Mars Odyssey hydrogen-content measurements have shown seasonal deposition of water/ice on Mars even at equatorial locations. This has been confirmed by the Opportunity rover in Meridiani by the observation of early morning frost on the rover:

More on "Frost on the rover solar panels".
http://bautforum.com/showpost.php?p=323577&postcount=6

This deposition of frost at Meridiani corresponded to the observation of clouds over the site during the local Winter:

Mars Rovers Spot Water-Clue Mineral, Frost, Clouds.
13-Dec-2004
http://marsrovers.jpl.nasa.gov/galle...20041213a.html

Since clouds have also been seen over the site during the current Summer season, I argue this should also correspond to water/ice deposition currently at the Meridiani landing site:

Space Sciences
Summer clouds over Meridiani?
Posted by Robert Clark on 12/31/2005 6:56:40 PM
http://habitablezone.com/space/messages/409185.html

The "Mars Rovers Spot Water-Clue Mineral, Frost, Clouds" press release showed the frost forming in early morning in the Winter season. The image of the frost was taken 11 minutes after sunrise, and a subsequent image showed the frost had burned off 3 hours later due to rising temperatures.
Perhaps the clouds in the images in the current season appear at night because of the coldness at night during this current Summer period. Then we might expect the greatest water/ice deposition to also occur at night.
Could the mini-TES detect H2O on the rover at night? Could we for example compare the spectra at night to the morning spectra?
Another experiment I suggest to try would be to press down with the RAT at night and keep the area covered till early morning. Then uncover the area soon after sunrise to see if there are any remaining signs of moisture.
This may have what occurred at the Gusev landing site with the Spirit rover landing bags with the observation of the "magic carpet" mud-like material. The Gusev landing occurred within the period that the Mars Odyssey readings showed the greatest water/ice deposition occurs during southern Summer. Then the landing bags covering the soil may have allowed deposited water/ice to be retained against sublimation/evaporation. When the bags were pulled away, moist soil would have been revealed.
That this deposition occurs may provide a means of obtaining water for consumption or fuel (hydrogen through electrolysis) by future manned missions. The method of a "solar still" allows water vapor in the air to be collected and condensed to liquid water even in desert regions:

Desert Survival
Collect Water in a Solar Still.
http://www.desertusa.com/mag98/dec/stories/water.html


Bob Clark

As I understand it the solar still has the capacity to produce about one liter of water per square meter of plastic sheeting in the Sonoran desert. I think there are some differences from Mars. In the first place the sun is less than half as intense.

Secondly, the atmospheric pressure in the Sonoran desert is about 100 times that of Mars, and the relative humidity is no less than 6%, and frequently in excess of 20%--at least twice that on Mars.

Thirdly, the soil has lots of water in it. Notice the vegetation in the photos on the web site provided by Robert Clark. The Sonoran desert receives in excess of 7 inches of rainfall per year, compared to zero on Mars.

From all of the above, I would think a solar still on Mars would yield much less than 1% of what a similar still would yield on Earth—something closer to a milliliter than a liter.

Of course, a thousand square meter plastic sheet might more than make up for that deficiency.

Bob

There have been some video posted to the Unmannedspaceflight.com site of these night-time clouds:


http://media.putfile.com/earthrise-oppy-sol-687


http://www.lyle.org/~markoff/op_movie/opp_687L1.gif


Do the fast bright streaks in the second video look like meteorite trails?


