An article published in the journal “Proceedings of the National Academy of Sciences (PNAS)” reports the results of an analysis of seismic data collected on the planet Mars by NASA’s InSight lander that concludes that the mid-crust of Mars could be filled with liquid water that saturates a layer of igneous rock. Vashan Wright and Matthias Morzfeld of the Scripps Institution of Oceanography and Michael Manga of the University of Berkeley used models similar to those used to map aquifers and oil fields to try to understand the composition of deep layers of the Martian subsurface.

The best explanation for the data collected by the InSight mission is that between 11.5 and 20 kilometers deep there’s a layer of igneous rock saturated with liquid water. The depth makes it impossible to reach it but if the entire mid-crust of Mars were made like this, there would be enough water to form an ocean between one and two kilometers deep on the surface.