The Sirens of Mars

by Sarah Stewart Johnson

  The lines date to the late 1800s, when they were first extensively recorded by Giovanni Schiaparelli, an astronomer in Milan who would forever change our vision of the planet. There had been much talk of Mars in the summer of 1877 as it swung particularly close to the Earth. An American astronomer had just discovered two moons through the great glass of a sixty-six-centimeter telescope at the U.S. Naval Observatory in Foggy Bottom. The lens of Schiaparelli’s telescope was much smaller, only twenty-one centimeters, but it was made out of high-quality glass, so he decided to see whether his instrument might also be suitable for observing planets. He climbed to the rooftop of the Brera Palace. A terrible storm had passed through, and he was struggling with the conditions, unable to resolve double stars in the windy, cold air. At just before 10 P.M., with one eye to the telescope, the other on his notebook, he made his first ever sketch of Mars: a circle near the book’s binding, a small white space denoting the polar cap, an apron of shading descending down from its edge, and, finally, a distinct round spot within a crescent of darkness. He noted in his observations that he couldn’t find the feature on an existing British map of Mars, considered the most accurate in the world. Puzzling. But then again, the air was not good.

  Schiaparelli observed Mars the next night, and the night after that. The more he observed the planet, the more he was confused by the British map, which looked like two cartoon hands of dark terrain rising up from the equator. The dark areas were designated as seas, and the light areas continents. But nowhere among Kepler Land, Dawes Ocean, Herschel Continent, or the De La Rue Sea were shadings that actually matched the ones Schiaparelli saw. In fact, none of the maps of Mars seemed to bear any resemblance to the planet he saw through his telescope.

  Given the wobbling atmosphere, Schiaparelli had to work fast, recording the image he saw before the vision of it faded. But he utilized a tool that few of the other mappers of Mars had: a tiny micrometer. He affixed the miniature contraption, which he’d learned to wield in Russia, to the eyepiece of his telescope. This helped him to locate several dozen points of longitude and latitude; he could then use these to quickly orient himself. Schiaparelli’s preternaturally sharp vision and this dedication to form resulted in a breathtakingly specific new map of the planet.

  During those nights up on the rooftop observing Mars, Schiaparelli noticed curious features crisscrossing the planet’s surface, connecting dark patches—lines that would entrance and bedevil scientists for decades. He interpreted each dark patch to be a sea, “the saltier the water, the darker it appears.” He conjectured that the lines linking them were waterways. In time, he identified dozens of these “canali.” They always originated in a dark patch and terminated in another dark patch or another one of the canali, never in the middle of a landmass. In some cases, canali even appeared to split, changing rapidly into two parallel canals, closely spaced.

  Within a few years, a French astronomer named Camille Flammarion seized on Schiaparelli’s maps and began interpreting them in the most optimistic light. In Italian, the word simply meant “channels.” Schiaparelli, who had trained in civil architecture and hydraulic engineering, thought that the features might be straits, like the English Channel or Mozambique Channel. But the word rushed into the wider world as “canals,” with everything that implied.

  In La Planète Mars et ses Conditions d’Habitabilité, Flammarion noted how the “canals” didn’t meander like streams and rivers. In fact, the canals on the maps seemed oddly geometric. Were they public works? Across the face of the Earth, technology was manifesting itself in new ways. The Erie Canal, dubbed the Eighth Wonder of the World, was completed in 1825 and twice enlarged in the second half of the nineteenth century. France had been heavily involved in the creation of the Suez Canal, a maritime shortcut around Africa that opened in 1869. In 1881, the French also commenced work in Panama on a new passage to link the Atlantic with the Pacific. Flammarion analyzed the canals in the context of other observations and concluded in a massive compendium of all the sketches of the planet made through 1892 that “the habitation of Mars by a race superior to ours seems…very probable.” What else could explain the scale and regularity of the Martian canals?

