Liquid water on Mars and regions of high color variability.
Robert Clark
imaging of Mars.
I just saw an article in Icarus suggesting
some surface units near Valles Marineris were due to water-lava
interactions ("Related Magma-Ice
Interactions: Possible Origins of Chasmata, Chaos, and Surface
Materials in Xanthe, Margaritifer, and Meridiani Terrae, Mars", M. G.
Chapman, K. L. Tanaka, Icarus, Vol. 155, No. 2, Feb 2002, pp.
324-339.) The reference #3 I cite in my post below also found color
variations in Marineris. Also the image of clouds/fogs
over Noctis Labyrinthus I cite shows great color
variations. It's my view that such low altitude, low latitude clouds
and fogs consist at least in part of supercooled liquid water
droplets.
And a recent multi-spectral infrared release from
THEMIS showed wide spectral variation in sedimentary layers in the
region that PI Phil Christensen attributed to hydrous weathering.
Quite likely there will also be wide visible light color variations in
this area as well.
It seems a legitimate conclusion to make that areas of recent or
current liquid water on Mars will have large visible light color
variations. This might also be expected in the infrared imaging but
the visible imaging system of THEMIS has a 20 m resolution compared to
a 100 m resolution for the infrared. Also it is known that a thin
layer of dust can mask the infrared signature of the underlying
material, whereas you would expect that a color image of an area would
allow the underlying color to show through with only a light dust
covering on top. This for example happened at the Pathfinder lander
site where a quite hard white rock was found to underlie much of the
site, overlain by a reddish dust:
Pathfinder's Finds.
"Britt classifies Scooby Doo and its kin as a
third kind of rock that he calls "caliche-like," after a cemented
mineral common in the Tucson area. When it rains in the desert,
calcium-rich salts leach out of the upper soil and begin to percolate
downward."
p. 9
http://pr.caltech.edu/periodicals/EandS/articles/Pathfinder%20Feature.pdf
Week 3
Red, White, and Somewhat Blue at the Pathfinder Site.
Eos Vol. 78, No. 31, August 5, 1997, pp. 317-318.
http://www.agu.org/sci_soc/pathfinder/eosweek3.html
Because of its hardness and white color it almost certainly consists
either of a hard carbonate such as caliche or some type of indurated
sulfate such as gypsum, but spectral data did not distinguish either
of these types.
Then such large visible color variations might be one thing to look
for in the search for recent or current liquid water on Mars.
Bob Clark
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From: Robert Clark (rgrego...@yahoo.com)
Subject: Re: First color images from 2001 Mars
Odyssey?
Newsgroups: alt.sci.planetary, sci.space.history,
sci.astro, sci.astro.amateur
Date: 2002-04-19 11:27:49 PST
Some reports that make use of color in their analysis of Martian
surface units:
1.) GEOLOGY OF THE REULL VALLIS REGION OF MARS:
EVIDENCE FOR MID-NOACHIAN SHEET FLOODS.
Lunar and Planetary Science XXVIII
Results: COLOR - The Martian surface in and around the Reull Vallis is
nearly monochromatic, as if the surface were composed of a single
reddish material.
Almost all color differences seem to be brighter and darker variants
of the same rusty hue, caused perhaps by changes in slope and solar
illumina-tion. Only the dark wind streaks on the leeward sides of
minor topographic rises (e.g. craters and hills) have significantly
different color. The colors of the streaks are consistent with
mixtures of the reddish material with <20% dark gray material (visible
albedo ~5%). The basement units of the plains sequence exposed in the
valley walls appear to be more yellowish than other materials, but the
difference is not
significant."
http://www.lpi.usra.edu/meetings/lpsc97/pdf/1033.PDF
This page has some enhanced color Viking orbiter
images from the USGS Astrogeology section:
Color Images of Mars
http://www.joshuaalmond.com/mars6.html
One of the regions shown is the Reull Vallis region discussed in the
report. The color variations in these images are exagerated, but they
do show color variations do exist. Then quite likely there would be
significant color variations at the 20 m/pixel resolution scale of
Mars Odyssey.
2.) GEOLOGY, COMPOSITION, AGE AND STRATIGRAPHY OF THE POLAR LAYERED
DEPOSITS ON MARS.
First International Conference on Mars Polar Science.
http://www.lpi.usra.edu/meetings/polar98/pdf/3009.pdf
3.) Identifying surface changes on Mars from Viking
and MGS.
Lunar and Planetary Science XXXIII (2002)
"Variable features are of particular interest
because of the information they yield about both the
geology and meteorology of Mars. Surface changes
due to wind erosion and deposition have been docu-
mented since the Mariner missions [1-6]. Even before
Mariner, Sagan and Pollack [7,8] correctly ascribed
the
long term secular changes in Mars' albedo that had
been noted for centuries by telescopic observers to
aeolian transport of sand and dust by saltation and
suspension. The systematics of aeolian surface changes
began to be understood with the extensive Viking data
set [9-11]."
