By Marc Kaufman
Washington Post Staff Writer
Sunday, February 27, 2011; W18
If it's just us in this universe, what a terrible waste of space. For thousands of years, humans have wondered about who and what might be living beyond the confines of our planet: gods, beneficent or angry; a heaven full of sinners long forgiven; creatures as large and strange as our imagination.
Some scientists now are on the cusp of bringing those musings back to Earth and recasting our humanity yet again. "Astrobiology" is the name of their young but fast-growing field, which immodestly seeks to identify life throughout the universe, partly by determining how it began on our planet. The men and women of astrobiology -- an iconoclastic lot, quite unlike the caricatures of geeks in white lab coats or UFO-crazed conspiracy theorists -- are driven by a confidence that extraterrestrial creatures are there to be found, if only we could learn how to find them. Most astrobiologists hold the conviction that if a form of independently evolved life, even the tiniest microbe, is detected below the surface of Mars or of one of Jupiter or Saturn's larger moons, the odds that life does exist elsewhere in our galaxy and, potentially, in billions of others, shoot up dramatically. A solar system that produces one genesis -- ours -- might be an anomaly. A single solar system that produces two or more geneses tells us that life can begin and evolve whenever and wherever conditions allow, and that extraterrestrial life may well be an intergalactic commonplace.
With goals so enormous and compelling, astrobiology has brought forth a new generation of outside-the-box researchers, field scientists, adventurers and thinkers -- part Carl Sagan, part Indiana Jones, part Watson and Crick, part "CSI: Mars." They are men and women who drop deep below the surface of Earth or tunnel into Antarctic glaciers in search of life in the most extreme places, who probe volcanoes for clues into how Earthly life began, who propel life-detecting robots into deep space and who will ultimately send colleagues to other planets. These explorers come up with ever more ingenious methods for detecting planets that circle distant suns; they scour our planet for Mars-like habitats they can minutely study for the life-supporting conditions astronauts might encounter when our spaceships arrive there. They probe the cosmos as far as 13 billion light-years away for signs of the earliest stirrings of the order and chemistry that created life on Earth. Some are even working to define and understand "life" by creating it in the lab.
These scientists have harnessed that childhood excitement so many of us felt when, on hot, hard-to-sleep summer nights, we tried to imagine what it would be like to visit Mars (very dry), or travel to the end of the universe (very confusing), be around when life first began (very lonely), or come across extraterrestrial life (most thrilling of all). The world has changed enough that today, a large and growing number of scientists are earning their livelihoods turning their imaginings into hypotheses and putting them to tests inconceivable even a decade ago.
Science moves ahead on hunches. Tullis Onstott, a Princeton University geobiologist, first descended into a South African gold mine on a hunch in 1996, using $6,000 of his own money and carrying, instead of the usual pickaxes and dynamite, a small hammer, a chisel, some vials for collecting water, and some sterilized bags for collecting rocks. Over the next decade, he and his fellow mine divers found microbes that broke nearly every rule of life. Until then, it was taken as scientific fact that to survive, a creature needs an energy source and an environment that isn't extremely hot or cold; isn't overly acidic, alkaline or salty; isn't suffused with radiation; or isn't under great pressure. Creatures also need to reproduce or split with some regularity. On his first trip into the mines, On-stott found microbes living as far down as two miles that struck out on virtually all of these counts. His prized discovery, made a few years later and confirmed in 2006, was of a bacterium nourished by food -- molecules, actually -- split apart by energy released by the radioactive decay of surrounding rocks. The microbe also needs some minerals to survive and some water, which is hidden from human view until miners open up tunnels and bore holes, tapping into underground lakes, streams and even tiny fissures within the rocks. Not only do these microbes live and move around miles below the surface, but also they seem to split -- that is, reproduce -- as seldom as once a century.
