pt en es
Radiation in space and within the Earth's atmosphere

Dr Patrícia Gonçalves, PhD

In interplanetary space in the Solar System the radiation population consists of: solar X-rays, Solar Event Protons (SEP) and alpha particles, solar event electrons, Jovian electrons, Galactic Cosmic Rays (GCR) and galactic X-rays and gamma-rays. In Earth orbits the radiation belts containing trapped electrons and protons constitute the major radiation source. In space, the radiation environment is responsible for spacecraft system, sub-system and component hazard and damage and it is also responsible by strict constrains on human space exploration.

At Earth's surface, the atmosphere in conjunction with the geomagnetic field provides considerable protection against both cosmic rays and solar particle events. However the protective layer of the atmosphere is reduced to about one third at normal subsonic cruising altitudes and to one tenth at supersonic altitudes leading to background radiation levels that are 300 to 1,000 times higher than at sea level.

Several studies and measurements have, in recent years, readdressed the problem of radiation exposure in air craft due to the susceptibility of modern microelectronics to single event effects (SEE), from neutrons and protons, and to the realisation of the need to restrict dose to aircrew and frequent flyers.  The former problem resulted in the generation of standards for avionics and terrestrial electronics, while the latter has led to the adoption of legislation within Europe and elsewhere requiring the monitoring and limitation of dose. In this presentation the subject of radiation environment in Space and inside Earth’s atmosphere at cruise altitudes will be described and current standards will be presented and discussed.