What's the point of Christensen making this outlandish statement if Head, Parker and others see morphological evidence for huge amounts of liquid water in Mars ancient past? When Mars Express gets into Martian orbit in December, we'll just see if Christensen's dry Mars holds up okay?

Do you really honestly think the Martian rampart craters, tributaries and tear drop islands are formed in a dry environment? Vast areas of Mars remain over the triple point of water during extended periods of time -- this means if there is ice, it melts, that means liquid water near the surface. It seems simple enough to understand. Occam's razor says the simplest explannation is usually the correct one. I would say water, glaciers and H2O ice meet occams razor criteria very nicely. Certainly liquid CO2 flows did not form the Martian tributaries...

BD