What is radiation?

Wave radiationExamples of this type of radiation are around us all the time. You are using it now to read this page, as light is a form of wave radiation. When you listen to the radio, the signal comes via radio waves; when you heat a meal in a microwave oven you are using wave radiation; to become suntanned you expose yourself to wave radiation; if you need an X-ray you expose yourself to wave radiation.

Particle radiation is around us all the time but it is harder to notice than wave radiation. The most common type of particle radiation comes from radioactive atoms. Almost everything is radioactive to some extent: rocks, soil, plants, animals and YOU.

Should we duck?The most energetic cosmic rays are dangerous because they are ionising radiation. Fortunately, on Earth we have two very effective lines of defence: the Earth’s magnetic field and its atmosphere.

Astronauts and cosmonauts who visit the International Space Station (ISS) orbit the Earth at an altitude of around 400 km and so are not protected by the Earth’s atmosphere. In fact, at one point in its orbit around the Earth, just off the eastern coast of South America, the ISS passes through the tip of the inner Van Allen Belt.At this point, the radiation levels around the ISS increase by a factor of about 30. In just one week on the ISS, astronauts are exposed to the equivalent of one year’s exposure on the ground.

International Space Station

Becoming an astronaut is neither simple nor straightforward; there are no schools for astronauts or university courses. So how do you become an astronaut and what qualifications and qualities do you need?