Situations requiring one or more crew members to exit the starship in an airless or otherwise hostile environment are known collectively as extravehicular activity (EVA). These include detailed visual inspections, periodic maintenance, damage control, and unique hardware modifications. They may be done alone or in concert with tele-operator and automated systems.
Various degrees of protection are available for starship crews. While the actual configurations carried by Starfieet vessels will vary according to major mission segments and swapouts for improved models, typical suit types are presented here. All suit types are available in customized versions for non-humanoid and handicapped crew members.
Extra vehicular Garments
The first, the low pressure environment garment (LPEG), is a close-fitting, lightweight suit, designed for benign airless operations. One use would be during an orbital starbase layover, where the spacecraft is in External Support Mode, well protected against radiation and micrometeoroid hazards.
The suit features simplified multilayer construction, affording atmospheric integrity, gas exchange, and thermal and humidity control without sacrificing mobility. All consumables and circulation equipment are mounted within an integral backpack, with controls placed for 50 percentile humanoids on the chest and forearm areas. The suit allows for exterior operations, though time outside is limited to three hours.
- EPG - A variant of the LPEG is the emergency pressure garment (EPG), designed for long-term storage in starship emergency equipment lockers. The EPG is capable of supporting life for two hours in most ship abandonment or isolated hull breach scenarios while crews await rescue.
Starfleet's mid-level suit is the standard extravehicular work garment (SEWG). This type is reinforced with additional radiation and pressure layers for extended operations, plus enhanced recycling devices. It is designed for most major industrial tasks and hazardous exploration assignments. Radiation and micrometeoroid protection is essentially unlimited. The suit controls are supplemented by advanced autonomic life support controllers within the suit computer.
These were the standard equipment EVA suits in use in Starfleet in 2381. In order to use more advanced suits, like the Tactical CONN and Security exosuits, special training in these departments needed to be completed before getting clearance to use them.
The design of the helmet allowed an almost normal field of view to the wearer. Though the vertical field of view was limited to eight degrees, 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. Audio equipment, like a microphone and speaker, were integrated.
Located on the back of the helmet were air hoses to an oxygen supply, and an electrical 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 EVA suit directly. Padding within the helmet made sure the wearer could not touch the visor with his or her face.
The EVA 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.
Life Support & 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, EVA 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.
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 electrical 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.
Gloves & Boots
The gloves had five digits and were connected to the EVA suit via a zip fastener just below the elbow. They were also self-sealing. The boots were made out of the same material as the EVA suit and could be magnetized.
Wearers 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.