Further evidence for current liquid water near the equator on Mars.

Posted to sci.astro:

From: rgregoryclark@yahoo.com (Robert Clark)
Newsgroups: sci.astro,alt.sci.planetary,sci.physics,sci.geo.geology,sci.geo.meteorology
Subject: Further evidence for current liquid water near the equator on Mars.
NNTP-Posting-Host: 141.158.40.198

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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Note that recent theoretical research suggests liquid water might
indeed be able to exist in some regions of Mars for short times:

Meteorological Control on the Formation of Martian Paleolakes.
http://adsabs.harvard.edu/cgi-bin/bib_query?2000LPI....31.1509H

Some of the areas were near the equator, however the authors ruled out equatorial areas because they were believed to be desiccated. This Mars Odyssey evidence suggests water does in fact exist near equator and therefore could become liquid for short periods seasonally:



Bob Clark

 

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The board didn't allow me to embed an image.
The image showing locations where liquid water might exist on Mars is at this link:

http://sciforums.com/attachment.php?attachmentid=3560


Bob Clark

 

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Alex Blackwell on the uplink.space.com board posted a link to some freely available journal articles on Mars:

Planetary and Space Science Volume 52, Issues 1-3, Pages 1-257,
Special issue: "Exploring Mars Surface and its Earth Analogues."
http://makeashorterlink.com/?C11835017

One of the articles calculates how deeply above freezing temperatures might penetrate the martian soil. This important since it relates to whether the melting point might be reached if ice for example is several centimeters subsurface.

Theoretical prediction of the thermal conductivity and temperature variation inside mars soil analogues.
Planetary and Space Science
Volume 52, Issues 1-3 , January-March 2004, Pages 91-99


Bob Clark

 

Theoretical prediction of the thermal conductivity and temperature variation inside mars soil analogues.
Planetary and Space Science
Volume 52, Issues 1-3 , January-March 2004, Pages 91-99

Two graphs in this paper gives the depth to temperature variations for both dry soil and frozen soil.

Graph for ice filled soil.
http://sciforums.com/attachment.php?attachmentid=3562

Graph for dry soil.
http://sciforums.com/attachment.php?attachmentid=3563

However, their calculations were based on surface temperature going all the way down to 148K. This report shows 180K is a more realistic minimum temperarture for a Summer near equatorial site:

The Martian Surface Boundary Layer
Authors: Wilson, G. R.; Joshi, M.
Journal: 31st Annual Lunar and Planetary Science Conference, March 13-17, 2000, Houston, Texas, abstract no. 1678
http://adsabs.harvard.edu/cgi-bin/bib_query?2000LPI....31.1678W

See their graph for modeled temperatures here:

Modeled Pathfinder temperatures.
http://sciforums.com/attachment.php?attachmentid=3564


Bob Clark

 

Thanks for the updates, mate.

 

Thanks for all the links, Mr. Clark - I'll take a bit of time to go throught them all. So, do you subscribe to the idea that Mars may go through alternating periods of dessication and relative wetness?

I know that, in deep equatorial basins, at times when a great deal of polar ice has sublimed, the pressure and temperature might be high enough to support liquid water (for a matter of a few weeks, perhaps, each Martian year). But if, due to a combination of factors, an excessive amount of ice - even the whole northern polar cap? - melted at once, it might thicken the atmosphere and increase the greenhouse effect enough to let surface lakes persist all year. This might have been the case, as little as a few centuries ago.

 

The alternating wet/dry periods may even occur yearly and seasonally:


Imaging at the Opportunity rover landing site in Meridiani Planum confirms observations using the HEND instrument on Mars Observer that water/ice is deposited near the equator seasonally on Mars:

Space Sciences
Whoa! Frost on the solar panels?
Posted by Robert Clark on 12/14/2004 7:32:38 AM
In Reply to: Sabkha or playa, take your pick... posted by Nick Hoffman on 12/13/2004 6:23:08 PM
http://habitablezone.com/space/messages/360805.html

However, the HEND instrument shows the greatest amount is deposited during southern Summer:

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.
"As it well seen from fig.1b,c,d, two distinctive “hollows” of neutrons flux reduction have been appeared in the northern hemisphere during northern summer at Ls=130°-170° and in first half of northern winter at Ls=270°-330°, being extended from high to low latitudes. At that, later “hollow” (Ls=270°-330°) is characterized by much stronger reduction of the neutrons flux and it traces from northern polar region up to low latitudes in the southern hemisphere. The first “hollow” is related with periods of the northern middle summer, while the second one – with of the southern middle summer. In both case the residual polar caps serve as main source of the water in the Martian atmosphere."
p. 2
http://www.geokhi.ru/~planetology/theses/47_kuzmin_et_al.pdf

Opportunity landed just barely after this time in southern Summer at about LS 340° (LS stands for solar longitude and indicates Mars position in its orbit.)
However, it is notable that Spirit did land near the end of the time period of Ls=270°-330°. Spirit is closer to the southern pole and this may explain how could experience deposition during this period while apparently not during the current northern Summer. Then the controversial indications of mud at the Spirit landing site early in the mission may indeed have been indications of this summer-time water deposition.
Opportunity has observed clouds during the current water deposition period and since the amount of atmospherically deposited water is greater during southern Summer, we would expect the cloud density to be even greater then. Indeed it could be of sufficient density to allow precipitation which could reach the ground as rain.
The next Ls=270°-330° period begins in August, 2005.

Come on Opportunity!


Bob Clark

 

Rain on Mars?!

Sounds like post-terraforming sci-fi... but the old cliches sometimes work for me.

Truth is stranger than fiction; the familiar can be as shocking as the strange...

How long will Opportunity be likely to function?

 

BTW, I got the times for the various LS (solar longitude) periods from a file showing the arrivals of the Mars missions according to LS. It's linked below.


Bob Clark

 

Here's the link to the chart of Mars solar longitude:

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Bob Clark