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THAT IS EXACTLY WHAT DANIEL Goldin has challenged NASA to do in the Origins program: locate and even photograph Earthlike planets outside our solar system. The initiative is headed by Edward Weiler, an agency veteran who also serves as chief scientist for the Hubble telescope. "That's a pretty lofty goal," says Weiler of Goldin's challenge. "You're talking about objects that are millions to billions of times fainter than the stars around which they're revolving." The only way to do it, he and other astronomers agree, would be to use a space telescope with a mirror as wide as a football field is long.
Such a gigantic scope is utterly beyond current technology, and beyond anything engineers can imagine for the next century as well. But astronomers know they can simulate a huge telescope by orbiting several smaller ones, widely separated, and combining their light electronically. This multimirror device is known as an interferometer, because rather than gathering light directly, it measures interference patterns created when light waves from several mirrors overlap each other.
Unlike traditional NASA projects, which tend to be expensive and complex, this one is relatively modest. "We really don't want to start out building the Battlestar Galactica," says Weiler. Instead he will start with a demonstration model by the turn of the century, a device consisting of four to six mirrors a foot or two across. Even at that size, the interim interferometer should be able to spot objects the size of Neptune around nearby stars.
Finally, by about 2010, NASA hopes to launch what it calls the Planet Finder: an interferometer with five 3-ft.-to-6-ft. mirrors spread over 300 ft., orbiting out by Jupiter, where the solar-system dust begins to thin out. The Planet Finder should allow scientists to identify Earthlike planets, which should show up as pale blue dots in images beamed back to ground controllers, and analyze their atmosphere for signatures of life like ozone, oxygen or carbon dioxide.
That is not ambitious enough for Goldin, though. He wants engineers to create a device so powerful that it could take pictures of Earthlike planets in such detail that we might see clouds, continents and oceans. "That's mighty tough," cautions Weiler, careful to say Goldin's vision isn't impossible. "It sounds way out, but when Kennedy said, 'We're going to be on the Moon in nine years,' a lot of people thought that was way out. On the other hand," he adds wistfully, "they got $25 billion."
Origins will receive nothing close to that. Goldin expects his scientists and engineers to do it for several hundred million dollars, drawing from existing programs and saving money by technological innovations as yet unspecified. And if his ambitious goals are not met, will he consider Origins a failure? "No!" Goldin fairly shouts. "I'm trying to say, let's expand our minds and let's see if we can answer some basic questions. It may be there's not a terrestrial-size planet out there."
One point in his favor: by keeping the budget low, proceeding in small steps and refusing to make firm promises about what the program will produce, Goldin may be improving his chances of keeping Congress on his side. Boss, for one, thinks Origins will endure even after Goldin is gone. "The momentum is building," he says. "The scientific imperative is there."