An advanced orbital EVA spacesuit from the hard science fiction anime Planetes. Image copyright Sunrise.

Advanced Spacesuits
Tech Level: 12
Bio Suits
Tech Level: 13
Tech Level: 14
Casual Wear Spacesuits
Tech Level: 16

Spacesuits are one of the most iconic technologies of the space age, past, present, and future. They are also sometimes called pressure suits, environment suits, vacuum suits, vacuum armors, vacc suits or vacc armors. They provide the most basic protection for an astronaut against the deadly environment of space. Ships may get an astronaut to his destination, but it is the spacesuit that allows him to work in and directly interact with the environment of space and different planets.

Some advanced types of combat armor can function as spacesuits; they will be addressed in their own article. Hazmat suits bear some superficial similarity to spacesuits but cannot be substituted for one. However, the opposite is not true--spacesuits can function as hazmat suits in a pinch.

Early spacesuits were adapted from the pressure suits developed for high-altitude flights. These early designs were expanded greatly into their modern forms, and are often mission-specific; spacesuits used in the NASA moon missions were substantially different than those used on the ISS, not just because of advances in technology, but because of the different requirements needed in different environments. There have been many iterations of spacesuits over the years, both real, proposed, and speculated upon.

Spacesuits come in three general types: hard, where the wearable components are stiff-shelled, much like medieval plate armor; soft, where the wearable components are composed of pliable fabrics; and mixed, with a combination of hard and soft components.


All spacesuits have to provide certain basic functions to keep their wearers healthy and active. These are summarized below.

Pressure Maintenance: A spacesuit must maintain an appropriate level of atmospheric pressure for the astronaut to stay comfortable and breathing properly, usually by means of tough, flexible, airtight fabric to keep the breathable gasses in. This does not have to be equivalent to full sea-level pressure on Earth, though some designs do accommodate that.

For example, both US and Soviets suits use internal pressures anywhere from one half to three-quarters sea-level pressure. This is easier to maintain, allows greater movement, and puts less stress on the suitís life support system. To keep the astronaut breathing and working normally, high oxygen gas mixtures, or even pure oxygen, are used within the suit. However, in order to avoid gas mixture complications such as the bends, an astronaut will have to enter a pure-oxygen chamber at normal pressure for a certain amount of time (longer for lower suit pressure) before a spacewalk in order to work the nitrogen out of his system so it doesnít bubble out of his blood.

Most suits allow the pressure to be fiddled with by the wearer while in use in order to address certain situations. For example, in the event of a small breach of the suit, the internal pressure can be increased to maintain proper airflow to the wearer until it can be patched or the astronaut reaches safety.

Breathing Mixture: The suit provides oxygen and other gasses for the wearer to breathe while in airless environments. Most suits carry a backpack that contains the bottled air used for breathing as well as other life maintenance machinery. Modern suits use rebreather technology to recycle exhaled gasses, providing the user with breathable air for up to a day or more, practically as long as the suitís internal power supply can hold out.

As with underwater diving, dealing with both pressure differentials and gas mixtures can be a tricky business. If everything is not balanced properly a number of mishaps may occur, such as anoxia or hyperoxia.

Thermal Regulation: The suit must also maintain a proper temperature for the wearer. This is actually more difficult than most realize. In orbit, the sun-facing side of a suit may be hundreds of degrees hot, while the side in shadow may be at a temperature far below zero. Providing proper insulation against these extremes as well as maintaining a comfortable temperature inside the suit require both excellent insulation and efficient thermal regulation systems. Modern suits uses insulating layers woven into their fabric as well as an outer protective sheath to help maintain proper temperature, as well as air conditioners and heaters built into the life support systems. Spacesuits also use a fluid circulation system throughout an undersuit worn under the main suit, called a Liquid Cooling Garment, to help maintain proper temperature as well.

