Seen with the naked eye, Mars is a campfire coal against the firmament. Because of its bloody hue, the Babylonians 3,000 years ago identified it with their god of death. Seven celestial bodies gave name to the seven days of the Babylonian week: the Sun, the Moon, Mars, Mercury, Venus, Jupiter, Saturn. Mars Day was Tuesday; the linkage survives in the French Mardi and the Italian Martedi. The name Mars itself comes from the Roman god of war.
Of all the planets in our solar system, Mars has sparked the greatest human interest. Konstantin Tsiolkovsky was a Russian scientist who lived from 1857 to 1935; known as the father of cosmonautics, he recognized many principles and concepts of space travel that scientists advance today. He once wrote, The Earth is the cradle of the mind, but one cannot live forever in the cradle. Will Mars be the next home beyond our blue-and-green cradle? Many proponents of space exploration say that it should be. A commitment to colonize Mars, these enthusiasts believe, would challenge Homo sapiens to make great advances: technological, intellectual, even spiritual.
Amazing Stories/Penn State Special Collections
A 1940's-era artist's idea of what Martians might tool around in: an atomic airship. People have long pondered what sorts of life forms may inhabit the red planet.
During the Renaissance, Mars helped European scientists understand that Earth is not the center of the universe, that it and the other planets orbit the Sun. In the early 1600s, the Danish astronomer Tycho Brahe collaborated with the German mathematician Johannes Kepler in calculating the orbit of Mars, whose erratic journeyings had given the pioneering Polish astronomer Copernicus fits some 60 years earlier. Kepler deduced that Mars has an elliptical orbit, and that all the planets move faster the nearer they draw to the Sun, then slow down the farther away they get from our solar system's hub.
To early astronomers, Mars was little more than a ruddy smudge that appeared in telescope eyepieces, writes Paul Raeburn in his book Mars: Uncovering the Secrets of the Red Planet (National Geographic Society, 1998). In 1877 the Italian Giovanni Schiaparelli observed on the surface of Mars a network of lines; he called them canali, which can mean either channels or canals. Percival Lowell, a self-taught American astronomer, seized on the second definition and concluded that highly evolved life forms had constructed the channels. Mars fever infected scientists and novelists alike. H. G. Wells's The War of the Worlds, published in 1898, described an attack on Earth by technologically superior Martians, fueling the fear and fascination, in Raeburn's words, with which we have long viewed our near neighbor.
The Soviet Union had a real thing about Mars. It lay there in the cosmos, a red presence, fourth planet from the Sun, a chunk of frigid rock upon which life—sapient? microbial?—might exist.
On October 10, 1960, three years after Sputnik 1—the basketball-sized satellite that had launched the space race between the U.S. and the U.S.S.R.—the Soviets aimed their first probe at Mars, but the ship veered off course and burned up upon re-entering Earth's atmosphere.
In October 1962 they sent up a rocket boosting a spacecraft intended to photograph Mars from a flyby trajectory. The vehicle fell apart in some unknown manner, its pieces circling the Earth in low orbit, prompting military radar operators to momentarily conclude that the United States was under Soviet nuclear attack. This was during the Cuban missile crisis, and it seems possible that fingers twitched perilously near to glowing buttons on Polaris sub instrument panels, and B-52s lumbered into the air from Dakota bases.
The Soviets crashed a lander onto the Martian surface in November 1971, and a month later achieved the first soft landing—although seconds after it touched down, Mars 3 fell silent, perhaps toppled by severe winds then scouring Mars in an immense dust storm.
The United States had not stood idly by as the Soviets reached for the red planet. Our National Aeronautics and Space Administration (NASA) had some early successes and some failures, too, including Mariner 8, which plunked into the Atlantic moments after liftoff. When the Russian Mars 3 descended into that dusty maelstrom, our Mariner 9—two weeks earlier it had become the first spacecraft to achieve Mars orbit—was transmitting photographs back to Earth. Scientists, and later the general public, saw gargantuan volcanoes surmounted with 50-mile-wide craters. Canyons long enough to reach from New York to San Francisco. Twisting, braided channels, presently dry, that must once have seethed with floodwater. We understood, then, that Mars is a geologically active world, and that at some time it had possessed surface water sufficient to radically change its face.
Mariner 9 sent back more than 7,000 pictures; NASA used the images to select touchdown sites for the two Viking spacecraft that landed successfully in 1975. The Viking landers carried instruments to sample the Martian soil, study the atmosphere and climate, and infer the planet's internal structure.
As Raeburn writes, The space shuttle consumed NASA's energy and, more importantly, its budget during the 1980s. It was not until December 1996—the Cold War ended, the Soviet Union fragmented, and space exploration less a political contest and more a quest for knowledge—that NASA landed another Mars probe. On July 4, 1997, the low-budget Pathfinder ($250 million, or about $20 million less than it cost to film The Lord of the Rings trilogy) landed on Mars. Slowed down by retro-rockets and a parachute and cushioned by clustered airbags, it bounced 15 times, came to rest, deflated and retracted its airbags, and transmitted an image of dun-colored rocks (one was later named Marvin the Martian), red dust, and a lemon sky. For the next 83 days, until its batteries died, Sojourner, the foot-long, 20-pound rover that the lander released, went tractoring around sampling and photographing rocks.
After Pathfinder's spectacular success, NASA launched three successive probes that failed, prompting a critical review and reorganization of the agency's Mars exploration program; one snafu was the infamous Climate Orbiter,
in which controllers sent commands in English units rather than metric, causing the craft to dip too low and burn up in the Martian atmosphere. The Mars Odyssey, launched in 2001, successfully reached an orbit from which it is studying Mars's climate, geology, and radiation levels. As of this writing, NASA is scheduled to launch two Mars missions, in May and June 2003; landers will release rovers carrying an array of instruments, including various spectrometers, a microscopic imager, and a rock abrasion tool.
So far none of the probes, Russian or American, has uncovered definitive evidence of life on Mars. Neither have analyses of the five Martian meteorites found on Earth (we know from whence they came, thanks to the geological data sent back by various missions), although one of the meteorites contained tiny tubular structures that some scientists suggest may be fossilized life forms. We continue to quantify the inhospitable nature of Mars, bitterly cold and with an atmosphere composed largely of CO2 with a hundredth the surface pressure of Earth's.
Which is not to say that scientists have given up on sending manned missions across the 77.5 million miles that separate Earth and Mars when their orbits bring them closest together. Because of their incongruent orbits, the distance between the planets varies by a factor of six over the course of a year. A launch window occurs about once every two years. And since both worlds are in perpetual motion, a spacecraft needs to travel in the neighborhood of 286 million miles before it can catch up with the red planet. Using today's liquid-fuel technology, that translates into about seven months.
It seems we won't be dispatching astronauts to Mars any time soon—although that depends, to a certain extent, on who you listen to. In the meantime we study Mars, we theorize about it, we photograph it and probe it, and we ponder the challenges and benefits of someday living on it.