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Airline crews flying long-distance high-altitude routes can be exposed to 2.2 mSv of extra radiation each year due to cosmic rays, nearly doubling their total exposure to ionizing radiation. Average annual radiation exposure ( millisieverts )
Material shielding can be effective against galactic cosmic rays, but thin shielding may actually make the problem worse for some of the higher energy rays, because of the increased amount of secondary radiation. [34] The aluminium walls of the ISS, for example, are believed to produce a net reduction in radiation exposure.
Orion's orientation during flight affected radiation exposure, which dropped by half when the spacecraft made a 90-degree turn flying past the inner Van Allen belt.
Radiation has also recently been linked to a higher incidence of cataracts in astronauts. Outside the protection of low Earth orbit, galactic cosmic rays present further challenges to human spaceflight, [45] as the health threat from cosmic rays significantly increases the chances of cancer over a decade or more of exposure. [46]
However, the heavy ion component of space radiation presents distinct biophysical challenges to cells and tissues as compared to the physical challenges that are presented by terrestrial forms of radiation. Soon after the discovery of cosmic rays, the concern for CNS risks originated with the prediction of the light flash phenomenon from single ...
Flying 12 km (39,000 ft) high, passengers and crews of jet airliners are exposed to at least 10 times the cosmic ray dose that people at sea level receive. Every few years, a geomagnetic storm permits a solar particle event to penetrate down to jetliner altitudes. Aircraft flying polar routes near the geomagnetic poles are at particular risk.
Flight-time equivalent dose (FED) is an informal unit of measurement of ionizing radiation exposure. Expressed in units of flight-time (i.e., flight-seconds, flight-minutes, flight-hours), one unit of flight-time is approximately equivalent to the radiological dose received during the same unit of time spent in an airliner at cruising altitude.
Once above the atmosphere, radiation due to the Van Allen belts, solar radiation and cosmic radiation issues occur and increase. Further away from the Earth, solar flares can give a fatal radiation dose in minutes, and the health threat from cosmic radiation significantly increases the chances of cancer over a decade exposure or more. [29]