Fact is no stranger to fiction.
Earthlings have, nevertheless, compiled a long list of entertaining but largely inaccurate fictional accounts about the Red Planet. Some of them, like the 1960s TV sitcom My Favorite Martian, are a joke. But others, including last years futuristic flick Mission to Mars, actually may contain a few grains of truth.
In reality, space probes have been visiting Mars since 1965 when Mariner 4 drifted past it at a distance of 6,145 miles. Rocket scientists have been trying to get their vessels to Mars even longer. Since the first unsuccessful attempt by the Soviets in 1962, 26 space probes have been launched toward Mars, hurtling upstream against the suns gravity like so many salmon.
Some were magnificent successes: the landings of the two Viking probes in 1976 and of Mars Pathfinder in 1997, for example. More often than not, though, the probes malfunctioned before completing their missions. NASA lost two Mars probes in 1999 alone.
So why go to the trouble?
Long ago, some people thought that civilizations adorned the surface of Mars. Percival Lowell, the founder of Arizonas Lowell Observatory, was one of them. One scheme from the 1920s, after Lowell had died, proposed communicating with Martians by digging huge trenches in New Mexico, filling them with kerosene and setting them on fire.
The misconceptions about Mars have scarcely become any less absurd with the passage of time and the acquisition of new knowledge. Consider the case of the infamous face on Mars. One of NASAs Viking orbiters innocently snapped a picture of the Cydonia region of Mars in 1976. The picture showed a surface feature that, to some, looked very much like a giant face.
Was the face a monumental sculpture left by some ancient Martian civilization or merely a fortuitous combination of light and shadow? In April 1998, an image taken by the Mars Global Surveyor camera, with a resolution 10 times better than the Vikings, revealed the face to be nothing more than a naturally eroded mesa, according to MGS chief scientist Arden Albee.
Some skeptics immediately suggested that the MGS image was doctored to conceal the truth, reminiscent of a conspiratorial effort along the lines of the movie Men in Black. But one scenario for life on Mars seems no less farfetched. It could be that humans are trying to get to Mars because, like spawning salmon, they are trying to return to their birthplace.
Scientists once regarded as impossible the idea that meteorites could come from Mars. Now that the idea is accepted scientifically, Stanford Universitys Richard Zare, for one, has even considered the possibility that life on Earth originally came from Mars via asteroid impact. In a way, Hollywoods belligerent cinematic depictions of Martians in movies like War of the Worlds and Mars Attacks! simply would reflect the traumatic ejection of Earths bacterial ancestors from the home planet.
Computer simulations conducted by Cornell Universitys Joseph Burns and his colleagues have shown that once every million years or so, an asteroid no smaller than a building strikes a glancing blow at Mars, launching bits of the surface into outer space. The simulations show that most of these Martian rocks are destroyed in subsequent collisions with asteroids or the sun. But some about four of every 100 pounds of material ejected from the Martian surface are snared in Earths gravity and fall to the ground as meteorites.
Remember The Blob, the 1958 movie starring Steve McQueen in which a meteorite delivers a cargo of predatory jelly to Earth? The blob aside, the underlying theory is actually sound.
Scientists know for a fact that meteorites are capable of transporting amino acids, the building blocks of life, to our planet. Although not from Mars, the Murchison meteorite, which fell in Australia in 1969, was teaming with amino acids. John Cronin, an Arizona State University chemistry professor, and other scientists have studied Murchisons amino acids thoroughly over the years. Cronin has said that scores of Murchisons amino acids are of a type that were previously unknown on Earth. If certain Martian meteorites are proven to contain the fossilized remnants of microbes, as University of Georgia geologist Christopher Romanek and others have argued, then maybe the earliest ones to reach Earth sowed the seeds of life on this planet. Evidence for this idea, gleaned from Martian meteorite ALH84001, was published in the Oct. 27, 2000, issue of Science by Benjamin Weiss at the California Institute of Technology and his co-authors at McGill and Vanderbilt universities.
Last April, NASA launched the Mars Odyssey spacecraft to study the composition of the Martian surface and to collect information about the planets potential radiation hazards for future human explorers. If humans actually do someday set foot on Mars, no respectable scientist expects to see any life forms as modest as a few plants, let alone cities full of little green men.
But experts like Romanek would settle for a few carbonate rocks chock full of microscopic bacteria dead or alive. And who knows? These Martian bacteria may turn out to be kinfolk to life forms on Earth, even if it does sound like some plot hatched for a Hollywood movie.