Life as We Don't Know It; Earth-Like Planets Aren't the Only Places to Look for Life
Byline: Ben Bova , SPECIAL TO THE WASHINGTON TIMES
One man's meat is another man's poison. And vice versa. The search for extraterrestrial life has opened our eyes to how diverse and tenacious life is here on Earth.
NASA astrobiology researchers have discovered a species of bacteria living in Mono Lake, Calif., that uses highly toxic arsenic as a normal part of its metabolism.
Arsenic is a deadly poison to human beings and most other life forms on Earth, but to little GFAJ-1, it's a vital ingredient for life.
The organism belongs to a common group of what are called the Gammaproteobacteria. But unlike any other organism on Earth, GFAJ-1 powers its metabolism with arsenic instead of phosphorus as all we other living creatures on Earth use.
Astrobiology is the study of the origin, evolution, distribution and future of life in the universe. How did life begin? How has it changed over time? Is there life elsewhere in space? What is the future of life in the universe?
Little GFAJ-1 has opened the door to a fresh look at these questions.
Up until about a quarter-century ago, most scientists were convinced that life cannot exist without the energy of sunlight, water and carbon-based building-block molecules. After all, every type of life on Earth that we knew of depended on those three factors.
But as scientists from many fields probed deeper, they began to find forms of life that exist under tremendous pressures at the utterly dark bottom of the ocean, bacterial organisms that live deep underground and never see the sun, organisms that thrive at temperatures, salinities and other conditions that would be instantly fatal to us.
Astrobiologists call these creatures extremophiles: organisms that can survive under conditions that are far too harsh for you and me.
There's even a species of bacterium that can withstand more than 100,000 times the radioactivity that our cells can take. Tough little Deinococcus radiodurans has been dubbed Conan the Bacterium by astrobiologists.
GFAJ-1 is the latest in this weird assortment of extremophiles. What these creatures are telling us is that living organisms can exist under a much broader set of environmental conditions than we thought possible a mere generation ago.
Life is tougher and more versatile than we had imagined. Indeed, the Earth on which life developed was nothing like the Earth we have today.
When our planet coalesced out of a swirling conglomeration of gases and dust, the Earth was molten from the heat of a constant infall of meteors, smashing into our newborn world. …