Halo around pole in Mars hydrogen map
One of the peculiar points in todays Mars Odyssey hydrogen data is the band of extremely low hydrogen data which surrounds the high data from the polar area.
This could be the result of some climatic effect concentrating hydrogen (water) in the polar area.
On the other hand, perhaps it is an artifact of Mars' weak magnetic field concentrating the gamma rays above the polar area.
It has been known that Mars has water, the question is how much. I don't know how deep below Mars' surface Odyssey's instruments can peer.
When do we get a carbon map for Mars?
EP