On Thu, 29 Jan 2004 19:32:15 -0600, "Paul F. Dietz"
wrote:

Cardman wrote:

That would be nice had they understood the nature of the environment,
but the soil is a big unknown, where the much more studied atmosphere
is capable of the more than a few surprises.

Unless you have an explanation of how there can be so much detected
water in the few meters of top soil, despite the low pressure problem,
then there is more than one possible explanation.

They detected *ice* in the top few meters of soil. Not liquid water.

No. Odyssey can only detect hydrogen, which is *assumed* (to a high
degree) to be due to water. These findings do not say one way or the
other if this is water ice, liquid water or the long shot of hydrogen
in another form like within rocks.

The problem for you presented by the Odyssey data is that hydrogen
levels in water form detected in the top few meters of soil can be
anything up to 70% of the volume. That would be based upon liquid
water, when this same amount in ice form would take up even more of
the soil volume.

That would result in a pure sheet of water ice covered by a thin layer
of soil, which is a very unlikely possibility.

Since even warmer regions have like 30% and 50% water levels, then
scientist are still working out how there can be so much. Having
warmer water rising from below is one possible explanation.

Not my theory mind you, but of some scientist who has the
qualifications to back it up.

Water cannot exist there because the pressure is too low (over almost
all the Martian surface).

Pressure you refer to involves the atmosphere, where under the soil
you have a natural barrier allowing for different pressures in limited
forms. I would even suggest small pockets between the grains, but
there could well be whole caves and underground lakes there.

The low pressure does not preclude the existence of ice, as I have
already explained.

Except in the very top soil due to a combination of the atmospheric
pressure and heat, when quite correctly such water ice would quickly
evaporate into gas.

Ice water can only exist in the polar regions due to the very low
temperatures freezing it out of the atmosphere.

As you point out ice can exist in the top soil if the atmosphere
immediately above it has a 100% humidity level, but that simply is not
going to happen beyond extremely rapid evaporation lasting a very
short time before the local Martian weather disperses it.

In other words your explanation cannot match the Odyssey data, when
ice cannot exist in the top soil in the warmer regions for more than a
brief time.

Now, are we going to iterate this several dozen more times, or are
you going to try to think about what I said? I'll give you one
more chance before I right you off as a hopeless moron.

Except that your logic is flawed, where it also seems that you missed
that Odyssey detected hydrogen and the claimed water ice.

I look forwards to seeing the results from Mars Express over the
coming months, which will be looking for both liquid and iced water in
the top soil and all the way down to a few kilometers in depth.

I have a feeling that a lot of liquid water is going to be found,
maybe all the way up to just below the surface. That would explain
some of those recent Martian water features after all.

Cardman
http://www.cardman.com
http://www.cardman.co.uk