NEW YORK: A panel of scientists convened by America's leading scientific advisory group says the hunt for extraterrestrial life should be greatly expanded to include what they call "weird life": organisms that lack DNA or other molecules found in life as we know it.
"The committee's investigation makes clear that life is possible in forms different from those on Earth," the scientists conclude in their report, "The Limits of Organic Life in Planetary Systems," published by the National Research Council.
Other experts hailed the report as an important rethinking of the search for life. "It's going to help us a lot to make sure we go exploring with our eyes wide open," said Michael Meyer, lead scientist for NASA's Mars exploration program.
Starfish, sequoias, salamanders and the rest of Earth's residents may seem very diverse, but they are surprisingly similar on the molecular scale. All species that scientists have studied need liquid water to survive, for example. Further, they all rely on DNA to carry genetic information, and they all use that information to build proteins from the same set of building blocks, known as amino acids.
NASA has long looked to life on Earth to guide its search for life on other worlds. Planets and moons that have hints of liquid water have been ranked high on the list of potential sites for life-detection missions.
But there is good reason to suspect that other kinds of chemistry could support life as well, the authors of the new report argue. Weird life could differ from life as we know it in small or big ways.
For example, while DNA uses phosphorus in its backbone, it might be possible to build a backbone out of arsenic instead. And life might exist in liquids other than water, perhaps ammonia or methane...
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