Why Don't Spacesuits Expand in the Vacuum of Space?

A common misconception about spacesuits is that they expand significantly in the vacuum of space. However, the reality is quite different. Spacesuits are designed to maintain a consistent internal pressure to protect astronauts during extravehicular activities (EVAs) and ensure their safety. Let’s delve into the details to understand why spacesuits don’t expand in the vacuum of space.

Pre-Pressurization and Launch

During launch, spacecraft are typically pressurized to a certain level to ensure the safety and comfort of the astronauts. This means that spacesuits worn during launch are already pressurized to a predetermined level, preventing them from expanding heavily even in the vacuum of space.

For example, the pressure inside the suit during launch is maintained at a similar level to the pressurized cabin of the spacecraft. Capsules, like the SpaceX Dragon, are pressurized during launch, and the suits worn during launch can be pressurized too, but they don’t have to be because the entire spacecraft is already pressurized. The suits are designed to adapt to the cabin pressure, and there is no significant change in pressure that would cause the suit to expand dramatically.

The Structure of the Spacesuit

The core of a spacesuit is an accordion-like structure designed to facilitate movement while providing an exoskeleton-like support. This structure ensures that the suit can flex and bend without losing its integrity under the pressurized conditions it experiences outside the spacecraft. The material layers in a spacesuit are strong and somewhat rigid, which helps to contain the pressure and prevent expansion.

Spacesuits are typically pressurized to approximately 4.3 PSI, which is equivalent to the pressure at an altitude of about 30,000 feet. This level of pressure is sufficient to protect the astronauts from the harsh conditions of space but is not so high that it would cause the suit to expand excessively. The design of the suit ensures that the internal pressure is balanced with the stretching force of the fabric, ensuring that the suit remains functional during EVAs.

Why Do They Sometimes Expand?

Although spacesuits are designed to prevent significant expansion, there can be instances where they do expand slightly. This occurs mainly due to the pressure difference between the internal pressure of the suit and the stretching force of the fabric. The suit is designed to be flexible and allow movement, but there is still a small amount of expansion that can occur under certain conditions.

One notable instance where spacesuits have expanded significantly is during the return to the airlock. In one famous incident, an astronaut named Piers Sellers needed to deflate his suit because his suit had expanded so much that he couldn't re-enter the airlock. This event highlights the rare but possible scenario where a suit can expand beyond its design limits.

Conclusion

In conclusion, spacesuits are designed to maintain a consistent internal pressure to ensure the safety and functionality of astronauts during EVAs. While the suits are pressurized to protect astronauts from vacuum conditions, they are constructed with rigid and flexible materials that contain the pressure and prevent significant expansion. Although there can be slight expansion under certain conditions, the design ensures that the suit remains functional and safe for the astronauts.