Possible Ancient Equator of Mars Revealed

A vast amount of evidence suggests that Mars used to be much warmer and wetter because water that did not evaporate at its surface went below, where it may still remain. A study shows that five basins may have been created by an asteroid that had once been orbiting around the sun. The 500-600 mile asteroid may have come too close to Mars, and been broken apart and sent to the Martian surface. The linear pattern with which the fragments struck aligns with the equator that would have been present on Mars at that time. It is believed that the present equator was the pole when those asteroid fragments struck Mars. So, the evidence of the past equator as left by these asteroid bits, gives more evidence as to where the pole was back then, which is where water would have been, and may still be stored in the subsurface!

http://www.space.com/scienceastronomy/050418_mars_equator.html