The scale of groundwater upwelling on Mars, as well as its relation to sedimentary systems, remains an ongoing debate. Several deep craters (basins) in the northern equatorial regions show compelling signs that large amounts of water once existed on Mars at a planet‐wide scale. The presence of water‐formed features, including fluvial Gilbert and sapping deltas fed by sapping valleys, constitute strong evidence of groundwater upwelling resulting in long term standing bodies of water inside the basins. Terrestrial field evidence shows that sapping valleys can occur in basalt bedrock and not only in unconsolidated sediments. A hypothesis that considers the elevation differences between the observed morphologies and the assumed basal groundwater level is presented and described as the “dike‐confined water” model, already present on Earth and introduced for the first time in the Martian geological literature. Only the deepest basins considered in this study, those with bases deeper than −4000 m in elevation below the Mars datum, intercepted the water‐saturated zone and exhibit evidence of groundwater fluctuations. The discovery of these groundwater discharge sites on a planet‐wide scale strongly suggests a link between the putative Martian ocean and various configurations of sedimentary deposits that were formed as a result of groundwater fluctuations during the Hesperian period. This newly recognized evidence of water‐formed features significantly increases the chance that biosignatures could be buried in the sediment. These deep basins (groundwater‐fed lakes) will be of interest to future exploration missions as they might provide evidence of geological conditions suitable for life.

Prior to the arrival of the Dawn spacecraft at Ceres, the dwarf planet was anticipated to be ice‐rich. Searches for morphological features related to ice have been ongoing during Dawn's mission at Ceres. Here we report the identification of pitted terrains associated with fresh Cerean impact craters. The Cerean pitted terrains exhibit strong morphological similarities to pitted materials previously identified on Mars (where ice is implicated in pit development) and Vesta (where the presence of ice is debated). We employ numerical models to investigate the formation of pitted materials on Ceres and discuss the relative importance of water ice and other volatiles in pit development there. We conclude that water ice likely plays an important role in pit development on Ceres. Similar pitted terrains may be common in the asteroid belt and may be of interest to future missions motivated by both astrobiology and in situ resource utilization.

Before acquiring highest-resolution data of Ceres, questions remained about the emplacement mechanism and source of Occator crater’s bright faculae. Here we report that brine effusion emplaced the faculae in a brine-limited, impact-induced hydrothermal system. Impact-derived fracturing enabled brines to reach the surface. The central faculae, Cerealia and Pasola Facula, postdate the central pit, and were primarily sourced from an impact-induced melt chamber, with some contribution from a deeper, pre-existing brine reservoir. Vinalia Faculae, in the crater floor, were sourced from the laterally extensive deep reservoir only. Vinalia Faculae are comparatively thinner and display greater ballistic emplacement than the central faculae because the deep reservoir brines took a longer path to the surface and contained more gas than the shallower impact-induced melt chamber brines. Impact-derived fractures providing conduits, and mixing of impact-induced melt with deeper endogenic brines, could also allow oceanic material to reach the surfaces of other large icy bodies.