Space suit

A space suit is a highly specialized environmental suit. It protects humans from the harsh conditions of outer space. The vacuum of space poses a major threat to the human body. Without pressure, gases in the body expand and liquids can evaporate. Space suits act as a portable pressure vessel to prevent this.

They also shield astronauts from extreme temperature swings and radiation. Additionally, they protect against micrometeoroids, which are tiny particles moving at high speeds.

To keep an astronaut alive, the suit must manage several complex processes. First, it maintains a stable internal pressure. While Earth's atmosphere is mostly nitrogen, space suits often use pure oxygen. This allows for lower pressure, which makes it easier for the astronaut to move. However, using lower pressure requires a process called pre-breathing.

Astronauts must breathe pure oxygen for a set time to purge nitrogen from their blood. This prevents decompression sickness, which occurs when nitrogen bubbles form in the body. The suit also manages gases by supplying fresh oxygen and removing carbon dioxide.

Temperature regulation is another vital mechanism within the suit. In space, heat cannot move through the air by convection like it does on Earth. Instead, heat is lost through thermal radiation or conduction to objects. Temperatures can reach 127 degrees Celsius in sunlight or drop to -157 degrees Celsius in shadow. To stay comfortable, advanced suits use a Liquid Cooling and Ventilation Garment (LCVG). This garment touches the astronaut's skin to move heat away.

This heat is then dumped into space through an external radiator in the Portable Life Support System (PLSS).

There are three distinct types of space suits designed for specific tasks. Intravehicular Activity (IVA) suits are meant for use inside a pressurized spacecraft. These are lighter and more comfortable because they only provide safety if cabin pressure is lost. Intra/Extravehicular Activity (IEVA) suits, such as the Gemini G4C, work both inside and outside. Finally, Extravehicular Activity (EVA) suits are the most complex.

These are used for spacewalks or planetary exploration. They must provide full protection against all space conditions while allowing for mobility.

The history of these suits began with individual inventors in the 1930s. They designed the first full-pressure suits for use at extreme altitudes. A major milestone occurred in 1961 when Yuri Gagarin wore the Soviet SK-1 suit. This was the first time a human wore a space suit in space. Since then, humans have worn suits in Earth orbit and on the lunar surface.

Engineers have continued to refine designs to improve safety and functionality.

Designers must solve the problem of mobility within a pressurized garment. A pressurized suit naturally wants to stiffen, making it hard to bend limbs. To fix this, engineers use careful joint design to maintain a constant volume. If a joint's volume changes when it bends, the astronaut must perform mechanical work to fight the pressure. This can lead to serious fatigue during long missions.

To protect against physical damage, the outermost layer is often a Thermal Micrometeoroid Garment. This layer protects against particles traveling at speeds up to 27,000 kilometers per hour.

Space suits also involve complex systems for communication and hygiene. Astronauts often wear a communications cap with earphones and a microphone. During the Apollo missions, these were nicknamed "Snoopy caps" due to their appearance.

The suit must also contain a way to collect bodily waste, such as a Maximum Absorbency Garment. Furthermore, scientists are studying how to manage lunar or Martian dust. This dust can contaminate spacecraft and pose risks to skin and lungs. New ideas like suitports are being explored to solve these contamination problems.