The cave that holds clues to life on Mars.

TO ENTER Lechuguilla Cave, first you secure a special permit and then hike into a remote desert canyon near Carlsbad, New Mexico. Then you rappel down a 90-foot rock face to a ledge, where you squeeze down a crevice into a small chamber. In the chamber is a 30-foot metal culvert--installed after the marvels of this place were discovered 12 years ago--with a hatch to keep out contamination from the surface. On the other side of the culvert lies the deepest cave in the continental United States, with arguably the most exotic (and creatively named) underground chambers in the world.

After a staircase of short climbs and rope drops, you lower yourself 160 feet from the Colorado Room through a black void to Pack's Peak, where researchers sometimes leave backpacks. You hike past Rim City and Glacier Bay, a honeycomb of etched gypsum, Windy City and Sugar Lands. You pause to catch your breath before Freak Out Traverse, the only way across a 100- foot abyss. At E-F junction, take the right turn to F Survey and scramble along passages lined with white gypsum crystals and through a tight crystal fissure called The Little White Bastard, to Lake LaBarge. Tiptoe around the edge and continue through another passage to the blue-green waters of Lake Chandalar. If you then drop down the LaBarge Bore Hole and travel the Yellow Brick Road, you'll find Tinseltown Maze and the Chandelier Ballroom.

From there, you can take the trail to Briny Pool. That's where you'll find a man bent over a small puddle, extracting samples with a 60-cc syringe. His name is Larry Mallory, and he's looking for life on Mars and a cure for cancer.

An entrepreneurial microbial ecologist with an academic background as a University of Massachusetts professor, Mallory has descended into this cave to find, study and figure out how to make use of tiny life forms. Unlike most caves, no water flows here, and no bats or insects bring in organic matter. That means almost no nutrients are transported in from above ground. So, until recently, researchers considered this place to be virtually sterile. But now, along with many of our planet's other seemingly inhospitable frontiers--such as hydrothermal vents on the ocean floor, Yellowstone Park's hot springs and the frozen plains of Antarctica- -Lechuguilla is surprising researchers with insights into life on this planet and possibly beyond.

For a handful of pioneering scientists, including Mallory, "beyond" really does mean Mars, the next planet beyond Earth away from the sun. Much of the research is being funded by the National Aeronautics and Space Administration (NASA), as part of a project devoted to examining the possibility of life on Mars. "We've been doing research in a general class of what are called 'Earth analogs,'" explains Chris McKay, research scientist at NASA Ames Research Center in California and one of the project's principle investigators. "We go to extreme places on Earth, study the life forms there, hopefully learn how they survive and apply that knowledge to Mars."

Four billion years ago, Mars and Earth had very similar climates and atmospheres. Geological structures on the Martian surface, such as channels and sedimentary rocks, suggest there was a significant amount of water. When the Martian climate experienced a radical cooling trend somewhere around three and a half billion years ago, the water would have frozen. The Martian atmosphere eventually thinned and let in ultraviolet light that probably killed life on the surface, leaving it effectively sterile. Analysis of meteorites indicates there may have been liquid water and possibly volcanic activity on Mars as recently as 100 million years ago--or almost yesterday, in geologic time.

Might there still be water underground on Mars helping to sustain subterranean life similar to ours? The answer could lie in the microbes Mallory and other researchers are studying--though it's hard at first to see how the simple questions Mallory asks in his daily work could lead him to life on another planet. "Are there microbes?" he starts out. "If so, how many bugs? A few? Many? Lots and lots? Are they active? Are they alive, viable, doing something? How many different types are there?" He sums up: "Basic questions."

Basic they may be, but they are also wonderfully clever, in that few other people have ever bothered to ask such questions in the new environments attracting microbiologists' attention. Mallory and his colleagues have found life in sedimentary rock, sandstone, limestone and even in lava tubes. Cave bacteria can be extremely hungry; researchers in one tropical cave watched their boots and gloves turn to soup in a matter of days as bacteria consumed the leather. Such bacteria clearly thrive on organic matter.

What about bacteria in a cave almost no organic nutrients: What do they eat? In recent years, Lechuguilla has turned out to be a perfect place to answer that question. Although the cave's entrance was discovered at least a century ago, the extent of what lay below was not even guessed at until 1984. That's when curious cavers dug through a thick layer of bat guano and were greeted with a blast of wind from the chambers below, which turned out to extend to 1,593 feet. The cave is now protected by an act of Congress, and only qualified cavers and scientists can enter.

