Distribution of Subsurface Water in the Sulfate‐Bearing Unit at Gale Crater, Mars, as Measured by the DAN Instrument on the Curiosity Rover

The Dynamic Albedo of Neutrons (DAN) instrument onboard the Curiosity rover has been used to study subsurface water distribution in the Canaima drill site region, where polyhydrated Mg sulfate (starkeyite) was identified in Martian soil for the first time. Multiple DAN measurements acquired in this local sulfate rich area (SRA) have shown unusually high concentrations of subsurface water. The distribution of subsurface water, likely bound in sulfate minerals, is heterogeneous both laterally and with depth. 60% of the surface area around the drill site can be characterized by a layered structure, with a more hydrated, sulfate rich layer (10–30 cm) above the material that is relatively dry. These straightforward calculations suggest that the total number of Mg‐sulfates in this 220 × 250 m area could be as high as 2,600 metric tons.