Soil Moisture at Meridiani

March 23, 2004

The latest pancams are in. At the very bottom of the center of the
crater, a few inches under the soil appears to be still moist. That
would be in line with what we are seeing in the larger craters, the very
flat bottoms, and evidence in the sand waves of standing water for a
short period of time after impact, or if you prefer, sinkhole slumping.

All over Mars you see the same thing, wherever there are sand waves in
the low spots where the land has slumped by water extraction, what you
have left over is dust, the glacial till of the muddy frozen ice sheets.

So I guess it could be decomposition by hydroxylation, rather than
dehydroxylation.

http://qt.exploratorium.edu/mars/opp...QP2404L7M1.JPG

Thomas Lee Elifritz
http://elifritz.members.atlantic.net

A headline lie, it's dry as a bone
Only signs of water, how many mega years ago?

On Tue, 23 Mar 2004, Thomas Lee Elifritz wrote:

The latest pancams are in. At the very bottom of the center of the
crater, a few inches under the soil appears to be still moist. That
would be in line with what we are seeing in the larger craters, the very
flat bottoms, and evidence in the sand waves of standing water for a
short period of time after impact, or if you prefer, sinkhole slumping.

All over Mars you see the same thing, wherever there are sand waves in
the low spots where the land has slumped by water extraction, what you
have left over is dust, the glacial till of the muddy frozen ice sheets.

So I guess it could be decomposition by hydroxylation, rather than
dehydroxylation.

http://qt.exploratorium.edu/mars/opp...QP2404L7M1.JPG

Thomas Lee Elifritz
http://elifritz.members.atlantic.net

William Elliot wrote in message ...
A headline lie, it's dry as a bone
Only signs of water, how many mega years ago?

Actually, there's substantial evidence that a sizeable
layer of burried perma-frost exists across much (perhaps
most) of Mars.

On Wed, 24 Mar 2004, Christopher M. Jones wrote:

William Elliot wrote in message ...
A headline lie, it's dry as a bone
Only signs of water, how many mega years ago?

Actually, there's substantial evidence that a sizeable
layer of burried perma-frost exists across much (perhaps
most) of Mars.

There's some evidence of perma-frost extending from the polar regions.
Meridiani is near the equator as is Gusev.

(Christopher M. Jones) wrote in message . com...
William Elliot wrote in message ...
A headline lie, it's dry as a bone
Only signs of water, how many mega years ago?

Actually, there's substantial evidence that a sizeable
layer of burried perma-frost exists across much (perhaps
most) of Mars.

I would correct you a bit. So that some waves of "water everywhere"
wouldn't think things are so simple and their flamegame opponents
wouldn't start another "War for the Worlds"

Note this is my IMHO. And please take it with a good grain of salt.
Better than hearing here those "ain't believe" or "and that means we
will go to Jupiter".

As the term permafrost may have a connection to a climate process,
common on Earth, I would first avoid a little bit using this term. But
that doesn't mean that permafrost processes aren't or weren't
occurring in Mars. However they are surely a fraction of the
hydrological processes that are happening there. No matter that most
water is presently frozen underground, their origins and nature cannot
be pointed only to a permafrost terming.

The underground water is mostly concentrated on the Polar regions and
above 40 latitude. However there is a assymetry on both hemispheres.
The water bearing regions are more harmonously spread in the North
plains. To the equator there are water bearing regions but they get
more scattered and localized over certain regions. Arabia is one of
them (a curious name if we count what is Arabia on Earth). Tharsis is
a region with a weird sign of water in certain places. But water does
not seem to be well spread there.

South Hemisphere is relatively poor on water, except on Hellas and
South Pole. Most of the surface of the hemisphere is of clear magmatic
origin so water had little chances to hold up underground. There are
spots, mainly around certain basins, but, generally, Mars is quite
draw here.

(Pedro Rosa) wrote in message . com...
The underground water is mostly concentrated on the Polar regions and
above 40 latitude.

This is an incorrect assumption based on incomplete
data. We know that the permafrost (or, if you like,
the high concentrations of underground Hydrogen, most
likely as H2O) extends some distance away from the
polar caps, but we do not yet know how far. The
data that points to this conclusion comes from the
Mars Odyssey Neutron Spectrometer, which measures
properties of the Martian surface only down to a
certain depth. We don't yet know how deep the
permafrost layers near the poles are and therefore we
do not know if there are permafrost layers deeper
than can be detected via the neutron spectrometer
below much of the rest of the surface of Mars.
There is a strong possibility that the permafrost
layers are deep, and that there exist permafrost
layers over most of the Martian surface with an
upper boundary at a depth corresponding to a
similar temperature as for the upper boundary of
the polar deposits (which would be deeper on
regions farther from the poles).

This is, of course, merely speculation, but the key
here is that the data we have is only a lower limit,
not an upper limit.

(Christopher M. Jones) wrote in message . com...
(Pedro Rosa) wrote in message . com...
The underground water is mostly concentrated on the Polar regions and
above 40 latitude.

This is an incorrect assumption based on incomplete
data. We know that the permafrost (or, if you like,
the high concentrations of underground Hydrogen, most
likely as H2O) extends some distance away from the
polar caps, but we do not yet know how far. The
data that points to this conclusion comes from the
Mars Odyssey Neutron Spectrometer, which measures
properties of the Martian surface only down to a
certain depth. We don't yet know how deep the
permafrost layers near the poles are and therefore we
do not know if there are permafrost layers deeper
than can be detected via the neutron spectrometer
below much of the rest of the surface of Mars.
There is a strong possibility that the permafrost
layers are deep, and that there exist permafrost
layers over most of the Martian surface with an
upper boundary at a depth corresponding to a
similar temperature as for the upper boundary of
the polar deposits (which would be deeper on
regions farther from the poles).

This is, of course, merely speculation, but the key
here is that the data we have is only a lower limit,
not an upper limit.

Myabe you have a point here. Still I didn't read the Odyssey's data on
that. I based my observations on the distribuion of streaks with a
clear signal that the agent is a fluid. Also I took into attention
data on the presence of water on the Polar caps.

Now I have a question. I made an assumption that water layers in
Arabia are mostly in a range 5-50 meters deep underground. Note that I
think they are mostly remnants of the surface water that once existed
in Mars, the density of the streaks suggests that. They are mostly
concentrated near the 5 meter level, going deeper due to local
specificities of the rocks or due to the presence of craters (in the
latter they may be a lot deeper). Can Odyssey sniff such level?

And note, as I said they are remnants. They can be only seen in some
regions and not in others. Janssen's crater is one of the biggest hot
spots for the presence of water. Maybe because that central crater
there seems quite recent.