Lowell conjured up a Mars that was ancient, arid, withered, a desert world. Still, it was an Earth-like desert. Lowell’s Mars had many features in common with the American Southwest, where the Lowell Observatory was located. He imagined the Martian temperatures a little on the chilly side but still as comfortable as ‘the South of England.’ The air was thin, but there was enough oxygen to be breathable. Water was rare, but the elegant network of canals carried the life-giving fluid all over the planet.
What was in retrospect the most serious contemporary challenge to Lowell’s ideas came from an unlikely source. In 1907, Alfred Russel Wallace, co-discoverer of evolution by natural selection, was asked to review one of Lowell’s books. He had been an engineer in his youth and, while somewhat credulous on such issues as extrasensory perception, was admirably skeptical on the habitability of Mars. Wallace showed that Lowell had erred in his calculation of the average temperatures on Mars; instead of being as temperate as the South of England, they were, with few exceptions, everywhere below the freezing point of water. There should be permafrost, a perpetually frozen subsurface. The air was much thinner than Lowell had calculated. Craters should be as abundant as on the Moon. And as for the water in the canals:
Any attempt to make that scanty surplus [of water], by means of overflowing canals, travel across the equator into the opposite hemisphere, through such terrible desert regions and exposed to such a cloudless sky as Mr Lowell describes, would be the work of a body of madmen rather than of intelligent beings. It may be safely asserted that not one drop of water would escape evaporation or insoak at even a hundred miles from its source.
This devastating and largely correct physical analysis was written in Wallace’s eighty-fourth year. His conclusion was that life on Mars – by this he meant civil engineers with an interest in hydraulics – was impossible. He offered no opinion on microorganisms.
Despite Wallace’s critique, despite the fact that other astronomers with telescopes and observing sites as good as Lowell’s could find no sign of the fabled canals, Lowell’s vision of Mars gained popular acceptance. It had a mythic quality as old as Genesis. Part of its appeal was the fact that the nineteenth century was an age of engineering marvels, including the construction of enormous canals: the Suez Canal, completed in 1869; the Corinth Canal, in 1893; the Panama Canal, in 1914; and, closer to home, the Great Lake locks, the barge canals of upper New York State, and the irrigation canals of the American Southwest. If Europeans and Americans could perform such feats, why not Martians? Might there not be an even more elaborate effort by an older and wiser species, courageously battling the advance of desiccation on the red planet?
We have now sent reconnaissance satellites into orbit around Mars. The entire planet has been mapped. We have landed two automated laboratories on its surface. The mysteries of Mars have, if anything, deepened since Lowell’s day. However, with pictures far more detailed than any view of Mars that Lowell could have glimpsed, we have found not a tributary of the vaunted canal network, not one lock. Lowell and Schiaparelli and others, doing visual observations under difficult seeing conditions, were misled – in part perhaps because of a predisposition to believe in life on Mars.
The observing notebooks of Percival Lowell reflect a sustained effort at the telescope over many years. They show Lowell to have been well aware of the skepticism expressed by other astronomers about the reality of the canals. They reveal a man convinced that he has made an important discovery and distressed that others have not yet understood its significance. In his notebook for 1905, for example, there is an entry on January 21: ‘Double canals came out by flashes, convincing of reality.’ In reading Lowell’s notebooks I have the distinct but uncomfortable feeling that he was really seeing something. But what?
When Paul Fox of Cornell and I compared Lowell’s maps of Mars with the Mariner 9 orbital imagery sometimes with a resolution a thousand times superior to that of Lowell’s Earthbound twenty-four-inch refracting telescope – we found virtually no correlation at all. It was not that Lowell’s eye had strung up disconnected fine detail on the Martian surface into illusory straight lines. There was no dark mottling or crater chains in the position of most of his canals. There were no features there at all. Then how could he have drawn the same canals year after year? How could other astronomers some of whom said they had not examined Lowell’s maps closely until after their own observations – have drawn the same canals? One of the great findings of the Mariner 9 mission to Mars was that there are time-variable streaks and splotches on the Martian surface – many connected with the ramparts of impact craters – which change with the seasons. They are due to windblown dust, the patterns varying with the seasonal winds. But the streaks do not have the character of the canals, they are not in the position of the canals, and none of them is large enough individually to be seen from the Earth in the first place. It is unlikely that there were real features on Mars even slightly resembling Lowell’s canals in the first few decades of this century that have disappeared without a trace as soon as close-up spacecraft investigations became possible.
The canals of Mars seem to be some malfunction, under difficult seeing conditions, of the human hand/eye/brain combination (or at least for some humans; many other astronomers, observing with equally good instruments in Lowell’s time and after, claimed there were no canals whatever). But this is hardly a comprehensive explanation, and I have the nagging suspicion that some essential feature of the Martian canal problem still remains undiscovered. Lowell always said that the regularity of the canals was an unmistakable sign that they were of intelligent origin. This is certainly true. The only unresolved question was which side of the telescope the intelligence was on.
Lowell’s Martians were benign and hopeful, even a little god-like, very different from the malevolent menace posed by Wells and Welles in The War of the Worlds. Both sets of ideas passed into the public imagination through Sunday supplements and science fiction. I can remember as a child reading with breathless fascination the Mars novels of Edgar Rice Burroughs. I journeyed with John Carter, gentleman adventurer from Virginia, to ‘Barsoom,’ as Mars was known to its inhabitants. I followed herds of eight-legged beasts of burden, the thoats. I won the hand of the lovely Dejah Thoris, Princess of Helium. I befriended a four-meter-high green fighting man named Tars Tarkas. I wandered within the spired cities and domed pumping stations of Barsoom, and along the verdant banks of the Nilosyrtis and Nepenthes canals.
Might it really be possible – in fact and not fancy – to venture with John Carter to the Kingdom of Helium on the planet Mars? Could we venture out on a summer evening, our way illuminated by the two hurtling moons of Barsoom, for a journey of high scientific adventure? Even if all Lowell’s conclusions about Mars, including the existence of the fabled canals, turned out to be bankrupt, his depiction of the planet had at least this virtue: it aroused generations of eight-year-olds, myself among them, to consider the exploration of the planets as a real possibility, to wonder if we ourselves might one day voyage to Mars. John Carter got there by standing in an open field, spreading his hands and wishing. I can remember spending many an hour in my boyhood, arms resolutely outstretched in an empty field, imploring what I believed to be Mars to transport me there. It never worked. There had to be some other way.
Like organisms, machines also have their evolutions. The rocket began, like the gunpowder that first powered it, in China where it was used for ceremonial and aesthetic purposes. Imported to Europe around the fourteenth century, it was applied to warfare, discussed in the late nineteenth century as a means of transportation to the planets by the Russian schoolteacher Konstantin Tsiolkovsky, and first developed seriously for high altitude flight by the American scientist Robert Goddard. The German V-2 military rocket of World War II employed virtually all of Goddard’s innovations and culminated in 1948 in the two-stage launching of the V-2/WAC Corporal combination to the then-unprecedented altitude of 400 kilometers. In the 1959s, engineering advances organized by Sergei Korolov in the Soviet Union and Wernher von Braun in the United States, funded as delivery systems for weapons of mass destruction, led to the first artificial satellites. The pace of progress has continued to be brisk: manned orbital flight; humans orbiting, then landing on the moon; and unmanned spacecraft outward bound throughout the solar system. Many other nations have now launched spacecraft, including Britain, France, Canada, Japan and China, the society that invented the rocket in the first place.