"Is there water on Mars? Is there not?"

This does get tiresome after a while.

Is there or isn't there liquid water on the surface of Mars? And why is the answer to that question so mysterious after 35 years of orbital and surface exploration? Will we ever have a definitive answer? Who knows?! Stay tuned!

There has been visual evidence of relatively recent surface flow of some volatile substance (perhaps water) since 1971/2. There has been evidence of surface deposits of ice on Mars since almost the beginning of the telescopic age, though the composition of that ice was subject to generations of dispute -- as it sometimes still is disputed though it is generally acknowledged to be both CO2 and water ice at the poles and frost coatings at lower latitudes are generally thought to be water ice only.

There is apparently a huge amount of -- apparently -- water ice (or even liquid water) not terribly far below the surface.

Transitory liquid water on the surface seems both likely and is deemed "impossible"... such is the typical martian controversy. Likely because of melting frost coatings at atmospheric pressures above 6MB, impossible because of so many critical temperature and pressure constraints leading almost inevitably to sublimation rather than melting.

No certain find of present day liquid water at the surface has ever been accepted, nor has any been found -- for certain -- below the surface.

Other volatiles have been proposed, such as brines and "battery acid" with the suggestion that water as such (in a more or less pure state) is found only at the poles as ice, and maybe subsurface here and there.

There are many, many light colored flows visible in orbital images. They have been seen and remarked upon for many years. Some do resemble fluid flows, and they may represent the dessicated remains of salt water flows -- or not.

There are dark-colored flows that also resemble fluid flows. Most of them (both light and dark) start from point sources on crater walls and other cliff faces. The point source argues against liquids pouring out of surface openings, as such things should be fairly explosive given atmospheric pressures and such. But it is not impossible for these channels or flows to be the result of fluids at the surface.

It would be nice if we actually had a way to find out, short of sending someone to sit and watch, but so far, no way has been devised and sent to Mars to do it.

At this rate, it will be another 35-50 years before we find out. If not longer.

But think of the endless disputation that can therefore ensue! Generations of it! Whoo hoo!

What fun!

BRFelix