BepiColombo has a larger and in many ways more capable suite of instruments relevant for determination of the topographic, physical, chemical and mineralogical properties of Mercury’s surface than the suite carried by NASA’s MESSENGER spacecraft. Moreover, BepiColombo’s data rate is substantially higher. This equips it to confirm, elaborate upon, and go beyond many of MESSENGER’s remarkable achievements. Furthermore, the geometry of BepiColombo’s orbital science campaign, beginning in 2026, will enable it to make uniformly resolved observations of both northern and southern hemispheres. This will offer more detailed and complete imaging and topographic mapping, element mapping with better sensitivity and improved spatial resolution, and totally new mineralogical mapping.We discuss MESSENGER data in the context of preparing for BepiColombo, and describe the contributions that we expect BepiColombo to make towards increased knowledge and understanding of Mercury’s surface and its composition. Much current work, including analysis of analogue materials, is directed towards better preparing ourselves to understand what BepiColombo might reveal. Some of MESSENGER’s more remarkable observations were obtained under unique or extreme conditions. BepiColombo should be able to confirm the validity of these observations and reveal the extent to which they are representative of the planet as a whole. It will also make new observations to clarify geological processes governing and reflecting crustal origin and evolution.We anticipate that the insights gained into Mercury’s geological history and its current space weathering environment will enable us to better understand the relationships of surface chemistry, morphologies and structures with the composition of crustal types, including the nature and mobility of volatile species. This will enable estimation of the composition of the mantle from which the crust was derived, and lead to tighter constraints on models for Mercury’s origin including the nature and original heliocentric distance of the material from which it formed.

The Hokusai (H05) quadrangle is in Mercury’s northern mid-latitudes (0–90°E, 22.5–65°N) and covers almost 5 million km², or 6.5%, of the planet’s surface. We have used data from the MESSENGER spacecraft to make the first geological map of H05. Linework was digitized at 1:400,000-scale for final presentation at 1:3,000,000-scale, mainly using a ∼166 m/pixel monochrome basemap. Three major photogeologic units of regional extent were mapped: intercrater, intermediate, and smooth plains. Materials of craters ≥ 20 km in diameter were classified according to their degradation state. Two classification schemes were employed in parallel, one with three classes and the other with five classes, for compatibility with existing MESSENGER-era quadrangle maps and the first global geologic map. This map will provide science context and targets for the ESA-JAXA BepiColombo mission to Mercury.

The smooth plains on the floor of Mercury's Caloris basin and those almost entirely surrounding it beyond its rim are usually accepted to be younger than the rim materials and to be lava flows rather than impact melt. High‐resolution imaging shows that the emplacement of interior and exterior plains was concurrent, with evidence of both inward and outward flow while they were being emplaced. The Caloris rim is breached in two places by continuous smooth plains that seamlessly connect interior and exterior plains. The gross‐scale spectral and compositional distinctiveness of interior and exterior plains is blurred on a scale of several tens of kilometers, which could reflect interfingering of flow units less than a few hundred kilometers long that tapped melt sources of different composition and/or depth inside and outside the basin followed by local mixing of regolith. Flows occurring both inside and outside the basin should be included in estimates of the total erupted volume.

MESSENGER mission data allowed the entire surface of Mercury to be mapped at various spatial scales, from both geological and compositional stand points. Here, we present a spectral analysis of the H05‐Hokusai quadrangle, using data acquired by the MESSENGER Mercury Dual Imaging System‐Wide Angle Camera. We defined a suitable set of parameters, such as reflectance and spectral slopes, to study the spectral variation though the definition of spectral units. The determination of spectral units permits to infer the physical and compositional properties of a surface by processing several parameters simultaneously, instead of the more traditional approach of interpreting each single parameter separately. We identified 11 spectral units within H05, six large scale and five localized units. The large scale units include the northern smooth plains of Borealis Planitia. South‐western H05 is characterized by two widespread spectral units, partially overlapping intercrater plains and intermediate plains. Furthermore, we found very localized spectral units corresponding to the low‐reflectance blue material of Rachmaninoff basin and the high‐reflectance red material of Nathair Facula. We investigated the link between spectral units and compositional maps obtained by GRS and XRS, to associate compositional information to the spectral units. We found some spectral units are correlated with Mg and Al variations displayed in the elemental maps. This implies that spectral variations associated to these units are mainly linked with composition rather than terrain maturity and/or grain size effects.