Earth Planet. Sci. Lett.http://doi.org/mjf (2013)

Credit: © NASA

Compared with basalts on Earth, most basaltic meteorites from Mars contain little water, but it is unclear whether this reflects a lack of water in the martian mantle or the release of volatiles from the rocks when they were erupted to the surface. Analyses of mineral grains in a martian meteorite suggest that the mantles of Mars and Earth may indeed be similarly wet.

Juliane Gross at the American Museum of Natural History and colleagues analysed the composition of the hydrous mineral apatite in the martian meteorite NWA 6234. The basalt in this meteorite did not experience degassing, so if any volatiles were present in the magma, they should still be contained in the rock. The apatite grains they analysed contained the highest contents of volatiles measured in martian meteorites to date. Furthermore, NWA 6234 contains similar ratios of the measured volatiles to those of terrestrial basalts. The findings suggest that the volatile content of the martian mantle is similar to that of terrestrial mid-ocean ridge basalts.

A wet martian interior could have fed an active hydrological cycle and is consistent with growing evidence from orbiter and lander missions for water on the surface of Mars.