Water, water everywhere

December 07, 2004

HAS GEOLOGY ever been more inspiring? Suddenly, a handful of rocks can fire the imagination. It helps, of course, that the rocks in question come from a crater on Mars.

Maybe you missed the news, but in an article published Friday, government scientists say rocks examined by NASA's Mars rovers are sedimentary. That means they accumulated layer by layer in water. That's right, water. Good old two parts hydrogen and one part oxygen. The rocks prove beyond a doubt that the red planet used to have water like Earth has water -- and not just the frozen stuff, but in liquid form, too.

The authors aren't certain how the water got there, but they suspect it was present hundreds of thousands of years ago. It might have covered tens of thousands of square miles. The water was very salty and exceedingly cold. But here's the significance of this discovery: Water is one of the crucial elements of life. Other such building blocks exist on Mars -- carbon, oxygen, nitrogen. Evidence of the chemical methane, another potential organic indicator, has also been found. The case for life on Mars has never been stronger.

If life does exist on Mars, it might be no more than ancient fossils or microbes. But that's still the stuff of science fiction. Indeed, the possibility of life on Mars is now so great that the article recommends that steps be taken to avoid cross-contamination between Earth and Mars. Microbes may have piggybacked from Earth by way of NASA's rovers. Martian microbes could pose a threat to Earth if samples are ever brought here.

In his classic The Martian Chronicles, author Ray Bradbury wrote of standing on the edge of an empty "fossil sea." That was 60 years ago. Today, on the Jet Propulsion Laboratory's Web site, one can see that empty sea, or at least the ripples in the landscape that rise like ocean whitecaps along the Martian soil. The dusty contours are broken only by the tracks of the rover's wheels. Mr. Bradbury must be proud.

If life could exist on our neighboring planet, then what are the chances that life may exist elsewhere, too? Perhaps the rovers won't find life, but what if they do? Then perhaps, as Jeffrey Kargel of the U.S. Geological Survey writes, we can forever set aside the view that places Earth and its life at the center of the universe. We can develop a whole new appreciation for what we have -- and what forms of life may exist on other worlds, too.

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