In 1958, the Explorer III satellite was launched with an onboard Geiger counter. The readings initially confused scientists because there were radiation spikes immediately followed by pockets of no radiation.
They discovered that the pockets of no radiation were because the Geiger counter was overloading due to the intensity of the radiation.
The famous quote from the mission was “SPACE IS RADIOACTIVE”
In future missions they could better estimate the radiation levels by surrounding the Geiger counter with radiation shielding.
Watch the above video if you haven’t yet. This information used to be much easier to find. I had to dig to find it.
AC