You can certainly build this chamber, but can you make it match Mars?

Can you get the chamber big enough to have winds move the dust around? Can you find the right surface materials? (For years, NASA used weathered Hawaiian basalt with a completely wrong chemical and physical composition as a soil simulant. I even have a bag of it myself in a drawer, somewhere, courtesy of JSC). Can you get away from the edge effects of the chamber, and can you run the chamber long enough for thousand-year or million-year cycles to equilibrate?

I don't say that you, or others shouldn't TRY, but don't expect to get it perfect first time.

A number of people ARE experimenting with Mars chambers, to study particular aspects of the surface, but each one is limited in some way, especially in the dimensions of time and space. Mars is a whole Planet!

Therefore, we DO need lots of measurements from the actual surface of Mars, to tell us what's happeneing in terms of physics and chemistry and geology. I agree with you here. What matters is the REAL Mars, as measured, not anything that any one of us thinks - me especially.

So I'll wait, more or less patiently, and see what conundrums and puzzles Phoenix comes up with. What I expect, is a surprise or two. There's always something we don't understand...