Radiation Protection: One of the more significant hazards of space is exposure to harmful radiation, from both the sun and cosmic sources. A spacesuit must provide adequate protection from exposure hazards outside of a ship or station, and this is usually accomplished with integrated layers in the lining of the suit. Most suits are not designed to handle truly extreme radiation exposure, as its usually assumed that the wearer will retreat to a nearby shelter such as a ship or a station if he encounters such. However, some suits may have additional external armor if its expected to handle an unusual amount of radiation.

Physical Armor: In the environment of space, there is always a chance of being struck with a small piece of debris, either natural or manmade in origin. At orbital speeds, even small grains of dust can hit like a small caliber bullet. Spacesuits must also provide physical protection against such kinetic impacts. As a result the outer layers of a suit will likely be as tough, if not tougher, than ballistic weave armor used in bulletproof vests. Helmet faceplates, despite some erroneous depictions in fiction, are not made of easily-cracked glass, but rather several layers of advanced, impact-resistant plastic and/or advanced composite transparent materials.

Life Support System: This includes the air supply, batteries, gas filters, pumps, heaters, regulators, air conditioners, humidifiers, and so on. In almost all models of spacesuits, these are usually carried in a consolidated backpack, though some early versions used umbilical hoses and cords to such machinery on board the spacecraft. Future suits may be able to miniaturize most of the systems so that they fit in a light hip pack or seamlessly within the contours of the suit itself.

Ergonomics: Spacesuits need to be fairly comfortable and to allow as much freedom of movement as possible, so astronauts can work efficiently on their assigned tasks. This, much more than physical protection or life support issues, have proven to be one of the most daunting hurdles of spacesuit design. Modern spacesuits are bulky, complicated, and heavy, and the many layers of protection the suit provides hampers maneuverability and dexterity. But they are still vast improvements over models from the dawn of the space age, where astronauts had trouble just bending elbows and knees.

Power: Power is essential to the ongoing workings of a spacesuit. On most suits, power is provided by batteries carried in the PLSS backpack, or by an umbilical to a nearby spaceship of station. If practical, it will be both.

Access: Getting in and out of a spacesuit is currently a very complex and demanding job. Besides undergoing decompression as mentioned earlier, an astronaut must don an undersuit that regulates temperature as well as provides sensors to monitor the astronautís state of health. Then he dons the outer suit. There are in general two ways to do this: with Russian suits, the astronaut enters the suit through a sealable hatch in the back. With American suits, the astronaut is lowered into the bottom half of the suit, and the upper half is fitted over them. Only after a long and exhaustive checklist of making sure all systems are working properly will the astronaut actually be allowed to proceed with his EVA. The whole process can take up to several hours, not including preliminary decompression.

Helmets: Helmets are often the most complex single component of a spacesuit. They are the central focus of the suitsís life support and air conditioning systems. It houses the suitís sensor displays, its communication system, and often its central computer. And all of this has to be done while incorporating the astronautís visible access through his or her visor, which will usually be several layers thick and have polarizing and shielding layers.

Depictions in early science fiction could show the helmet as a single solid globe of glass, called a bubble helmet, or more akin to an old diving suitís metal helmet with only a few small glass ports to see out of. Several decades of practical experience however have shown that neither of these work as well as the visored helmet that has now become the norm. Most visored helmets have glare shields that can be pulled over the normal visor, and some may have hard-shelled blast shields to be used in an emergency.

Some futuristic depictions of spacesuits also show suits with no visor or viewports at all, with everything being displayed to the astronaut via video feeds. While workable, it seems important for human psychology to be able to see things first-hand, meaning that visors will almost always be incorporated into suits when practical. Some future suits may be able to switch between the two, as depicted in the in the science fiction anime Planetes. In that series, a blast shield can be lowered over the suitís visor when necessary, and the interior surface of the shield acts as a display monitor for the suitís external cameras.