"Next Steps: We will continue to explore automated
procedures for change detection; a more sophisticated
approach would track the history of surface brightness
variations to identify those changes that persist over
time. We also look forward to the availability of
cali-
bration procedures for MOC blue filter images. Incor-
poration will greatly assist the interpretation of
color information of surface changes and allow us to
spot distracting condensate clouds more easily."
http://www.lpi.usra.edu/meetings/lpsc2002/pdf/1982.pdf
The authors here present the view that the secular
and seasonal albedo changes seen on Mars are only due
to variations in the distributions of dust on Mars.
However, one of the regions discussed here Noctis
Labyrinthus is known to present variable low level
fogs
than might be an indication of near surface liquid
water (Noctis is both low altitude and low latitude,
which means daytime conditions will frequently be in
the range to permit liquid water):
Colorful Water Clouds Over Mars
http://antwrp.gsfc.nasa.gov/apod/ap010417.html
4.)MAPPING UNIQUE SPECTRAL MATERIALS IN VALLES
MARINERIS.
Lunar and Planetary Science XXX.
"Within the canyons and surrounding terrains, strong
evidence for variable mafic mineralogy in low albedo
units, variable states of hydration or apparent water
content of the soils, and unusual spectral properties
associated with anomalous color in Viking orbiter
images have all been identified [3,4,5,6]."
"Extensive examination of spectra from the Valles
Marineris region reveals many occurrences of materials
that differ in important but subtle ways from the more
common materials in the scenes. For example, [6]
showed that ISM spectra for a region of anomalous
Viking color in western Candor Chasma exhibited a 1 mm
absorption broadened to shorter wavelengths,
consistent with a surface enriched in crystalline
hematite."
"The ISM data have been co-registered to a Viking
Orbiter MDIM to provide essential context for the
relationship to surface morphology. In addition, red-
green-violet color images were used to provide
visible-
color information. In the valley floor of Eos Chasma,
the Viking color data show that much of the floor is
covered by a relatively gray material. Some regions of
the valley floor have a distinct relatively blue
color,
while the plateau plains are slightly brighter but
with
color that is between gray and blue."
http://www.lpi.usra.edu/meetings/LPSC99/pdf/1484.pdf
The region West Candor Chasm mentioned here is
another area presented on the page "Color Images of
Mars",
http://www.joshuaalmond.com/mars6.html, of enhanced
color images.
This page describes this enhanced color image in more
detail:
West Candor Chasm (Enhanced Color)
http://www.solarviews.com/cap/mars/pia155.htm
It suggests the color variations as due to former
lakes and hydrothermal activity.
Bob Clark
rgrego...@yahoo.com (Robert Clark) wrote in
message
news:<832ea96d.02040...@posting.google.com>...
> You wouldn't get the impression that Mars is a
colorless world from
> this Hubble image either:
>
> Hubble Captures Best View of Mars Ever Obtained From
Earth
> http://oposite.stsci.edu/pubinfo/pr/2001/24/
>
> Impossible not to notice that the darker areas have
greenish tinge to
> them.
> I found this web site that says this is common from
telescope views
> from Earth but attributes it to an optical illusion:
>
> Mars
> "When Mars is viewed through a telescope, it looks
like a red and
> orange disk. An observer can easily see white ice
caps at the north
> and south poles of Mars. These caps grow and shrink
throughout the
> Martian year, just as the polar caps of Earth do.
The darker areas of
> Mars's surface may look greenish to the observer,
but this is an
> optical illusion caused by the contrast in color
between the dark
> patches and brighter areas. Scientists believe that
the dark areas are
> regions of relatively unweathered bare rock, while
the bright areas
> are regions with deposits of weathered material,
especially fine
> dust."
> http://www.cosmiverse.com/reflib/marspage1.htm
>
> Whether this seasonal change is an optical illusion
or not is
> something color light imaging from THEMIS could also
address.
> I imagine examination of the spectra of this Hubble
image also could
> address the question of whether these dark areas
really are reflecting
> most strongly in the green part of the spectrum.
>
>
> rgrego...@yahoo.com (Robert Clark) wrote in
message
news:<832ea96d.02040...@posting.google.com>...
> > he...@spsystems.net (Henry Spencer) wrote in
message news:<Gtwp...@spsystems.net>...
> > > In article
<10176897...@server.gh.wh.uni-dortmund.de>,
> > > Holger Isenberg <H.Ise...@ping.de> wrote:
> > > >> http://mars.jpl.nasa.gov/odyssey/ Pretty
color pictures are probably
> > > >> not a high priority...
