Ever since NASA retired the silver lamé Mercury spacesuits of the early 1960s astronauts have fallen a little behind in the fashion department, but now a new generation of spacesuits is being developed for both the public and private sectors. Suiting up for the final frontier isn't just about looks of course, it's about surviving and working in one of the harshest environments possible – an environment that will kill you in just 20 seconds without some high-tech protection. So what exactly is a spacesuit, and what will the spacefaring fashionistas of the future be wearing?

The next decade will see a major return to manned spaceflight as NASA starts its Orion deep space missions, China develops its own space station, and commercial companies compete with the Russian space agency to ferry crews to the International Space Station (ISS). Then there's plans to send tourists into space on suborbital junkets or to visit hotels in low Earth orbit, as well as return astronauts to the Moon or land on Mars.

One important factor in these plans is that space travelers are going to need new and more advanced spacesuits to meet new challenges. There are already projects for many different type of suits, but for each new idea there are many misconceptions about what a spacesuit is and what it does.

One example of these misconceptions is the recent release of images of the spacesuits that will be used by astronauts aboard SpaceX's Crew Dragon spacecraft. This sleek, neatly tailored garment is definitely a spacesuit, but it's surprising how many people talked about it and criticized it as if it was going to used for spacewalks or strolling about on the Moon's surface.

The same is true of similar suits designed for Virgin Galactic or Boeing's manned spacecraft. Each of these have been mistaken for suits used by astronauts working outside the ISS when, in fact, they will never be used outside of a spacecraft except when walking out to the launch pad on Earth.

This is because the Boeing, SpaceX, and Virgin Galactic spacesuits are not exactly that. They are to a true spacesuit what a parachute is to an airplane. Each fulfills a very real and very serious function, but it's also a very different one from those required when working outside the ISS or on the Moon.

The job of these spacesuits is to protect the wearer inside the spacecraft in the event of an emergency, including a sudden loss of air pressure. Otherwise, their purpose is to simply be comfortable and not get in the way.

A true spacesuit, on the other hand, isn't like the ones in science fiction films that go on like overalls in a matter of seconds. They are more like deep sea diving suits using a mixed-gas rig, and are just about as complicated to get into. They are loaded with high tech gear and require a lot of preparation time before each use.

Space is a nasty place

Why do we need spacesuits? The answer is very simple: Space is nasty. It is phenomenally hostile – so much so that at one time, it wasn't certain that a space traveler could even survive long in weightlessness for more than a few minutes. Today, many scientists are not sure if it's possible to undertake a prolonged mission to Mars without suffering major medical problems. Even a trip to the Moon outside of the Earth's magnetic field has been implicated in cardiovascular problems suffered by the returning Apollo astronauts.

A spacesuit is an astronaut's personal spacecraft. It duplicates all the systems of a spacecraft in miniature, plus a couple more of its own tacked on for good measure. This is absolutely necessary because without a suit, a person would be dead within 20 seconds.

To understand this better, think of humans as being a bit like fish. They evolved to live in the sea and we evolved to live in an ocean of air that not only allows us to breathe, but also protects us against radiation, dehydration, and extremes of temperature. More to the point, we not only live in our air ocean, we live at its very bottom. So we're less like the colorful fishes of the shallow coral reef and more like the denizens of the deep that rupture and die if brought to the surface too quickly.

This is apparent if we look at how the human body responds to higher altitudes. At sea level, we are very comfortable, but an elevation of even a few thousand feet can make breathing uncomfortable and any physical activity difficult. Above 20,000 ft (7,000 m), special breathing apparatus is needed to remain alive and conscious. Above 28,000 ft (8,500 m), the body needs 100 percent oxygen. Between 40,000 and 50,000 ft (12,000 to 15,000 m) the oxygen needs to fed in under pressure in a breathing mask or helmet. Above 50,000 ft, a person must be inside a pressure suit or breathing becomes too much of an effort to sustain for long as the lungs fight to not only inhale, but to exhale carbon dioxide.

Then, at 63,000 ft (19,000 m), the Armstrong line is reached. This is the point where the air has only five percent of the pressure it has at sea level. At this altitude, water boils at the temperature of the human body and a full pressure suit becomes literally vital. Without it, oxygen starvation sets in, consciousness is lost within 15 seconds, and death follows around five seconds later.

However, many science fiction films to the contrary, a person's blood will not boil nor will they explode like a popping balloon. Skin is actually very tough, so the blood will remain under pressure and, while the skin will stretch, it will not burst. This is why, in 2001: A Space Odyssey, astronaut David Bowman could jump between spacecraft without his helmet.

But a sudden loss of air can still be extremely dangerous. Trapped air in the body would be deadly, causing lung embolisms, bursting sinuses and ear drums, and exploding teeth due to trapped gases inside dental work.

Just to add insult to injury, it can also be embarrassing. Pilots undergoing training in high altitude chambers often experience massive farting attacks as the gas in their bowels suddenly expands and looks for the nearest exit.

