Up at the top of the atmosphere the oxygen we breathe is replaced by highly reactive ‘atomic oxygen’ – created by high-energy ultraviolet splitting apart oxygen molecules into separate atoms. Low-orbiting space missions can be susceptible; the effect was first uncovered as early Space Shuttles returned to Earth with their thermal blankets eaten through. ESA’s Materials and Electrical Components Laboratory was tasked with investigating the resilience of ‘beta cloth’ fibre intended for ESA’s Aeolus wind-mapping mission. Testing took place using the Lab’s atomic oxygen generator, followed by microscopic inspection.