Exploring life at the core

Cave teeming with microbes makes case for life on Mars

Sue Vorenberg | The New Mexican

3/27/2008 - 3/27/08

With ice strapped to the interior of her bright orange suit and breathing refrigerated air through a face mask in the 140-degree heat, cave scientist Penny Boston was on the hunt for life, miles below the Earth's surface.

She walked up giant gypsum crystals that were easily three times her height, gathering samples from the cavern at the bottom of a mine in Naica, Chihuahua, Mexico.

It might look like a scene from the science fiction film The Core, but the surreal landscape holds science facts about how creatures can live in some of the harshest environments, not just on Earth, but in space.

And that's what Boston, head of the Cave and Karst program at New Mexico Tech, was looking for, and what she brought back to New Mexico.

"I didn't go there with any expectations, but it turns out we found microbial remains, and I believe there was and possibly still are live materials in parts of those crystals," Boston said.

The cave, which looks a little like the center of a geode, is hot because it's closer to molten lava circulating deep in the Earth.

You can stand there for about 5 minutes without gear on, but it's not something Boston said she'd recommend.

"Even with the ice pack around your core and in your helmet, you can't stay in that long," Boston said. "Your arms are exposed, and your limbs get baked. It hurts your hands and it hurts your face."

The longest she spent inside the cavern was 52 minutes — when she was digging at a particularly interesting rock sample, she said.

"That was way too long," she said with a laugh.

Boston and her fellow scientists had to leave the cave for two hours between each typically 40-minute trip as part of the safety precautions, but she just didn't want to wait two hours for that sample, she said.

The cave and its crystals likely formed millions of years ago, when a pocket in a limestone rock bed underground cracked and as a pool of lava rose beneath it. Afterward, hot water flowing underground seeped into those cracks from several directions, she said.

"That stuff is a stew of minerals and metals," Boston said. "It makes perfect conditions to grow these giant gypsum crystals."

It's also a place you might not expect to find life, but life finds a way to seep into some pretty strange environments, said Diana Northup, a biology professor at The University of New Mexico, who is investigating some of the samples Boston brought back.

"You find some of these organisms, called extremophiles, like to live in extreme hot or extreme cold," Northup said. "They eat all sorts of things to produce energy. In the cave in Mexico, they eat sulfide and pee sulfuric acid. We're fairly mundane as people compared to the organisms we find in environments like Naica."

Northup is analyzing DNA from critters found in tiny liquid pockets inside crystals that Boston brought back from the cave, but she doesn't yet have results.

She's hoping to find genetic proof of some new species, new genus of bacteria, extremophiles and other life, she said.

"We're hoping we find novel species," Northup said. "Which is a good bet."

In Lechuguilla Cave, near Carlsbad, which has many similarities to Naica, Boston and Northup found a whole new family of critters, which is a pretty big deal in the scientific world, Northup said.

"With that family, we found their closest relatives are from South African gold mines, which is pretty interesting," Northup said, noting that DNA profiles let scientists track a creature's family history.

And the study of creatures that live in extreme environments is important because it can lead to new products, like antibiotics or construction materials and even ways to clean up nuclear waste — which some microbes actually eat, she said.

And there are more unknown microbes out there than any other kind of life, she said.

"People always talk about the Amazon as a place for unparalleled diversity," Northup said. "But it turns out the world is actually dominated by microorganisms, and we don't know most of them."

The study of extremophiles also makes a strong case that life has evolved in other places in the solar system, such as on Mars, Boston said.

"Mars has a lot of sulfur on its surface," Boston said. "Finding creatures in acidic, sulfur-rich waters makes the case for microbial life on Mars stronger and stronger."

Recent news that there are salt lakes on Mars also makes life on that planet look more probable, she said.

"All this information is pointing in the same direction," Boston said. "Either there are still critters there, or at least if they evolved in the past they should be preserved. I think finding these systems is certainly heartening."

Contact Sue Vorenberg at 986-3072 or svorenberg@sfnewmexican.com.