Then there is the matter of temperature. On Earth, the atmosphere regulates the temperature all around us, so we take for granted being able to walk from one spot to another and remain relatively comfortable. But in the vacuum of space, there is no such protection.

In full sunlight, the temperature of a dark object reaches 250° F (121° C). Going into the shade is no relief because the thermometer plungers to -271° F (-168° C). An astronaut won't freeze instantly because there's no air to conduct heat away. However, saliva, tears, and delicate exposed tissues are vulnerable to evaporation and freezing. Eye tissues could dry or freeze quickly, rendering you blind.

And let's not forget radiation. On Earth, the atmosphere and the magnetic field filter out UV and infrared radiation as well as Cosmic rays, but in space, these are intense enough to be deadly if you are unprotected. If this isn't enough, there are micrometeoroids and space debris whizzing past at 30,000 ft/sec (9,100 m/sec), making something the size of a grain of sand hit like a .50 caliber bullet.

Add all of this together, and the case for wearing a spacesuit is obvious.

What is a spacesuit?

All true spacesuits used today are pressure suits. In other words, they provide a layer of air around the wearer using a human-shaped bladder that contains an artificial atmosphere. It provides air for breathing, protects the body against vacuum, and provides pressure to support normal breathing by forcing air into the lungs and helping to expel carbon dioxide. In addition, it shields the wearer against radiation and micrometeoroids, and it regulates temperature.

Let's look at a typical spacesuit, using the A7L Apollo spacesuit of the 1960s as our example. Variations of this were used on the Apollo flights as well as the Skylab and Apollo/Soyuz missions in the 1970s. It's also the direct ancestor of the modern Extravehicular Mobility Unit (EMU) suit used by NASA on the Space Shuttle and the ISS since 1982. The Apollo suit contains more features than today's specialized suits. It differs mainly in that it's a single mission suit, meaning, once Armstrong, Aldrin, and Collins returned from the Moon, their suits became museum exhibits, while the EMU is designed to be used many times by many different people, so it's adjustable and made to be overhauled regularly.

Costing US$100,000 in 1969, the A7L weighed a staggering 220 lb (100 kg) on Earth, but only about 37 lb (17 kg) on the Moon. It was made by ILC Dover, a division of the Playtex corporation that was previously famous for making brassieres. That may seem like an odd company to win a space contract, but the Apollo suit was a complex piece of tailoring that required many layers of specialized cloth to be stitched together without a single mistake. A bad seam in a dress can be an embarrassment. In a spacesuit, it can be deadly.

The ins and outs of the spacesuit

The Apollo suit is so familiar to the public that describing it is a bit like describing Santa Claus's outfit. But each piece is a serious bit of engineering. The suit itself looks like a bulky arctic suit covered with umbilical couplings, pockets, flaps, and controls with anodized aluminum rings at the collar and cuffs to secure the helmet and gloves. It's a complex assemblage of various layers and some cunning tailoring to make it airtight as well as providing some radiation protection against UV and infrared and even some cosmic rays, though the life support backpack gives most of the shielding against the latter. Meanwhile, the white top layer protects against tears and abrasions while reflecting away sunlight. Originally, this top layer was supposed to be a separate suit that fitted over the pressure suit, but by the time Apollo 7 flew in 1968, it was incorporated into the primary suit itself.

The layers of the suit are made of nonflammable materials divided into pressure layers to keep in air, structural layers to provide strength, thermal layers to protect against heat and cold, and protective layers to ward off damages. The materials used include Teflon, fire-resistant Beta cloth, aluminized Kapton polymer. Teflon-coated Kapton, aluminized Mylar, Dacron, Neoprene-coated nylon, nylon, Neoprene, a knit jersey laminate, and Nomex.

One later addition to the suit came after the Apollo 12 mission. On the first two moon landings, mission control had trouble telling the two astronauts apart on the video feeds, so from Apollo 13 to this day the mission commander was given a red stripe on the suit's arms and legs as a designator.

The suits up until Apollo differ from the modern EMU in that the former were designed for one mission and were custom fitted to each astronaut right down to taking molds of his hands and head for a perfect fit. Today's suits are modular and adjustable. Where the Apollo suit is a one-piece garment, the EMU suit is in two parts with the legs and torso joined by a large aluminum ring at the waist.

Getting in and moving about

In the modern EMU suit, the wearer wriggles into the torso with its hard glass-fiber cuirass, then the legs are fitted on. The Apollo suit saw the astronaut squeeze through a zippered gap in the crotch like a snake getting back into its old skin. It's a tight fit, but, with practice, the astronauts could get into both types of suits in five minutes, though that is only a first step as the other bits are added.

Once inside and pressurized, the big problem with the A7L, as with any spacesuit, is moving about. At its most basic, a spacesuit is a human-shaped balloon. The pressure layer is essentially a bladder made of a rubbery material that's slightly larger than the layers above it, so it can't overinflate and pop. Unfortunately, when it is inflated, the wearer is almost immobile because moving inside the suit is like trying to bend a tire with your bare hands.

