[lepton]

Unless the temp was a couple hundred degrees below zero, AND martian atmosphere was almost 100% CO2, water (ice) makes alot more sense.

95% CO2, and in the Martian Winter, -170F or colder.

[djf]

Given how this debate seems to have done nothing but rage on and on and on, it seems a high school chem student would take about ten minutes to come up with a test for water or CO2. Heck, spectroscopic data during an occultation should tell us, doesn't Mars occult Regulus every once in a while?