The soil is 90% water in some places . . . But, here's the part that really caught my attention:
The Odyssey data are used to estimate the mass of the deposit, which can then be compared with the thickness to obtain a density. The dry ice layer appears to have a fluffy texture, like freshly fallen snow . . .
OK . . . if there wasn't adequate motivation to put humans on Mars, there certainly is now. Off to wax my snowboard . . .