Lechuguilla is comprised of what NASA's McKay calls "a giant carbonate reef" of calcium generated over millions of years by plants near an ocean shore that once existed in what is now New Mexico. "The result was a big chunk of chalk, essentially, sitting here in the middle of this desert," says McKay. "On Mars, we think there are huge carbonate deposits just like the Guadalupe Mountains, formed maybe by biology or maybe independent of biology. There's probably also acid on Mars, because we see a lot of sulfur, and we see acidic conditions in the soil. It's logical that there could be acid-carved caves in the limestone deposits."

Mallory and other researchers in Lechuguilla have discovered bacteria that, amazingly, oxidize minerals in a process called chemolithotrophy (which translates to eating of rocks). The evidence, says Mallory, "strongly suggests" the organisms derive energy from the rocks. In a similar phenomenon, scientists studying volcanic thermal vents on the ocean floor, where sunlight can't reach, have found organisms oxidizing sulfur in the water. There is sulfur in Lechuguilla too, as the cave was created not by surface water trickling down from above, but by acid bubbling up from below. Its cavities were excavated by sulfuric acid released from petroleum deposits perhaps 250 million years ago.

The pools Mallory and other researchers sample from are so lacking in floating particles, and therefore so clear, that you literally can't see the water. Yet where there is water, there is life.

Mallory has found bacteria able to oxidize manganese and iron, and possibly sulfur, all of which are present on Mars. These days, he is most interested in microorganisms that consume the trace amounts of organic matter in the cave, which raises the question of where that matter comes from. Scientists don't know for sure, but they speculate it is produced by the "rock-eating" bacteria, which do generate organic matter as they oxidize minerals.

Researchers have also found what may be microbe fossils: U-shaped tubes thought to be the residue of bacterial colonies and large deposits of what might be bacteria-digested dolomite. The red-gray, meringuelike substance ices some of the cave's surfaces and ledges like cake frosting, from a millimeter to several inches thick, and is so frangible you could cut it with a butter knife. "These things might exist elsewhere," says Mallory, "but the reason we're using caves is simply that the cave is the best way to deliver the researcher to the bugs. You can drill core samples, but the heat you produce by drilling can alter the results. There are also no eyes on a drill."

Microbes on Mars would have to be able to survive intense cold. "Bacteria are really different from the rest of us," says Penelope Boston, McKay's co-principle investigator in the NASA project and a biologist with Complex Systems, a NASA contractor in Boulder, Colorado. "We're all based on the same genetic material, but bacteria have one foot in biology and one foot in chemistry. Bacteria can be freeze dried; in fact, that's the conventional way of storing them. If the internal constituents remain undamaged, you can rehydrate them, put them in conditions they like, and bang, you got bugs. And on Mars, the chances of subterranean or cave bacteria being hit by solar radiation and damaged is minimal."

Reviving dormant bacteria on Mars could tell us what life was like on the red planet a hundred million years ago, but mention the idea to fans of the movies Outbreak or The Andromeda Strain, and it can seem unwise. What if, however, the bugs were actually useful? That's what a cave specialist from the National Park Service asked Mallory a few years ago while the two men were on a trail in Lechuguilla's silent depths. Recalls Mallory, "He said, just off the top of his head, 'What are these microbes good for?' I said, 'Who knows? I didn't know there was a reason to think they were good for anything.' He said, 'Well, maybe they cure cancer?' I said, 'Well, they might.' Then I got a phone call from a man named Jim Bigelow."

Bigelow is a pharmacology researcher at the Vermont Cancer Center and the University of Vermont Medical School. He is also a recreational caver who, acting on something between a hunch and a hypothesis, performed a computer search to look for microbiologists working in caves. The computer kicked back Larry Mallory's name.

Says Bigelow, "I'd read an old 1976 text book that said cave bacteria are essentially the same as surface bacteria. I didn't believe that. There's a large group of bacteria which produce the volatile compounds that smell earthy in good soil. Caves smell very earthy. It occurred to me that it might be a good place to look for pharmacological agents." As the cave bacteria compete with each another, they give off byproducts that could be toxic substances warding off intruding bacteria or viruses--much the way bread mold produces penicillin.

