SETI Search Site Startup

Super. Sorry.

The famous technologist will be inaugurating the initial 42 antennas of his namesake, the Allen Telescope Array (ATA) – the first major radio telescope designed from the pedestal up to efficiently (which is to say, rapidly) chew its way through long lists of stars in a search for alien signals. Within two decades, it will increase the number of stellar systems examined for artificial emissions by a thousand-fold. The ATA will shift SETI into third gear.

This telescope is truly a geek's barn-burner. In the last two decades, high-performance radio amplifiers have gotten smaller and, more importantly, much cheaper. This has changed the recipe for building radio telescopes, and the ATA is taking advantage of the new formula.

Consider: the single most consequential characteristic of a radio telescope (at least, for SETI) is its collecting area: the number of square meters boasted by its "mirror." There are two ways to increase this area: either build a bigger antenna, or build lots of smaller ones and hook them together. As an example of the former strategy, imagine doubling the diameter of the antenna's "dish", thereby increasing the collecting area by a factor of four. A good thing, surely. But since an antenna is a three-dimensional device, the amount of aluminum and steel necessary for the larger antenna has gone up by a factor of eight. Expensive. It's cheaper by half to build four of the original-size antennas.

This is a simple scaling argument, but it boils down to this: it's always more economical to assemble a large collecting area by constructing small antennas, rather than large ones.