  It was the heir of a textile fortune who brought the canals to America and who would become their loudest and most prominent proponent. Percival Lowell had grown up in a grand mansion on Heath Street in Brookline, a Boston suburb. The house was nicknamed “Sevenels,” for the seven Lowells living there. Lowell’s brother would become a president of Harvard and one of his sisters a famous poet. Like his siblings, Lowell had access to a vast fortune. Upon graduating from Harvard, where he studied mathematics and dabbled in astronomy, he left on a customary grand tour and later spent several years traipsing through the Far East on various cultural and diplomatic missions. He was a self-proclaimed “man of moods,” one moment jocular, holding court among friends in his piazza, the next somber, alone, chain-smoking cigars. He liked tennis and walking, but not golf, not motoring. He owned one of the fastest polo ponies in America. He had tremendous personal magnetism and typically struck others as boyish and eager, though he was a hermit at heart.

  Upon Lowell’s return in 1893, his aunt Mary presented him with a copy of a La Planète Mars et ses Conditions d’Habitabilité as a Christmas gift. Fluent in French, Lowell devoured it, electrified by the Schiaparellian network that Flammarion had interpreted as a series of waterways flanked with vegetation, carved deep into the surface to irrigate the land. The scope of the excavations was simply dazzling. There was tangible evidence of a civilization at hand. What could this be if not the biggest discovery ever made, if not a natural extension of the Copernican Revolution? Inside the book, Lowell scrawled, “Hurry!” The family motto was occasionem cognosce—“recognize opportunity”—something Lowell had become quite good at. He knew that in just a few months Mars would swing into opposition—when Mars and the sun aligned on opposite sides of the Earth. It would be Mars’s closest approach to our planet in fifteen years, and he wasn’t going to miss it.

  In January, he met with a rugged young astronomer named William Pickering. Pickering had observed the linear features on Mars himself, reporting on them in an 1890 article in The Sidereal Messenger. He had also just returned from a remote outpost of the Harvard College Observatory in Peru, where he had developed his “Standard Scale” for rating astronomical vantage points. Pickering convinced Lowell that optimal viewing conditions could be found in the Arizona Territory. Smog and light pollution, by-products of industrialization and urbanization, were becoming major problems, so Lowell quickly set out to build an observatory “far from the smoke of men.” He decided on a high mesa at Flagstaff, a place where the atmosphere was steady and the night was cloaked in deep darkness. As Lowell insisted, “the best procurable air.”

  Pickering designed a prefabricated dome that was shipped west by rail. Ground was broken that April, and the first observations of Mars were made in May. Not lacking for funds, Lowell’s Arizona outpost soon acquired a beautifully crafted sixty-centimeter refractor from Alvan Clark and Sons in Cambridge, Massachusetts, the leading optical manufacturer of the day. Alongside the telescope Lowell affixed a ladder assembly, atop which he set a kitchen chair. From his solitary perch, “but one watcher, alone on a hilltop with the dawn,” he scrutinized the planet through his state-of-the-art lens, sketching elaborate maps of the Martian canals, rendering them as perfectly distinct lines. Confident in his exceptional optics and eyesight, from an observation post reputed to be as good as our planet could provide, he identified dozens more canals than Giovanni Schiaparelli ever had.

  Lowell patiently mapped the entire planet, including even the dark patches of the surface that had long been understood to be oceans. The canals were everywhere, even there. Lowell conjectured that he was not looking at a planet like Earth, awash in salt water, but rather at a world that had lost its seas, a world where the rain had stopped. Thus the need for a
global network capable of pumping what precious water there was from the melting polar snows toward the equator each spring, giving rise to dark patches of vegetation. “If…the planet possesses inhabitants, there is but one course open to them in order to support life. Irrigation, and upon as vast a scale as possible, must be the all-engrossing Martian pursuit.” And since the canals were Mars-wide, and since there were no visible boundaries between regions or nations, Lowell reasoned that the planet had probably reached a kind of geopolitical end state where a group of benevolent oligarchs had come to direct the social order.

