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nce it was asked in whispers, or with winks. The timid among us, though undeniably curious, feared raised eyebrows. Jokes about little green men. Who could take such a question seriously, yank it from the misty realms of science fiction and drop it under the searchlight of science? Well, our national space agency, for one. What’s more, NASA seems pretty confident these days about the answer: Astrobiology, as defined on an official agency website, is “the study of the living universe.”

James Kasting is a bit more guarded. Astrobiology is the search for life in the universe, the Penn State professor of geosciences and meteorology told a keen audience at the first talk in last January’s Frontiers of Science lecture series. Although the term itself may be recent, “This is not a new field,” Kasting said. He got his first taste of it as an undergraduate, reading Intelligent Life in the Universe, a 1966 book by Russian astronomer I.S. Shklovskii and a young American named Carl Sagan, who later wrote, “We have every reason to believe that there are many water-rich worlds something like our own.” Kasting was hooked.

In recent decades, Kasting acknowledged, the field has known a bit of a slump. It fell out of favor after the 1976 Viking mission to Mars. “Viking was very successful,” he explained. “We learned a lot — but we didn’t find life. The perception was that all that money was wasted.”

Today, astrobiology is back. The reports, over the last five years, of some 30 planets spotted outside our Solar System — the first of these by Penn State astronomer Alexander Wolszczan — have made all those potential watery Earths that Sagan speculated about less hypothetical.A great stir, too, has been caused by the discovery, in a melon-sized meteorite plucked from the ice of Antarctica, of a fossil-like remnant that, according to Kasting, looks a lot like Earthly bacteria — “except smaller by a factor of ten.” Martian microbes? Opinions vary. The possibility was strong enough, however, to warrant a press conference at which President Clinton said, “If this discovery is confirmed, it will surely be one of the most stunning insights into our universe that science has ever uncovered.”

There have been other, quieter, advances. We know now, for instance, that organic, i.e., carbon-based, molecules — crucial to any sort of life we can imagine — are virtually everywhere in the universe. And that, here on Earth, living organisms thrive in what once seemed the unlikeliest of places, from hot springs to frozen lakes — even far below the planet’s crust.

In 1998, NASA announced formation of an Astrobiology Institute, a partnership formed for study of “the origin, distribution, evolution, and future of life in the universe.” Penn State is one of 11 lead members. No surprise, then, that last winter’s annual Frontiers of Science series, organized by the Eberly College of Science and sponsored by the pharmaceutical company Pfizer, Inc., took astrobiology as its topic. On six straight Saturday mornings, the large lecture hall in the Thomas Building at University Park was filled to overflowing with people eager to hear talks by three planetary scientists, two molecular biologists, and a geologist. Astrobiology, these listeners learned, is no loopy fringe pursuit; it is coordinated, systematic, and broadly interdisciplinary. And it involves a lot more than just outer space.