The A7L gets around this by using special constant volume joints at the knees, elbows, and other joints, which are pockets of fabric that create bellows in the pressure layer. When the wearer bends a joint, it compresses one side of the bellow, forcing air to the other side and keeping the volume equal to when it's unbent. Other ways to make the suit more mobile and keep it from ballooning include mechanical rotating joints for the shoulders, restraining ribbons, pulley systems, and clever stitching. In some early suits, the lack of these adjustments resulted in a test subject looking like he was shrinking as the helmet rose up over his ears.

Another factor that affects mobility is the pressure inside the suit. Ideally, engineers would prefer the relative pressure inside the suit to be 10 lb/in² (0.68 atm), but this would make the suit too stiff and it would have to be heavier to contain the pressure. This is why the A7L has a pressure of about 4 lb/in² (0.27 atm), so it's lighter and easier to move around in, but it still provides as much oxygen as someone sitting in a pressurized passenger airliner at 30,000 ft (9,100 m).

This wasn't a problem during the Apollo mission because the spacecraft was filled with pure oxygen at low pressure. Today, spacecraft and stations use high pressure closer to that at sea level, with a mix of oxygen and nitrogen. This is to minimize the risk of fire, as well as the fact that space medicine specialists are concerned about the long term effects of breathing pure oxygen around the clock for months at a time.

While this arrangement may be safer, it makes spacesuit work extremely difficult. On the ISS, using the EMU suit means purging the body of the 78 percent nitrogen that air contains by breathing pure oxygen through a mask for 24 hours.

This is similar to the procedure used by mixed gas deep sea divers. If an astronaut didn't do this, the drop in pressure while wearing the suit could result in the bends, where the nitrogen dissolved in the tissues bubble out like the carbon dioxide dissolved in a can of soda when it's open. The astronaut's blood would literally fizz and the bubbles formed in the tissues could cause excruciating pain, severe organ damage, and even death in a matter of minutes.

Space gloves

Though they may seem like an afterthought, the gloves on a spacesuit are a major engineering headache – one that will probably continue to be for many years to come. This is because the hands are small, yet are fantastically complex and require as many degrees of movement as the rest of the body put together. Many early spacesuit designs actually did away with gloves altogether and replaced them with claws, hooks, or built-in toolkits.

The glove problem is so great that it's one of the arguments for using robots instead of astronauts. What's the point of sending people into space, the argument goes, when they can't do any work once they get there? It's a reasonable point. Working in spacesuit gloves means losing significant manual dexterity. Try installing a new hard drive in your computer while wearing hockey gloves kept in a deep freeze.

The deep freeze bit is important because, where in the rest of the suit it's mainly a problem of keeping cool, the gloves have the problem of staying warm. Astronauts are always complaining of cold, numbed fingers. This isn't helped by the fact that the gloves are a complex assemblage of miniature bellows, hard joints, and restraints designed to keep the glove's shape under pressure. In this situation, it's very hard to provide both adequate protection and heating while allowing for enough degrees of movement.

Modern US spacesuit gloves are also particularly hard on the fingernails. They have hard silicone plastic caps over the fingertips that can cause an astronaut's fingernails to fall off as well as intensely painful injuries to the fingers. In addition, moisture in the glove can cause bacterial or yeast infections in the nail beds. It's no wonder astronauts prefer to wear simpler, softer gloves for suits used inside the spacecraft.

One thing neither the A7L or EMU have is boots. The astronauts aren't barefooted – instead the boots are an integral part of the space trousers. However, the Apollo astronauts who walked on the Moon did have lunar booties that sat over the feet of the spacesuit like galoshes. These silicone plastic sandals insulated the feet against the hot lunar surface, provided traction, and protected the suit from abrasion and punctures.

One thing the Apollo A7L had over the modern EMU is that you could walk in it. All modern suits lack many of the joints used on Apollo because the legs aren't used much on spacewalks, so they don't need much freedom of movement. Some early spacesuit designs did away with legs altogether and replaced them with a pressurized trunk.

Life support

Having a spacesuit is all well and good, but without a life support system, wearing one is just a way to suffocate in minutes instead of seconds. This is why spacesuits must either be attached to the spacecraft by an umbilical cord or, more likely, have a Personal (or Primary or Portable) Life Support System (PLSS) – the familiar backpack.

The PLSS is probably one of history's most unappreciated examples of miniaturization. Take all the systems needed to sustain life on a spacecraft and reduce it to a backpack and you have a PLSS. It provides power, communications, air, and heating and cooling to the astronaut while removing carbon dioxide from his exhalations for up to eight hours.

The battery-powered PLSS contains one or more oxygen bottles, a filter containing of lithium hydroxide and activated charcoal to remove carbon dioxide and impurities, pumps, fans, and (in the EMU) a computerized monitoring and warning system. In addition, there's an oxygen purge system to provide 30 minutes of emergency oxygen if the pack should fail.

There's also a clever cooling system for the suit using a sublimator. It works by spraying water into a small chamber from a reservoir. The water instantly freezes into ice, then sublimates into water vapor. That is, since the chamber is a hard vacuum, the water evaporates straight from the ice state without changing into water again. This sucks up a lot of heat very quickly.