> > > >
> > > >Can you explain further? We send the first real
color camera to Mars orbit
> > > >and its pictures are low priority in relation
to 20 m/pixel b&w pictures,
> > > >which already had been taken back in 1972 by
Mariner 9?
> > >
> > > They're (probably) low priority because they
don't *tell* you anything
> > > new. It was established early that Mars is not
a colorful place -- that
> > > is, its color doesn't *vary* much -- and that
(conventional) color imaging
> > > thus doesn't add much information compared to
B&W images. So tripling the
> > > data volume to bring back color isn't very
attractive.
> > >
> > > Note that THEMIS is primarily an IR instrument.
The visual part is mostly
> > > just a supplement to the IR imaging.
> >
> > I agree with you that the IR images should have
higher priority but I
> > don't agree that color images wouldn't tell you
very much. I copied
> > below a post discussing some questions that color
imaging could
> > answer. Other questions that would be interesting
to answer is what
> > are the colors of the dark streaks seen forming in
current times? In
> > the MGS images they look just look black to
varying shades of grey.
> > What about the color of the "dalmation spots"
that some have claimed
> > to be indicative of life?
> > A region I'm especially interested in is Solis
Lacus. This has long
> > been known to be a variable feature on Mars both
seasonally and long
> > term. This is interesting because there are
several lines of evidence
> > suggesting there could be near surface liquid
water in Solis. Are the
> > known albedo changes in Solis accompanied by
color changes?
> > This web page by the Association of Lunar &
Planetary Observers lists
> > several variable features on Mars that very likely
would also be
> > accompanied by color changes:
> >
> > 1998-1999 Aphelic Apparition of Mars: Part 3
> >
http://www.astroleague.org/marswatch/Newsletr/imv03i06.html
> >
> > Bob Clark
> >
> >
**************************************************************
> > From: Robert Clark (rgrego...@yahoo.com)
> > Subject: On the colors of Mars and the mystery of
the "Sinton bands".
> > Newsgroups: sci.astro, alt.sci.planetary,
sci.astro.seti, sci.bio.misc
> > Date: 2002-02-02 15:19:44 PST
> >
> > The color imager on Mars Odyssey should have about
the same resolution
> > as the Viking orbiter, about 20 meters/pixel.
> >
> > A question about some features on Mars is
whether some color
> > differences are real or are only apparent in
comparison to surrounding
> > terrain.
> >
> > White Rock for example has been claimed to not
really be white but
> > only lighter than the surrounding area. Will the
color imager be able
> > to determine if it really is white?
> >
> > Another area where the interpretation of its
color has been
> > controversial is the Syrtis Major region. It has
long been known to
> > present an apparent bluish tint that appears to
change seasonally.
> > William Sinton made some spectrographic
observations of the area in
> > the 50's that appeared to show it's spectrum
matched that of complex
> > organic molecules. This and the seasonal changes
led Sinton to
> > originally propose the spectra were due to life.
Will Mars Odyssey be
> > able to determine if Syrtis Major really does
become blue seasonally?
> > Some of the bands Sinton observed have been
explained as actualy due
> > to HDO in Earth's atmosphere. However, the bands
at 3.4 microns which
> > are frequently seen in complex hydrocarbons have
not been definitively
> > explained. Will the THEMIS infrared imager on Mars
Odyssey finally be
> > able to resolve the mystery of the "Sinton bands"?
> >
> > The history of the Sinton bands is told in the
second chapter of
> > Barry DiGregorio's book, _Mars: the Living
Planet_,
> >
http://www.amazon.com/exec/obidos/ASIN/1883319587/marsbugstheelect
> >
> > References on the Sinton bands:
> >
> > Home Page for IRTF Mars Image Gallery
> > Sinton bands in February 1995 IRTF images
> > http://marswatch.astro.cornell.edu/irtf.html
> >
> > 3-4m mm IMAGING SPECTROSCOPY OF MARS.
> >
http://www.lpi.usra.edu/meetings/LPSC98/pdf/1658.pdf
> >
> > It's also discussed in the dissertation of David
Klassen:
> >
> > Infrared Imaging Spectroscopy of Martian Volatiles
> > by David R. Klassen
> >
http://elvis.rowan.edu/~klassen/papers/dissertation/chapter1.htm
> >
> > Bell et.al. have also proposed the aluminum
mineral diaspore
> > for the origin of the "Sinton bands":
> >
> > SPECTROSCOPIC EVIDENCE FOR DIASPORE (a-AlOOH) ON
MARS.
> >
http://www.lpi.usra.edu/meetings/lpsc2000/pdf/1227.pdf
> >
> >
> > Bob Clark
> >
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