Life on Mars? The Answer May Be in Antarctica

John Priscu, a microbial ecologist at Montana State University in Bozemann, has been studying extreme life forms on permanently ice-covered lakes in Antarctica since 1984. "It's the only place on the planet that environmental conditions are such that you get a permanent ice cover from 3 to 6 meters thick over liquid water," he says.

He began by studying how microbes carry out photosynthesis and how they grow. He found organisms that grow in sea ice at a temperature of about 35F. The McMurdo dry valleys, where Priscu works, are the largest ice-free region in Antarctica. "This is an area that has some barren soil -- much like you'd see on Mars," he says. The lakes in the bottom of the valleys "are 10,000 years old, and they are fed by glacial melt, in a real delicate balance with the atmosphere."

Gases in the ice were studied to determine the presence of life. "We found evidence with gas distribution that there was something happening in the ice," he remembers. Nitrous oxide should not have been present, but it was. A layer of sediment about two meters down in the ice appeared to be harboring life. "Further studies showed there was bacterial activity in there; photosynthesis by cyanobacteria primarily. These are ancient bacteria."

The soil is mostly bereft of microbes, because there isn't much water on the surface. But microbes that settle on the ice "melt their way down, and there's liquid water. They grow for about two or three months a year, and then they freeze again." He thinks that he will find life in at least one of the lakes he is studying, Lake Vostok. "There's liquid water. There are nutrients there. There's a feed coming in from the surface. People have identified microorganisms in the ice above it. ...I'm very optimistic that life is there."

The lake could contain scattered microbes, or more. "Some people think this depression the lake is in is a rift. If it's a rift area, you could have geothermal fluids coming in." The fluids would be warm and rich in nutrients, and they could spawn large, vibrant communities of various organisms.

Priscu's studies say something about the possibility of life on asteroids, comets, or other planets -- and especially Mars. "On Mars, it warms up to about minus 70, and that's not too different [from Antartica]," Priscu says.

Lake Vostok, under more than two miles of the east Antarctic ice sheet, is the size of Lake Ontario and 1,650 feet deep. The water it contains could be 1 million years old. "The lake hasn't been penetrated yet," he says. "We don't want to contaminate this lake. The lake could really replicate conditions you might see during the evolution of life on Earth, on Mars, or on Europa, one of the moons of Jupiter, where we know there's an ice sheet with water underneath it."

Does Priscu expect to find life on Mars, or Europa, one of Jupiter's moons?

"I think Mars is a really good chance. Because during the evolution of the planets, Mars and the Earth were very similar, created about 4.8 billion years ago. At that time, Mars had an atmosphere, and we see evidence of liquid water all over Mars. There are ravines, there's water ice on it. Mars lost its atmosphere because there is no plate tectonics to regenerate CO2. And it became a cold planet. So life could exist as fossils, or it may exist in ice, or down below the surface of the soils.

"Europa is another story. We know there were a lot of meteorites flying around, and that's when a lot of planets received their pockmarks. The thread that gives us hope in the case of Europa and some of the other moons of Jupiter is the fact that there is water on it. If you can give things water and minerals, from what we know on Earth, there's no sort of bar against life any more. It should happen. You need a seed -- either evolution from a primordial soup, like we think life formed on Earth, or it was transferred there, like in the lake I studied."

By Paul Raeburn

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11: Creatures on the Fringe Hold Secrets of Life

ONLINE ORIGINAL: Life on Mars? The Answer May Be in Antarctica

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