Asteroid impacts on Mars created underground cracks in the ground that filled with water and might have been the perfect hiding place for Martian life, according to scientists at Brown University, USA.
Lee Saper and Jack Mustard studied 4,000 ridges in two cratered regions of Mars – Nili Fossae and Nilosyrtis. They surmise that the ridges formed when the cracks were filled with subsurface water carrying minerals that were then deposited within the underground cracks. The mineral deposits would have been harder than the surrounding rock, so after the water dried up wind erosion weathered the rock but left the deposits, which today form ridges on the ground.
The ridges are orientated in radial fashion away from the impact craters, which suggests that they formed during the impact and are not a result of, for example, volcanic magma. In addition, the ground around the cracks is rich in iron-magnesium clay, which could only have formed in flowing, liquid water.
“The association with these hydrated materials suggests there was a water source available,” says Saper. “That water would have flowed along the path of least resistance, which in this case would have been these fracture conduits.”
While much of the previous exploration of Mars has focused on evidence for liquid water having once flowed on the surface, these findings are particularly exciting because they suggest a new environment in which to look for evidence of past life on Mars.