Humans are embarking on a new era of space exploration with the plan of sending crewed spacecraft to the Moon, Mars, and beyond. Extravehicular activities (EVAs) will be an essential part of the scientific activities to be carried out in these missions, and they will involve extensive geological fieldwork. These EVAs entail many challenges as real-time support from ground control cannot be provided to astronauts. Hence, new human–machine interfaces are urgently needed to enhance mission autonomy for astronauts and reduce ground communication dependability for real-time operations. This study introduces an Augmented Reality (AR) Internet of Things tool for astronauts to carry out geological activities. It proposes a theoretically-informed user-centred design method supported by expert feedback and an evaluation method. The tool was assessed via questionnaires and semi-structured interviews with European Space Agency (ESA) astronauts and geological field activities experts. Content analysis of the interviews revealed that user satisfaction was the first most mentioned (32% of 139 quotes) usability aspect. Key design factors identified were: displaying solely important information in the field of view while adjusting it to the user's visual acuity, easy usage, extensibility, and simplicity. User interaction was the second most mentioned (24% of 139 quotes) usability aspect, with voice seen as the most intuitive input. Finally, this research highlights important factors determining the usability and operational feasibility of an AR tool for analogue training missions and provides a foundation for future design iterations and an eventual integration of AR into the spacesuit's visor.