The Universe and Galaxies: Human Beings in Space

Discovery Space: Human Beings in Space

Space is an unfamiliar and extremely dangerous environment for human beings. People are only able to create environments for living and working in space with extensive technical support.

An unprotected person in space would be exposed to an environment that is airless and a near vacuum. Without the pressure and warmth of the Earth’s atmosphere, bodily tissues would quickly suffer serious damage; the person would soon lose consciousness and die. In addition, temperature variations are extreme because the sun’s radiation is not blocked in space.

Surfaces in the inner solar system can reach more than 248°F (120°C) under direct solar radiation, while temperatures in the shade fall below -148°F (-100°C). Therefore manned spacecraft, space stations, and space suits require sophisticated life-support systems.

Life-support systems

In order to protect humans in space, support systems must supply air, water, food, and energy; regulate temperature and pressure; and provide bodily hygiene. Oxygen may be stored in liquid or gaseous form, or produced as required through the electrolysis of water recycled on board—for example, from washing water or urine.

Nitrogen is added to the oxygen to provide Earthlike air for breathing, and the carbon dioxide breathed out by space travelers is removed from the air using special chemicals. The electricity used in space generally comes from solar cells, fuel cells, or batteries. In future bases on the moon or Mars, greenhouses and artificial ecosystems may play an important role.


On Earth, gravity gives us a sense of “up and down.” However, in space, astronauts experience weightlessness, which disturbs the balance organs of the inner ear. At the beginning of a space mission, this can lead to “Space Sickness,” Causing dizziness, nausea, headaches, and vomiting. After an adjustment period, astronauts usually learn to control their sense of orientation in space and these problems recede.

During longer periods of weightlessness, bone and muscle mass decline and the body’s blood volume is reduced; however, these effects can be partially counteracted through exercise. By studying these symptoms in astronauts, scientists hope to gain insight into similar medical conditions on Earth. After returning from a mission, astronauts are usually able to regain their previous, normal physical state.


Space suits made of numerous layers of textiles and artificial materials provide breathable air and protect astronauts from the near vacuum of space.

The inner suit is lined with water tubes that help cool the body. Next come gas-impermeable layers. The outer layers are fireproof and rein- forced against tearing.


SPACE TRAVELERS are variously known as astronauts (if American or European), cosmonauts (if Russian), ortaikonauts (if Chinese).

DURING A SPACE MISSION, astronauts are responsible for carrying out a wide range of scientific and technical experiments, as well as the day-to-day running of the spacecraft.