  Whatever the likelihood of his political speculation, Lowell’s telescopic evidence struck the world as wildly exciting news. He didn’t have an advanced degree, but neither did many prominent astronomers at the time. There wasn’t all that much to learn in graduate school, because there wasn’t all that much to teach. Lowell courted the scientific journals and newspapers, and copies of his book Mars flew from the shelves. With its publication, much of the literate world was persuaded that proof of intelligent life had been discovered on the Red Planet. In English, French, and German, he addressed large crowds in North America, Paris, and Berlin. A “brave and brilliant début for the new science,” heralded the Boston Evening Transcript. The public’s fervor exploded as professionals and amateurs alike crowded in to hear Lowell’s talks and raced to purchase telescopes.

  But Lowell had just begun. He soon started to construct a narrative for Mars’s history, a chronicle of events to account for how Mars came to be. It fit perfectly with his interpretation of planetary formation and the idea that planets would march toward an evolutionarily advanced state—both physically and biologically.

  As an undergraduate at Harvard, Lowell had completed a thesis on the nebular hypothesis. The theory, first suggested on a somewhat intuitive basis by the philosopher Immanuel Kant during a foray into astronomy, and later by the celebrated French mathematical astronomer Pierre-Simon Laplace, held that rings of gas shed by the cooling, contracting sun condensed to form planets. Since entropy—the tendency toward disorder—was unidirectional, it would eventually lead to the senescence of the solar system, with the smaller planets dying first. So, from the time of their birth as molten masses, Lowell reasoned, the planets progressed through stages of development. Mars was clearly in a terrestrial stage where oceans had disappeared, but it was rapidly approaching a dead stage, an airless stage, the stage of Mercury and the stage “so sadly typified by our moon, a body now practically past possibility of change.”

  The implications for our own planet were not lost on Lowell. Mars had advanced to a state that the Earth too would reach. Earth was still in a terraqueous phase—its sedimentary rocks laid down by water—but its fate was sealed: “The outcome is doubtless yet far off, but it is as fatalistically sure as that tomorrow’s Sun will rise, unless some other catastrophe anticipate the end,” Lowell wrote. “It is perhaps not pleasing to learn the manner of our death. But science is concerned with only the fact, and we have Mars to thank for its presentment.” Mars, he realized, was giving us a glimpse of our own future.

  Lowell’s tour de force of popular science would hold sway over the public for years. Yet slowly, quietly, hints of doubt about the canal theory began to emerge, mostly in foreign periodicals. As early as 1894, a British solar astronomer had noticed that series of tiny sunspots tended to be drawn by the eye into lines and wondered whether the same thing might not be the case with small details on Mars. In 1903, he arranged a simple demonstration to challenge Lowell. He asked a group of schoolboys at the Royal Hospital School in Greenwich to copy a series of black-and-white drawings, placed at the front of the classroom, on which dark dots had been inscribed. The boys at the desks near the front mostly drew dots, but the boys at the back of the room drew lines: For them, the dots appeared to merge together. Lowell, never one to be dissuaded, countered that linear features would also appear as lines at great distances.

  Taken aback by the challenge to what he viewed as his most important scientific legacy, Lowell turned to photography, hoping it would quiet the controversy. Because of its ability to build up an image of a faint object over time, photography was a tremendous asset in stellar astronomy. It had also revealed new moons around the outer planets, but pinpointing the dot of a distant object and resolving its features were very different challenges. Even under perfect atmospheric conditions, painfully slow film speeds meant that details in the images of Mars would show up blurred. Nevertheless, one of Lowell’s assistants designed a new planetary camera and took on the challenge. The photographs that emerged from the fixing solution in the Lowell Observatory’s darkroom after the 1905 opposition were half a centimeter across, hardly the kind of images that allowed for a comprehensive examination of minute terrestrial features, but Lowell still distributed them widely. He heralded them as foolproof evidence that the canals were real, and the president of the British Astronomical Association followed suit in 1906, proclaiming that the photographs proved the “objective reality of the canals.”

