This is the strongest evidence of the presence of water yet, on the Red Planet. The Mars Rover, Opportunity, has discovered some sediments of a shiny mineral called gypsum, which most definitely was deposited by liquid water. When that sediment was deposited, is not quite known, but it is definitely millions (or even billions) of years old.
Gypsum is an extremely common mineral on Earth and is frequently processed to make Plaster of Paris.
We had earlier reported about evidence of possible flowing water here.
This discovery was made at the rim of the crater Endeavour, a 14 mile wide crater on Mars. The mineral veinwas found to be about 50 cm (or about 20 inches) long and about 3 cm wide. Opportunity studied this mineral deposit with both optical range camera as well as its X-Ray spectrometer. They concluded beyond doubt that this was gypsum, or moist calcium sulphate. The mineral vein is called “Homesteak” and NASA released an official photo of it in its press release.
There is really no second option, says Steve Squyres of Cornell University, attached to the Opportunity mission as its principal investigator. Why? He clarifies:
This tells a slam-dunk story that water flowed through underground fractures in the rock… There was a fracture in the rock, water flowed through it, gypsum precipitated from the water. End of story. There is no ambiguity about this, and this is what makes it so cool.
Here, both the chemistry, mineralogy, and the morphology just scream water. This is more solid than anything else that we’ve seen in the whole mission.
Why the excitement? Squyres obliges yet again:
This stuff is a fairly pure chemical deposit that formed in place right where we see it. That can’t be said for other gypsum seen on Mars or for other water-related minerals Opportunity has found. It’s not uncommon on Earth, but on Mars, it’s the kind of thing that makes geologists jump out of their chairs.
What is most interesting is the fact that gypsum forms in nearly neutral water, i.e. the water is neither acidic or alkaline. This is more suitable to the presence of Earth-like lifeforms. Earlier discoveries of minerals like Jarosite pointed to the presence of highly acidic water, which wasn’t all that conducive to life as we know it.
Scientists have long been trying to detect the presence of water on Mars. The new Mars Rover Curiosity’ will soon reach Mars (in August, 2012) and begin a more in-depth study. Spirit and Opportunity have been invaluable in this regard. Both are well past their proposed period of operation, and while Spirit has been declared dead earlier this year, Opportunity is still in great shape.
Please note that a direct evidence of water may be hard to find, but this is surely exciting. Even the possibility that Mars once harbored life is a tantalizing prospect!