If carbon dioxide froze into dry ice at the north pole of Mars, why did water freeze at the south pole?
There is frozen carbon dioxide and sub surface ice at both polar regions on Mars. Due to seasonal variations at Mars, the carbon dioxide will shrink at the northern pole and grow at the southern pole. There is sub surface ice at both poles on mars. We are unable to detect as much water at the northern polar region due to the thickness of the carbon dioxide ice. We expect to be able to see more sub surface ice in the northern polar region over the next year.
