| Radiation belts, or Van Allen radiation belts, are located
within the magnetosphere and thus, outside the Earth's
'atmosphere.
(picture 1) They consist
of electrons
and ions
(mainly protons)
(picture 2) of very high
energy, whose movements around the Earth are strongly
constrained by the terrestrial. (video
1)
The radiation belts (picture 3)
were discovered at the end of the fifties by James Van
Allen, using a
Geiger counter installed on board of the first American
satellite, Explorer I. The team of Van Allen observed
that the signal of the counter initially increased gradually
to fall then brutally to zero: in fact, the satellite
went through an area where radiations were so high that
the capacity of the Geiger counter was exceeded and
the counter saturated.
The particles of the Van Allen radiation belts (picture
4) are the main cause of radiations to which satellites
are submitted.
 Magnetic axis |
| Rotation axis |
They are among others at the origin of the deterioration
of certain satellite components (such as the solar panels),
disturbing electronics and the appearance of electric
discharges between various parts of the satellite.
|