  With much fanfare, Lowell announced that he would finance an expedition to the Andes to collect even better photographs of the planet in 1907. The much-hyped expedition was led by the well-known Amherst astronomer David Peck Todd, accompanied by his wife and Earl Slipher, a recent astronomy graduate from Indiana University. Amherst’s forty-five-centimeter refractor, weighing seven tons, was shipped from New York to Chile via the just-opened Panama Canal. It was set up in the open air in the nitrate-mining town of Alianza, some seventy kilometers inland from the old port city of Iquique. While Todd made visual observations of the usual kind, showing canals, the true master proved to be young Slipher. Even though he had only trained in Flagstaff for a few months, he quickly figured out the planetary camera and over the course of six weeks took nearly seven thousand photographs of Mars. The gelatin-emulsion glass plates, laced with silver salts, were crated up and returned to Flagstaff.

  Reproductions of the images, grainy as they were, were published a few months later in The Century Magazine. Anticipating that readers were unlikely to be impressed, Lowell insisted on including the disclaimer that the photographs were three steps removed from their original negatives, having undergone photographic printing, halftoning, and press printing. Despite his reassurance to readers that on the original negatives “[the canals] are there, and the film refuses to report them other than they are,” they could hardly be seen.

  Things continued to unravel. The same year, the celebrated British naturalist Alfred Russel Wallace, who independently conceived of the theory of natural selection, launched an attack on the concept based on his own research, arguing that Mars was likely too cold for liquid water and that a planetwide irrigation system was an absurdity. In 1909, the Greco-French astronomer Eugène Antoniadi, a longtime supporter of Lowell, published a map of Mars without any canals, practically the first such depiction in twenty-five years. Based on his own observations using the largest refractor in Europe, Antoniadi had changed his mind, concluding that only the “natural agencies of vegetation, water, cloud, and inevitable differences of colour in a desert region” were needed to account for the various phenomena on Mars. And all the while, the pioneering psychologists Sigmund Freud and Carl Jung were crisscrossing Europe and the United States, lecturing about the role of the unconscious, likely raising suspicions that observers might be seeing a vast network of canals on Mars because of an underlying desire that the canals existed. As Lowell’s evidence for an advanced society on Mars withered, his own discipline began to shift beneath his feet. Einstein’s theory of special relativity had been published, and space science swerved toward astrophysics, slowly relegating planetary science to a backwater it would not emerge from in Lowell’s lifetime.

  Lowell continued to write and lecture, seeking to inspire students as he became more and more marginalized from the scientific mainstream. He died of a stroke in 1916. In a moving tribute, his secretary des
cribed him as “filled by the warmth of his fire; thrilled by his achievements, with eye single towards the discovery of ‘the light that shifts, the glare that drifts’—which is truth itself.”

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  AND YET THOSE lines that Schiaparelli had documented and that had so consumed Lowell continued to haunt Mars science. Every time the planet swung into one of its biennial oppositions, Lowell’s assistant Earl Slipher took photographs of Mars, one after another after another, from his early twenties until his eighties. Photographs from Flagstaff, Chile, South Africa. On countless nights, he stood and sat at the eyepiece of large telescopes, sometimes huddled in a plaid flannel overcoat, switching the plates, clicking the shutter, switching the plates, clicking the shutter, and so on as the hours passed.

  Over the course of his lifetime, Slipher took over one hundred thousand images of Mars. In 1962 he arranged the best of them, sometimes alongside sketches he had made, into a volume he entitled The Photographic Story of Mars. “A vast collection of facsimiles and information has been amassed,” he wrote in the foreword. It was the compendium of his life’s work, and it became the basis of the planning map that hangs in my office, put together by the U.S. Air Force that same year.

  In the early 1960s, of course, hardly anyone still believed that the lines on Mars were the handiwork of an intelligent society, but no one could say for sure what they were. Nearly seven decades after Lowell stumbled across Flammarion’s treatise, the former head of the Royal Astronomical Society of Canada wrote: “The so-called ‘canals’ of Mars…have been plotted in various forms by most observers of the planet…I can sum up the present situation by saying that there is general agreement on the reality of the canals, in other words that they are not illusions, but result from something on the Martian surface that produces the effects drawn by the visual observers and recorded on the photographs…” Samuel Glasstone affirmed, “There definitely appear to be a number of linear features on the surface of Mars,” in The Book of Mars, a NASA special report in 1968.