Paleomagnetism has played a pivotal role in developing our modern understanding of the Earth, and remains one of the primary tools used to study the structure and dynamics of the Earth and other planets. However, some of the most interesting and controversial periods of Earth’s history occur far beyond the current limits of our confidence in the paleomagnetic signals used to study them. NanoPaleoMag will solve this problem by dramatically increasing the range of materials that are suitable for paleomagnetic study, thereby opening up periods of Earth history that have hitherto defied conventional paleomagnetic analysis.Rocks are chemically, mineralogically, texturally and magnetically heterogeneous materials, with heterogeneity occuring at all length scales – from metres to nanometres. There is a pressing need to push the spatial resolution of paleomagnetic studies beyond their current limits and to extend the analysis into 3D. Adopting cutting-edge techniques from physics and materials science, NanoPaleoMag will perform paleomagnetic measurements at submicron length scales. 3D measurements of the volume, shape and spacing of all magnetic particles within a microscale region of interest will be made using a focused ion beam workstation. Combined with high-resolution paleomagnetic measurements and nanometre/nanosecond electron/X-ray magnetic imaging, NanoPaleoMag will characterise the magnetic properties of geological materials at fundamental length scales and time scales. Sample-return missions to asteroids, comets, moons and planets will soon provide unprecedented opportunities for extraterrestrial paleomagnetism. NanoPaleoMag will provide the methodology and instrumentation needed to analyse these precious materials.