Extravehicular Activity

Extravehicular Activity is any activity that is done by an astronaut or cosmonaut outside a spacecraft and beyond the Earth's atompshere (in space).

NASA

SpaceSuit

Referring to NASA space shuttle space suit Extravehicular Mobility Unit (EMU)

Oxygen

Oxygen is considered the most vital system that is need to survive in open space. usually in the backpack, there consist of two oxygen tanks that provide compressed gas for around 9 hours. These tanks can be refilled with oxgyen easily back in the spacecraft.

C0 2 Removal

As astronauts breath in oxygen, they release carbon dioxide which need to be removed. However, removing carbon dioxide means removing vaulable oxgyen which are scarce in space. Hence, the similar concept of carbon dioxide removal in the spacecraft, the carbon dioxide in the spacesuit undergoes a filtering system chemically where it is located in the backpack known as the Comtaminant Control Catridge. Traditionally, Lithium Hydroxide is used but since its a one of use material, the metal oxide is often used as a better alternative.

Pressure

Pressure is important to maintain, so that astronauts can breathe probably and not have too much pressure upon their lungs. The used of a Secondary Oxygen Pack that have a higher pressure oxygen then the primaty in which the pressure sensors can trigger this tank to assist on maintaing stable pressure in the suit. If a micro meterire, or sharp debris, tears a hole in the suit, the secondary oxygen tanks can maintain stable pressure or around 30 minutes which is sufficient enough to return to the ship safely.

Food and Water

The suit will provide a Drink Bag where it will only supply water, if there was sucktion (Mouthpiece). This is a protective mechanism to disable any water flowing out and causing havoc in the space helmet. A Food Bar is placed in front of the astronauts mouth, which they can nibble on it, incase they get hungry.

Communication

To be able to ask request and assistant, a communication to the surrounding team member, the space ship control unit and ground unit, help ensure safety.

Power

To control and make the suit functional, power need to be supplied to help the fans, heat, light, communication system.

SpaceSuit

Layers (Inner to Outer):

Comfort Layer: Help provides comfort to the skin
Liquid Cooling Garment: Thin tubes that run cool water to keep the suit cool
Pressure Restrain: Contains rubberized fabric with a holdin Kelvar layer to support and keep the gas and pressure in the suit
A piece of Layer: To seperate the two layers
Multilayer Insulator: Made from aluminium foil that acts to insulate the suit (Thermal Control)
Outer Skin: Very strong material to resist any holes and tear. It is white for thermal control and relfect the sun's heat

Stability and Training

Stability

Stability is required to do useful work in space. This is important becuase in space, if one tries to for example to turn a screwdriver, instead of turning the tool
they themselve, if unstable if turn instead, and this is why stability is imporant; to be able to grip and move / transition through doing work with ease.

Training

Most training were dealt under water, as it simulated a similar environment as vacuum.

Spacesuit Flexibility and Pressure

Spacesuits are just like balloons. They have a lot og pressure and gas, that disables the suit to bend and become flexible.
This stiftness can be derive from, In order to increase the flexibility of a space suit, we want to minimize the work that needs to be done to bend it. For a gas, the work W is given by:

Work = ∫ Pressure (dV)

Preventing Decompression Sickness

When there is a decrease from high pressure to low pressure, in the human body, the nitrogen from our body can bubble from our body tissues
To control, the method is to breathe in 100 % oxygen to wash out the nitrogen in our body, before the astronausts get depressurised.

Hard Suits, Visibility, and Tools

Flexibility

Convolute joints are simply the design on on suits that provide flexible yet reducing the change in volume, cause due to ∫ Pressure (dV)
As a changing volume will affect the pressure and hence the work require to make a move in the suit. Another implementation on the suit is the use of roller joints that require 'O rings' to connect them. They are very flexible, however, they pose too muh disadvantage
as they are bulky, and prone to dust and tear and holes/openings.

Visibility

Visibility isn't of a issue for space suit, as thick layer of glass is used to provide vision. There visors, are require to keep clear from defogging and hence,
beforehand, they are wipe with a soaping agent. During work outside in space, the air provide in the suit, flow from the back of the helmet and flows up and around the head
on the visor, which provide defogging.
Another factor, is the sun and its ultra bright light that is harmful to look at. To protect the eyes, the visors ar equipment with a golden shielding visor that enable
a more clearer vision.

Future

Future SpaceSuit Design

Future designs to the spacesuits required the increase in efficiency that allows the astronaut to work. As, the sleeves and suits must be flexible for very useful moments.

Vulnerability to depressurization, meaning that a change in pressure, makes the suit harder to move and sustain life.
Stiffness in suit, is due to the gass-filled suit, making its harder to move. When work is done to move around, the suit's volume will change applying more pressure.
Fammability in the 100 % oxygen atompshere, involves protecting the pressure from nitrogen, but as the suit functions with electronics, flames and fire will burn very actively.
Dust, is a difficulty that spacesuit are evitably dealt with as the space debris and small particles, can harm the technology in the joints.
High cost and maintenance

One Future design is the Elastic Pressure that hold directly to the skins and thus, its requires no gas and provide more flexibility.

Future

Space Robotic

Both robots and humans can cooperate to achieve tasks that one or the other can not do, with ease (creates a more powerful system).
Robots makes good use for space exploration where humans are deem to be to dangerous to be at and too slow and inefficient to send.
Probes can be classified as robots to assist movement of spacecrafts.
Planetary Robots are also classified as robots, known as Rover. They collect data about the environment and soil of the planet and any sighting that may be useful for scientist back on Earth.