Sen— The image of Buzz Aldrin on the surface of the Moon with his space suit protecting him from certain death is one of the most iconic images of space exploration. Without his suit he would have survived for only a few seconds, but instead with this portable environment he could live and breathe on the hostile surface of the Moon, albeit in a cumbersome fashion.
The evolution of the space suit has its origins with high altitude jet pilots. The story of its development is a fascinating one that involves some ingenious design ideas and a constant battle to keep costs to a minimum.
Before looking at how it has developed over the decades, it is perhaps appropriate to first look at why the protection of a space suit is even needed! Here on Earth we are protected from the hazardous conditions of space by the atmosphere, the thin shell of gas which surrounds our planet. On average it is only 100km thick but without it, we wouldn't be able to survive. If a human being wants to function and survive high up in the atmosphere or even above it then the conditions we experience at the surface of Earth need to be replicated. For the most part this is done inside the space craft but of course nip outside to fix a satellite or walk on the surface of another world like the Moon and you need to take a portable environment with you or it will be certain death!
It would only take around 15 seconds for you to become unconscious due to a lack of oxygen. Additionally the lack of air pressure would cause your blood and bodily fluids to boil and then freeze which would cause the organs in your body to expand. If that is not enough to finish you off, your body would experience extremes of temperature from -100 to 120 degrees Celsius, not to mention the various types of radiation you would be exposed to. I think you would agree, space exposure without a protective suit is a pretty crazy idea.
The first suit developed specifically for space exploration was used by Yuri Gargarin and was called the SK1 - short for Skafandr Kosmicheskiy #1 which translates to 'diving suit for space'. This suit only provided extra protection whilst in the spacecraft and during emergency ejection within the atmosphere, but was not pressurised and provided no life support function.
NASA and the American military were the first to develop a pressurised space suit which was designed for the Mercury program that began in 1959. These were simply a modification of pressure suits that were used by the US Navy high altitude jet aircraft pilots. The astronauts aboard the Mercury spacecraft wore suits constructed from an inner layer of nylon fabric coated in Neoprene and an outer layer of aluminised nylon. The suit was designed to provide air pressure to stop the body boiling, and a helmet to assist with the provision of oxygen. A little extra mobility was designed into the suit by the addition of break lines sewn into the fabric. In reality, these pressure suits were worn 'soft' or deflated and were there simply in case of cabin pressure failure. If they had inflated the suits, an occasion which never happened, then the astronaut would have suffered restrictions on their mobility but given the small size of the capsule this wouldn't have caused any major operational problems.
The Mercury modules were manned by a single astronaut but the next series from NASA, Gemini, facilitated an additional astronaut therefore a larger cabin space meant they would need more mobility than the Mercury suits offered. If the Mercury spacesuits were inflated for example, there wouldn't be sufficient mobility to move around and allow operation of the craft so new developments were sought to improve it, particularly around the upper body. This was finally solved by employing a restraining layer over the pressurised layer. Like the Mercury design, a neoprene layer provided a pressure tight inner (known as a pressure bladder) which was enshrouded by a net made from Teflon and Dacron, a polyester based material. The net, which was slightly smaller than the pressure bladder, served to restrain how much it could expand and therefore stop it becoming too stiff, providing the upper body with more mobility.
By the time the Apollo era arrived in the late 1960s a whole new set of challenges arrived. Walking on the surface of another world meant that the suit would be the only protection and life support for the astronauts. Without protection from the spacecraft, the suit would have to protect from radiation, the heat of the Sun and even micrometeoroids. This all meant that the suit design had to be far more complex than its predecessors.
The suit, known as the A7LB, started with a liquid cooled under garment not too dissimilar to thermal underwear but with the addition of a network of tubing sewn into the fabric where cool water circulated. The water drew heat from the body and transferred it via the backpack out into space. Over the undergarment was a layer of nylon followed by the pressure bladder made from neoprene coated nylon. Shaped joint segments gave greater mobility and the whole lot was encapsulated in a nylon layer which acted like the netting of the Gemini design to stop the pressure bladder from becoming rigid. Several additional layers of thermal insulation were added before the outer layer of teflon coated glass fibre to offer physical protection from the rugged lunar surface and potential micrometeoroid impacts. That protected the body but the extremities too needed careful consideration.
The gloves were custom made for each astronaut and connected to the suit by a special mechanical connection that provided an air tight seal. Like the suit, they also employed a pressure bladder and several layers to provide thermal insulation along with moulded silicon thumb and finger tips to give the astronaut a sense of touch. The boots slipped over the pressure bladder of the main suit and like the gloves, had several layers to provide thermal insulation. The outer layer needed to be tough to protect against the rough lunar surface so a metal woven fabric was developed with a ribbed silicon sole.
One of the more unique features of the A7LB suit was the design of the helmet. Unlike the Mercury or Gemini suits, the Apollo helmet was fixed to the suit with a pressure ring just like the gloves and allowed the astronaut's head to move around inside. It was made from a polycarbonate material which was incredibly strong and had a detachable outer visor to protect against UV radiation. The backpack carried by astronauts provided all environmental supplies such as oxygen, coolant water and power along with radio communications equipment. Drinking water was supplied from pouches which were fitted around the neck under the suit and helmet.
Since the Apollo era and the Moon landings there have been only a few changes to spacesuit design. Those changes that were made were designed to lower costs and bulk. Missions focussed on space stations and space walks rather than the rugged environment of the Moon's surface. The external boots were eliminated, a more lightweight micrometeoroid protective outer layer was used and a more simplified and less expensive outer visor was developed. Space walks (or EVAs) and space station activities just didn't require the same level of protection as lunar visits.
NASA recently released details of a proposed next generation spacesuit called the Z-1. Many commentators feel it looks like Buzz Lightyear's space suit! One of the more significant differences is that it has a one piece design so the astronaut slides into it through a large hatch in the back. There is even talk of this being permanently attached to the outside of the spacecraft so the astronaut can just slide straight in and detach themselves and as a result, airlocks will become a thing of the past. Many of the detail remains a little bit of a mystery but it looks very likely that future astronauts who visit other worlds will be wearing this new design.
Until then, the space suit we all recognise looks likely to be around for a while. It will take something like a return to the Moon or even explorations to Mars before the Z-1 design will see its inaugural outing. Beyond that, with modern materials and a new drive for more lightweight, durable, protective and more flexible suits it is very likely that significant changes will be seen and the iconic white space suit of the Apollo era will finally become a thing of the past.