Posted to sci.aastro:

From: rgregoryclark@yahoo.com (Robert Clark)
Newsgroups: sci.astro,alt.sci.planetary,sci.physics,sci.geo.geology,sci.geo.mineralogy
Subject: Latest Mars Odyssey results suggest free water at equator on Mars.
NNTP-Posting-Host: 68.81.141.219

The post copied below was posted to the Space.com board
uplink.space.com in regards to a new paper that suggests clays may
explain the high levels of water detected by Mars Odyssey in some near
equatorial regions on Mars:

Stability of hydrous minerals on the martian surface.
David L. Bish, J. William Carey, David T. Vaniman and Steve J. Chipera
Los Alamos National Laboratory, Mail Stop D469, Los Alamos, NM 87545,
USA
Icarus, Volume 164, Issue 1, July 2003, Pages 96-103.
http://dx.doi.org/10.1016/S0019-1035(03)00140-4

A similar theory is proposed by Tetsuya Tokano:

Spatial inhomogeneity of the martian subsurface water distribution:
implication from a global water cycle model.
Tetsuya Tokano
DLR––Institut für Raumsimulation, 51170, Köln, Germany
Icarus, Volume 164, Issue 1, July 2003, Pages 50-78.
http://dx.doi.org/10.1016/S0019-1035(03)00105-2

Bob Clark

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exoscientist
07/19/03 04:09 AM
Re: Hydrous Minerals at Mid-latitudes of Mars

Thanks for the link. This might explain the variable amounts of
hydrogen dependent on season seen near the equator in the latest
Odyssey GRS reports:

Latest Odyssey results prove free water at equator.
exoscientist
06/27/03 11:24 AM
http://uplink.space.com/showflat.php?Cat=&Board=sciastro&Number=516193

This idea of clays on Mars containing water that could vary diurnally
according to day/night temperature fluctuations was also discussed in
reports by Bish et.al.:

WATER-BEARING MINERALS ON MARS: SOURCE OF OBSERVED MID-LATITUDE WATER?
D. L. Bish, J. W. Carey, C. Fialips, Mineralogy & Geochemistry, Los Alamos
National Laboratory, Mail Stop D469, Los
Alamos, NM 87545, b***@lanl.gov
Lunar and Planetary Science XXXIV (2003) 1786.pdf
http://www.lpi.usra.edu/meetings/lpsc2003/pdf/1786.pdf

CAN HYDROUS MINERALS ACCOUNT FOR THE OBSERVED MID-LATITUDE WATER ON MARS?
D. L. Bish1,2, D. T. Vaniman2, C. Fialips2, J. W. Carey2, W. C.
Feldman2, 1Dept. of Geol. Sciences, Indiana University,
Bloomington, IN 47405, b***@indiana.edu; 2Los Alamos National Lab, MS
D469, Los Alamos, NM 87545.
Sixth International Conference on Mars (2003) 3066.pdf
http://www.lpi.usra.edu/meetings/sixthmars2003/pdf/3066.pdf

PROPERTIES OF POTENTIAL MARTIAN MINERALS UNDER SIMULATED SURFACE CONDITIONS.
D. L. Bish1, D. T. Vaniman1, S. J. Chipera1, and J. W. Carey1,
1Hydrology, Geochemistry, and Geology, Los Alamos National Laboratory,
MS D469, Los Alamos, NM 87545 b***@lanl.gov.
Lunar and Planetary Science XXXIII (2002) 1895.pdf
"A better knowledge of Martian hydrous mineralogy,
measured under conditions representative of the
Martian surface, can provide answers to key questions
such as: (1) Can water deposits formed during early
Martian hydrologic cycles survive for time spans on the
order of hundreds of millions of years over which life
would form; (2) What is the difference in water retention
between polar and equatorial regoliths, and how
would these differences influence a search of Mars for
evidence of life; (3) What are the relationships between
permafrost and hydrous solids on Mars; and (4) Can
hydrous-mineral deposits in a brackish regolith provide
a water resource for human exploration and development of Mars?"
http://www.lpi.usra.edu/meetings/lpsc2002/pdf/1895.pdf

A key question to answer is if this water when released from the
clays could remain as liquid water diurnally and/or seasonally at low
elevation sites.

