Table of Contents

A Life-preserving Suit

Environments harmful to humans

The human body is a complex and fragile machine. Favourable environmental conditions are essential for humans to survive. Such an environment is rich in oxygen, and has prevailing temperatures of around 22 °C. Its atmospheric pressure is close to 100 kPa, and the level of harmful radiation is low. All these conditions are not necessarily easy to meet at the same time. As a result, many environments, even on Earth, could not support life without artificial means of protection.

Let’s take water, for example. In order to breathe under water, we need sophisticated diving equipment that provides us with air at an ambient pressure. In addition, despite using such equipment, we cannot continue diving indefinitely because of the increased risk of nitrogen saturation due to the increased pressure towhich our body is exposed.

Even where sufficient air exists, problems can arise if it is not consistently renewed. In closed environments, the carbon dioxide we exhale gradually replaces the oxygen, which can be fatal.

Our body is made to live in an environment where the pressure does not vary much from that observed at sea level. In a complete void (imagine a place where all gases have been removed), there is no pressure to keep body fluids in their liquid state. Under these conditions, they would literally begin to boil and would finally evaporate.

We are also very sensitive to temperature and our body does not tolerate a very large temperature range. Prolonged and unprotected exposure to temperatures from 12 to 15 °C can cause hypothermia (a dangerous drop in normal body temperature) and, in contrast, heatstroke can occur from 40 °C.

The atmosphere also protects us against the effects of harmful radiation (ultraviolet rays, microwaves, gamma rays and X rays). In instances and in places (like space) where the Earth’s atmosphere is unable to protect us we must turn to technology to create a suitable environment for life.

Reproducing an Environment Suitable for Humans

The space shuttle and the International Space Station reproduce living conditions, which, while not identical to those on Earth, are still acceptable for missions lasting from a few days to a few months. The air, which is recycled mechanically, is rich in oxygen and the pressure is similar to that found at sea level. Astronauts can therefore move about without auxiliary systems.

Astronauts must sometimes leave the shuttle or space station to perform duties outside, in the void of space. In such cases, a sophisticated suit is required to protect them from the hostile environment of space. An orbiter is a complex machine. At twelve million dollars apiece, so is the spacesuit, since it is truly a small, human-size spacecraft that attempts to reproduce a viable environment for astronauts.

• Functions of the Spacesuit