[On May 6, 1997, the New York Times carried a major story on the changing scientific view toward possible life beyond the earth. The following text consists of excerpts from that article, written by William J. Broad.]
A quiet revolution is now shaking the foundations of exobiology, the study of the possibility of life elsewhere in the cosmos.
Alien life, the new thinking goes, might not actually need the warming rays of a nearby star. It might thrive inside dim moons and planets. The dark ecosystems would be warmed by inner heat, bathed in melted ice and powered by chemicals.
Lightless realms on Earth have been found to teem with interesting creatures. Now scientists wonder whether similar environments elsewhere in the universe are home to alien microbial hordes and, in some cases, to large beasts and beings higher up the extraterrestrial food chain.
This change in thinking drives the excitement over Mars and Europa, a large moon of Jupiter, both of which have recently yielded tantalizing clues of conditions favorable to subsurface life. Scientists also speculate that the interiors of up to 10 bodies in the solar system may harbor extraterrestrial forms of life. So might the dim netherworlds around distant stars, where scientists have been finding more and more evidence of planets.
If these theories are right, alien creatures may be far more numerous throughout the cosmos than previously thought -- and much closer to home. That idea is rapidly changing plans for space probes as well as for research programs that study dark ecosystems on Earth, which are increasingly seen as a good way to get to know the extraterrestrial odds.
"We're in a paradigm shift," Dr. Frank D. Drake, a pioneer in the scientific hunt for extraterrestrials, said in an interview. "We're realizing that biology is very opportunistic and can adapt to a much greater variety of conditions than we imagined.
"The number of planets capable of supporting life is probably much greater than we thought in the past."
Dr. Wesley T. Huntress Jr., associate administrator for space science at the National Aeronautics and Space Administration, said discoveries on Earth were largely behind the changed view of the possibility of life elsewhere.
In the past, exobiologists always focused on surface life, he said. "Now we've found that life on Earth doesn't need light and can exist under extreme conditions we never expected," Huntress added. "Those aren't so different from what exists on other planets. So the probability that life may have arisen somewhere else in this solar system has gone up."
The tumult is changing not only mind-sets but also exploratory plans. The National Science Foundation, the government's main source of financing for basic science, recently started a program called Life in Extreme Environments, which [seeks] clues to the existence of otherworldly life.
And NASA is revamping its whole approach to alien hunts. Biologists are being hired to help shape the agenda as other agency experts revisit and revise plans for existing probes of Mars, Jupiter and Saturn as a first step toward the development of new missions.
[One] target is Titan, an icy moon of Saturn that is already scheduled to be explored by NASA's Cassini spacecraft, which is in Florida being readied for launching this fall.
While orbiting and studying Saturn, Cassini is to deploy a probe to explore Titan, itself the size of a small planet. The probe will ride a parachute through the moon's dense atmosphere, which is thought to be similar to that of the early Earth.
Huntress said the new ideas about alien biospheres "could affect the way we do the observations" of Saturn and Titan. "That's all yet to be determined," he said.
Original file name: CNI - alien life.NYT
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