How can astronauts breathe pure oxygen?

Astronauts rely on a carefully controlled system to breathe pure oxygen during space missions. In space, the air is not breathable, so astronauts use a specialized atmosphere within their spacecraft to ensure their survival. This environment is maintained by technology that provides a safe and breathable level of pure oxygen for the astronauts.

The spacecraft’s life support systems remove impurities and carbon dioxide from the air, allowing astronauts to breathe in a clean and oxygen-rich atmosphere. This setup mimics the conditions found on Earth and enables astronauts to function effectively during their missions in space. By providing a constant supply of pure oxygen, astronauts can perform their duties and experiments in a controlled and safe environment.

The Gas Composition Dilemma

When it comes to outer space exploration, astronauts face numerous challenges. One of the most critical issues they encounter is the need for a suitable breathing atmosphere. In the vacuum of space, the absence of atmospheric pressure exposes astronauts to potentially lethal conditions. To combat this, astronauts breathe pure oxygen while in space. This article will explore the reasons behind this choice and how it is achieved.

Your Body’s Oxygen Needs

Oxygen is a vital component for sustaining human life. In an environment like Earth, where atmospheric pressure allows for proper gas exchange, our bodies receive the oxygen needed through regular breathing. However, in space, the lack of pressure makes it impossible for astronauts to intake pure oxygen naturally.

For space travel, including spacewalks or living in a spacecraft or space station, astronauts are required to rely on a controlled atmosphere. This controlled atmosphere, known as the Extravehicular Mobility Unit (EMU), is necessary to maintain life-supporting conditions while exploring the void of space.

The Benefits of Breathing Pure Oxygen

High-Fidelity Oxygenation

When astronauts breathe pure oxygen, it provides higher levels of oxygenation to their bodies compared to regular air. This boost in oxygen intake allows for increased performance and endurance during spacewalks and other physically demanding tasks.

Reduced Decompression Sickness Risk

Breathing pure oxygen helps avoid decompression sickness, also known as “the bends.” When a person ventures into space, the rapid transition from a pressurized environment to the vacuum of space can cause nitrogen bubbles to form in their body tissues, leading to decompression sickness. By breathing pure oxygen before and during space activities, astronauts purge their bodies of nitrogen, reducing the risk of this potentially dangerous condition.

Fire Safety

Another reason why astronauts breathe pure oxygen is related to fire safety in the spacecraft or space station. Fires in space can be extremely hazardous due to the energy-efficient nature of combustion in a microgravity environment. By maintaining a pure oxygen atmosphere, the risk of fires can be minimized, as they require a certain level of ambient gases to sustain themselves. In the event of a fire, a pure oxygen atmosphere allows for better control and detection, thus improving crew safety.

Creating a Pure Oxygen Environment

The Pre-Breathing Process

Preventive Measures
Before astronauts venture out into space, they undergo a process called “pre-breathing.” This process involves spending time in a Reduced Pressure Breathing (RPB) space suit, where they breathe pure oxygen for a specific duration. This helps flush out the nitrogen in their bodies, reducing the risk of decompression sickness as mentioned earlier.

Spacecraft Atmosphere

Oxygen Storage
For extended space missions, such as those conducted on the International Space Station (ISS), a continuous supply of oxygen is required. Oxygen is stored in specially designed tanks or systems that can deliver it when needed. These systems ensure that astronauts have access to pure oxygen throughout their stay in space.

Scrubbing Carbon Dioxide
In addition to ensuring ample oxygen supply, the spacecraft’s life support systems also remove carbon dioxide exhaled by the astronauts. Carbon dioxide scrubbers help maintain a stable and breathable atmosphere by eliminating the waste gas and replenishing it with oxygen-rich air.


Portable Life Support Systems (PLSS)
During spacewalks, astronauts wear Portable Life Support Systems (PLSS) to provide them with a continuous supply of pure oxygen. The PLSS serves as an independent life support system, including a suit ventilation system, cooling technology, and oxygen storage. It allows astronauts to explore space outside of the controlled atmosphere provided by the spacecraft.

Limited Endurance
Despite the advantages of breathing pure oxygen, astronauts cannot rely solely on this method for extended periods. The human body requires a balance of different gases, and prolonged exposure to pure oxygen can lead to health issues. Therefore, astronauts only breathe pure oxygen for specific activities, such as spacewalks, while relying on the spacecraft’s controlled atmosphere for the majority of their time in space.

Breathing pure oxygen is crucial for astronauts during their space missions. Through a carefully controlled atmosphere and the use of specialized equipment, astronauts can ensure their bodies receive the necessary oxygen while avoiding potential risks like decompression sickness and fire hazards. As our understanding of space exploration continues to advance, so too will our ability to create even more optimized breathing environments for astronauts, allowing them to safely explore beyond the confines of our planet.

Astronauts aboard space missions are able to breathe pure oxygen by using specialized life support systems that provide a controlled environment inside their spacecraft or spacesuit. This allows them to safely navigate the challenges of space exploration and perform their duties effectively while breathing pure oxygen.

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