I suggested the current deposition of the water/ice at Meridiani may become liquid at some point because of the warm maximum temperatures during the current Summer season. This is supported by the detection of
carbonate in dust by the rovers, and also from orbit:


January 09, 2004
Spirit Lowers Front Wheels, Looks Around in Infrared.
"We came looking for carbonates. We have them. We're going to chase them," said Dr. Phil Christensen of Arizona State University, Tempe, leader of the Mini-TES team. Previous infrared readings from Mars orbit have revealed a low concentration of carbonates distributed globally.
Christensen has interpreted that as the result of dust interaction with atmospheric water. First indications are that the carbonate concentration near Spirit may be higher than the Mars global average."
http://marsrovers.jpl.nasa.gov/newsr...20040109a.html


On Earth in nature carbonate is produced by iteraction with *liquid* water. There have been some laboratory experiments that attempt to show it can form with water vapor alone but this hasn't been seen in nature.
I suspect in fact in these experiments some small amounts of liquid water are involved undetected by the experimenters.
It is quite key then that the HEND instrument on Mars Odyssey shows water/ice deposition occurs on Mars even at near equatorial locations:


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/th...zmin_et_al.pdf


This deposition was confirmed by Opportunity by the detection of frost on the rover during the Winter season. But I consider it quite key here that HEND shows the deposition is actually higher during the current southern Summer season. So since maximal temperatures can exceed melting currently, the carbonate may form in the period when temperature is above melting but before it reaches the boiling point in
the low atmospheric pressure on Mars.
I therefore propose to search for this liquid water by the rovers. However, I am informed that for technical reasons the rover engineers prefer not to deploy the rover arm in the middle of the night. During the current Summer season, the greatest deposition probably occurs at night because of the colder temperatures. You want to cover the area during the night to preserve this water before it burns off in the daytime.
So some other methods: perhaps the RAT could be applied not in the middle of the night but close to but just before sunrise. I don't know if this would be sufficient to preserve the moisture. Another
possibility: move a small rock in the middle of the night to cover a small area. Then uncover the area during the early morning, as soon as light is available.
Another possibility: it may work to use a wheel to cover the area. This would have to be done at night to insure the deposition has already occurred. Then as soon as light comes, move the vehicle to uncover the area. The problem is this might disturb the area so much to make the moisture no longer visible.
Still another possibility: I remember reading the rover could move all the wheels so that they all dug into the ground at the same time. Then we could do that so that the bottom of the rover clung tightly to the ground. Then move the rover to uncover this area at sunrise. A problem with this is that if the rover bottom is this close to the ground it may be difficult to extract the rover from this position.
Any others?


Bob Clark

From: Robert Clark
Date: Sat, Feb 11 2006 9:32 pm
Email: "Robert Clark" <rgregorycl...@yahoo.com>
Groups: sci.astro, alt.sci.planetary, sci.physics, sci.geo.mineralogy
Subject: Re: Could We Make A "Solar Still" On Mars?

The following reports to be presented to the 2006 Lunar and Planetary
Science Conference discuss seasonal variations in the bound water
content even at near equatorial latitudes:

SPATIAL AND TEMPORAL VARIATIONS OF BOUND WATER CONTENT IN THE MARTIAN
SOIL WITHIN THE GUSEV CRATER: PRELIMINARY RESULTS OF THE TES AND
MINI-TES DATA ANALYSIS.
R. O. Kuzmin1, P. R. Christensen2, S. W. Ruff2, T. G. Graff2, A. T.
Knudson2, M. Yu. Zolotov2, Athena Science Team, 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, USA.
http://www.lpi.usra.edu/meetings/lpsc2006/pdf/1673.pdf


MAPPING OF SEASONAL BOUND WATER CONTENT VARIATIONS ON THE MARTIAN
SURFACE BASED ON THE TES DATA.
R. O. Kuzmin1, P. R. Christensen2, M. Yu. Zolotov2 and S. Anwar2.
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.
http://www.lpi.usra.edu/meetings/lpsc2006/pdf/1846.pdf