A reading of the genome of Onstott's astounding bacterium, as well as analysis of the "age" of the water that is often its home, says that the microbe has not seen the light of day, or interacted with anything produced from sunlight, for perhaps up to 40 million years. But it has DNA, reproduces and is clearly alive. The researchers who sequenced its genome found that the microbe has highly unusual abilities to take in needed carbon and nitrogen from nonliving sources -- very useful abilities, given the absence of carbon-based life in its isolated and unrelentingly harsh environment. It even had genes for a tail of sorts, a whiplike growth that would allow it to swim to hidden sources of nourishment. The bug, Onstott concluded, is widespread in a 130-mile-long subterranean region of the gold belt of South Africa. To honor the creature and the world to which it long ago traveled and made its home, the team (co-directed by geologist Lisa Pratt of Indiana University) sought a name in line with the achievement -- first of the bug's existence, and then their discovery of it. They found it in the secret Latin inscription on a scrap of parchment that Professor von Hardwigg, hero of the Jules Verne classic "A Journey to the Center of the Earth," comes across at the beginning of the book. The parchment directs him to a volcano in Iceland and tells him: Descende, audax viator, et terrestre centrum attinges (Descend, bold traveler, and you will attain the center of the Earth). And so the world was introduced to Desulforudis audaxviator, extremophile par excellence.
South Africa is today the center of Onstott's research not because similar microbial life doesn't exist far below New York or London or Tokyo, but simply because it is where the deepest mines have been dug. Onstott had first explored the deep underground for microbes as part of a Department of Energy drilling program in Savannah, Ga., and later at a Texaco well site in western Virginia. Frustrated by his limited results and fearing contamination in his samples, he cast around for alternatives and landed on South Africa's gold, platinum and diamond mines -- with shafts descending two miles and more. But mine owners were reluctant to let strangers into their domains. It took Onstott and others two years of negotiating to get into the mines to later achieve their breakthroughs. Today, he and Esta van Heerden, the head of the Extreme Biochemistry research group at the University of the Free State in Bloemfontein, have won the confidence of the people who run many of the mines of the Witwatersrand Basin, the most productive in the world. When a potentially interesting section of mine is opened, or is going to be shut in forever, the mine operators now call van Heerden to give a heads-up.
Their cooperation has been a godsend to astrobiology and has led Onstott and others to conclude that D. audaxviator and untold trillions of other underground microbes also live miles below your shopping center, your bedroom, your favorite national park. Or miles below the surface of Mars, for that matter. Eons ago, our most similar planetary neighbor was far more hospitable to life than was Earth, which had endured the collision with a smaller planet that produced the moon. But Mars somehow lost its magnetic field, its atmosphere and, thus, its ability to hold liquid water on its surface or to protect against solar radiation and deadly ultraviolet light. Mars scientists have long speculated that primitive organisms met the new challenges by descending below the surface and adapting through a desperate evolution. Now, living proof exists of a potentially parallel scenario on Earth.
I wanted to see this proof for myself, or, at least, see its subterranean home. That's how I found myself suiting up for a descent into a mine owned by Northam Platinum, a sprawling operation in the northern bush of South Africa, just beyond the aptly named Crocodile River. The daily routine on the surface was ordered, polite and matter-of-fact. Geologists in their white coveralls inspected new equipment; managers made sure the shifts were coming and going as planned. Even the miners, lined up in long rows waiting for the trip down to their work, were smiling and chatting; and some were swaying to the bouncy music coming from the loudspeakers. The grass was clipped; the grounds were clean; the 5,000-worker plant was humming.
Our group of scientists was outfitted in coveralls highlighted with fluorescent striping, heavy rubber boots and goggles, hard hats capped with a miner's light, and a mandatory safety kit strapped to our belts that included a breathing device that can filter out carbon monoxide. The chatter ended as we were ushered into the manager's cage; the miners piled into another. The doors slammed shut, and both cages picked up speed, plunging down to Level 7 -- a 30-mph express ride into Earth's crust, accompanied by the sound of falling rocks hitting our carrier as we sped by. We jolted to a stop, an attendant pried the door half open, and we stumbled out into a high-ceilinged, man-made chamber that housed a railyard for miniature ore trains. Accompanied by an array of mine officials, we passed through this small island of light and set off for the outer reaches of Level 7. We were 1.1 miles below ground and surrounded everywhere by dark, gloomy rock.
The scientists, a South African, a Belgian and a Spaniard, all affiliated with the Extreme Biochemistry group, some 300 miles away, have descended many times into the deep underworld in search of extreme forms of life. It remains a daunting -- and risky -- venture, but the search for extremophiles is sending researchers to scores of equally harsh environments around the world: mile-deep Antarctic ice, hot springs, highly acidic rivers, scalding thermal vents at the bottom of the ocean. The word "extremophile," after all, means literally a lover of extreme places. For them, it's our world that's toxic.
