Mars was covered in water just like the Earth The surface of mars The team then created bomb sags of their own, firing particles into grains the same size as those found by Spirit. They calculated that the speed the particles must have been moving to recreate the divot would have required an atmospheric pressure 20 times greater than that found today. This suggests Mars once had a thicker atmosphere, said prof Dufek. He said: "Atmospheric pressure has likely played a role in developing almost all Mars' surface features. The planet's climate, the physical state of water on its surface and the potential for life are all influenced by atmospheric conditions. Our study is consistent with growing research that early Mars was at least a transiently watery world with a much denser atmosphere than we see today. We were only able to study one bomb sag at one location on the Red Planet. We hope to do future tests on other samples based on observations by the next rover, Curiosity. An earlier study found gypsum on Mars - indicating there was once water on Mars and the possibility of life. Journal Science reports that the gypsum could only have been formed in water below 60 c and writes: "That means that conditions conducive to life once existed on the edge of the crater."