QUOTE (tasp @ Jun 17 2008, 05:23 AM)
...No peroxides would imply something even more exotic, interesting, and perhaps (bwa, ha, ha, ha) alien.
Not necessarily all that alien. I'm not a chemist, but I just now looked in several freshman chemistry books. Strongly oxidizing conditions, promoted by UV or cosmic radiation, might actually produce a variety of species or surfactants, especially under extremely dry and cold conditions. Peroxide, best known (for its bleaching properties on hair) as its hydrogen compound H2O2 is one (CaO2 is also possible); superoxide, which might combine with H to form HO2 (KO2 is better known), is another, not quite as strongly oxidizing. Given the presumed high sulfate content of the soils, you might get oxidizing, acid molecules such as peroxysulfuric acid, H2SO5 or peroxydisulfuric acid, H2S2O8, or their salts. Ozone, O3, has been mentioned. Another possibility, which I've described in several talks and a paper, would be to oxidize by driving off hydrogen gas from hydroxides, yielding species such as oxy-clays or oxy-amphiboles. A likely possibility is that you might not be talking about identifiable molecules or species at all, but about unsatisfied valences on crystal surfaces, caused by UV damage that knocked electrons away from oxide ions. So failure to identify peroxide molecules as such might not require a complete trip back to the drawing board. Albert Yen of JPL has done many interesting lab experiments related to this topic, but the surface of Mars provides a natural laboratory for processes that might be difficult to duplicate in the lab.
-- HDP Don