The European Space Agency ESA
The qoute about radiation in space and the Apollo project.
Beyond Earth’s magnetic field spacecraft and their occupants will be exposed to the full force of the GCR (Galactic Cosmic Rays) and the solar eruptions. Missions to the Moon and Mars will venture into this harsher and unpredictable radiation environment for periods of many month or even years.
During the Apollo missions of the 1960s–70s, the astronauts were simply lucky not to have been in space during a major solar eruption that would have flooded their spacecraft with deadly radiation. Essentially, they took risks and got away with it. For the kind of long-duration journeys being talked about today, a far more robust system of predicting radiation doses is required.
"The main uncertainties in these calculations are our knowledge of the space radiation environment beyond the Earth’s magnetic field, and the biological response to radiation," says Ersmark.
credits to ESA