Since the Apollo missions, human spaceflight has been advocated as a means of promoting positive attitudes towards science. In 2015, Principia launched Britain's first government-funded astronaut to the International Space Station, a core objective being education and inspiring young people. In this study, we examined how spaceflight education policy was enacted during the Principia mission, found out the ways in which young people encountered space, and how these encounters shaped their attitudes. Semi-structured interviews were conducted with 102 children and analysed through the construction of an actor-network. Young people encountered space through formal education in school as well as through non-formal encounters with family, friends, media and social media. Social media influences were associated with forming positive attitudes, whereas friends and teachers were associated with both positive and negative attitudes. The human dimension of spaceflight was important in young people encountering space but was not sufficient to stimulate sustained interest in space: children and young people wanted to know more about the science of human spaceflight. Young people confused science with science fiction. In some schools, young people became 'spaced out' by saturation of the curriculum with space. The findings have implications for policymakers and practitioners. The scientific stories associated with human spaceflight need greater attention. Social media could be used to greater effect in communicating science directly to young people. Non-formal education initiatives must be designed to align with teachers' objectives, and there needs to be recognition and reward of teachers' time and contributions.