One significant way in which the Apollo PLSS differs from the EMU PLSS is the shape of casing. In the EMU, the shape isn't relevant and it can be boxy, the Apollo pack is angular with rounded edges. The reason is that in testing NASA found that a boxlike pack could trap an astronaut on his back like a tortoise if he fell over on the Moon. The revised shape provided more leverage for rolling over.

The air, water, power, and communication from the Apollo era PLSS were fed into the suit by a number of umbilical cords. This arrangement allowed the suit to hook directly to the spacecraft's life support system and made it easy to recharge the pack between EVAs. In the later Apollo suits, an extra umbilical port can be seen on the suits. This isn't an oversight. That's an emergency port that allowed two astronauts to link their suits together for buddy breathing in an emergency.

Another difference is that the EMU PLSS has a Simplified Aid For EVA (SAFER) propulsion system latched beneath it. This is a simple device consisting of a number of thrusters fed by a nitrogen tank. Intended only for emergency use, SAFER allows spacewalking astronauts to get back to safety if they should inadvertently float away from the station.

Helmet

The helmet for the A7L evolved from flight helmets – especially those from the U2 and X-15 programs. Where the helmets for the Mercury and Gemini flights were snug fitting with a faceplate that opened, the Apollo helmet is a spherical dome that's a compromise between low mass, pressure compensation, and field of view. Since it's made from one piece of Lexan high-impact plastic, you'd need a sledgehammer to break it. It also holds the astronaut's head facing forward in an "alligator head" configuration, so the only way to look sideways is to move your whole body.

For communications, and to keep hair from getting in the eyes, the astronaut wears the "Snoopy cap" – more formally known as the Communications Carrier Assembly (CCA), which contains earphones and two microphones just in case one mic fails. These mics have to deal the constant hiss of air as it's blown into the helmet to prevent fogging, as well as into the trunk and limbs for ventilation.

Over the helmet sits the ExtraVehicular Visor Assembly (EVVA), which shields the astronaut from sunlight and has three visors that can be lowered over the face. The first is a protective plastic visor to ward of impacts, then a gold anti-glare visor, and the third is made of three opaque shades that can be used to block out the sun entirely. The one used on the EMU is very similar to the one used on Apollo, with the major change being the inclusion of a pair of lights and video cameras.

The Apollo missions resulted in a couple of other improvements to the helmet based on EVA experiences. One of the first improvements was a canteen to feed the astronaut with water or orange drink. This was followed by a fruit bar dispenser and the very welcome addition of a velcro pad for nose scratching.

However, the helmet also demonstrates that spacewalking isn't a stroll in the park. One standard NASA precaution is for astronauts to use a transdermal dimenhydrinate anti-nausea patch to prevent vomiting in the helmet. But this didn't help much on July 16, 2013 when Italian astronaut Luca Parmitano almost drowned after his PLSS's water separator clogged and his helmet started to flood, which led to NASA developing the world's first space snorkel.

Space underwear

So what does an astronaut wear under the suit? The answer is a strange looking set of long underwear made of spandex and nylon with 265 ft of plastic tubing stitched inside of it.

The purpose of this odd bit of fashion is to overcome one of the great hazards of spacesuits – overheating. Though sunlight can present a high temperature hazard, this is relatively easy to counter by making the suit of white material to reflect it away. The real problem is that without air, there's no way to conduct heat inside the suit away. This makes a spacesuit a very large thermos bottle.

This became very obvious during the first spacewalk by Alexey Leonov during the Voskhod 2 mission in 1965. Not only did his Berkut spacesuit overinflate, meaning he couldn't get back into the airlock, but it overheated to the point where his boots were full of sweat.

Even asleep the human body generates as much as a 100 Watt incandescent bulb, and while exercising that increases by up to 15 times. One depressing conclusion from the pre-Apollo spaceflights was that the spacesuit technology of the day simply wasn't up to the task. The Mercury and Gemini suits used air ventilation to carry away heat, but this not only proved inadequate, it soon became clear that a self-contained suit couldn't carry enough air for both breathing and cooling.

For the A7L, NASA turned to the RAF, which had developed the Liquid Cooling Garment (LCG) for British high altitude bombing crews, who wore their own domestically produced pressure suits for protection. This garment sits close to the skin and cool water is pumped from the PLSS after it's been chilled by the sublimator, with the wearer manually setting the degree of cooling. This proved to be so efficient that it almost eliminated perspiration, even when an astronaut was pushing out 4,000 BTU/hr (1,000 kilocalories/hr), which is the equivalent to a 180 lb (82 kg) man sawing down a tree in the tropics.

Space diapers

Now for the most unpleasant question. How does an astronaut handle calls of nature while suited up? Well, it depends.

For urine, the Apollo suit used a permanently attached receiver that emptied into a small tank riding on the stomach. That's one better than what Alan Shepard on the Freedom 7 mission had in 1961. Due to a prolonged launch delay of eight hours on his suborbital flight, he had to relieve himself straight into his suit.

