Life beyond us: Search goes on

Arizonans among those seeking clues in cosmos

SIGNS OF LIFE: First in a three-day series

Stare up at the shimmering points of light in Southern Arizona’s velvety night sky — each a distant shining sun — and the question is inescapable:

Is there life out there?

The Greeks puzzled over it thousands of years ago. Italian Renaissance philosopher and poet Giordano Bruno argued that the universe has an infinite number of worlds, each inhabited by intelligent beings. He was declared a heretic and burned at the stake.

A century ago, Flagstaff astronomer Percival Lowell convinced himself that super-intelligent canal-builders, possibly a race of gilled giants, inhabit Mars.

In the future, Lowell wrote, mankind “is destined to discover any number of cousins scattered through space.”

“That we are the sum and substance of the capabilities of the cosmos is something so preposterous as to be exquisitely comic,” Lowell wrote in 1895.

Today, space telescopes peer into the far reaches of the cosmos, robotic spacecraft alight on other worlds, and giant radio antennas listen for messages from space.

But we haven’t heard from any extraterrestrial “cousins,” and there’s still no solid evidence for any life — even primitive pond-scum-level organisms — beyond our home planet.

Is life unique to Mother Earth, or is it as common as the grains of sand on a beach? How did life begin on our own planet? We still don’t know.

But Arizona researchers and their colleagues around the globe are amassing the knowledge and tools that could, finally, yield some answers in this new century.

Some of them are probing the origins of life on Earth and cataloging the broad range of hellish conditions that microorganisms can tolerate.

That inventory will inform future searches for life elsewhere, and it suggests that microbial worlds may be far more common than intelligent ones.

Other Arizona researchers are helping the National Aeronautics and Space Administration identify the most likely places to find evidence for life on other planets and moons in our solar system.

On Mars, the search is for fossil microbes, not the brainy canal-builders imagined by Lowell.

At Jupiter’s moon Europa, Arizona researchers on NASA’s Galileo mission helped uncover strong evidence for an ocean beneath the satellite’s icy outer shell.

They recently proposed new instruments for a future mission to settle the Europa ocean issue, which bears directly on the potential for a subsurface biosphere there.

Beyond our solar system, nearly 30 Jupiter-sized planets have been discovered in the last five years.

Arizona astronomers are designing huge space telescopes that will search the skies for smaller, more Earth-like planets and check their atmospheres for signs of life.

Maybe we are alone in the universe. Or perhaps Lowell and Bruno were right.

Either way, finding an answer to the question, “Is there life out there?” will irrevocably alter our view of the myriad shimmering points of light in the desert’s clear night skies.

Photo illustration by James S. Wood, The Arizona Daily Star: Saguaros lift their arms toward star trails that streak the clear desert sky in this time-lapse photo.