re: BBC: Mars not a watery world
The major difference is that hematite and olivine aren't obscured so easily by a covering of dust as is carbonate. This is proven by ACTUAL MEASUREMENTS IN THE FIELD, as opposed to just LABORATORY measurements as used by Christensen et.al.
Christensen's claims for the ability of TES to detect carbonate would be much more convincing if he did actuall FIELD studies. I haven't seen those yet.
Bob Clark