The other problem was, and still is, the job of the Maximum Absorbency Garment (MAG). This is, to put it bluntly, a diaper filled with sodium polyacrylate, which can absorb 300 times its weight in liquids, along with additives to kill bacteria. It can hold up to two liters of urine, blood, or feces. Thankfully, one benefit of the pure oxygen in the suit is that it quickly breaks down the smell.

The EMU suit uses the same waste collection system, though it includes a new version for women. In fact, the MAG itself was first designed in anticipation of women astronauts, who couldn't be expected to use the rather primitive plastic bag system used inside spacecraft. However, one particular problem that the ISS astronauts face is that without gravity, it's hard to know when to go, so a pre-spacewalk visit to the loo is essential to avoid overloading the system.

The modern spacesuit

So far, we've looked at the Apollo spacesuit and its modern variant, but there is more than one type of suit. Today's spacesuits come in several varieties that can be categorized in two ways. One is by function and the other is by basic design.

In terms of function, there are three kinds of suits: the IntraVehicular Activity (IVA), ExtraVehicular Activity (EVA), and Intra/ExtraVehicular Activity (IEVA). The A7L and the EMU are EVA suits designed to be used in orbit or on the surface of the Moon. Other versions of EVA suits are the Russian Orlan suit that's been in service since 1977, and the Chinese Haiying (an imported Orlan-M variant) and Feitian suits.

The IVA is the type of suit that SpaceX and Boeing have been showing off in recent years. These are suits worn by passengers and crews on spacecraft during launch and reentry to protect them against sudden decompression. They're made to be lighter and more comfortable than the full-on moon suit, and they may incorporate features to protect the wearer against blacking out from acceleration forces by preventing blood from being forced down into the legs and buttocks.

An example how important such suits are is illustrated by the Soyuz 11 tragedy of June 30, 1971. Three cosmonauts, Vladislav Nikolayevich Volkov, Georgiy Timofeyevich Dobrovolskiy, and Viktor Ivanovich Patsayev, were returning from a fortnight visit to the Salyut 2 space station when a ventilation valve failed during retrofire about 100 miles (160 km) above the Earth.

To save weight and space, the Soviets had abandoned using IVAs during launch and reentry in 1967. This meant that the three men had no protection when the valve failed and they died of asphyxiation within seconds.

The Russians learned their lesson very well. It's to prevent this sort of thing from recurring that Sokol IVA suits are now routinely worn and have been since 1973. According to Roscosmos, a returning ISS crew was saved by their suits earlier this year when a parachute buckle struck and cracked the seam of their Soyuz capsule during reentry.

NASA has or had its own IVA suits, like the Advanced Crew Escape Suit derived from the suits worn by SR-71 spyplane pilots, which was used on the Space Shuttle from 1994 until its retirement. The Chinese also have the Shenzhou IVA, which is based on Russian designs.

In fact, the suit that defined the spaceman in the 1960s was an IVA. The shiny silver spacesuit worn by the Mercury Seven astronauts may have seemed like something that fell out of the future in 1960, but it was actually a variant on the standard US Navy Mark IV high altitude flying suit. The puzzling thing is, why did the Navy have such a suit when it didn't have any high-altitude planes?

The answer lies in Cold War politics. During the 1950s, it was often difficult to tell who the US armed forces regarded as the real enemy – the Soviet Union or the other branches of service. With the Air Force having a monopoly on high altitude bombers and strategic missiles, the Navy thought it was becoming irrelevant, so it started becoming involved in matters of spaceflight with programs like Vanguard and the development of spacesuits, rather than pressurized flight suits.

For Mercury, the original design was for a shirt sleeve environment with the astronaut only wearing a G suit to protect against acceleration blackouts. But in February 1959, Maxime A. "Max" Faget from the Space Task Group at the NASA Langley Research Center and USAF aeromedical specialist Lieutenant Colonel Stanley C. White concluded that it might not be possible to build a completely reliable life support system that would fit in the Mercury capsule.

The Mark IV high altitude flying suit had a reputation for being comfortable when pressurized, so it was chosen for modification for spaceflight, though it was something of a quick fix. At a cost of US$5,000 each, the standard suit was given new elbow and leg joints to fit the capsule, as well as new tailoring and restraint ribbons to improve mobility. Each suit was custom fitted to its wearer by means of precise paper patterns and molds of the head and hands.

In addition, lighter materials were chosen and a new glove was designed that was less prone to ballooning. The suit was formed into the shape of a person in a seated position when inflated, and it had tiny lights incorporated into the fingertips for reading instruments in the dark.

But the most famous alteration was coating the suit in an aluminized material to give it a futuristic silver sheen. The official story is that this was for heat protection, but Matthew Radnofsky, an ex-Crew Systems Division specialist NASA, said that there were no real requirements to make the suit silver and that the real purpose was to "jazz it up a little." Whatever the truth is, it was a brilliant piece of public relations.