This confirms observations of the HEND instrument on Mars Odyssey of
seasonal variations in the deposited water/ice content of the soil.
Note that this strongly implies the varying bound water is due to this
seasonal water deposition.
One type of mineral found containing the bound water is carbonate. Then
this carbonate should arise from this seasonal deposition. Most
importantly this implies this carbonate is currently forming.
One small discrepancy in the bound water observations and the HEND
measurements is that HEND suggests that in the south, the greatest
deposition occurs in the southern Summer, while the bound water
measurements show the largest amount of bound water is observed in the
southern Winter.
A possible explanation is based on the idea that the currently forming
bound water minerals are formed from liquid water brines. Since these
latitudes are near the equator, mid-day temperatures could be within
the range of liquid water brines even during Winter.
However, the Summer daytime temperatures may be too high to permit the
water to remain liquid for long before evaporating.
Evidence for this is that during southern Summer, clouds have been seen
by the Opportunity rover at night when the temperatures are low, while
the clouds and frosts have not been seen during the day. Since similar
clouds corresponded to observed frost deposition on the Opportunity
rover during the southern Winter, it is very likely water/ice
deposition occurred during the southern Summer as well, though at night
when the clouds appear.
I want to suggest that a search be made for this night-time deposition
by methods such as described in the post to sci.astro below.
Note experiments in simulated Mars conditions show that water can stay
liquid in brines for short times on Mars:


Water just might stay liquid on Mars
Studies show salty water can persist, raising hopes for life.
http://msnbc.msn.com/id/10052714/from/RL.2/


For this reason it very likely the currently forming carbonate on Mars
is formed from liquid water as it is on Earth.


Bob Clark


================================================== =========
From: Robert Clark
Date: Thurs, Jan 19 2006 12:15 pm
Email: "Robert Clark" <rgregorycl...@yahoo.com>
Groups: sci.astro, alt.sci.planetary, sci.physics
Subject: Re: Could We Make A "Solar Still" On Mars?


There have been some video posted to the Unmannedspaceflight.com site
of these night-time clouds:


http://media.putfile.com/earthrise-oppy-sol-687


http://www.lyle.org/~markoff/op_movie/opp_687L1.gif


Do the fast bright streaks in the second video look like meteorite
trails?


I suggested the current deposition of the water/ice at Meridiani may
become liquid at some point because of the warm maximum temperatures
during the current Summer season. This is supported by the detection of
carbonate in dust by the rovers, and also from orbit:

January 09, 2004
Spirit Lowers Front Wheels, Looks Around in Infrared.
"We came looking for carbonates. We have them. We're going to chase
them," said Dr. Phil Christensen of Arizona State University, Tempe,
leader of the Mini-TES team. Previous infrared readings from Mars orbit
have revealed a low concentration of carbonates distributed globally.
Christensen has interpreted that as the result of dust interaction with
atmospheric water. First indications are that the carbonate
concentration near Spirit may be higher than the Mars global average."
http://marsrovers.jpl.nasa.gov/newsr...20040109a.html

On Earth in nature carbonate is produced by iteraction with *liquid*
water. There have been some laboratory experiments that attempt to show
it can form with water vapor alone but this hasn't been seen in nature.
I suspect in fact in these experiments some small amounts of liquid
water are involved undetected by the experimenters.
It is quite key then that the HEND instrument on Mars Odyssey shows
water/ice deposition occurs on Mars even at near equatorial locations:

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/th...zmin_et_al.pdf

This deposition was confirmed by Opportunity by the detection of frost
on the rover during the Winter season. But I consider it quite key here
that HEND shows the deposition is actually higher during the current
southern Summer season. So since maximal temperatures can exceed
melting currently, the carbonate may form in the period when
temperature is above melting but before it reaches the boiling point in
the low atmospheric pressure on Mars.
I therefore propose to search for this liquid water by the rovers.
However, I am informed that for technical reasons the rover engineers
prefer not to deploy the rover arm in the middle of the night. During
the current Summer season, the greatest deposition probably occurs at
night because of the colder temperatures. You want to cover the area
during the night to preserve this water before it burns off in the
daytime.
So some other methods: perhaps the RAT could be applied not in the
middle of the night but close to but just before sunrise. I don't know
if this would be sufficient to preserve the moisture. Another
possibility: move a small rock in the middle of the night to cover a
small area. Then uncover the area during the early morning, as soon as
light is available.
Another possibility: it may work to use a wheel to cover the area. This
would have to be done at night to insure the deposition has already
occurred. Then as soon as light comes, move the vehicle to uncover the
area. The problem is this might disturb the area so much to make the
moisture no longer visible.
Still another possibility: I remember reading the rover could move all
the wheels so that they all dug into the ground at the same time. Then
we could do that so that the bottom of the rover clung tightly to the
ground. Then move the rover to uncover this area at sunrise. A problem
with this is that if the rover bottom is this close to the ground it
may be difficult
to extract the rover from this position.
Any others?


