Analysis of Gravity Potential Along Paleo-shorelines on Mars: Implications for Ocean on Very Early Mars

Analysis of gravity potential along the paleo-shorelines identified by Clifford and Parker (Icarus, 2001) suggests that the ocean was present before Tharsis rise formed. This interpretation is consistent with mineralogy inferred from data of the infrared mapping spectrometer OMEGA onboard MarsExpress. The volume of the ocean has been calculated and would represent 3 10-5 MMars, a value consistent with the idea that the amount of volatiles would come from the outgassing of the magma ocean. Estimates of the formation of Tharsis rise suggest that the ocean was stable during less than 100 My, a period during which the Sun was active in UV and would have favoured atmospheric escape. If confirmed by future missions, the existence of oceans on very early Mars has implication on the development of life and the likelihood of finding ancient life on the red planet.