SPACE SUIT

SPACE SUIT

A space suit is a complex system of garments, equipment and environmental systems designed to keep a person alive and comfortable in the harsh environment of outer space. This applies to extra-vehicular activity (EVA) outside spacecraft orbiting Earth and has applied to walking, and riding the Lunar Rover, on the Moon.

Some of these requirements also apply to pressure suits worn for other specialized tasks, such as high-altitude reconnaissance flight. Above Armstrong's Line (~63,000 ft/~19,000 m), pressurized suits are needed in the sparse atmosphere. Hazmat suits that resemble space suits are also used when dealing with certain types of biological hazard

SPACE SUIT REQUIREMENTS

Several things are needed for the space suit to function properly in space. It must provide:

A stable internal pressure. This can be less than earth's atmosphere, as there is usually no need for the spacesuit to carry nitrogen.

Lower pressure allows for greater mobility, but introduces the requirement of pre-breathing to avoid decompression sickness.

Movement is typically opposed by the pressure of the suit; mobility is achieved by careful joint design.

Breathable oxygen. Circulation of cooled and purified oxygen is controlled by the Primary Life Support System.

Temperature regulation. Heat can only be lost in space by thermal radiation, or conduction with objects in physical contact with the space suit. Since heat is lost very slowly by radiation, temperature is regulated by a Liquid Cooling Garment and heavy insulation on the hands and possibly feet.

Shielding against harmful electromagnetic radiation

Shielding against particle radiation

Protection against micrometeoroids, provided by a Thermal Micrometeoroid Garment, which is the outermost layer of the suit

A communication system

Means to recharge and discharge gases and liquids

Means to maneuver, dock, release, and/or tether onto space craft

Means of collecting and containing solid and liquid waste

OPERATING PRESSURE

Generally, to supply enough oxygen for respiration, a spacesuit using pure oxygen must have a pressure of about 4.7 psi, equal to the 3 psi partial pressure of oxygen in the Earth's atmosphere at sea level, plus 40 torr CO2 and 47 torr water vapor pressure, both of which must be subtracted from the alveolar pressure to get alveolar oxygen partial pressure in 100% oxygen atmospheres, by the alveolar gas equation.The latter two figures add to 87 torr (mm Hg) which is about 1.7 psi, which is why many modern spacesuits don't use 3 psi, but 4.7 psi (this is a slight overcorrection, as alveolar partial pressures at sea level are not a full 3 psi = 155 torr, but a bit less). In spacesuits that use 3 psi, the astronaut gets only 3 - 1.7 = 1.3 psi of oxygen, which is about the alveolar oxygen partial pressure attained at an altitude of 6,100 ft. (1860 m) above sea level. This is about 78% of normal sea level pressure, about the same as pressure in a commercial passenger jet aircraft, and is the realistic lower limit for safe ordinary space suit pressurization which allows reasonable work capacity

REPRESENTATION OF SPACE SUIT WIT IT'S VARIOUS PARTS

COURTESY: WIKIPEDIA