The loneliest planet
Percival Lowell's sketch, circa 1895, of Martian "canals" suggested a dying race's heroic efforts against the forces of nature.
(Correction: Because of an editing error, an item in the Examined Life column in Ideas section on Oct. 16 gave the date of Giovanni Schiaparelli's observation of what appeared to be canals on Mars as 1978. Schiaparelli announced his discovery in 1878.)
IN 1878, the Italian astronomer Giovanni Schiaparelli announced his observation of what appeared to be channels crisscrossing the surface of Mars, giving birth to one of the great myths about the red planet. More recently, NASA's robotic rovers have given new life to old fears about the future ''desertification" of Earth by sending back startling evidence that for millennia water-a prerequisite for life as we know it-flowed over Mars's surface. In his new book, ''Dying Planet: Mars in Science and the Imagination" (Duke), Robert Markley notes that, from Schiaparelli to the rovers Spirit and Opportunity, Mars has been at the center of scientific and philosophical debates not only about the possibly grim ecological future of Earth but humankind's place in the universe.
Markley, a professor of English at the University of Illinois at Urbana-Champaign who reads scientific journals and sci-fi novels with equal enthusiasm, spoke with me via phone about comparative planetology and little green men.
IDEAS: Lines observed on the surface of Mars-which scientists now believe to be dark layers of rock exposed periodically by dust storms-were once widely believed to be humanoid-built canals. Why?
MARKLEY: During the Martian spring and summer, its polar caps shrink and a wave of darkening can be observed spreading across the planet from the poles toward the equator. Until Schiaparelli discerned what he called canali on Mars, scientists puzzled over why the poles would warm up before the equator did-the opposite of what happens on Earth. In 1895 the Boston-bred astronomer Percival Lowell put two and two together and said we were witnessing the artificial irrigation of the planet. By 1905 American newspapers, particularly in Lowell-proud Boston, routinely ran scientifically minded stories about Mars's canal-building inhabitants.
IDEAS: How did we arrive at the notion-popularized by H.G. Wells, Edgar Rice Burroughs, and other writers and filmmakers-that Mars is a ''dying planet"?
MARKLEY: Mars was thought to be an Earth-like planet that had evolved faster and lost its water and atmosphere, hence the need for a massive system of canals. Scientists believed they were looking at what the future held in store for our own planet, in a geological and climatological sense....Also, planetary and biological evolution were linked by 19th-century science, which is why Lowell argued that the Martians must be highly evolved. It was but a short leap from there to Wells's hypothesis that Martians are an advanced race, ''different beyond the most bizarre imaginings of nightmare," who might invade us.
IDEAS: You argue that in the 20th century, both science and science fiction presented Mars as a ''refracted image of our own efforts to live on a despoiled Earth." Does that still hold true?
MARKLEY: Kim Stanley Robinson's influential trilogy ''Red Mars" (1993), ''Green Mars" (1994), and ''Blue Mars" (1996) uses Mars as a way to think about environmental degradation on Earth. His characters develop an ''eco-economics" that takes environmental stewardship seriously. And Jeff Moore, a planetary scientist at [the research lab] NASA-Ames, likes to say that talking about climate change on Earth is like a doctor trying to diagnose a disease on the basis of only one patient. According to NASA, studying the ''limit conditions" of life on Mars, whose climatological history we've only just begun to receive accurate data about, may eventually help us understand the history and future of life on Earth.
Joshua Glenn is the associate editor of Ideas. E-mail firstname.lastname@example.org.