Further evidence for current liquid water near the equator on Mars.
From: Robert Clark (rgregoryclark_at_yahoo.com)
Date: 11/25/04
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Date: 25 Nov 2004 00:37:34 -0800
In this post to the Habitablezone.com/space/ bbs I discuss seasonal
changes observed by the Gamma Ray Spectrometer on Mars Odyssey in near
equatorial water on Mars:
Latest Mars Odyssey observations prove free water at equator.
Posted by Robert Clark on 6/27/2003 8:03:48 AM.
http://www.habitablezone.com/space/messages/286216.html
A report presented to October, 2004 Vernasky/Brown Conference
provides further evidence of these seasonal changes:
47 - EVIDENCE OF THE SEASONAL REDISTRIBUTION OF WATER IN THE SURFICIAL
MARTIAN REGOLITH BASED ON ANALYSIS OF THE HEND MAPPING DATA. R.O.
Kuzmin, E.V. Zabalueva, I.G. Mitrofanov, M.L.Litvak, A.V. Parshukov,
V.Yu.Grin'kov, W. Boynton, R.S. Saunders.
http://www.geokhi.ru/~planetology/theses/47_kuzmin_et_al.pdf
The authors note an increase in northern near equatorial regions of
the water content during the northern Summer and southern Summer. They
argue this should be due to transport of water vapor to the equator
from northern polar regions during northern Summer and from the
southern polar regions during southern Summer. Evidence for this is
its seasonal nature but also the fact the highest increase is shown in
the measurements closest to the surface. These are figures 1d and 1c,
which show the water content within 10cm (4 inches) and 20-30cm (8-12
inches), respectively. Note the highest increase in the measurements
occurs within 10cm (4 inches) of the surface.
The authors suggest either the water vapor is deposited as frost on
the surface or incorporated into clathrates or evaporates near
surface:
"The observing maximum value of the reduction of the higher energy
fast neutrons flux (in the period with Ls=270°-330°) approaches ~
20%.That is the abundance of the water (in form of water ice or
clathrate CO2·6H2O) in ~ 10 cm thickness surface layer could be
increased notably in the period on. As water source for this
apparently serves the water vapor mass transferred meridionally to
here from residual southern polar cap due to the significantly lower
partial pressure of H2O over the cold surface of the northern seasonal
cap and its surrounding region. We suggest that the visible reduction
of the neutrons flux outside of the seasonal cover of the CO2-ice (up
to the equatorial regions), may to be associated with both
condensation of the H2O frost on the surface and hydration of a salts
minerals (mostly sulfates and chlorides) contained in the surface
layer of the regolith. The neutrons flux reduction observing in the
period Ls=130°-170° is rather associated with hydration process in the
surface regolith due to high atmospheric humidity in the period."
EVIDENCE OF THE SEASONAL REDISTRIBUTION OF WATER IN THE SURFICIAL
MARTIAN REGOLITH BASED ON ANALYSIS OF THE HEND MAPPING DATA, p. 2
However, note that if it is frost then there are locations near the
equator at low altitude and it would be expected to melt to liquid
water at these low elevations sites as seasonal daytime temperatures
increased. (Temperatures near the equator can reach 80 degrees
Fahrenheit during daytime in Summer.)
Also important to realize is that either the clathrate or evaporate
explanations would require liquid water for their formation and within
4 inches of the surface and occurring currently and seasonally.
Bob Clark
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