re: BBC: Mars not a watery world: It sure is!
TES cannot see through Martian dust period! Study your subject before you post.
Ancient Floodwaters and Seas on Mars
"Michael Carr (U. S. Geological Survey, Menlo Park) and James Head III (Brown University). They examined the features previously mapped as shorelines by Timothy Parker (Jet Propulsion Lab) and colleagues but found that more compelling evidence for the past presence of large bodies of water are deposits within the northern plains."
http://www.psrd.hawaii.edu/July03/MartianSea.html