The next suit in the US inventory was the Gemini, which was an IEVA. Unlike Mercury, where the astronaut remained in the capsule for the entire flight, Gemini would see the first American spacewalk as the astronauts practiced the equipment and skills that would be needed to reach the Moon. With EVAs as long as 25 minutes planned, movement became the primary requirement.

Three major variants of the Gemini suit were constructed between 1965 and 1966: the G3C for intra-vehicle use, the G4C for EVA and intra-vehicle use, and the special G5C suit with a soft hood instead of a helmet for the 14-day Gemini 7 mission. These required special testing and NASA started using pools for underwater simulations as well as special trapeze harnesses to recreate zero and low gravity conditions.

Hard suits

Another way of classifying spacesuits is by how they are constructed. So far, all the suits we've looked at (with the exception of the hybrid EMU, which has a hard chest piece) have been soft suits. All soft suits have some hard parts, some even have hard joint bearings. But they are generally made of fabrics.

However, there are alternatives – ones that engineers prefer because they don't rely on highly skilled sewing to construct them. That's where hard suits come in. These don't use fabric, but, as the name suggests, are made out of hard metal or composite materials like Space Age armor. Though none have ever flown, they were the focus of several major research efforts going back to the 1950s and may well be the suit of tomorrow.

Soft suits have many positives, but they also have profound negatives: They are vulnerable to scrapes, tears, and punctures; they have to be made by hand by skilled personnel; they work best at low pressure; they require oxygen pre-breathing; and they are complicated to get into.

Worse, they are hard work to use. When a soft suit is inflated, it wants to return to its resting posture. In an IVA, for example, this is the posture of a pilot in a couch. This means that moving out of that resting posture and holding a different pose takes constant effort. This is why the fingers on spacesuit gloves are partially closed when inflated, so it's easier to grasp things and work controls.

Hard suits, on the other hand, are much simpler. Instead of donning a hard suit, you get inside it like a vehicle – like the hard suits used in very deep sea diving in areas too deep for mixed gas breathing rigs. Instead of relying on elaborate helium oxygen gases delivered under high pressure, a hard diving rig is a suit of armor that holds off the ocean's weight while the diver rests in the same pressure as at sea level.

The same is true of the hard spacesuit. Cloth and rubber are replaced with aviation alloys and composites shaped like the exoskeleton on a lobster. Constant volume joints are replaced with swivel joints and ring bearings. Getting inside is by way of a hatch in the back instead of complex zips and sealing rings. And no pre-breathing is needed because there's no pressure difference from that of the spacecraft.

Equally important, engineers like hard suits because instead of needle and thread, they can be made out of standard aerospace materials shaped by machine tools, so they are easy to design, they have a lower center of gravity to make them more stable, they can be mass produced, and they are more durable and are easier to maintain. They can even be fitted with a heat exchanger, so there's no need for the liquid cooling garment, and the PLSS is built into the suit itself. And, though they may seem bulky, they can be broken down and stowed easier than soft suits and in as little space.

In addition, they need very little effort to move a joint and hold it in position. They have 95 percent of the mobility of a naked person, unlike pressure suits, though the swivel bearings do require some practice to get the limbs in the desired place. Future suits could also include powered exoskeletons to turn an astronaut into a space-faring Iron Man.

While hard suits haven't been used to date, that may change in the future. The cancelled Apollo missions 18 to 21 would have used hard suits for their extended stays on the Moon and research continues to this day to develop the technology.

Hybrid suits

The next type of suit, and the most common for EVA work today is the hybrid suit, which incorporates both hard shells and fabric parts. The most familiar is the EMU with its glass fiber cuirass, but there is also Russia's Orlan spacesuit. Originally designed for the Soviet lunar program, the Orlan is a semi-rigid, one-piece space suit with a solid torso and flexible arms. The helmet, gloves, and life support system are all integrated into the suit, and getting in and out is through a large door in the back.

In reality, most suits are a mixture of hard and soft elements. Most soft suits have hard parts, including shoulder rings; glove, helmet, and waist seals; joint components; and plates to control ballooning in various areas.

Future spacesuits

With the EMU suits reaching the end of their service life, development of manned commercial spaceflight, and planned deep space missions to the Moon, Mars, and the asteroids, we're seeing the biggest push to develop new, practical spacesuits of various types since the 1960s. This is because we now have a much better understanding of spaceflight and the hazards that are involved – many of which took the NASA and Soviet pioneers by surprise.

For example, in going to the Moon, Mars, and the asteroids, dust will be a major problem. Before the first unmanned NASA Surveyor landings in the mid-1960s, the main concern about dust was that the lunar surface might not actually be entirely solid, but that the great seas and giant crater bottoms might be oceans of incredibly fine dust and that any astronaut setting foot on what looked like firm ground might sink like a stone.

That didn't turn out to be the case, but what dust there was was just as surprising. Billions of years of micrometeorite falls have coated the lunar surface with a fine dust that's given a healthy dose of static electricity by the solar winds and the totally airless environment. This caused the Apollo astronaut's suits to become coated with a gray/black mess that followed them into the Lunar Module. This dust got everywhere inside the spacecraft, making the crew look like coal miners and causing more than one pilot in the orbiting Command Service Module to jokingly threaten to not let the landing party back onboard.