Portable Life Support System (PLSS): Most suits have their life support equipment consolidated into a backpack, called a Portable Life Support System, or PLSS. Some suits, especially in early years of the space program, eschewed these in favor of umbilicals to a main spacecraft. Very advanced suits may miniaturize this equipment into a half-pack or even a hip pack. The PLSS contains the suitís supply of breathing gasses, filters, pumps, pressure gauges, monitors, and other related equipment. The PLSS is also where the suitís main power supply is kept.

Older PLSSs could only last as long as its bottled breathing mixtures, usually four hours or so. More modern versions using rebreather technology are not only lighter but can keep functioning much longer, sometimes for over twenty-four hours or as long as their power supply holds out. Between spacewalks, the PLSS would be recharged and refilled with the needed gasses for the next excursion.

Today, PLSSs are integral to the suits themselves, and cannot be easily removed. However, in the future when EVA activity may become an everyday occurrence, different PLSSs may be designed for different mission requirements, and made modular to allow them to be easily swapped between suits as needed.

Waste Management: Dealing with human waste within the suits is a necessity, especially with long EVA excursions. The simplest and easiest solution is to use a high-absorbancy undergarment around the necessary body regions. In laymanís terms, this is basically a high-tech diaper. While this solution usually elicits giggles among those who first hear of it, it has proven to be the best system for dealing with the problem with current technology. The alternativeóhaving waste and urine mixing in the breathing gasses of the astronautóis not acceptable for obvious reasons.

Alternative systems, which use pumps to evacuate the waste material and liquids to a holding chamber, have been investigated by various space aganecies and while not practical as yet, may be incorporated into future suits.


Despite popular belief, not all environments in space are equal. Spacesuits are designed for certain specific environments, and each has different requirements.

Training Suits: These are designed to emulate the actual suits used in space, but are used in training facilities on the ground to help make astronauts proficient in their use. Despite their operational similarities, changes are made to make sure they can operate in their environments without mishaps. For example, a number of practice suits are used by astronauts in specially-built water tanks to simulate weightlessness. These suits are outfitted with asjustable air tanks to help zero out the astronautís buoyancy as much as possible.

Low Earth Orbit EVA Suits: These are suits designed to work in a microgravity environment and within the protective envelope of Earthís magnetic field. These require only moderate radiation protection compared to other suits and will usually be outfitted with a MMU (Manned Maneuvering Unit) in case the astronaut needs a form of propulsion outside the ship. Suits designed for use in freefall can be made bulkier, and thus carry more machinery, equipment, and/or armor, as the wearer will not have to contend with lifting all that up under the weight of gravity.

Deep Space EVA Suits: Though there has been no call to design such a suit as yet, their use will become inevitable as space exploration ventures farther afield, especially on trips back to the Moon and the long haul to Mars or nearby asteroids. These will be similar to their Low Earth Orbit cousins, except they will have much heavier radiation protection.

Moon Suits: These are the suits astronauts used on the Moon during the Apollo missions. They also require heavy radiation protection, as well as a reconfiguration of life support pack components to enable the astronaut to stand upright in the lunar gravity. One feature future moon suits will have that the Apollo suits lacked was far more extensive sealed systems into order to protect against the very corrosive lunar dust.

Mars Suits: Mars has an atmosphere, but its atmosphereís surface pressure is still about one hundredth Earthís, necessitating the need for spacesuits very much like those used on the Moon and elsewhere. These will be similar to Moon Suits, but with slightly less radiation protection as well as a redistribution of key equipment in order to maximize the astronautís movements in Marsís lighter gravity. Martian dust is thought to be as hazardous as the Moonís, and precautions will probably be taken in any suit designed for that environment.

Other: As other environments become accessible, spacesuits will be optimized for them. For example, if an astronauts were ever to step foot on the surface of Mercury, their spacesuits would need very heavy radiation protection.

Tech level: 12

A number of advanced spacesuit designs have been put forth in recent years. One is the Mark III developed by NASA and ILC Dover. Though heavier than current suits used aboard the space shuttle, the MARK III is designed to operate at normal sea-level pressure and gas mixture. This means that an astronaut can transition from a similar environment (such as that aboard the ISS) right to the spacesuit and EVA without having to go through a lengthy depressurization process.