Bigelow has been testing microbes from another cave against cancer cells in test tubes, with some promising, though very preliminary, results. "Once you know what kills cancer cells," he explains, "you have to isolate a chemically pure bacterial product, figure out how it works, what else it kills, how it moves in the body, how long it remains effective, how much of it you need. These steps are all part of the long road of drug development. You want to kill the cancer but not the patient." He adds, "The nice thing about developing a drug from bacteria is you don't worry about depleting a species. All you need is one."

Mallory hopes to isolate and culture thousands of new strains of bacteria, all of which can eventually be tested for their medicinal properties. The prospects are exciting enough that Mallory left his university position to join Bigelow in forming a private company called Biomes Inc. Their goal is to develop drugs and possible treatments for cancer and other illnesses. "When you're in academia," says Mallory, "you always have it in the back of your mind that you would like to help people with your research. I've put in years and years of learning that, hey, there are bugs underground. But then to find out that maybe one or two of these bugs could be used as a kind of cancer treatment: Well, that's very exciting."

And it's a bit premature to speculate, but if we ever run out of microbes on this planet, the bright red planet nearby could be full of microbes to exploit. The next Martian probe, scheduled for 1997, jointly sponsored by the United States and Russia, will examine only surface soils, but McKay hopes to have a drill included on a subsequent mission. Unlike on Earth, surface contaminants aren't a problem on the barren outside skin of Mars.

A cure for cancer coming from Mars?

Preposterous.

But it sure would beat a discovery of those legendary little green men.

Although Massachusetts, writer Peter Nelson enjoys writing about caves, he prefers life above ground. Massachusetts photographer Kevin Downey, on the other hand, travels the world to explore and photograph caves. His work is included in Lechuguilla: Jewel of the Underground (Speleo Projects, 1991).

Sound farfetched? Then why is NASA so interested in the strange microbes researchers are discovering under a New Mexico desert?

DEEP IN Lechuguilla Cave, a researcher ponders slots carved millions of years ago by dripping sulfuric acid. Though the cave was formed by acid bubbling up from below, here gases condensed on the chamber's ceiling and then rained down. Scientists think Mars may also hold caves carved by sulfuric acid. On Earth, almost all other caves are formed by flowing water.

"We go to extreme places on Earth, study the life forms there, hopefully learn how they survive and apply that knowledge to Mars."

AT THE LAKE of the Blue Giants, a caver can't discern the water depth. As at other pools within Lechuguilla, the water holds none of the small particles that usually help us "see" liquid. But water still makes life possible here, and scientists have found bacteria that oxidize and may derive energy from manganese, iron and possibly sulfur--all of which exist on Mars.

How Big Is Lechuguilla?

To gauge Lechuguilla's size, scientists have used measurements of the amount of air entering and leaving the single known entrance in reaction to changes in barometric pressure outside. The cave's estimated volume of air would fill a 10-foot by 20-foot structure extending as far as 600 miles. In real terms, Lechuguilla has perhaps 80 miles of passages. Mammoth Cave in Kentucky, the largest in the world, has about 350 miles of known passages, a figure that may eventually reach 500 miles.

ONCE SUBMERGED in a mineral-rich pool, two stalactite tips (far35 left) became encrusted as the water dried. When the three ingredients of air, water and mineral met, the 36tips may have hosted microbial life.

THE BLACK line (arrows, top left) at a pool edge contains bacteria35 and fungi living on tiny amounts of organic matter. Researchers suggest that the nutrients are byproducts of bacteria that oxidize minerals.

SCIENTISTS THINK these "U tubes" (left), found near a pool, are likely 35 the residue of former bacterial colonies. Elsewhere in the cave are other such remnants of microbial life, in various exotic forms.

"The nice thing about developing a drug from bacteria is you don't worry about depleting a species. All you need is one."

SURROUNDED BY the large gypsum crystals of the Chandelier Ballroom, 35 about 1,000 feet below the entrance, a caver helps give a sense of scale to the extraordinary structures. Passing through exotic chambers like this one in the utter silence, scientists contemplate not only clues to life on Mars but also how they may lead to drugs to fight cancer and other diseases on Earth.

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Title Annotation:	Lechuguilla Cave in New Mexico
Author:	Nelson, Peter
Publication:	National Wildlife
Date:	Aug 1, 1996
Words:	2531
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Topics:	Bacteria Research Caves Research Mars (Planet) Natural history