Despite its crucial role in biological and geological processes, information about water on Mars is still controversial. In addition previous geochemical studies of Martian basalts (shergottites) have raised unsettled questions over the sources of the parental magmas.
The researchers studied two meteorites that provide different samples from the Martian mantle and crust. "There are several competing theories that account for the diverse isotopic and geochemical compositions of Martian meteorites," said Tomohiro Usui, a former NASA/LPI post-doctoral fellow who led the research. "Until this investigation there was no direct evidence that primitive Martian lavas contained material from the surface of Mars."
The researchers also report direct evidence that the dry Martian mantle retains a primordial ratio of hydrogen and its heavier isotope deuterium that is similar to the ratio in water on earth. This further implies that terrestrial planets including earth have similar water sources, which are chondritic meteorites, and not comets.
