them to explore environments with different atmospheric conditions than those on Earth. (TOS: "The Naked Time", et al.) Other cultures also used EV suits. (ENT: "Silent Enemy", "Breaking the Ice", et al.)
In 1969, the first men to set foot on Earth's moon, Luna, wore space suits. Astronauts continued to use space suits for space walks in Earth orbit. (Star Trek: Enterprise title sequence; TOS: "The Cage")
During the initial flight of the Phoenix in 2063, noted inventor Zefram Cochrane and his copilots – Geordi La Forge and William T. Riker – did not wear any pressure or flight suits. Cochrane made history by making First Contact with an alien species, the Vulcans, after the Phoenix's flight had ended. (Star Trek: First Contact)
In the 2140s, Vulcan EV suits were relatively large, as Jonathan Archer once commented that the act of wearing one was "like you're flying around inside your own little starship." (ENT: "Breaking the Ice")
Aboard the Y-class Earth Cargo Service freighter ECS Fortunate, signage on a door gave instructions what to do in an emergency situation. It read that in the event of sudden pressure loss everyone should immediately proceed to the nearest communications panel and activate the emergency seal to close all the doors. All duty personnel should then wear pressure suits. (ENT: "Fortunate Son")
A new EV suit was introduced as standard issue on Enterprise NX-01, the first ship of the NX-class. These suits were copper colored with gray padding, and were comprised of several components, including a helmet. (ENT: "The Catwalk")
On each NX-class starship, at least six EV suits were present. Senior officers and some security personnel had their own suits, while the rest of the suits were shared for general use. (ENT: "The Catwalk", "The Crossing")
The EV suit was made as one full piece that closed at the front via a zip fastener and ended just below the elbow. The suit was self-sealing, meaning that if it were punctured or damaged in some way, sealant would be automatically applied to prevent the suit from decompressing. Although the suit was solid enough to protect its wearer from the rigors of space, a hypospray could still penetrate it in case of an emergency. (ENT: "Minefield") Even with the heavy padding and protection, even within a starship, the suit could only protect its wearer against a neutronic wavefront for about twenty-two minutes. (ENT: "The Catwalk")
Worn beneath the standard environmental suit was a distinct under suit. This form-fitting uniform was dark-gray in color and featured ribbing along the sides and chest, zipping at the front. The suit could be worn with a belt capable of holding a sidearm and various other pieces of equipment. It was also worn with booties that fit within the gravity boots of the outer EV suit. (ENT: "Sleeping Dogs")
The design of the helmet allowed an almost normal field of view to the wearer. Though the vertical field of view was limited, the amount of room inside the helmet allowed the wearer to compensate by simply moving his or her head. The helmet had a clear visor integrated into the front that could not be opened separately. It featured two outside lights, one on either side, and two ambient lights inside to illuminate the wearer's face. When the helmet was sealed, the ambient lights would activate. A small earphone was attached to the helmet, which the wearer could insert in his or her ear, making it possible to stay in contact with a ship or other space vehicle. Padding within the helmet made sure the wearer could not touch the visor with his or her face. (ENT: "Fight or Flight")
Located on the back of the helmet were air hoses to an oxygen supply, and a power connector for light, communication, and propulsion units. The helmet connected to the life support and propulsion unit via a secondary connection ring and not to the EV suit directly. (ENT: "United")
Life support and propulsion
The life support and propulsion unit (or "LSPU") consisted of a hard upper torso body-shell and a harness. This unit contained the essentials for survival in space: communication equipment, oxygen, propulsion unit, EV controls, and the power supply. It was padded to give the wearer some extra comfort. The LSPU also held an extra oxygen hose for refilling or sharing the oxygen supply. This extra hose allowed oxygen to be replenished from any device that held liquid oxygen, provided the physical connection would fit. (ENT: "United")
On the front of the unit, the following switches were present: communications, oxygen transfer, lighting and propulsion activation.
On the back were the incoming and outgoing oxygen connections. These hoses were fastened via a bayonet joint to prevent accidental release. Below one of the oxygen connections was an air supply indicator, divided into eight equal parts. This indicated the level of oxygen by means of color coding – green, yellow, and red. In 2154, this air supply indicator was removed and replaced by an analog indicator on the right side of the LSPU. The back of the unit also contained an power cord, which transferred power and communications from the LSPU to the electrical connector at the back of the helmet.
