BOSTON — NASA'S announcement that traces of Martian bacteria landed on Earth 13,000 years ago is a great summer science story. It fires the mind to imagine larger realms - at a time when Americans are already immersed in "Independence Day" extraterrestrials, "X Files," and other interplanetary ruminations.
The refrain "Are we alone in the universe?" is the talk - even if newly discovered shapes that "resemble some forms of fossilized filamentous bacteria" have not uttered the famous alien request, "Take me to your leader."
Yet whether the discovery is truly "stunning," as President Clinton stated in tones reminiscent of John F. Kennedy planning a moon visit, is not yet determined. Even if confirmed as a bona fide Martian being - albeit a primitive, single-celled one - many scientists say the find likely won't lead to a radical reappraisal of life as we know it.
For one thing, bacteria traces found in a meteorite by a NASA team are similar to those found on Earth. Such microbes are said to have emerged on Earth 200 million years after the planet was formed. Higher intelligence took 3 billion more years to emerge. Hence, the find is not comparable to the profound stir that would be caused if evidence of higher order life were found - traces, say, of a hypothetical Martian Neanderthal skeleton.
"These little straws of information really get whipped up into something big," says Owen Gingerich, a professor at the Harvard-Smithsonian Center for Astrophysics. "If real, they are interesting and allow for questioning. Still, between microorganisms and intelligent life there is an enormous gulf."
The bacterial microbe is found in the most ancient geologic formations on Earth; Earth's rocks are "teeming with them," says one scientist. This has led to speculation that in the 3 billion years available, the microbe could have originated on Earth, been jarred loose, got caught in the Mars orbit, only to have been sent packing back to Earth during a Martian surface disturbance. "If a microbe could find its way here, it could also find its way there," Dr. Gingerich says.
In recent years, the discovery of several planets that circle stars, just as the Earth orbits the sun, has led to speculation and excitement about intelligent life elsewhere. No objective proof of higher life has been discovered. About half of the astrophysics community does believe in forms of higher intelligence in the universe. Biologists and evolutionists, however, are more skeptical.
Physicists and astronomers work to reduce nature to simple and elegant forms, and often argue that to assume that in the vast realm of space time there is no other higher form of life is limited and arrogant. But biologists, who thrive on the examination of the complexity of life forms, tend to ask for more proof.
Some scientists warn that great expectations in highly touted new discoveries sometimes don't pan out. In the 1950s, for example, scientists Harold Urey and Stanley Miller created a sensation by devising an enclosed primordial terrestrial atmosphere and running a spark of electricity through it for a week. The result was a kind of modified amino acid, which many scientists thought would lead to a revolution in the understanding of evolution, though that did not prove to be the case.
THE question of higher forms of life or consciousness in the universe may not be answered by a microbe trace. But some thinkers say the discovery may lead to further awareness of how little human beings do know and perceive. Physicists sometimes tell their students to imagine a dog contemplating the work of Isaac Newton or Albert Einstein. Then they remind pupils that, to forms of higher intelligence, humans may seem a bit like the dog, not fully grasping the deeper principles of existence.
Gingerich, for example, remains philosophical about discovering higher intelligence, noting that human civilization on Earth has lasted only several thousand years. In a universe billions of years old, that's minuscule. "We may have missed other civilizations, or they have missed us, since in the order of magnitude we are talking about, a thousand years is just a drop in time."
But possible life on Mars is capturing the imagination. One Boston youth this week, when told of the discovery, asked his father: "Dad, is anything possible?"