Learning About Life on Mars, via a Detour to a Desert in Mexico Karla Zabludovsky - New York Times
go to original June 27, 2012

Researchers preparing to take samples of sediment in a pool of water in the desert near Cuatro Ciénegas, Mexico. The samples may give clues to how Mars has changed over billions of years. (Rodrigo Cruz/New York Times)

CUATRO CIÉNEGAS, Mexico — Studying Mars usually involves tilting one’s head up toward the heavens, but not here in the Chihuahuan Desert, where the vast, scorching plain is so inhospitable — and so Mars-like — that scientists seeking insight into that distant planet look down at their feet.

Largely arid and extremely hostile, Cuatro Ciénegas is inhabited by organisms able to survive on few nutrients, high salinity, soaring temperatures and high ultraviolet radiation. Scientists say such an environment resembles that of Mars billions of years ago.

And the gypsum dunes in the valley, blindingly white in the afternoon sun, are not unlike the Gale crater on present-day Mars, where NASA’s Curiosity rover is scheduled to land in August, scientists say.

A team of researchers piled into a caravan of off-road vehicles last month and drove for hours across the valley, in the northern Mexican state of Coahuila. They searched for the pockets of water that may house their study subjects: microbes, bacteria and fish that survived in an environment similar to one scientists say Mars once had.

No water in sight.

But then, like a mirage in the desert, an archipelago of scattered lagoons sprouted from the ground. Some had cerulean-tinted water beckoning the heat-stricken group; others were foul-smelling, crimson muddy dumps. A few were the size of Olympic pools; others were no bigger than puddles one might find on the street.

Cauliflower-like structures filled several of these ancient pools. These fossils called stromatolites, vestiges of the earliest Earth microbes, could provide insight into the possibility that life arose on early Mars when it was warmer and wetter, scientists say.

“If we understand the origins of these ecosystems, we can extrapolate them and develop them in other planets,” said German Bonilla, a doctoral student at the National Autonomous University of Mexico, as he held down the outstretched legs of a colleague leaning over a lagoon to collect samples.

But just as water on Mars eventually ebbed, the water in Cuatro Ciénegas, which some scientists say has biological diversity rivaling that of the Galápagos Islands, is under threat.

Experts and activists working in the region say that local farmers, stockbreeders and other landowners, aided by a lack of oversight from the government, have free access to the waters of Cuatro Ciénegas, which are recognized internationally as important wetlands.

“The problem is that they have no way to measure how much water they extract,” said Arturo Contreras, director of the Cuatro Ciénegas Center for Scientific Investigation, a research station affiliated with the University of Texas. “We believe that the majority takes out more water than they are entitled to.”

Evan Carson, a biologist at the University of New Mexico, had a dejected air about him as he walked around sparse shrubs, carrying a fishnet. Dr. Carson studies the recovery of fish here, but had little to inspect.

“We used to swim here,” said Valeria Souza, a scientist with the National Autonomous University of Mexico, as she walked over a gypsum field with cracks cutting through the dry ground like deep scars.

Mexican authorities have been trying to reach a long-term solution that would satisfy both the researchers and the landowners and rectify an uneasy coexistence.

The government designated the valley a protected area in 1994. It was not until 2007 that President Felipe Calderón took the first steps toward limiting water extraction in the region. He is expected to sign a broader ban in the coming months.

As it is now, water level markers stick out of the ground like misplaced hairpins throughout the valley, left there by scientists tracking changes in the size of some of the pools.

Scientists who work in Cuatro Ciénegas say that with budget cuts in space exploration, which most likely means fewer spacecraft going to Mars in the coming years, research on Earth is increasingly important.

“If we know what to look for based on our study at Cuatro Ciénegas basin, then our Mars missions will be more prepared to identify signs of life,” said Sherry L. Cady, editor in chief of the journal Astrobiology, which plans an edition dedicated to Cuatro Ciénegas this summer.

The Cuatro Ciénegas region is prone to drastic climate changes — a hurricane flooded the valley in 2010 — but experts agree that last year marked a record low in the water level.

“The ecosystem has lost its resilience,” Dr. Souza said. “It’s very damaged now.”

Dr. Carson, the biologist studying fish, said it was too soon to tell how much had been lost, but warned that the system may have already collapsed.

During a recent afternoon, the scientists, leaving their gloves and notebooks behind, gathered by one of the blue-green lagoons to admire the deep pink and purple hues above the setting sun. As Dr. Carson marveled at the beauty, he was unable to shake off a sense of impending dread.

“There’s an irony,” he said, “to the sunsets here.”

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