Bob Clark



Robert Clark wrote:
> Note we might already be seeing an example of this. See the MI images
> here:
> Erebus Outcrops.
> http://www.markcarey.com/cgi-bin/mt/..../27390/discus...
> The flattened areas have a mushy appearance to them. Another check for
> this might be to perform a RAT observation early in the morning where
> there might be residual moisture left and compare this to a RAT
> observation of a spot nearby later in the afternoon when moisture would
> be expected to burn off.
> Would there be a difference in the appearance in the two RATted areas?
> Bob Clark
> Robert Clark wrote:
> > Mars Odyssey hydrogen-content measurements have shown seasonal
> > deposition of water/ice on Mars even at equatorial locations. This has
> > been confirmed by the Opportunity rover in Meridiani by the observation
> > of early morning frost on the rover:
> > More on "Frost on the rover solar panels".
> > http://bautforum.com/showpost.php?p=323577&postcount=6
> > This deposition of frost at Meridiani corresponded to the observation
> > of clouds over the site during the local Winter:
> > Mars Rovers Spot Water-Clue Mineral, Frost, Clouds.
> > 13-Dec-2004
> > http://marsrovers.jpl.nasa.gov/galle...20041213a.html
> > Since clouds have also been seen over the site during the current
> > Summer season, I argue this should also correspond to water/ice
> > deposition currently at the Meridiani landing site:
> > Space Sciences
> > Summer clouds over Meridiani?
> > Posted by Robert Clark on 12/31/2005 6:56:40 PM
> > http://habitablezone.com/space/messages/409185.html
> > The "Mars Rovers Spot Water-Clue Mineral, Frost, Clouds" press release
> > showed the frost forming in early morning in the Winter season. The
> > image of the frost was taken 11 minutes after sunrise, and a subsequent
> > image showed the frost had burned off 3 hours later due to rising
> > temperatures.
> > Perhaps the clouds in the images in the current season appear at night
> > because of the coldness at night during this current Summer period.
> > Then we might expect the greatest water/ice deposition to also occur at
> > night.
> > Could the mini-TES detect H2O on the rover at night? Could we for
> > example compare the spectra at night to the morning spectra?
> > Another experiment I suggest to try would be to press down with the RAT
> > at night and keep the area covered till early morning. Then uncover the
> > area soon after sunrise to see if there are any remaining signs of
> > moisture.
> > This may have what occurred at the Gusev landing site with the Spirit
> > rover landing bags with the observation of the "magic carpet" mud-like
> > material. The Gusev landing occurred within the period that the Mars
> > Odyssey readings showed the greatest water/ice deposition occurs during
> > southern Summer. Then the landing bags covering the soil may have
> > allowed deposited water/ice to be retained against
> > sublimation/evaporation. When the bags were pulled away, moist soil
> > would have been revealed.
> > That this deposition occurs may provide a means of obtaining water for
> > consumption or fuel (hydrogen through electrolysis) by future manned
> > missions. The method of a "solar still" allows water vapor in the air
> > to be collected and condensed to liquid water even in desert regions:
> > Desert Survival
> > Collect Water in a Solar Still.
> > http://www.desertusa.com/mag98/dec/stories/water.html
> > Bob Clark

================================================== ============