First Contact Read online

  Scientists are also probing whether Mars was more hospitable to life at its inception than was Earth, which after all did take quite a hit when a Mars-sized body crashed into it and ejected the material that most planetary scientists believe became the moon. And if life did start on Mars, could it have traveled via ejected rock-turned-asteroid to Earth? Bacteria in Antarctica and other glaciers frozen for hundreds of thousands of years come back to discernible life when brought to higher temperatures, and researchers contend they could last in a suspended state (or maybe even carrying on life functions) for millions of years more. Other microbes have shown a previously unimaginable ability to withstand the cosmic radiation of space. Put all this together and the unavoidable question becomes whether, at bottom, we’re all Martians—quite literally descendants of life from Mars. If methane can ultimately be traced to a biological source on Mars, astrobiology will enter an entirely new phase and the quest to find extraterrestrial life will become something more like a race.

  Have we actually already found extraterrestrial life on previous Mars missions and in meteorites found on Earth? This is one of the most contentious issues in astrobiology—and in science as a whole—and many highly qualified scientists on opposing sides of the issue are 100 percent convinced they’re right. Feelings are especially high because as astrobiology’s patron saint, Carl Sagan, once said, “Extraordinary claims require extraordinary proof.” But extraordinary proof is very hard to come by, and tantalizing findings are hard to keep under wraps. The result has been a number of long-running scientific grudge matches—intellectual blood sport at the highest of levels, with seemingly many rounds to go. Interdisciplinary cooperation is the mantra of astrobiology but it has yet to repeal the laws of human nature.

  The most significant dispute is no doubt over the contested discovery that gave birth to the new era of astrobiology: the 1995 announcement that NASA scientists had discovered a meteorite from Mars that contained numerous features consistent with extraterrestrial life. Critics quickly tore into the report and left it seriously wounded. But the authors have continued their work and say they are more convinced than ever that many Martian meteorites show signs of long-ago extraterrestrial life.

  Just as those immersed in astrobiology now theorize that extraterrestrial life does—perhaps even must—exist, astronomers long theorized that planets circled stars in other solar systems. It wasn’t until the mid-1990s, however, that the first definitive detections were made. Now, more than five hundred exoplanets have been identified, seven hundred more are awaiting confirmation, and billions more are believed to exist throughout the universe. As much as any other discoveries, the peek into the world of exoplanets has supercharged astrobiology and encouraged scientists to substantially increase their bets on the existence of extraterrestrial life. But the discoveries have come with big surprises. Most of the extrasolar planets found so far are large gas giants like Jupiter, orbiting close to their suns with smaller but also giant planets farther out—a kind of solar system that virtually nobody predicted. That so many of the planets discovered are in this category is, to a substantial extent, a function of how astronomers are looking for them—bigger and closer to the central star is what we have the technology to detect. But the notion that any Jupiter-sized planets would be orbiting their suns in four or five days was, until recently, unthinkable. Equally unexpected was the discovery that many solar systems consist of planets that travel in wildly eccentric orbits, not the circular or near-circular ones we’re accustomed to. The fact that solar systems come in such peculiar arrangements has both promising implications for astrobiology—with solar systems so varied, the probability is that some others are “just right”—and some negative because planets in those wildly eccentric orbits would probably make their solar systems unstable and uninhabitable.

  So the big question for planet hunters is no longer simply how to find planets, but rather how to find more of the smaller, rocky, Earth-sized planets the right distance from their suns to be potentially habitable, and to find solar systems structured in ways that could allow these cousins of the Earth to become nurseries for life. NASA’s Kepler spacecraft was launched in 2009 to make a broad search for Earth-sized planets, and it’s expected to begin delivering substantial results in 2011. But much of the serious planet hunting is being done using Earth-based telescopes, and the ingenuity of the scientists operating them is the stuff of legend. Anyone betting against them finding habitable planets and solar systems has not been following their fevered discoveries.