The harness consisted of two leg bands that were connected to each other via a belt that was also used to hold small tools as necessary. The LSPU was secured to the harness at four attachment points to keep the unit in place.
The gloves had five digits and were connected to the EV suit via a zip fastener just below the elbow. They were also self-sealing.
In 2152, when Captain Jonathan Archer assigned Doctor Phlox to purge the osmotic filters aboard Enterprise NX-01 while wearing an EV suit, Archer explained that operating the valves was normally not a problem, but his wearing EV gloves to perform the task might make it more difficult. Phlox assured Archer than back on Denobula, he was known for his fine motor skills, and doubted a pair of gloves would deter him. (ENT: "The Crossing")
During the 23rd century, the EV suit had considerably advanced from the primitive suits of the century before. There were different types of suits for different environments, but only one of them was standard issue for Federation starships and various Federation facilities like the Elba II asylum. These EV suit were significantly more flexible than their predecessors before and less bulky. Late in the 23rd century, the standard issue EV suit changed dramatically.
The helmets of the standard-issue EV suits were more spacious and elongated, yet still smaller than their 22nd century counterparts. The clear, fixed visor was much more vast and took up a majority of the helmet. It stretched from the front of the helmet, all the way to the back. A strange ambiguous light emanated from the bottom of the helmet and upward for the occupant to see. Late in the 23rd century, the helmets became more domed with the visor facing forward. These helmets were also spacious and allowed a lot of head room.
The EV suit was a chromo-metallic and form-fitting one-piece suit with a white belt that fastened around the waist. A phaser could be either holstered or attached to the white belt, depending on the severity of the away mission. The helmet was detachable and the name tag of the occupant could be seen on it. The upper chest and neck area of the suit had a built-in communicator. Late in the 23rd century, the EV suit generally remained the same except the color varied.
A thruster suit was an environmental suit, that could be equipped with a detachable thruster pack for use to travel short distances, and has been in use among other Starfleet personnel at the Epsilon IX station as well as the drydock where the upgraded USS Enterprise was refurnished.
A short time later, Spock utilized such a suit with a thruster unit, when entering and exploring the V'ger entity in the early 2270s. James T. Kirk subsequently used a thruster suit to retrieve Spock. (Star Trek: The Motion Picture)
Life support and propulsion
All life support and propulsion systems were interwoven together as part of the EV suit in order to function better in hostile environments. Later in the 23rd century, propulsion relied upon a jet propulsion pack that was placed on the back of the EV suit. The jet propulsion pack was detachable.
EV gloves had five digits and were connected to the EV suit. They were detachable and fastened just below the elbow.
Each EV suit came with magnetic boots made out of the same material as the EV suit.
In the alternate reality created by Nero's incursion, there was at least one type of EV suit in use in the 2250s. The suit was available in all three division colors with a Starfleet insignia displayed prominently in the center of the chest piece and featured breathing equipment, including a helmet and oxygen, for use outside of Class M environments. It could also be equipped with a parachute for orbital skydiving missions. (Star Trek)
A similar, copper-colored suit was highly heat-resistant. It could even be worn inside a volcano. (Star Trek Into Darkness)
During special emergencies, officers employed special suits with maneuverable propulsion thrusters to facilitate travel through open space. These suits also contained a holographic navigation module in the helmet visor. (Star Trek Into Darkness)
Early 24th century
By the 24th century, the EV suit had changed into a white tight-fitting suit (TNG: "The Child"). Some pieces of the suit were gender-specific, allowing a more customized fit than some of the previous suits. Some suits could be folded for storage in a container inside a cargo bay. (TNG: "The Hunted")
The helmet was smaller than its 22nd century counterpart but retained the clear and fixed visor. Inside, two ambient lights were present on each side of the helmet to illuminate the wearer's face. Audio equipment, like a microphone and speaker, were integrated.
The EV suit was made as one part and was not self-sealing.
The life support unit consisted of a hard upper-torso body-shell, which was different for men and women. This unit contained the essentials for survival: communication equipment, oxygen, EV controls, power supply, and again an extra oxygen hose that made it possible to share oxygen. Alerts were available visibly via the color-coded EV controls and also by audio.
The gloves had five digits and were connected to the EV suit via a self-sealing mechanism.