At the Northam Platinum mine, each turn on the journey to the Level 7 outskirts led to a smaller, darker, hotter tunnel. Like the strands of a spiderweb, the tunnels radiate out from the center in a mazelike order quickly incomprehensible to the unguided. The dry path gave way to sloppy mud from the water seeping through the fissures of the rocks -- boot-grabbing stuff that hid the old railway ties and pipes waiting to trip us up. A massive ventilation system worked to keep the heat down, pumping air and sometimes water through wide, striated tubing made of dun-colored fabric. Fastened to the sides of the winding tunnels, the tubes gave new visual meaning to the phrase "bowels of the Earth."
Time slipped away in the dark sameness of the march. We passed loudly buzzing ventilation substations, rest areas where sooty and muddied miners were far less likely to talk or smile than those on ground level, and some tunnel branches sealed up with hazard signs warning of methane gas or rock slides or water. I could tell we were nearing our destination when the temperature spiked. We were in a dark, dead-end area that housed an array of equipment installed to stop a flow of water into the tunnel (with only limited success). The lights from our miner's hats gave fleeting glimpses of the spectral landscape. All around, the soggy heat had aged the gears, chains and metal slabs in fast-forward, producing what looked like a very long-ago, sea-bottom shipwreck. Dripping stalactites of calcium carbonate took the place of seaweed; corrosion and rust replaced the barnacles. Water dripped from small fracture holes in the rock, spat out of a corroded valve and drained into a shin-deep pool. I reached out to touch the spray, and it was bathwater hot.
The most excited man in the darkness was Gaetan Borgonie of the University of Ghent in Belgium, a nematodologist on the verge of a potentially major discovery. He had set out a few years before in search of new varieties of the minuscule but ubiquitous and extraordinarily hardy roundworms. These creatures, Borgonie was eager to explain to me, are many-celled and have both a nervous system and a digestive tract. They are among the most primitive life forms to have that in-and-out system, a rudimentary nervous system, and the ability to reproduce both sexually and as single-sex hermaphrodites. He thought that finding these complex creatures alive this deep in the netherworld would be the first strong signal that further evolved life just might survive alongside single-cell bacteria and other microbes far below the inhospitable surface of Mars or other celestial bodies -- places where the sun also never shines and where the products of sunshine are similarly completely absent. Nematodes, and even three-foot-long tube worms, were discovered some decades ago at or near the dark bottom of the deep ocean, but the extraterrestrial implications of their discovery there were less dramatic because the creatures fed on life produced in collaboration with the sun, nourishment that then made the long drop to the ocean floor.
Borgonie's search had taken him to the tiny Caribbean island of St. Croix, to a sulfur-based ecosystem in Mexico, and finally to the South African--American team that had pioneered deep-mine searches for bacteria. Over the previous two years, Borgonie -- who as a young man wanted to be an astronaut but now was regularly headed in the opposite direction -- had descended into South African mines more than 20 times, and with his colleagues had found an impressive number of nematodes and their eggs in mines as far down as 2.2 miles. Most of the nematodes had come out of capped boreholes, but not all: He had learned on previous samplings that before the minerals harden to produce the long, hard stalactites hanging before us, they sculpt cones that, while still wet, can provide an improbable home to nematodes and their eggs.
Virtually nobody in the field (including the committee at his university that granted him a sabbatical) believed Borgonie's deep-mine nematode research would succeed because, on land, the worms are known to live only in the soil and near subsoil. He was eager to test his dissenting views and hopeful that he would confirm that nematodes (like bacteria) can adapt to life deep underground, and that he would be able to determine how they got there and whether they've been there long enough to evolve into unique creatures.
"These are good, very good," he said to nobody in particular as he waded back and forth between the stalactites hanging from the spectral ironworks on the walls and the measuring and collecting instruments stored in his beaten-up backpack. He carefully removed several cones and collected the precious drips from others. "This system they've worked out is just beautiful to think about and to see," he said.
It was time to go to our primary destination -- another dead-end tunnel a little farther on with a borehole that was running especially hot water. The Northam mine's chief geologist had called van Heerden to tell her the Bloemfontein team might want to come down to take a look before the section was dynamited.
Having left the shipwreck site, I marched behind the others. It was unnerving to be so far underground, so completely surrounded by rock. But the tunnel was straight and solidly dug, the ventilation brought in some fresh air and took out the noxious gases, and the periodic sight and sound of miners down branch tunnels kept things from becoming too other-worldly. I came to a junction, made a sharp left to follow the others, and, with the suddenness of a fast-passing train, was staggered by a blast of heat. I reached for the wall to keep standing. Working in this kind of heat is known to bring on hallucinations. Only later did I learn that both Borgonie and Derek Litthauer, a rugged and experienced professor and mine diver from Bloemfontein, have on occasion been evacuated from an especially hot or airless tunnel and sent back to the surface.
