Looks like Dan Quayle was right.
time to pull out the snoopy snow cone machine. slushies for everyone!
Can they rule out solid CO2 (Dry Ice)? I haven't seen this possibility mentioned anywhere, and unless/until they do the claim of solid evidence for water ice is still a bit fluid, IMO. Might there be a big underground "carbonifier" of solid CO2 that keeps the soil temperature low? There's something hard down there. What is it?
Hartman: "...the claim of solid evidence for water ice is still a bit fluid..."
Beautifully phrased! Made my day.
It totally made my day to see that come across my Twitter feed. Love it when machines say "w00t" :)
Hartman, from the comments on the linked page:
Re: Dry Ice (CO2 ice) vs Water Ice
In the Martian summer it is much too hot for dry ice to be solid. There is abundant dry ice (frozen CO2)on Mars in the winter. The melting point of dry ice on Mars is -193 F. Today's weather report from the Canadian weather station on Phoenix shows a low of -112 F -- way too hot for dry ice to stay solid right now
Solid CO2 does not melt to a liquid phase except at high pressure: it sublimates directly to the gas phase. CO2 freezes at -78 C (-108 F), cf. -112 F (-80 C) you cite for the local temp up there (where did the m.p. of -193 F "on Mars" come from? That's not possible.). The phase transition temp is probably somewhat lower than -78 C at the partial pressure for CO2 in Martian atmosphere, but anyway, it seems to me that solid CO2 could exist below the surface especially if covered by a layer of insulating dust. I look forward to chemical identification of what these evanescent chunks are.
the melting point you mention is at 1 atm (earth atmospheric pressure - Mars is much lower, so it is in a different part of the phase diagram.
Check the phase diagram here:
Liquid CO2 does not exist below about 5 bar ppCO2, either on Mars or on Earth. The ppCO2 on Mars is only about 0.3 bar, so the liquid phase cannot exist at any temperature: only gas and solid. The transition temp at that pressure is about 190 K, or -83 C (-118 F).