  Astrobiologists are constantly searching for habitats on Earth that can be studied as near cousins to environments that might be found on other planets or moons—the parched Atacama Desert in Chile, the hydrothermal vents of Yellowstone Park and the ocean floor, the dry valleys and deep glaciers of Antarctica. One of the more compelling sites is Lake Bonney in Antarctica, which has a deep covering of ice over liquid water known to support microbial slimes and life. Jupiter’s moon Europa also has a thick layer of ice over what is now believed to be a vast ocean of liquid and perhaps life-supporting water, and NASA and the European Space Agency have proposed it as a major “flagship” mission for the 2020 time period. NASA believes Lake Bonney can serve as a useful analogue to Europa for research purposes, and so it is testing sophisticated submarine vehicles there—autonomous robots whose offspring may well find themselves someday on that moon’s icy surface.

  But the study of habitats has a more cosmic meaning, too. Solar systems are now described as having (or not having) “habitable zones”—regions where rocky planets with atmospheres could exist, and where the sun heats the planet to the right temperature for liquid water. Since we now know that the complex carbon-based organic materials that are the building blocks of life on Earth can be found throughout the universe—that they fall on exoplanets just as they fall on Earth—it seems quite unlikely that life wouldn’t start and evolve quickly on an otherwise habitable planet. This, of course, is based on the presumed dynamics of early Earth, our one and only example of a life-supporting planet. Earth is known to have formed about 4.5 billion years ago and to have undergone hundreds of millions of years of meteorite bombardment and generally hellish conditions. Yet early forms of life have been traced as far back as 3.8 billion years on Earth, suggesting that life arose not too long, in geological terms, after conditions became favorable.

  In trying to define what makes life possible, astrobiologists are forced to confront another question: Is life inevitable, or the result of a series of accidents? Did the universe have to be finely tuned to make it possible? This is an unavoidable question because the slightest change in many of the basic physical and cosmological laws of the universe would make it an entirely inhospitable place. A minute increase in the extreme weakness of gravity, for instance, would make stars like our sun burn out in 10,000 years instead of 10 billion. If the neutrons found in every atom were not .01 percent heavier than protons found in every atom, then the universe would allow for no chemical reactions because all atoms would be stable and unchanging. Is this kind of “fine-tuning” a coincidence of almost unimaginable proportions? Does it mean the universe itself is the product of a sort of Darwinian evolution? Does it mean there are many, perhaps an infinite number, of other universes that are not organized in a way that can support life, leaving us by definition in the one that can? Or, leaving the realm of science for a moment, is this “fine-tuning” a cosmic reality that supports the argument for a Creator?

  The broad-based effort to answer these and many other questions is remarkable because it has finally made it legitimate for white-coated scientists (actually, mostly the blue-jeaned kind) to spend their careers studying the possibilities, locations, and signatures of alien life. Astrobiology projects now attract more grant proposals from members of the National Academy of Sciences (who are invited to join because of their accomplishments and prominence) than any other subject at NASA. In astrobiology today there’s no talk of UFOs, no wormholes or time tra
vel, no giant “gasbag” creatures floating through the upper reaches of Jupiter (as imagined by Sagan himself). Rather, it’s about hard-core science that, until recent years, was technically impossible or simply unimagined, and it stretches from the bottom of deep Earthly mines to the farthest reaches of the universe with its 100,000,000,000,000,000,000,000 (or more) stars, and their unfathomably large number and variety of planets and moons. Even the search for extraterrestrial intelligence, or SETI, has become much more scientifically sophisticated—enough so that NASA and the National Science Foundation have reopened their grant competition to SETI projects, and Microsoft cofounder Paul Allen donated $25 million to begin construction of an array of 350 radio telescopes in northern California designed in part to pick up transmissions from distant civilizations.

  NASA has embraced this search, but quietly. Unlike the Apollo missions to the moon, construction of the international space station, or the George W. Bush administration’s proposals to settle astronauts on the moon and send them to Mars, no big announcement was ever made about a new NASA push to find extraterrestrial life—and that’s probably politically astute. Imagine the chuckling and high dudgeon in Congress had it received an expensive and dicey proposal to find ET. A NASA vision statement released in 2002 made this emphasis on astrobiology explicit, declaring the agency’s goals thus: “To improve life here; To extend life to there; To find life beyond.” By 2006, all reference to finding “life beyond” had been removed, but the goal had already been hardwired into the actual workings of the agency.

