Water on/in Mars and the Moon

Abstract The speculation of an ancient ocean, river and lake on Mars, the observation of geological features andthe findings of H2O on the Martian surface, and the detection of a “water lake” beneath 1.5 km in Mars are all consistent with the scenario of water envisaged earlier by Liu (Phys Earth Planet Inter 49: 142–167, 1987; Icarus 74: 98–107, 1988). Unless sealed in cavities, liquid water or naked ice should not survive on the Martian surface. These materials cannot possibly exist on the lunar surface either, regardless of the recent claims made by space missions to the Moon, because the lunar mass is even much smaller than Mars. Both the disappearance of the Martian ancient ocean and the scarceness of the findings in the space missions manifest that water and ice are not physically stable on the surface of Mars and the Moon. Otherwise, significant amounts of water and/or ice should have had been accumulated during the long history of these planets. Depending on the origin, the Moon may or may not contain ordinary hydrous minerals. Whether a volatile can stably exist on the surface of a planet, in either liquid or solid, depends on whether the volatile can exist as a component of the planet’s atmosphere.