Science: Cosmic Search

Listening for life in space

As it points serenely skyward from a ridge dotted with apple orchards, the 84-ft.-wide dish appears to be just another space-age antenna. But last week, the Harvard radio telescope, 30 miles northwest of Boston, became the center of a champagne inaugural and worldwide scientific attention. As colleagues and reporters clustered around him inside the observatory’s control room, Harvard Physicist Paul Horowitz tapped a few keys on a computer terminal. A minute or so later, a jumble of jagged lines flickered onto a video monitor. They represented the random squawks and beeps of the universe that had just been picked up by the giant antenna. Only slightly disappointed, Horowitz sighed, “Looks like the same old noise.”

Despite the inauspicious start, the event was something of a milestone. It marked the beginning of the most sophisticated search yet for evidence of intelligent life in the vast realms of space beyond the earth. Under a pledge of $120,000 from the Planetary Society, an organization of space advocates begun by Astronomer Carl Sagan (Cosmos), Horowitz and his colleagues will be scanning the heavens for the next four years. They hope to pick up some orderly signal, besides the chaotic noise of the stars, that would indicate that E.T. (for extraterrestrial) is not just a Hollywood fantasy.

For the past two decades, radio astronomers in the U.S. and abroad, especially the Soviet Union, have conducted dozens of such searches. None have picked up the slightest hint of a signal that might have been given off by a distant planetary civilization orbiting a remote star. Indeed, even diehards like Sagan are forced to concede that there is not a scintilla of hard scientific evidence that life of any kind exists on far-off worlds. But the search efforts so far have admittedly been slapdash, concentrating on only small parts of the sky and tuning in to just a few of the vast range of radio frequencies that might be used for transmissions. Horowitz, who caught the SETI (Search for Extraterrestrial Intelligence) bug after Cornell’s Sagan lectured on the subject at Harvard, decided to improve the odds. He developed a compact multichannel receiver that can be hooked to a large antenna and can listen to 131,072 closely spaced channels simultaneously.

Even the gifted E.T. could hardly be expected to pick out an intelligent signal in that electronic haystack. But Horowitz, who designed his “suitcase SETI” in collaboration with scientists at Stanford, the University of California at Berkeley and the NASA Ames Research Center, overcame the difficulty. The telescope’s signals can be fed into a computer and rapidly analyzed for the telltale blips that might mean a message. In addition, Horowitz centers his listening on certain “magic” frequencies, like those around the natural radio emissions of the hydrogen atom, which gives off beeps of a precise wave length. These frequencies would presumably be preferred by an advanced civilization for broadcasts because there is little interference in that part of the radio spectrum. In preliminary work at Berkeley, Jill Tarter, using a similar receiver developed under NASA’s auspices, picked up a number of tantalizing signals. Virtually all, it turned out, could be explained as local disturbances, as for example the static given off by the ignition of a passing truck.

Until recently, NASA had been blocked from undertaking such cosmic experiments because of the unwavering opposition of Wisconsin Senator William Proxmire, who once gave SETI a “Golden Fleece” award as a waste of taxpayer money. But Proxmire eventually relented, thanks to Sagan’s own faith in SETI (“an aperture to the future”) and to a persuasive argument that there might be welcome byproducts from the work, among them advances in computer technology. NASA will soon begin its own intensive searches, using even larger radio “ears,” like the 300-ft. Goldstone dish in the Mojave Desert and the 1,000-ft. Arecibo antenna in Puerto Rico. So, E.T, if you are really there, please call your friends. –