Tom Paris and Harry Kim were kept alive by the backup system of their environmental suits, by "keeping their vital functions going" while unconscious. The system kicked in due to an environmental seal in their suits had been compromised, depleting the oxygen. (VOY: "Demon")
In 2366, the escaped Angosian prisoner Roga Danar hid a pressure suit he found inside a cargo bay container to cause USS Enterprise-D personnel to think he would use it to leave the starship through an airlock or torpedo tube. Security chief Worf was not fooled, however, and waited for Danar to reappear. Danar fought with Worf and escaped anyway, assisted by prior acts of sabotage on Danar's part. (TNG: "The Hunted")
Late 24th century
By 2380, Starfleet had introduced a more form-fitting EV suit that was considerably less bulky. This model featured magnetic boots with a Starfleet emblem and "shooting star" pattern on their soles (mirroring the standard uniform boots worn at this time), integrated maneuverability thrusters, and a display panel on the wearer's right arm. (LD: "Second Contact", et al.) Additionally, at least some helmets incorporated a tactical display into the face shield. Helmets worn by Andorian officers had two sheaths on top, to accommodate their antennae. (LD: "First First Contact")
It was at least during this time period that it was standard protocol to sign out the gravity boots of EV suits, ostensibly so there was a record of who was outside in space, particularly for starships to avoid accidentally leaving crew behind. (LD: "I, Excretus")
Gelrakian EV suits
- Star Trek films:
- DS9: "Empok Nor"
- "Second Contact" (Season 1)
- "Temporal Edict" (Starfleet and Gelrakian EV suits)
- "Cupid's Errant Arrow"
- "Terminal Provocations" (in storage; holographic versions also seen)
- "Much Ado About Boimler"
- "Veritas" (flashback)
- "Where Pleasant Fountains Lie" (Season 2)
- "I, Excretus" (physical and holographic versions)
- "First First Contact"
Parts of two different TOS environmental suit costumes (the silver helmet from "The Tholian Web" and the red jacket, trousers and gloves from "The Naked Time") were used in Mork & Mindy's seventh episode ("Mork Goes Public", 1978). They were worn by Fred to convince a tabloid newspaper reporter that he, Mindy and Mork were just crackpots and that Mork was not an alien.
For further information on the design and miniature used in The Motion Picture,
- see: Thruster suit model
With the beginning of Star Trek: Deep Space Nine's fourth season, the opening sequence was changed and included a cargo management unit and three repairmen in EV suits. These elements were executed as CGI effects by ILM's John Knoll, who, while preparing for the pre-production of Star Trek: First Contact, pitched in with the work for the sequence out of courtesy, "I made about half a dozen little bits and pieces for the sequence, including a generic alien ship with blue glowy engines." (Star Trek: Deep Space Nine Companion (p. 335))
The EV suits designed for Star Trek: First Contact, and later reused with minimal modifications in Star Trek: Deep Space Nine and Star Trek: Voyager, were designed by Deborah Everton and illustrated by Gina A. Flanagan. She noted the script described them as "very modern and very light", so she used her experience designing underwater suits for The Abyss to perfect light suits which would allow the fabric to have a lot of give, "so we could really see the silhouette of the man in the suit. I think they looked pretty sexy." Everton further noted "helmet design is the bane of my existence." (Star Trek: The Magazine Volume 1, Issue 13, pp. 64-65) The suits were fabricated by Christopher Gilman and his prop company Global Effects, Inc.; the helmets were manufactured by another company.
Regarding this design's reuse on Voyager, Robert Blackman noted: "every time the suits were specified in a script, you could hear the howling across the lot from the actors," citing the lack of cooling fans and insufficient lighting. (Star Trek: Costumes, p. 161)
When it came time to design the suits for Star Trek: Enterprise, Blackman was determined to include "every bell and whistle I could manage: a cooling system, several light systems, external lights – all kinds of stuff." (Star Trek: Costumes, p. 161) Blackman worked with Neo Innovative Technologies (Neotek) to design and manufacture the environmental suits, of which seven were initially produced. (Star Trek: Communicator issue 135, p. 72)
Vincenzo Natali produced design concepts for the Star Trek: Discovery Starfleet and Klingon environmental suits.  In a commentary track for "Through the Valley of Shadows", from Star Trek: Discovery, Spock actor Ethan Peck described these as being a "nightmare" to wear.