robert clark

Orbiter measurements from the TES instrument on Mars Global Surveyor
and the mini-TES intrument on the MER rovers show there are seasonally
variable amounts of "bound water" on Mars.

Research Articles
Initial Results from the Mini-TES Experiment in Gusev Crater from the
Spirit Rover.
Science 6 August 2004: Vol. 305. no. 5685, pp. 837 - 842.
http://www.sciencemag.org/cgi/content/full/305/5685/837 [free full
text with registration]

GLOBAL MAPPING OF MARTIAN BOUND WATER AT 6.1 MICRONS BASED ON TES
DATA: SEASONAL HYDRATION-DEHYDRATION OF SURFACE MINERALS. R. O.
Kuzmin1, P. R. Christensen2, and M. Yu. Zolotov2, 1Vernadsky Institute
of Geochemistry and Analytical Chemistry, Russian Academy of Sciences,
19 Kosygin str., Moscow 119991, Russia, e-mail:****@geokhi.ru,
2Department of Geological Sciences, Arizona State University, Tempe,
AZ 85287
Lunar and Planetary Science XXXV (2004) 1810.pdf
http://www.lpi.usra.edu/meetings/lpsc2004/pdf/1810.pdf

This can be water that is contained within microscopically and
nanoscopically small pores in minerals:

clay-bound water.
http://www.glossary.oilfield.slb.com...-bound%20water

In such a case this water is not in the form of a *chemical bond* to
the containing minerals. Essentially this is just water that is only
physically trapped within very tiny pores. Is this always the case for
"bound water"?

Note the chemical formulas used to represent bound water in hydrated
minerals.

ON TES DATA" report:

"Discussion: The results imply the existence of water-bearing surface
minerals in a belt surrounding the edge of seasonal ice caps in both
hemispheres, and that these minerals are able to dehydrate and hydrate
over the course of the Martian year. Stability of hydrated minerals on
Mars (e.g., salts) generally mimics the seasonal stability changes of
water ice, as inferred from thermodynamic analyses [16, 19] based on
Viking's surface temperature [14] and the atmospheric H2O abundance
[15]. Hydrated minerals are stable at higher temperatures than ice is,
which allows their existence beyond the edges of seasonal ice caps.
During the winter season in each hemisphere, highly hydrated minerals
(e.g., MgSO4·7H2O, Na2SO4·10H2O, MgCl2·6H2O, CaCl2· 6H2O, CaSO4·2H2O)
are stable at lower latitudes. In summer seasons, when seasonal ice
caps sublimate, less hydrated minerals and anhydrous phases
(MgSO4·H2O, Na2SO4, MgCl2·4H2O, MgCl2·2H2O, CaCl2·H2O, CaSO4) become
stable at lower latitudes."

Does the H2O attached to the rest of the formula with a dot indicate
this water is also only contained within micropores in the mineral and
not attached in the form of a chemical bond?

In any case this bound water is able to be released at temperatures
that fluctuate at the surface of Mars raising the possibility it could
become free liquid water within the right temperature range for the
low atmospheric pressures on Mars:

Extreme Planet Takes Its Toll.
June 12, 2007
"Seasonal Change
"During their exploration of Mars, the rovers have recorded
temperatures ranging from midday highs of about 35 degrees C. (95
degrees F.) in spring and summer to nighttime lows of about minus 110
degrees C. (minus 166 degrees F.) in winter. Spirit has experienced
greater swings in temperature because its location is farther from the
martian equator, which puts it seasonally closer to or farther from
the Sun than Opportunity."
http://marsrovers.jpl.nasa.gov/spotlight/20070612.html


And this report gives locations on Mars for which liquid water could
be possible for short times seasonally. (The lengths of time given are
totals since such water would freeze over at night):

Meteorological Control on the Formation of Martian Paleolakes.
http://adsabs.harvard.edu/cgi-bin/bi...PI....31.1509H

Note that as indicated in Fig.1, the Spirit site in Gusev is within
the area for which this would be possible for a total of 10 sols, and
the Opportunity site at Meridiani is within or near the region where
it would be possible for 5 sols. See Fig. 1 here:

Fig.1 Duration (Sols) and location where liquid water could be stable
on present day Mars.
http://sciforums.com/attachment.php?...0&d=1101516966


Bob Clark