What do you know about pressure suits?

July 31, 2003

Felix Baumgartner jumps off a plane above Dover, England and lands in Cap Blanc-Nez near Calais, France covering a distance of 35 km in less than 14 minutes. In the process, he becomes the first person to achieve unpowered flight across the English Channel.

Felix pulled off the stunt by wearing an aerodynamic jumpsuit with 6-foot carbon-fibre wings across his back, which enabled him to glide.

When he broke the sound barrier without vehicular power on October 14, 2012, Baumgartner was fitted with a full-pressure suit and helmet, which served as his life support system through the jump. The suit used for this project might soon serve as a prototype for explorers of the next generation.

Whether it be for such daredevil acts or for survival in outer space, the protective suits that are worn have become indispensable. Before we look into how these suits offer us protection, it might do us good if we understand the hazards to which we might be exposed to.

Extremely hostile

Let us take the case of an astronaut performing an extra-vehicular activity. Lack of oxygen could lead to unconsciousness in a matter of seconds. Sunlight temperatures of around 120 degree Celsius that can go down up to -100 degree Celsius in the shade clearly denotes extreme conditions. Being well beyond the Earth’s atmosphere, it also implies direct exposure to harmful radiation.

Then there is “ebullism”, a condition wherein low surrounding pressure could lead bodily fluids to turn into gas and expand dangerously. And if all this were not enough, there is space debris. Floating around in space, even dust sized particles travel at such high speeds that they can knock out the astronaut on minimal impact, and might even prove fatal otherwise.

Feels like home

Given these, it becomes obvious that the role of these suits is to protect the person inside from these dangers by providing an Earth-like environment within the suit itself, while at the same time not compromise on the movements and activities that the individual can perform.

As the name suggests, pressure suits help maintain the air pressure so fluids in the tissues remain in liquid state. A rubberised fabric restricts the suit that is inflated like a balloon, analogous to air inside a tyre.

We know that as we move away from the sea level, pressure keeps dropping, prompting us to carry oxygen cylinders even while out on an expedition to, say, Mt. Everest. This shows that these suits surely can’t use normal air, as the low pressure would cause oxygen levels in our blood and lungs to go to perilously low levels. So while these suits provide pure oxygen atmosphere for breathing, it becomes necessary to pre-breathe pure oxygen before suiting up in order to eliminate any risks involved.

Now that we know how the need for oxygen is tackled, how the carbon dioxide exhaled is treated becomes a natural follow up. Space suits usually have lithium hydroxide canisters that remove the carbon dioxide which an astronaut breathes out.

Reflective outer layers of fabric along with layers of insulation providing materials are used in tandem to cope with temperature changes. These multiple layers of fabric also afford some sort of armour against space debris, but only limited protection when it comes to radiation.

Special joints in the fabric to aid movements and helmets that help visibility are the last part of the jigsaw puzzle. Makes it clear that much deliberation and practice goes into making every move while out in space, or when in a free fall.

ganesh.a.s@thehindu.co.in