Understanding the Pressure Inside Space Suits: Is It the Same as Atmospheric Pressure on Earth?

In the captivating world of space exploration, the question of what pressure lies within space suits is often a topic of curiosity. Contrary to popular belief, the pressure inside a space suit is not the same as the atmospheric pressure on Earth. This article delves into the specifics of pressure inside space suits, comparing it to Earth's atmospheric pressure, and elucidating the unique design features that make astronauts' survival in space possible.

Space Suits on the International Space Station (ISS)

On the International Space Station (ISS), the atmosphere inside the living quarters is indeed similar to the surface pressure on Earth, maintaining a partial pressure of about 14.7 pounds per square inch (psi), or 1 atmosphere. This environment contains approximately 79% nitrogen, 21% oxygen, and traces of other gases.

Space suits used around the ISS share this mixture. These suits are designed for extravehicular activities (EVAs). However, the pressure within these suits is significantly lower, acting more like an atmosphere that is invisible to the naked eye. This low-pressure system ensures that the suit can withstand the vacuum of space without being overly cumbersome.

The Vacuum of Space and Space Suit Dynamics

Interestingly, the pressure inside a space suit is not meant to be "pumped up" as one might imagine. Instead, it is the vacuum of space that ultimately exerts pressure on the suit. This pressure comes from all directions, pulling the suit inwards. The air added to the suit is a mixture of nitrogen and oxygen, which is much less pressurized than the Earth's atmosphere. This lower pressure is equivalent to being at around 5,000 feet above sea level.

Historical Context and Traditional Pressurization

Astrologists and space historians will remember that early space suits, such as those used during the Apollo missions, were pressurized to a partial pressure of oxygen similar to that in Earth's atmosphere, which was known to be 3.7 psi. This is quite different from today's space suit designs.

Current Space Suit Designs and Pressurization

Presently, the primary U.S. spacesuit, known as the Extravehicular Mobility Unit (EMU), operates at 4.3 PSIA (pounds per square inch absolute). The Russian Orlan suit operates under a pressure of 5.8 PSIA. Recent prototypes are designed to operate at 8 PSIA, ambitions that aim to eliminate or significantly reduce the need for a pre-donning pre-breathe period of pure oxygen at high pressure. This process, which currently takes hours, is a time-consuming and challenging aspect of space suit preparation.

The need for high-pressure pre-breathing is primarily to eliminate nitrogen from the astronaut's blood to prevent decompression sickness, a condition known as "the bends." However, the challenge of designing a suit that remains flexible at high pressure is significant. Imagine trying to fold a basketball in half; this is essentially what the engineers are trying to achieve with modern space suits.

Real-World Applications and Preparing for Spacewalks

When astronauts prepare for spacewalks on the ISS, they must follow a protocol that involves breathing pure oxygen for several hours before putting on the suit. This process, known as "pre-breathe," helps to remove nitrogen from their blood. As a result, the pressure inside the suit is reduced to around 4.5 to 5 pounds of pressure in pure oxygen. This approach makes the suit lighter and less cumbersome while ensuring that the astronauts have all the air they need to survive.

Conclusion

The pressure inside space suits is not a simple matter of atmospheric pressure from Earth. There are specific design considerations and operational protocols that make space travel possible. By understanding the complexities of space suit pressure, we can gain a deeper appreciation for the incredible work that astronauts do to explore the final frontier.