  The NASA astrobiology program was formally initiated late in the Clinton years with a modest budget and a small bureaucracy of its own. The agency’s Astrobiology Institute gives out modest but still very competitive grants totaling about $50 million each year. But that’s only the most obvious effort. NASA and European Space Agency missions are regularly designed with extraterrestrial life in mind. The most eagerly anticipated include the Mars Science Laboratory (designed to scour Mars for signs of the chemical building blocks that make life possible), two joint NASA-ESA missions to Mars (inspired and configured, to a significant extent, by the discovery of methane on the planet), and an increasingly possible NASA-ESA mission to Europa. Then there’s the biggest prize on the horizon—a mission to Mars to gather up rocks and soil and bring them back to Earth for the kind of exhaustive analysis scientists have dreamed of for decades.

  As science has found Earth to be a mere speck in the universe, the notion of our human specialness has diminished—perhaps one reason why the centuries-old debate about the existence of extraterrestrial life has at times been so raw. When the discovery of extraterrestrial life comes, the process begun by Copernicus and Galileo in the sixteenth century of pushing the Earth away from the assumed center of the universe will have come full circle. But there is also the strong possibility that astrobiology will introduce people to a transformed understanding of the cosmos and our place in it. That’s what Steven J. Dick thinks. He’s a trained astrophysicist who served for many years at the U.S. Naval Observatory and later as NASA’s chief historian, and is the author of numerous books about the history of thinking about extraterrestrial life. “With due respect for present religious traditions whose history stretches back nearly four millennia,” he suggests, “the natural God of cosmic evolution and the biological universe, not the supernatural God of the ancient Near East, may be the God of the next millennium. … As we learn more about our place in the universe, and as we physically move away from our home planet, our cosmic consciousness will only increase.” Because what, in the end, is nature?

  If life is found on Mars or Europa, then isn’t that nature as well? And if carbon-based organic material fills significant portions of space, and is found in meteorites broken free from planets, comets, and asteroids, then isn’t that nature, too? Feeling at home in nature suddenly has a very different, much bigger meaning. That, really, is what astrobiology wants us to understand: that the universe we’re privileged to inhabit is more complex, more fertile, and more mysteriously grand—yet also more knowable—than we could possibly imagine.

  2 REALLY EXTREME LIFE

  Science moves ahead on hunches. Tullis Onstott, the Princeton University geobiologist, first descended into a South African gold mine on a hunch in 1996, using six thousand dollars 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. Up 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 under great pressure. Creatures also need to reproduce or split with some regularity. On his first trip into the mines Onstott found microbes living as far down as two miles that lost out on virtually all of these counts. His prized discovery, made a few years later, was of a bacteria nourished by food—molecules, actually—freed up using energy released by the radioactive decay of surrounding rocks. The microbe also needs some few minerals to survive and some water, which is hidden away from 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 they seem to split—that is, reproduce—as seldom as once a century.

  A reading of the genome of Onstott’s star bacteria, 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 3–40 million years. But it has DNA, reproduces, and is clearly alive. The researchers who sequenced the genome found that it had highly unusual abilities to directly 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 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 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 his research not because similar microbial life doesn’t exist far below New York or London or Tokyo, but simply because this 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, Georgia, and later at a Texaco well site in western Virginia. Frustrated by his limited results and fears of 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—so much potentially to lose, so little to gain. It took Onstott and others two years of negotiating to get into the mines and 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 men who run many of the gold, platinum, and diamond 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.

  Maybe it was to re
deem the dark history of those mines—flashpoints during the apartheid era and still controversial because of the pay and inevitably harsh work conditions—that operators took a chance and allowed the scientists in. Or maybe mine officials saw value in having their mines become known for something other than producing shiny metals and wealth at a sometimes high environmental and human cost. In any case, 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 Earth, which had endured the collision with a smaller planet that produced the moon. But Mars somehow lost its magnetic field, its atmosphere, and ultimately 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 one January day in 2009 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 overalls 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 five-thousand-worker plant was humming.