WASHINGTON, Jan. 5 (UPI) -- Questions about the possibility of life on Mars have persisted for at least 125 years, ever since Italian astronomer Giovanni Schiaparelli trained his new telescope on the red planet and wrote down a word that resulted in one of the biggest misunderstandings in history.
Schiaparelli observed what appeared to him to be strange lines across the Martian surface, perhaps channels carved by water. So he wrote the Italian word for channels in his journal, "canali."
When Schiaparelli's report reached the English-speaking world, it caused a sensation. His canali were thought to be canals, trenches connecting Martian oceans dug by intelligent beings.
Twenty years later, the Martian canals idea inspired H.G. Wells to write his classic novel, "The War of the Worlds," which described a Martian invasion of Earth. The fascination with Mars continued throughout the 20th century, starting with claims by Guglielmo Marconi, the wireless telegraph inventor, that he had received radio messages from Mars. Mars mania also included the notorious broadcast by Orson Welles of a radio version of "The War of the Worlds," which caused a panic on Halloween, 1938, because thousands of people thought the broadcast was real.
Along with the sensationalism, Mars has generated an intense and sustained interest among the international scientific community. Four space agencies -- American, Russian, Japanese and European -- have attempted to reach the red planet 35 times since 1960. Only 13 missions have succeeded, beginning with the flyby of the Mariner 4 spacecraft in 1965 and culminating with the twin, picture-perfect executions of the European Mars Express orbiter on Christmas Day and the landing of NASA's Spirit robotic rover last Saturday night.
The Mars Express has begun its high-resolution survey of the planet's surface, and will continue to listen for signals from the tiny Beagle 2 lander, which also made its rendezvous with Mars on Christmas, but thus far has remained silent.
Spirit, which signaled its mission managers it had landed safely on Jan. 3, is the first of two, exquisitely sophisticated new vehicles launched by NASA to the red planet last June. The second craft, called Opportunity, is scheduled to land on Jan. 25. Both are designed to roam hundreds of yards over the Martian surface during their expected 90-day operational lifetimes.
All these spacecraft have been launched because, next to Earth, Mars is the most likely place in the solar system to harbor life. If so, it would mean life exists somewhere else in the universe and if life exists in two places, it could exist in thousands -- or perhaps millions -- of others. Though no one yet knows whether life exists on Mars, after nearly half a century of study, there seems to be no question life on the red planet is possible.
"We know that Mars has all the elements needed to support life," said Bruce Jakosky, director of the University of Colorado's Center for Astrobiology. "We are trying to find the nature of planetary habitability." Mars, he said, represents a model for studying how life could have gotten started in the solar system.
In a sense, Mars is a better place to study life than Earth, because even if life exists there, it does so at the margins -- probably under the surface or near the planet's hot volcanic vents. Despite the 13 missions, no one yet has been able to confirm the existence of a single cell on Mars -- alive or fossilized. The Express orbiter -- along with NASA's Mars Global Surveyor and Odyssey, which are still operational -- will continue to search for signs of life on the planet from above. Meanwhile, Spirit and Opportunity -- if it matches its twin's success -- will probe the surface. The prize for these efforts is a possible answer to some of humanity's biggest questions.
"You don't want to just land on Mars," said Matt Golombek, one of the Mars Exploration Rovers' principal mission scientists. "You want to be able to ask the fundamental questions."
Those questions, in terms of the MER missions, Jakosky said, are threefold:
--What is the origin of life and how did evolution begin?
--What role does planetary environment play in that process?
--What is the potential for life in the solar system and what is its actual distribution?
Perhaps the questions are even more basic than that, Jakosky said. "Where do we come from, where are we going, and are we alone?"
If any answers can be found by the current crop of Mars probes, there is no doubt they will shape human exploration of the red planet -- and the rest of the solar system -- for generations.
Next: Follow the water
Phil Berardelli is UPI's Science and Technology Editor. E-mail firstname.lastname@example.org
(Editors: UPI photos WAS2004010501 and WAS2004010502 are available)