White Rock on Mars could still be an evaporite deposit.

The argument that the White Rock formation on Mars is not a
kilometer-scale evaporite deposit, carbonate or sulfate, is based on
the lack of distinguishing features in the infrared spectrum. However,
Dr. Laurel Kirkland has argued that mineralogical signatures can be
obscured by roughness of the surface or simply a dust cover. See the
description of her work and her published paper "Infrared stealthy
surfaces: Why TES and THEMIS may miss substantial mineral deposits on
Mars" he

Laurel Kirkland
Infrared Remote Sensing of Mars and Earth
http://www.lpi.usra.edu/science/kirkland/

I believe the results of the subsurface analysis of the outcropping at
the Meridiani site have proven her to be correct. The mini-TES
spectrometer was not able to determine any distinguishing features of
this rock from its surface, and images of the surface showed it indeed
to be quite rough and dust covered. Yet analysis of the subsurface
showed the outcroppingto be a sulfate.
The TES instrument on Mars Global Surveyor is quite similar to the
mini-TES on the MER rovers and therefore would also be simlarly
"blind" to evaporites with a similar rough or dust-covered surface.
Then the conclusion based on TES observations that White Rock is not
an evaporite deposit or indeed that there are no large scale carbonate
deposits on Mars becomes in doubt.
The Opportunity rover is to explore similar light colored outcroppings
during its traverse. It it finds again that the mini-TES can not
distinguish the spectrographic signatures of evaporites of these
deposits which are later determined from subsurface analysis to be
evaporitic, then that will strongly imply that the light colored
deposits seen globally over Mars are likewise evaporites which the
current class of spectrometers sent to Mars are unable to detect.
In regards to the White Rock formation in particular more accurate
determinations of its albedo should be made to see if it is in fact an
instance of these light colored outcrops seen on Mars:

Space Sciences
It could be...
Posted by Robert Clark on 6/25/2003 6:10:57 AM
http://www.habitablezone.com/space/messages/285900.html


Bob Clark