For years, scientists have claimed evidence supporting the existence of water on the Martian surface at some point in the distant past (or even in the not so distant past). However, researchers at the Carnegie Institute for Science think they may have detected vast reservoirs of water underneath the Martian surface.
At least they think they have evidence that it existed at some point: "There has been substantial evidence for the presence of liquid water at the Martian surface for some time," Erik Hauri, an investigator at Carnegie, said in a statement by the institution. "So it's been puzzling why previous estimates for the planet's interior have been so dry. This new research makes sense and suggests that volcanoes may have been the primary vehicle for getting water to the surface."
The paper makes no claim as to where these vast reservoirs of water are now, or even if they are still on Mars, but does point to an Earth-like amount of subsurface water being present early in Mars' evolution.
Researchers studying the chemical content of two meteorites determined to have broken off from Mars some 2.5 million years ago before finding their way to Earth have found evidence of water present during the planet's formation. It's believed these particular samples originally formed in the Martian mantle (the semi-solid layer below the hard outer crust), but then crystallized in the shallow subsurface and on the surface.
Analysis of the mineral apatite within the samples has found 70-300 parts per million (ppm) water. Compare this to samples of Earth's upper mantle which have 50-300 ppm water.
"The results suggest that water was incorporated during the formation of Mars," claims Carnegie Institution investigator Erik Hauri in a University PR release "and that the planet was able to store water in its interior during the planet's differentiation."
This discovery is potentially important for two reasons: 1) If these findings are confirmed, this could mean that some form of Martian life could have existed, or potentially may still exists today somewhere on ol' Redface and 2) should humans visit Mars one day, they may have a source for life-sustaining H2O.