How can there be any dispute any more?

"Everybody knows" there can't be liquid water on the surface of Mars. This was conclusively proven by Mariner 4 in 1965. Too cold. Too dry. Too little atmosphere.

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And Christensen says that "trickling water" under snowpacks is responsible for all those gullies seen around the crater rims. Or at least that's what he said in February.

But let's examine: "trickling water"...

The now-famous martian gullies were created by trickling water from melting snow packs, not underground springs or pressurized flows, as had been previously suggested, argues Dr. Philip Christensen, the principal investigator for Odyssey's camera system and a professor from Arizona State University in Tempe. He proposes gullies are carved by water melting and flowing beneath snow packs, where it is sheltered from rapid evaporation in the planet's thin atmosphere. His paper is in the electronic February 19 issue of Nature.

The scale of these gully formations is fairly enormous for a "trickle" but in Mars study, anything that suggests significant amounts of water at the surface under any conditions at the present day is considered heretical. "Everybody knows," after all. So, Christensen says "trickle" to avoid the wrath of his peers. Snow deposit would have to occur during periods of extreme obliquity, and mantling dust would preserve the snow from sublimation (and perhaps prevent direct detection...)

But we are talking a significant amount of liquid water at the surface of Mars every day right now and in thousands of locations.

Despite the disputes over the amounts of subsurface ice revealed by the GRS and whether any of it can liquify at the surface, let alone flow as liquid beneath the surface, the insight Christensen had regarding present-day surface liquid water flow may be profound.

If this insight is correct, we could well be witnessing present day Martian biological habitat without recognizing it.

Cheers, BRFelix