Van Allen Belts - Discovery

The inner belt was first discover in January 1958 by the US satellite Explorer 1 (designed originally to detect and study the intensity of cosmic rays from greater distances than could be measured from earth) using a Geiger counter. The existence of this belt was later confirmed by similar instruments on board the US satellite explorer 3 and the Russian satellite Sputnik 3 later that year.

The outer belt was first discovered in December 1958, also using a Geiger counter. This was discovered by Pioneer 3 (although Russian scientists working on data collected by Sputniks 2 and 3 claimed to have detected evidence of this second radiation belt prior to this).

The Primary mission of the Pioneer 3 probe was a lunar fly-by, but due to a fuel cut-out in the spacecraft’s main engine, the probe only managed to reach an altitude of 102,360km, this caused the probe to fall back to earth and burn up. However before burning up the probe’s Geiger counters provided important data that allowed Van Allen’s team to detect the existence of this second, outer belt. This was then confirmed by instruments on board the US probe, Pioneer 4 the following year.

Explorer 3