The apparent void of space is actually awash in high-energy particle radiation, which can have just as harmful an effect on delicate satellite components as it does on living tissue. The threat to spacecraft varies greatly based on their orbits. Ali Zadeh, head of ESA’s Components Space Evaluation and Radiation Effects section explains how electrical, electronic and electro-mechanical (EEE) components – the fundamental building blocks of any space mission – are tested for this harsh environment, assessing their suitability for space. The Agency’s ESTEC technical centre in Noordwijk, the Netherlands, hosts a Cobalt-60 irradiation facility for highly-penetrating gamma ray testing, supplemented by a network of external European particle accelerator sites for electron, proton and heavy-ion radiation testing.