The suits also incorporates composite graphite-epoxy bearings in many joints, which are lighter and more durable than current aluminum models. The Mark III is significantly more dexterous than suits currently worn by astronauts.

The I-Suit, also developed by ILC Dover, seeks primarily to reduce the weight and improve the dexterity of current spacesuits. Using graphite-epoxy joints as well as a complete soft suits design, it weighs a mere 65 lbs compared to the 107 lbs of the ISSís current EMU suit.

NASA and other space agencies are planning on incorporating other types of innovations into spacesuits in the future. These include:

-- A digital Heads-Up Display linked to a multi-purpose suit computer.

-- A digital see-through display integrated into the helmetís visor.

-- GPS tracking and navigational capability (for Low Earth Orbit only.)

-- Speech recognition software to allow the user to give commands to the suit systems hands-free.

-- Electronic textiles for use as buttons incorporated into the suit.

-- Full-suit internal sensors, to monitor every aspect of the suit and user in real time.

-- Full-suit exterior microcameras, situated at all convenient points of the suit. At Tech level 12 and above, the cameras would be so small that they wouldnít add noticeably to the suitís bulk or mass. Their output would be routed to both mission control and the userís HUD, and may also feed into a "black box" recorder.

-- Increased modularity and customization, to allow the same suit to be used by a wide variety of astronauts with different heights and body types. Ideally, the system would be automated, allowing it to instantly Ďreadí a wearerís biometrics and adjust itself accordingly, and could save different configurations for individual astronauts.

-- Integrated sensors. While not a requirement for orbital work, sensors integral to the suits such as infrared, thermal imaging, low-light, telescopic imaging, and even radar may be advantageous when exploring and working in new unknown environments, such as on the Moon, the asteroids, Mars, and other worlds. The sensor read-outs would be fed to the helmetís HUD or see-through visor display and to mission control.

-- Chin and mouth controls. Seen in some science fiction versions of spacesuits, these are small switches and buttons within the spacesuit helmet that could be manipulated by the chin, lips, or tongue, allowing the user to work certain aspects of the suit while his hands may be otherwise occupied. Whether these could be made practical in real life is unknown.

-- Integrated Maneuver System. Also seen occasionally in science fiction works, these are small gas jets situated at strategic points along the suit, used in place of or in conjunction with more standard backpack maneuvering units. They are usually placed along the arms or boots, but may occasionally be seen at other points on the suit. These ports have their own dedicated (if very limited) gas supply, and usually are meant for short quick bursts instead of long burns. It is thought that this system in the hands of an experienced user would allow much more precise maneuvering than backpack maneuver units alone.

-- Food and Water Recycling: Very advanced suits may provide both food and water in the form of sipping tubes accessible within the suitís helmets. On most missions, these would be pre-loaded into the suit, with the food mostly being a high-nutrition semi-liquid slurry. However, in some science fiction sources such as in Larry Nivenís Known Space series, spacesuits are designed to be worn for days, weeks, or even longer at a time. For these suits, water and waste recycling was incorporated into the main life support systems, to keep the user alive and operational a long as possible.

Tech Level: 13
NASA's and MIT's current vision for a Biosuit. Image courtesy NASA.

Also known as Space Activity Suits. Biosuits, if ever fully developed, would represent a truly radical departure from previous models.

Instead of using a volume of gas to maintain proper pressure around the user, the biosuit uses layers of contoured, body-hugging smart fabric to apply the pressure instead. The concept was first seriously explored by NASA in the 1960s, and was recently revived by researchers working at the Massachusetts Institute of Technology under the direction of professor Dava Newman.