In the latest Odyssey GRS reports, there is a definite difference in
the readings for the near equatorial area at about 15 degrees N lat.
and 15 degrees E long. for Winter compared to Summer as indicated by
the image in the MSNBC article:

Mars probes find more frozen water.
Northern ice boosts search for ancient life.
"Two false-color images show epithermal neutron flux during winter
(left) and summer (right) in Mars' northern hemisphere. Dark blue
hints at the presence of water ice. The north pole is covered by
frozen carbon dioxide in winter, but a summer "thaw" reveals the
frozen water beneath."
http://www.msnbc.com/news/931744.asp?0cv=TA00

The image appears as Fig. 1 in the recent Science article by
Mitrafanov et.al.:

CO2 Snow Depth and Subsurface Water-Ice Abundance in the Northern
Hemisphere of Mars.
I. G. Mitrofanov, M. T. Zuber, M. L. Litvak, W. V. Boynton,
D. E. Smith, D. Drake, D. Hamara, A. S. Kozyrev, A. B. Sanin, C.
Shinohara, R. S. Saunders, V. Tretyakov
SCIENCE,VOL 300, 27 JUNE 2003, p. 2081-2084
http://www-geodyn.mit.edu/hend.mola.pdf

This seasonal difference for this area is even more clear in a report
given at The 36th Vernadsky/Brown Microsymposium on Comparative
Planetology by Litvak et.al.:

Microsymposium 36, MS063, 2002
SEASONAL VARIATIONS OF SUBSURFACE HYDROGEN AS SEEN BY HIGH ENERGY NEUTRON DETECTOR, MARS ODISSEY.
M. L. Litvak, I. G. Mitrofanov, A.S. Kozyrev, A.B. Sanin, W. Boynton,
C. Shinohara, D. Hamara, R. S. Saunders.
http://www.planetary.brown.edu/planetary/documents/Micro_36/Abstracts/063_Litvak_etal.pdf

Figure 1 in this report shows the variations in this near equatorial
region for 4 seasons.

I think therefore it would be useful to search for *seasonal*
differences in the high-resolution MOC images in this area.

Also very interesting are the fast neutron maps showing some areas
with moderately high hydrogen amounts. The fast neutron measurements
are most allied with the near surface hydrogen amounts, within a few
centimeters.

See the maps of fast neutrons in these reports:

ATMOSPHERIC CORRECTIONS FOR NEUTRONS REVEAL VARIATIONS IN SURFACE COMPOSITION IN THE THARSIS REGION.
T. H. Prettyman, W. C. Feldman, W. V. Boynton, G. W.
McKinney, D. J. Lawrence, and M. T. Mellon.
Lunar and Planetary Science XXXIV (2003)
http://www.lpi.usra.edu/meetings/lpsc2003/pdf/1950.pdf

Microsymposium 36, MS070, 2002
FIRST RESULTS OF MARS MAPPING OF NEUTRON FLUX BY HIGH ENERGY NEUTRON DETECTOR, MARS ODISSEY.
I. G. Mitrofanov, M.L. Litvak, A.S. Kozyrev, A.B. Sanin, W. Boynton,
C. Shinohara, D. Hamara, R. S. Saunders.
http://www.planetary.brown.edu/planetary/documents/Micro_36/Abstracts/070_Mitrofanov_%20etal.pdf

These images though don't give the seasonal differences for this close
surface water so you can't tell if there is a seasonal and/or diurnal
variation, which would indicate free water quite close to the surface
near the equator.

In Fig.1 of this first report, there is a strip of dark blue
indicating significant amounts of hydrogen at around -10 to -20 S.
lat. and -165 E long. There are also scattered, small light blue areas
indicating moderate amounts of hydrogen.
These would also be good places to search for seasonal changes in the
MOC images.
I found an interesting image in one of these areas:

Finely-dissected terrain in Memnonia/Sirenum region.
http://ida.wr.usgs.gov/html/m08025/m0802500.html

I had previously been interested in the Memnonia region because it
shows indications of surface fogs that I thought might indicate near
surface water in the near equatorial region:

"Early Morning Surface Fog. The presence of morning fogs in some
crater and channel bottoms is a Viking discovery with possible
implications for the future biological exploration of Mars. These
early morning views of the Memnonia region were taken one-half hour
apart using a violet filter to enhance the contrast of the
condensates. The areas marked by arrows are noticeably brighter in the
later picture. The fogs indicate specific spots where water is
exchanged, probably on a daily cycle, between the surface and the
atmosphere. The surface and lower air layers in this region become
unusually cold at night because of the thermal properties of the
surface. When the surface warms in the morning, it seems that a small
amount of water vapor-estimated to be about one-millionth of a meter
thick if liquefied is driven off; this vapor recondenses in the
atmosphere, which warms more slowly, to form a ground fog of ice
particles. [P17487; 13°S,147° W]"
http://history.nasa.gov/SP-441/ch12.htm

cf.:

From: Robert Clark (rgregoryclark@yahoo.com)
Subject: Re: And now the weather ... on Mars! (Forwarded)
Newsgroups: sci.astro, alt.sci.planetary, sci.geo.meteorology
Date: 2002-07-03 17:34:57 PST
http://groups.google.com/groups?&selm=832ea96d.0207031634.1821e37f%40posting.google.com

Bob Clark

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