The National Aeronautics and Space Administration reported this week that ancient rocks on Mars analyzed by its Curiosity rover, which landed on the Red Planet in August, show that what is today a barren and inhospitable environment might well have supported living organisms quite comfortably in the distant past. Several billion years ago, scientists say, Mars had a thicker atmosphere and warmer weather and was awash in water flowing across its surface that was safe enough to drink.
Humans, of course, did not yet exist in that primeval past, which long predated even the appearance of the first dinosaurs on Earth some 230 million years ago. But microbial life could easily have flourished during that era. Though Curiosity's lab isn't equipped to detect Martian life, past or present, it can determine whether the kind of organic molecules that are essential to life — at least as we know it — are present in the Martian environment. NASA says researchers will have to carry out further experiments before that question can be settled.
The mere fact that simple organisms might once had lived on Mars, however, is enough to revive speculation about where else in the universe life may exist and whether there are other intelligent creatures with whom we might one day come into contact. Whether we are alone in the infinite vastness of space is one of the most intriguing questions of our existence, and it has long been the stuff of science fiction. Certainly the discovery of any kind of life elsewhere in the universe would be an epochal event in human history.
Curiosity's discovery of conditions on Mars in ancient times highlights one of the curious paradoxes of our musings about life on other planets. Though Mars, at some 36 million miles from Earth at its nearest, is far away in terms of terrestrial distances, it is even more remote when measured on the cosmic time scale. We are separated from the planet's fertile conditions not only by millions of miles but by billions of years. Even if we send a manned mission there, we can never revisit the era in time when Mars might have harbored life.
Such considerations apply with even greater force when it comes to life on planets outside our solar system. In recent decades astronomers have discovered scores of planets orbiting distant stars in our galaxy, at least some of which may have conditions similar to those on Earth. Multiply that by the billions of galaxies in our universe, and it seems likely there are many millions of Earth-like planets floating among the cosmos.
The problem is that they are so far away, and the universe is so old — some 14 billion years by recent estimates — that the chances of intelligent life occurring on any two of them at the same time are remote. Years ago, the British astronomer Fred Hoyle tried to calculate the likelihood of our ever being able to communicate with an advanced extraterrestrial civilization and found the odds vanishingly small.
What was interesting about Hoyle's calculation was the reason for that pessimistic outlook. It had nothing to do with the obvious difficulty of having to wait hundreds or thousands of years for answers even to messages transmitted at the speed of light. Rather, the more fundamental problem lay in his conclusion that a technically advanced civilization would have need a life span of at least 150,000 years in order to have any chance of overlapping in time with similar civilizations elsewhere in the universe.
When one considers that advanced, technological civilization on Earth is only about 100 years old, and adds to that the magnitude of the threats posed by natural disaster, overpopulation, environmental destruction, climate change and nuclear proliferation, it appears life on our planet will be lucky to survive a few more decades, let alone another 150 millennia. Is it only a matter of time before events overwhelm us or we self-destruct?
I'd like to believe our species can stick around long enough to find kindred spirits living on other worlds, or at least uncover evidence that life is indeed a universal principle of the cosmos. But if we fail in that endeavor, the fault will not lie in our stars, as the poet said, but in ourselves.Copyright © 2015, CT Now