Friday, January 6, 2012

The Growing Evidence for Mars' Watery Past

From questioning the probability of life of distant worlds, we turn to evidence of life, past or present, on worlds within our own solar system. Beginning with a look at the mounting evidence suggesting that Mars may, at the very least, have once been home to one of the key elements to the development of life as we understand it, Water.

In 1877, Italian astronomer Giovanni Schiaparelli, was the first to suggest that water may have once flowed on the Martian surface, after observing what he described as canals or "Canali", crisscrossing the planet's surface. Years later, in 1895, astronomer Percival Lowell, concluded that Schiaparelli's canals, must have been the work of a once great Martian civilization. Though we all now know that no such civilization ever existed on the red planet, and that even the canals themselves don't actually exist. Today, the consensus amongst planetary scientists still seems to be that Mars was once a wet world, much more similar to our own than it is today.

Observations made in recent years during various missions to Mars, have revealed, amongst other things, the presence of Jarosite -a mineral formed in the presence of highly acidic water- as well as gypsum, and other water-based minerals on the Martian surface. In 2008, the Pheonix lander confirmed the presence of water ice just beneath the soil in the planet's southern hemisphere. And in August of last year, images from the HRISE camera on board the Mars Reconnaissance orbiter, seemed to suggest that small amounts of salt water might still be seeping out from just beneath the planets soil.

A series of dark trails were observed radiating down from the edges of steep slopes of Mars' Newton Basin crater in the planet's southern hemisphere. Evidence suggested those lines may have been created by small amounts of salt water -lying frozen on or just beneath the soil- melting in the heat of the sun, and then trickling down the basin slopes. However, no one actually saw the water itself and instruments on board the MRO also failed to detect the presence of water in the Martian atmosphere. So the actual cause of those mysterious dark lines, remains inconclusive.

But the most recent, and what is being described as the most unambiguous evidence yet seen for the presence of liquid water in Mars' past, came in December of last year with the announcement that the Opportunity rover had discovered a small vein of Gypsum (seen in the false-color image to the left) just above the bedrock around the rim of Mars' Endeavor crater. Unlike previous detections of the mineral in the loose sands of various dunes, this newly found deposit -which is only 16 - 20 inches long, and about the width of a human thumb- was found in a fixed state, right where it was originally formed. A fact which Opportunity's principal investigator Steve Squyres, referred to as a; "slam-dunk story that water flowed through underground fractures in the rock,".

Normally, this would be the part where I warn you not to get to excited about the implications of such findings. And like any other new scientific discovery, this one will require multiple confirmations before it truly becomes an accepted fact. But it does, to my completely uneducated eye, seem as though the Phoenix rover's latest find is in fact another major step towards the absolute confirmation of Mars' watery past. Which would obviously have profound implications where the potential for life on the red planet -past or present- is concerned. But then again, I know as much about geology, as I do the ancient Mongolian art of fish-juggling. Which is to say nothing, since I just made that whole fish-juggling thing up. So I guess we'll just have to wait and see.


Source: NASA/JPL
Image credits: NASA/JPL/Caltech/Cornel/ASU

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