I think most regular readers of this bbs know by now my view on the
temperatures on Mars and the possibility of liquid water on the Red
Planet. A pet peeve of mine is that USUALLY scientists cite the
lowest temperatures or average temperatures on Mars to conclude that
liquid water can not exist on Mars (yes I know there are exceptions!)
My view is that a more relevant temperature to give is the maximum
temperature on Mars. I'm faily certain for example that the average
temperature in Fairbanks, Alaska is below zero, but would you
conclude from that then that liquid water can not exist in Fairbanks,
Alaska? (BTW, here's an image of the Chena River in Fairbanks:
http://www.dashdeli.com/photos.shtml )
This occurred again in regards to the recent announcement of the
results from Mars Odyssey indicating large amounts of water in the
southern hemisphere:

Odyssey Finds Large Concentrations of Water on Mars
"The scientists know that the water is ice rather than liquid,
because the temperatures on Mars are well below freezing. The average
temperature of Mars is –63 C (–81 F) and the instruments of Odyssey
indicate the coldest temperature in the Southern Hemisphere right now
is -101 C (–150 F).
"It's just too darn cold for it to be liquid water,' says Boynton."
http://nai.arc.nasa.gov/news_stories/news_detail.cfm?
article=odyssey.cfm

What's interesting here is that they refer to Odyssey instruments
giving this coldest temperature. Yet there was an infrared image
released from the THEMIS infrared imager on Odyssey showing above
zero temperatures being reached in the southern hemisphere of Mars:

First THEMIS Infrared and Visible Images of Mars
http://mars.jpl.nasa.gov/gallery/polaricecaps/PIA03461.html

Also, the TES imager on Mars Global Surveyor has shown that
temperatures can exceed 20 C as far south as 60 S latitude:

http://wwwflag.wr.usgs.gov/USGSFlag/Space/MGS_TES/spole99.html

Since the Odyssey infrared imager has a better resolution than the
TES instrument, I presume the THEMIS instrument would confirm this as
well.

Bob Clark