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SPACESUITS

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A spacesuit is used to assure the survival of a person in a space environment. There are two main outfits.
The EMU (Extravehicular Mobility Unit) suit used for maintenance in the space vacuum or the exploration of the Moon.
The ACES (Advanced Crew Escape Suit) suit, for intravehicular use, was designed to face a potential accidental depressurisation of the cabin.

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How does a spacesuit work?

The spacesuits protect the astronauts from various dangers related to space vacuum. Indeed, outside the spacecraft, the human being has to deal with many risks.
The suits include a helmet with a clear plastic pressure bubble allowing the crew members to breathe in space. It is designed to withstand impacts, and protects the spacewalker from being harmed by micro-debris during extravehicular activities.
Extravehicular activities can last several hours, that is why spacesuits are equipped with a tube keeping the astronauts hydrated as well as with a CO2 and steam removal system.

A camera and lights are fixed on the side of the helmet, allowing teams on Earth to communicate and follow the progress of the mission in real time.

A backpack containing water supplies is attached in the back to regulate the body temperature (a cooling system by water circulation in tubes incorporated in the Liquid Cooling and Ventilation Garment (LCVG)). Indeed, in space, the temperatures are extreme, ranging from 120 °C in the sun to -160°C in the shadow.

WHY ARE THE SPACESUITS WHITE?

We could ask ourselves why the spacesuits are not bearing the colours of the nations.
There are two main colours for the spacesuits.
The orange spacesuits, dedicated to journeys between the Earth and space, and vice versa.
The orange colour makes the astronauts easily recognisable in case a technical problem would force them to leave the capsule.
The white colour is used for spacewalks, white being the colour reflecting the best the sun’s harmful radiations, and consequently, heat.

THE DESIGNING OF A SPACESUIT

As an example, we will talk about the spacesuits used for the Apollo missions, the A7L.
Indeed, many suits have been designed, and continue to be.

Spacesuits include two garments.

The body underwear:

This underwear is made of elastane, which is an extensible fibre. It has 91.5 meters of narrow tubes throughout, in which water circulates to regulate the temperature.

In parallel, the astronauts are provided with a Maximum Absorbency Garment (MAG). It is basically adult-sized diapers.
Spacewalks may last as long as 8 hours, so it would be too complex to come back on board the space station or the spacecraft to use bathrooms for natural needs.

The EMU suit:

The A7L spacesuits of the Apollo programme are custom-made by American companies ILC Dover and Hamilton Sundstrand, and were used between 1968 and 1975. They weigh 72 kg, but the Moon’s gravitational pull being five times weaker than the Earth’s gravity, astronauts felt like they were barely carrying 14 kg.

The suits are made of 14 layers:

(1-3) The body underwear (detailed above) represents the first three layers.

(4) On top of this garment is the bladded layer. It creates the proper pressure for the body. It also holds in the oxygen for breathing.
It is made of nylon and covered with urethane (a synthetic rubber).

(5) The next layer holds the bladder layer to the correct shape around the astronaut's body. It is made of Dacron (the same material as camping tents).

(6) The ripstop liner is the tear-resistant layer.

(7-13) The next seven layers are Mylar insulation and make the suit act like a thermos. The layers keep the temperature from changing inside. They also protect the spacewalker from being harmed by small, high-speed objects flying through space.

(14) The outer layer is made of a blend of three fabrics. Two fabrics are waterproof, and one fabric is in KEVLAR (material used to make bullet-proof vests).

source : https://www.nasa.gov/audience/foreducators/spacesuits/home/clickable_suit_nf.html

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THE FUTURE OF SPACESUITS

The Nasa is currently working on future spacesuits.
On the same basis as EMU, the xEMU (Exploration Extravehicular Mobility Unit) will be more flexible, particularly thanks to knee and hip joints.
They will also be more resistant to lunar dust, which could infiltrate everywhere during Apollo missions.
The NASA plans to create a wider range of sizes. Indeed, the current outfits are not suitable for all body shapes, specifically for women.

The colours of these suits will change. The current ones are only prototypes shown to the public.

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