Biosuits use whole-body scans of a wearerís body to create a skin-tight suit of specially engineered material that applies mechanical counterpressure to the userís form, ideally approximating earth-normal atmospheric pressure. The suits would require a standard helmet for breathing and certain mechanical attachments to the groin for waste management. Gloves are much trickier to manage with this system, so the air circulation system that supplies breathable gas mixture to the helmet would also do so to the gloves to allow the astronaut to use standard spacesuit gloves. Other components, particularly the PLSS, would be similar to that of standard space suits.

Such a suit would not only be much lighter than conventional spacesuits, but would also allow much greater dexterity and movement, almost as great as if the astronaut were wearing normal clothing. It would allow for smaller, lighter, and more durable PLSS units as well, as gasses would only be needed to pressurize the helmet and gloves, as opposed to the whole suit. Sophisticated thermal exchange layers could help keep the astronaut at the proper temperature, and studies have shown that the astronaut can endure small breaches in the suit, up to a millimeter square, and would suffer no long term adverse effects

There are issues with biosuits, however. Any crease in the fabric would result in painful bruises to the wearer, so each suit must be made custom-fit for each user. More advanced and developed versions of this technology may ease this requirement, with programmable fabrics that could adjust itself to different body types.

Whether it could offer adequate physical protection beyond just counter pressure is also up for debate. While the fabric making up the biosuit would be very tough and hard to tear, it may not be able to stand up to micrometeoroid impacts such as those faced by astronauts during orbital EVA. The wearer could just don an outer sheath that would act like armor, but such a move may reduce the suitís one great advantage over older models, namely its flexibility and ease of movement. The same issues arise with radiation protection. Biosuits may therefore be ideal in lower hazard environments like Mars, while more traditional, heavily-armored suits would still be used for orbital and deep space EVA work.

Versions of this technology have appeared in science fictions works such as David Weberís Honorverse series, Larry Nivenís Known Space series, Kim Stanley Robinsonís Mars trilogy, and on countless bodies of buxom female space explorers in pulp fiction and comics.

Tech Level: 14
A lunar rover design with two suitports shown. Image courtesy NASA

A suitport is an alternative of sorts to a standard airlock. Instead of a standard outer airlock door, entry to a rear-entry spacesuit is set flush and sealed to the outer hull of the ship, station, or base instead. On the outside, it would appear as if one or more empty suits are just hanging on the outer hull. This system helps eliminate the need for depressurization in an airlock or in a spaceshipís main cabin for EVA work. Instead of a full airlock, a smaller man-sized chamber or even a simple set of double pressure doors may suffice for the astronaut to enter the suit, seal it, and detach himself from the ship or station.

On the Moon and Mars and similar environments with corrosive dust, such a system may allow for easy EVA while minimizing contaminating the main habitat with dust. In the case of effecting an emergency evacuation, a suitport may be preferable over a lifeboat or rescue ball as it would allow the evacuees a greater number of options once away from the ship, station, or base, depending on circumstances.

Tech Level: 16

These are basically biosuits that become so light, durable, and easy to wear that they can be worn as normal clothing in everyday use. The old scifi meme of jumpsuits as space station or spaceship uniforms arose partially from the notion that in case of an emergency, personnel wearing dual purpose spacesuits/uniforms could don a helmet, PLSS, and gloves and be ready for exposure to vacuum much quicker than if they had to don a full spacesuit.

Of course, there would be a great many barriers to such a scheme, not the least of which is cost. Biosuits will be expensive, at least as much as standard spacesuits, and their price and general availability would have to drop dramatically before theyíre used in such a capacity. Their general durability would have to increase dramatically as wellóas tough as spacesuit fabric is, using it for normal activities for weeks or months could put small stresses on the fabric that may not show up until its needed for vacuum work. Plus thereís also the factor of general comfort; constant contact and friction between the smart fabric and the skin may lead to chaffing, rashes, and so on.

Belters and other hard core spacers in Larry Nivenís Known Space series used casual-wear spacesuits at times. The costumes of some hi-tech superheroes, such as the Fantastic Four, are sometimes shown as being able to operate as spacesuits with the addition of only a helmet and life support system.