Newspaper article Pittsburgh Post-Gazette (Pittsburgh, PA)

Looking for Life on Mars Nasa's Evidence of Liquid Water on the Planet Helps Confirm Duquesne University's Research on How Microbes Can Survive by Metabolizing Arsenic Instead of Oxygen

Newspaper article Pittsburgh Post-Gazette (Pittsburgh, PA)

Looking for Life on Mars Nasa's Evidence of Liquid Water on the Planet Helps Confirm Duquesne University's Research on How Microbes Can Survive by Metabolizing Arsenic Instead of Oxygen

Article excerpt

John F. Stolz was thrilled when NASA announced last week that there's evidence of liquid water on Mars. It raises the plausibility that life exists, or perhaps once existed, on our closest planetary neighbor.

"Microbes can survive without oxygen as long as they are provided an alternative," said Mr. Stolz, who holds a Ph.D. in biology. "But nothing can survive without water."

And that's where the Duquesne University geomicrobiologist and director of the university's Center for Environmental Research and Education steps in. For 20 years, with NASA funding, he and Ronald Oremland, a geomicrobiologist in California with the U.S. Geological Survey, have been studying how microbes can survive by breathing and metabolizing arsenic rather than oxygen.

Such bacteria or microbes sustained by arsenic, selenium or perchlorate could survive Mars' extreme conditions that pose severe challenges to life.

"You won't see herds of elephants tromping around on Mars," Mr. Oremland said. "The term we come up with is that it's habitable. But that doesn't mean it's inhabited. It is possible for microbes that can sustain extreme environments, but no pythons."

Dribbles of brine

The NASA study published Sept. 28 in Nature Geoscience announced that it discovered water on Mars based on satellite analysis of rills and rivulets running down Martian slopes that weren't previously seen. That indicates water is ever present there, although the source remains unclear.

Spectrum analysis also found the water to be a brine containing forms of perchlorate, a chlorine salt. That gave Mr. Stolz another reason to celebrate. Research already reveals how certain microbes breathe and metabolize perchlorate, which would be toxic to nearly all other life forms on Earth. But its presence in the water provides another scenario where microbes not requiring oxygen could be living on Mars.

Nora Noffke of Old Dominion University, who's worked with Mr. Stolz, published a study in December identifying Martian rock forms she says could represent mineralized and fossilized microbial mats. She was first to discover such mats in sedimentary rock on Earth. "There is a high chance of fossil microbes in the rocks," she said.

But life as we know it isn't possible without liquid water, even if what NASA discovered is what Mr. Oremland described as "dribbles of dense, nasty brine."

"For us," Mr. Stolz said, "what is really exciting is that this means that there could definitely be life there or at least in the past, and we haven't been toiling in vain."

Tough place to live

When scientists speak of life on Mars, they aren't referring to humanoid Martians of "War of the Worlds" fame, or even creatures the size of mice, cockroaches or gnats. Microbes, if they exist at all, would be at the top of the planet's family tree.

But such microbes would have evolved under extremely harsh conditions, especially after catastrophic events early in Martian history caused its oceans and atmosphere to disappear, leaving today a barren planet with a scant atmosphere.

"Mars is at the extreme of permissible life as we know it," said Mr. Oremland, who holds a Ph.D. in marine sciences. "It is a cold place that's half the diameter of Earth, and that tells us quite a lot. It might be Earth-like superficially, but if you do your high school geometry, it's 12 percent of the mass of Earth, and that means Mars got the short end of the stick. …

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