Searching for a microscopic E.T.

Norman Pace strides across his office and returns with a small rock plucked from the frigid wastes of Antarctica. The University of Colorado biologist, who is credited with finding organic life in some of the harshest places on Earth, turns the stone in his hand and says, "A fundamental question is whether there is photosynthesis going on, on the surface of Mars," itself a frosty wasteland.

"If there is life on Mars, this is what you're going to see," says Dr. Pace, pointing to a colored layer in the rock, once home to millions of microorganisms.

Speculation about life beyond Earth has been fueled in recent years by the Galileo spacecraft's detailed images of Jupiter's icy moon Europa and by microscopic lumps on a meteorite, interpreted by some scientists as fossilized evidence of past microbial life on Mars.

In late June, planetary scientists displayed detailed Mars Global Surveyor photos of the red planet suggesting that water - either as a liquid, ice, or a mixture of ice and carbon dioxide - has carved channels into the sides of Martian craters and canyons within the past 1 million to 2 million years. If the results hold up, they would suggest that large amounts of water - critical for organic life - might still lie near the Martian surface.

And if life on Mars proves a bust, try Europa. In April, Richard Greenberg of the University of Arizona's Lunar and Planetary Laboratory, described at meeting of astrobiologists how recent images of Europa, combined with computer simulations, indicate that tidal forces acting on the moon raise the ridges seen on the icy crust by "pumping fluid and slush to the surface on a daily basis," in the process forming "a variety of habitable environments."

Many of these announcements are as much products of "spin" by the National Aeronautics and Space Administration (NASA) as they are of science, according to Pace, a co-investigator at the university's Astrobiology Institute and a member of the National Academy of Science's Committee on the Origins and Evolution of Life.

But, he adds, the science of astrobiology is advancing - driven by an increasing appreciation of the diversity of habitats on Earth. "Over the past 20 years, and particularly in the past 10 years, it has become evident that life is rich in many places we once thought to be sterile," he explains in an interview. "Wherever conditions are appropriate, life can make it, potentially."

Those conditions, he says, include temperatures that can range from minus 58 degrees F. to 248 degrees F., and liquid water, because "water enters into many, perhaps most, biological reactions," he says. Water either is split to condense molecules or is introduced to break down molecules. "Beyond that, you need thermodynamics: You've got to have something to eat, and you've got to have something to breathe. Life is in the business of capturing energy and transferring that energy into chemistry."

For a walk on the wild side, he suggests microorganisms associated with deep-sea hydrothermal vents, found along ridges where magma wells up from Earth's mantle to form new crust.

In the faults and fissures where seawater circulates, "What is there to eat? You have hydrogen," he says, describing how hydrogen mixes with sulfides in seawater to form hydrogen sulfide. "Many organisms can breathe oxygen from seawater and eat hydrogen sulfide." Others eat hydrogen and breathe carbon dioxide.

"This is the world of hydrogen-driven chemistry, not carbon-driven chemistry like we are," Pace says. "When you begin to think in these terms, and when you look around the planet and see where life is, these aren't extremes; they're just another way of doing things."

Now shift to Mars. While the planet has no plate tectonics, Pace says, there is water in the rock and soil that overlays Martian bedrock. Moreover, the planet has vast shield volcanoes. "That means that somewhere down there, there's a magma dome," a source of energy. "You're going to have hydrogen, you're going to have carbon dioxide. You're going to have all the stuff that life needs, in principle."

Teasing out data relevant to the question of life on Mars will be hard, Pace says. Despite its Mars exploration program, NASA doesn't have missions on its agenda that he sees as cutting to the chase.

One such effort, he says, should include a mapping satellite that could spot features as small as a yard across - perhaps down to 8 inches - and whose camera could be steered more widely than the camera on the Mars Global Surveyor now orbiting Mars. The imaging technology exists, he says, but it resides with the US military.

With that level of resolution, he says, it's feasible to design instruments that can scan the surface at wavelengths of light suited to picking up telltale signs of microbial pigments. Such surveys could then give researchers the "targets" they need to send penetrators into the surface.

Pace acknowledges that NASA's Mars program is "doing important things." But the Mars Global Surveyor was "kludged together" and is underfunded, he says, adding that the International Space Station is diverting money from the program.

NASA's "virtual" Astrobiology Institute, which sponsors programs at 11 NASA centers and universities, including the University of Colorado, is funded at about $11 million a year, Pace notes - not enough to support the new faculty and new courses NASA wants at existing institutes, let alone the three new ones the agency is seeking.

As for the Mars program, "the bottom line is that the program is capped at $550 million a year for the next decade. Half a billion dollars is not small fries," Pace says. "It's just not enough."

(c) Copyright 2000. The Christian Science Publishing Society

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