Geekathon, part three

There are good days and there are bad days. WorldScience.net has some news from a bad day:

Scientists have dreamed of finding evidence for past life on Mars, where they believe there was once plenty of liquid water. But now they’re saying it might have been too salty.

“Not all water is fit to drink,” said Andrew Knoll, a Harvard University biologist who is on the science team for the NASA Mars rover Opportunity.

High concentrations of dissolved minerals as well as acids may have thwarted microbes from developing on the red planet, he added. ...

Opportunity spent recent months examining a bright band of rocks around the inner wall of a crater in the planet’s Terra Meridiani region. The crater turned out to lie atop an underground water table, according to scientists. Knoll said the rover - which serves as a robotic geologist - found that the water, which once covered the area, left behind evidence of its high acidity and salinity.

“This tightens the noose on the possibility of life,” considering salt is a preservative, he added. Conditions may have been more hospitable earlier, with water less briny, Knoll said. But “life at the Martian surface would have been very challenging for the last 4 billion years. The best hopes for a story of life on Mars are at environments we haven’t studied yet - older ones, subsurface ones.”

On the other hand, as I mentioned just the other day, we keep finding life in places we previously thought impossible - including a lake in California with water three times saltier than sea water but which still contains an ecosystem including microbes, plankton, and small shrimp. So it does tighten the noose, but it by no means chokes off the possibility.

And, of course, the real purpose is not to find life but to learn and discover what we can, whatever the answers to any of the questions turn out to be. It's just that finding life somewhere else would be really, really, really cool.

Footnote: Opportunity and Spirit rovers have now lasted 16 times longer than their planned mission. They began their fifth year on Mars last month.

Footnote to the footnote: The Phoenix lander is on schedule to enter Mars' atmosphere on May 25.