This was bad enough on the short Apollo landings, but extensive expeditions to the Moon and Mars could make dust a major hazards. Lunar dust is made up of small, very hard, and very sharp glass-like particles and bits of carbon. These can damage airtight seals, play havoc with electric motors and moving parts, scratch lenses, and short out electronics. On top of that, breathing the dust could lead to silicosis – a debilitating lung disease.

The problem worse on Mars, where the waterless soil produces perchlorates and other corrosive, highly volatile compounds that can have all kinds of nasty effects on astronauts and machines. To prevent this, EVA suits need to be designed to reduce dust contamination to a minimum.

One way of doing this is with what is called a suitlock. Put simply, it prevents dust from getting inside the suit, ship, outpost, rover, or astronaut by keeping it firmly on the outside. Instead of coming back in through an airlock, the astronaut backs up to a special recess designed to fit around a hatch on the back of the suit. After clamping the suit in place, the air is cycled in the gap between the suit and an inner hatch to both pressurize the space and to flush away as much dust as possible. The inner hatch opens, and the astronaut climbs inside while the suit remains outside hanging on the bulkhead. To leave, simply reverse the procedure.

Z-Suits

One example of a suitport is incorporated in NASA's experimental Z-1 suit, which was introduced in 2012. The Z-1 Prototype Spacesuit and Portable Life Support System (PLSS) 2.0, to give it its proper name, is made up of a combination of several hard elements mounted on a suit of fabric that's flexible when uninflated.

The Z-1 is designed to be lighter and more flexible than the EMU with a soft torso and a more advanced PLSS. Where the current life support system can only be used in a vacuum due to its sublimator cooling unit, the Z-1 uses an evaporator that passes water through a membrane like sweat through skin and can be used on Mars. In addition, the lithium hydroxide carbon dioxide scrubber, which needs to be baked or replaced between EVAs is swapped for a device that collects and dumps carbon dioxide overboard every few minutes.

This was followed in 2014 by the Z-2, another experimental Mars suit that has a hard composite upper torso for greater durability, shoulder and hip joints that are more mobile, and boots that are more like those that would be found on a space-ready suit. In addition, the Z-2 can withstand a full-vacuum during tests.

It's also a bit more stylish than the Z-1. Where the former was coined the "Buzz Lightyear suit" for its white and green color scheme, the Z-2 was the focus of a public competition to select a more fashionable outer cover layer. The winning design included sci-fi elements, including Luminex wire and light-emitting patches for crew identification. It also has exposed rotating bearings, collapsing pleats for mobility, and abrasion-resistant panels on the lower torso.

Prototype eXploration Suit (PXS)

Another technology demonstrator suit is NASA's Prototype eXploration Suit (PXS). It's also equipped with a suitport, but has the added ability to incorporate 3D printed parts. These could be fabricated aboard the spaceship to meet individual mission requirements, and would greatly reduce the number of spare parts that would need to be carried along on a voyage.

Constellation

The controversial suit developed for the Constellation – the first spacecraft chosen to replace the Space Shuttle – was intended as an all-in-one, modular design that could be quickly changed from an IVA to an EVA suit for particular missions by adding on or swapping components. After the Constellation program was cancelled to make way for Orion, the suit fell out of favor due to its price tag in the hundreds of millions of dollars.

Orion missions

When the first Orion manned missions launch, the crew will use a new suit based on the Advanced Crew Escape System (ACES) from the Space Shuttle program. The current purpose of the ACES IVA suit is to protect the astronaut in the event of an emergency, but it will also do double duty as an EVA suit.

According to NASA, the advantages of the ACES suit are that it has over 30 years of experience behind it, is low cost, the infrastructure for supporting it is already in place, and it's designed to be easily upgraded.

The main modifications to the suit will be to make it more suitable for regular work. It will operate with a PLSS as well as the systems on Orion, operate for hours instead of minutes, and it will have more flexibility in the elbows, wrists, and other high mobility joints. The trick will be to do so without introducing too many hard points that might injure the wearer on take off or hinder an escape in an emergency.

In addition to use aboard Orion, the new suit will also be part of NASA's plan to recover and study a small asteroid in cislunar orbit.

Earthbound suits

Then there are the Earthbound spacesuits. Since an EMU spacesuit costs US$12 million and isn't designed for planetside use, a new breed of suits has been developed to help plan future space missions and create new EVA suits. At first glance, the Austrian Space Forum's Aouda.X suit and the North Dakota suit may seem like a bit of silly cosplay by would-be Flash Gordons, but these stripped-down, lightweight suits serve a real purpose. They'll never be used off Earth, but they do allow scientists and engineers to simulate Mars mission tasks, study different suit designs, assess contamination problems, and explore advanced ideas like incorporating computer networks into suits.