I inched my way to the researchers and mine officials gathered ahead. Already, the scientists had attached their equipment to a narrow metal pipe poking out from the rock and were collecting water. It was a borehole, one drilled by miners to see what conditions were like inside the rock. The temperature gauge showed the water was a scalding 150 degrees Fahrenheit at the end of the pipe. Mine geologist Werner Lamprecht, clearly proud of the extremity of it all, said the temperature several feet inside the rock face was probably in the range of 170 degrees. Steam danced up from the water pooled on the tunnel floor.
I sat on a discarded board beside the tunnel wall and watched. The tunnel had no insects, no spiders, none of the unexpected movement that comes with creatures. Yet previous expeditions had proved that we were not alone -- that even this place somehow supported life in the tiny, watery cracks in the rock face, in the dripping stalactites and who knows where else. We knew something was there, because four years earlier Onstott had discovered several microbes at or near the bottoms of South African deep gold operations. One, located in 2005 in this same Northam Platinum mine, 1.2 miles down, was a highly unusual "star" bacterium featuring a four-to-nine-point star formation -- an adaptation that gives the bacterium increased surface area to capture more of the "food" it needs to survive.
It was hard for the parboiled scientists to stay at the final collection site, but it was also hard for them to pull away, since they never know when they'll be invited for a return expedition. They had a dozen or more tests to conduct and a variety of filters to place on the flowing water in the hopes of collecting unusual bacteria, nematodes or something even more unexpected. But as excitement gave way to exhaustion, they packed up for the hike back to the cages. They knew they had to conserve energy, because they would return with the 4 a.m. morning shift to collect their filters.
There's an inevitable needle-in-a-haystack quality to these subterranean searches -- the mines are huge, and the hiding places for microbes and nematodes are small and dispersed -- so Borgonie was not particularly disappointed when initial cultures and examinations in the lab came up empty for nematodes from Northam Platinum. The setting still seemed hospitable for his "worms," especially if his theories were on target about how the nematodes follow their prey (the bacteria) through rock cracks to the deep underground, and then adapt to life there. But nobody strikes gold with every dig. The samplings continued, and the very next week, at the gold mine at Driefontein to the southwest, his fortunes changed dramatically. The catch: four healthy nematodes. In all, he found worms or their eggs in seven of more than 20 deep underground South African mine sites he sampled over six months -- a discovery that, if nailed down, would dramatically change our understanding of what can survive in the deep netherworld and how it comes to be down there.
Borgonie left for Belgium soon after to spend some time in his lab in Ghent. He hadn't initially planned to return to South Africa, but the lure of the mines and the creatures they hide quickly pulled him back -- especially once he was able to persuade Onstott to join him in writing the scientific paper they hoped would introduce the "worms from Hell" to the world. This time, Borgonie would place filters on the boreholes and leave them for weeks or months to see what else might be living in the rocks.
Six months later, Borgonie, Onstott and their colleagues produced a paper describing, for the first time, the presence of multicelled organisms as many as 2.5 miles below Earth's surface. Several of the organisms that had been cultured had begun to squirm and even reproduce asexually in the lab. The team tested for possible contamination -- nematodes brought in on miners' shoes or deep "old" water that somehow had mixed with water from near the surface -- and found that the nematodes coming out of the rock were different from anything found in the tunnels. What's more, the water used for ventilation and cleaning in the mines contains chemicals that kill bacteria and nematodes -- strengthening the case that the creatures Borgonie had found in his filters came from deep in the rock, and not from a miner's boot. Although the paper has yet to be published and fully critiqued by the scientific community, Borgonie and Onstott said in their submission letter to a scientific journal, "The presence of nematodes kilometers beneath the surface of the Earth is like finding Moby Dick in Lake Ontario."
Borgonie was relieved that his physically punishing and time-consuming nematode bet had paid off. When future scientists start digging in earnest on Mars, he now had to believe, similar surprises could easily await them.
Marc Kaufman is a Washington Post staff writer. This article is an excerpt from his book "First Contact: Scientific Breakthroughs in the Hunt for Life Beyond Earth," to be published by Simon & Schuster in April. He can be reached at firstname.lastname@example.org or at www.habitablezones.com.