When ever you go out in cold winter's day. You wear shirt, jackets gloves, garments to protect you from cold. Now, if you go to outer space you will need much more stuff to protect you. Therefore Space suit must provide all of the comfort and support to astronaut to provide Earth like environment.
Unlike Earth outer space is an extremely hostile place. If you go out of spacecraft without space suit, the following could happen:
- Due to no oxygen, you will become unconscious within 15 seconds.
- As there is no air pressure in space, your blood and body fluids could "boil" and then freeze.
- Due to boiling fluids, your tissues (skin, heart, other internal organs) could.
- You will face extreme changes in temperature from 120 degrees Celsius in sunlight to -100 Celsius in the shade.
- You would be exposed to radiation, such as cosmic rays, and charged particles emitted from the sun.
- You could be hit by micrometeorites or debris from satellites or spacecraft.
Therefore to protect you from above dangers, a space suit must:
- Maintain pressurized atmosphere similar to Earth.
- Provide breathing air ie give you oxygen and remove carbon dioxide
- Maintain a comfortable constant temperature despite of outside temperature conditions
- Protect you from micrometeorites and from radiation.
- Allow astronaut to see, move easily and allow communication with others.
Achieving all of this trough single space suit is not easy, and by creating an Earth-like environment within the suit itself, space suits allow humans to walk around in space in relative safety. Space suits provides following to an astronaut:
As space is complete vacuum, there is no atmospheric pressure to keep the fluids in your body in a liquid state. So due to lack of vacuum your body fluids boil, so to prevent bodily fluids from boiling space suit maintains pressure. Space suits acts as an inflated balloon or Tyre and is made of Neoprene-coated fibers. The air in space suit supplies air pressure to the astronaut inside.
Space shuttle have normal atmospheric pressure but space suit have lower atmospheric pressure. Therefore, before going to space the airlock pressure is reduced before an astronaut gets suited up for a spacewalk. There is always a risk of getting the bends because of the changes in pressure between the space suit and the shuttle cabin.
Space suits cannot use normal air ie 78 percent nitrogen, 21 percent oxygen and 1 percent other gases. This is because the low pressure of space suite causes dangerously low oxygen concentrations in blood. Therefore space suits provide a pure oxygen atmosphere for breathing.
Both the shuttle and the International Space Station have normal air mixtures similar to our atmosphere. So before going for spacewalk, astronaut have to breathe pure oxygen for some period of time before getting suited. This eliminates any nitrogen present in the body minimizing the risk of the bends.
The astronaut breathes out carbon dioxide. Therefor in space suit carbon dioxide can grow to hazardous levels if not removed. Space suits use lithium hydroxide canisters to remove carbon dioxide which are located in space suit's life support backpack.
Since temperature outside are extreme, space suits are heavily insulated with layers of fabric. The astronaut produces heat from his/her body, especially when doing strenuous activities. Also body heat is removed by water pipe in the space suit.
These are too dangerous as they fly at very high speeds. So space suits is made of multiple layers of durable fabrics such as Dacron or Kevlar. These layers also prevent the suit from tearing on exposed surfaces of the spacecraft or a planet or moon.
Space suits only offer limited protection from radiation. This is done by using reflective coatings of Mylar. So, spacewalks are planned during periods of low solar activity as this reduces the risk of radiation.
Clear sight is important but helmets are tinted to reduce glare and are made of durable poly-carbonate. Modern space suit helmet have mounted lights so that the astronauts can see into the shadows.
Mobility Within the Space suit:
Moving within an inflated space suit is tough and offers limited mobility. Therefore space suit have special joints to help the astronauts bend their arms, legs, knees, therefore increases mobility.
Space suits are equipped with radio transmitters/receivers to offer seamless communication with other astronauts and ground staff.