Ask Dr. SETI ®
by H. Paul Shuch
"To cross the Golden Gate," wrote the late Dr. Bernard M. Oliver fifteen years ago, "you need a bridge 6,000 feet long. Six thousand bridges of one foot each won't cut it." His analogy was intended as constructive criticism of the Project Argus all-sky survey then being launched by the nonprofit SETI League.
Oliver, one of the giants of SETI science, had good reason to be skeptical of our efforts. As the chief architect of Project Cyclops, the greatest radio telescope never built, he proposed in 1971 an array of a thousand dishes, each 100 meters in diameter, to scan the skies for electromagnetic radiation of intelligent alien origin. Surely our modest proposal to network 5,000 backyard satellite TV dishes, each only three to five meters across, seemed paltry by comparison. We SETIzens hoped to make up in strength of numbers what we lacked in budget, sophistication, or capture area. But 5,000 bridges of three meters each, Barney reasoned, would be incapable of spanning the gulf of interstellar space.
I disagreed with my esteemed mentor then, and still do today, although it turns out he was right in at least one respect: Project Argus has yet to capture SETI's holy grail. In fact, it hasn't even come close. But that's a matter of economics, not scientific or technological merit.
The five thousand dish goal was by no means arbitrary. Given the four pi steradian surface area of a sphere, and the three milli-steradian capture area of our small antennas, that's how many elements (properly coordinated and appropriately aimed) our virtual array would require to see in all directions at once. What we proposed was a first for sky surveys: real time all sky coverage, so that no direction on the sky should evade our gaze. And, in 1995 when first proposed, that goal seemed entirely achievable.
We should have been there by now. But in 2010, instead of 5,000 Project Argus dishes, our network is composed of just twelve dozen. Barney had questioned how much could be accomplished with a global phased array. He should instead have questioned how we were going to accomplish building one.
Of course, neither we nor Barney Oliver could anticipate what would transpire during the early years of the 21st Century: new global wars, recessions, economic meltdowns, and realignments of finite resources. What felt entirely feasible in the heady days of the dot-com boom now seems wildly optimistic. Though our hearts still scan the skies, our minds have been brought back down to Earth.
At last year's International Astronautical Congress, in a paper recapping lessons learned from Project Argus, I grudgingly admitted defeat. But, while outlining the project's current status and lessons learned, I also proposed a future direction for The SETI League, and other privatized scientific endeavors. These are the handful of recommendations in that paper, which I put before the SETI League membership today:
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this page last updated 6 February 2010
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