Privately developed suits

Then there are the private spacesuits we touched on earlier. For the passengers and crew of Boeing's CST-100 Starliner, the company has come up with its Blue spacesuit, which is an emergency IVA suit. It's not only a bit more stylish than its NASA counterparts, but is also more advanced than the current generation of IVAs.

The Boeing Blue spacesuit is 40 percent the weight of current NASA suits, due in part to eliminating the hard helmet and neck ring in favor of a smaller soft version secured by a zipper and a wider polycarbonate visor for better visibility when pressurized. There's also an integrated communications system in the helmet and under the blue outer covering is a new layered fabric that includes a more breathable design for the suit and boots to keep astronauts cool, without the need for external cooling systems under normal conditions. There are also zips in the torso to allow the wearer to move from sitting to standing comfortably. In addition, the lighter gloves include touchscreen-friendly surfaces to allow the astronauts to use their devices and touch displays in space.

Meanwhile, SpaceX has revealed its own streamlined spacesuit. Though the company hasn't released any details beyond a couple of images, the lack of bellows and tie downs seen on other suits indicate that it is certainly an IVA.

Skin suits

The spacesuit of the future could be much more radical than an advanced version of an EMU or a suit of space armor. Perhaps it will look a bit more like a scuba diver's wet suit and be as easy to move around in without the need for bellows or special joints.

In the wild experimental days of the 1960s, one off-the-wall idea was the Space Activity Suit (SAS). Also called a Mechanical Counter-Pressure (MCP) suit, the idea behind the SAS is that human skin makes for a surprisingly good natural spacesuit, which is why you wouldn't explode if you went out the airlock without a helmet.

To recreate the characteristics of skin, NASA engineers developed a body stocking made of several separate layers of skin-tight latex. These were extremely difficult to get on in the prototype, but once it was on the suit elasticity pressed in on the wearer's body to provide the same level of protection against a vacuum as the air trapped in a conventional pressure suit. Furthermore, if the suit was compromised, the effect on the wearer was a bruise under the tear rather than a fatal leak.

The suit didn't cover the head, which was protected by a helmet that connected to a "neck dam" that sat on the shoulders. This sealed the helmet off from the rest of the suit. Since the suit wasn't inflated, there was no need for special joints and the wearer had almost as much freedom of movement as if naked. In tests, it had 400 percent more freedom than a conventional suit and movement required only 20 percent of the energy. However, because there was no air in suit, there was no counterpressure to deflate the lung while breathing. To keep the wearer from suffocating, a bladder or a small cuirass covered the upper torso to provide the needed pressure. Bladders or bags of gel or foam were also set in the cavities in the groin, armpits, and behind the knees. A cup was also needed to protect the genitalia.

Being sealed in a latex body stocking may seem like it would be uncomfortably hot, but the suit was porous, allowing sweat to escape easily. This meant that the SAS had no need of an elaborate cooling apparatus. This, plus the fact that only the helmet needed to be supplied with air, meant that the PLSS was much lighter and simpler.

All of this made for a suit that could be folded up and tucked into the helmet when not in use. It was also remarkably inexpensive with a cost of only US$60,000 in today's money.

Despite its successes, the skin suit never went past the laboratory stage and the latex prototype rotted away in storage after a few years. Though the idea was sound, the materials available weren't up to the job of providing uniform pressure, getting the suit on was an ordeal, and fitting the suit to the wearer was extremely difficult.

But the idea of a suit that would do for space travel what scuba gear did for the hard hat diver was too attractive to remain on the shelf. In recent years, a team led by Dava Newman, a professor of aeronautics and astronautics and engineering systems at MIT, revived the concept as the Biosuit. This new iteration uses laser body measurements, modern fabrics, and computer modeling, to produce an updated and more practical counter-pressure suit.

However, the Biosuit was still hard to get on to the point where it was even suggested that it would have to woven on the wearer by an elaborate machine. To overcome this, Newman's team created a loose fitting version of the prototype spacesuit that incorporated coils formed out of tightly packed, small-diameter springs made of a shape-memory alloy (SMA)into the suit fabric. Memory alloys are metals that can be bent or deformed, but when heated, return to their original shape.

The idea is that the wearer could don the Biosuit easily, then an electric current would be applied. The heated coils would cinch up to automatically tighten the suit, with buckles maintaining the tension when the current was turned off. To take off the suit, the buckles are unfastened.

The Biosuit is still in development and even if the bodysuit is perfected there are still many details that need to be addressed. The helmet and neck dam need to be sorted out as well as the best way to deal with body cavities. Then there are the gloves, which will probably torment engineers for any type of suit devised.

So what will the well dressed astronaut of tomorrow be wearing? Like Earthside clothing, that will depend on the occasion. It might be a stylish IVA suit for shipboard use, a lighter version of the EMU for spacewalks, or a specialized outfit for roaming the mountains of the Moon or the dead sea beds of Mars. It may be a skintight garment, a modular system, or a suit of powered armor that's more aerospace engineering than tailoring.

But whatever they are wearing, so long as human beings explore the final frontier they will need to carry a bit of their native environment with them to protect themselves.

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