Water in the history of Mars: An assessment

This paper presents a review of recent literature concerning issues related to the origin of water in planet Mars and its role in the geologic evolution of that planet. The baseline case of our discussion is the Grand Tack model of planetary migration in the solar nebula and an early planetary orbital instability according to the Nice Model. This discussion also benefits from a comparison with the Earth's accretional history. Recent observations are used to check the results of planetary accretion models, leading to a new picture of the early history of water on planet Mars. The embryo forming the basis of the planet is found to have been very deficient in water. During the following period, predating the formation of the Earth's Moon, the accreted water may have been as high as similar to 5 km Global Equivalent Layer (GEL) while the amount accreted at later times may have been as low as similar to 10 m GEL according to recent studies. In particular, the trans-planetary source was insignificant, at whatever time it was active. The proposed resurfacing event creating the Borealis basin could have been important for the loss of a significant part of the early Martian water inventory.