Much ice has been discovered poleward of 60 degrees in both hemispheres. Basically, after about a meter, the ground contains mostly ice in those locations. So, if you dug down a meter, a bucket of the dirt at the bottom would be over 50% ice.
The poles both contain about a km or two of ice. That area is about twice the size of AZ.
The minerals examined by the Rovers have been modified by water. But, much of the alteration could have been done from films of water that are only a few molecules thick. The reasoning is that at times the rotational axis of Mars changes. During that time, the water at the poles and in frozen in the ground poleward of 60 degrees melts. Much or most or all of it will turn into a gas, travel to a cold place (near the equator) and condense as frost. Durnng the thousands of years when this is taking place, huge amounts of ice will accumulate in certain areas. At times during the year, it will be warm enough for the water to melt and flow--that is when minerals can change or maybe a dormant life form will grow and reproduce. Of course a large meteorite could strike and melt the ice and form channels in the process. Alternatively, magma may move around and melt the deposits.
This is my understanding of the water question for Mars. In the past year of so a lot of good articles have appeared in journals--especially Nature and Science. On my website, I have about 100 links to information about Mars. In one section, I've listed sources for many articles.
http://paws.flcc.edu/~secoskjj
Isn't it a great time to be alive to learn about Mars.
Jim Secosky
]]>This weeks "Economist" gives an unvarnished account of what NASA has found that does not jibe at all with their heroically optimistic web articles.
The Economist says that so far NASA has found no signs of life (while admitting the rovers were not set up for that) and that at most, a thin film of very salty brine may have covered some large areas. The so-called sedimentation layers are more likely to have been produced by successive wind-born deposits of dust.
For more on this NASA salesmanship (for a maned mission), see: http://www.velocitypress.com/pages/water_on_mars.php]http://www.velocitypress.com/pages/water_on_mars.php
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