Space.com (September 21, 2009)
"Mars was not always red, according to a new theory for how the planet took on its characteristic ruddy hue.
"Until recently, Mars' color was thought to be a product of liquid water, which scientists think flowed over the planet's surface billions of years ago, rusting rocks. But after the Mars Exploration Rovers Spirit and Opportunity landed on the planet in 2004, they found evidence of certain minerals that would have been destroyed by water, suggesting that the red dust on Mars never came into contact with flowing water.
" 'That was a surprise to everybody,' said Jonathan Merrison of the Aarhus Mars Simulation Laboratory in Denmark.
"Now new research has found a possible mechanism to explain Mars' rusty color without liquid water. In fact, the study implies that the red tones on the planet are a relatively recent development. A simple grinding down of rocks from erosion could produce a red mineral that stains the dust on Mars, the new thinking goes...."
The article describes an experiment that demonstrated how sand on Mars could get red fairly fast - without water to 'rust' it.
Although there's evidence that water - or some liquid - was present at least for short times on Mars, those water-sensitive rocks show that either something's been protecting them from water - or, more likely, there wasn't water around to protect them from.
We're used to Earth, a downright damp planet - about 3/4 of the surface is covered in the stuff. Mars isn't like that. At all, possibly.
Awww - No Martians?I'd be extremely surprised if there were Martians of the 'take me to your leader' sort. On the other hand, I think there's still reason to believe that there might be at least microbes on Mars.
The comparative lack of water may not be as big a problem to life as we think.
As I wrote back on March 5, 2009, "The University of Giessen's Joop Houtkooper has suggested that the 'peculiar chemistry' that a Viking lander found was life that uses a H2O2/H20 mix. Creatures like that would require tiny amounts of water - which they could absorb from the Martian atmosphere. We're talking about really tiny amounts here...."
Joop Houtkooper's idea may be the explanation for the odd results from the Viking life experiment. It's possible that what was written off by some as 'peculiar chemistry' was Martian microbes exploding when they came in contact with 'way more water than they were designed to handle.
Back to Dry-Process Color for MarsThe lab test is not proof that the idea of Merrison and colleagues is 'the answer' to why Mars looks the way it does: But it opens the possibility that Mars has been red for millions, rather than billions of years. And that should open up all sorts of possibilities to test.
Other posts, about "Mars, Mostly."