Allen Telescope Array In Action

DIY News writes "36 of an eventual herd of 350 dishes are now operational in a remote area 250 miles northeast of San Francisco. These antennas, 20 feet in diameter and the height of a football goal post, are the first installment of the Allen Telescope Array, and they are ideal for short SETI projects while the array is being built." From the articel: "The young ATA's first foray into SETI will be known by the straightforward (if not overly galvanic) name of Inner Galactic Plane Survey. The word 'survey' may surprise many who are familiar with this telescope's design. After all, it's being finely tuned to speedily examine large numbers of star systems in a so-called "targeted search". The completed array will be exceptionally nimble at such individual scrutiny, and will leave previous targeted searches in the data dust."

Comments

Re:Has Anyone Considered...

[Graymalkin]

SETI's search parameters are based on some really well though out assumptions about how ET civilizations might try communicating. In a technological society where eletromagnetic radition is reasonably well understood it shouldn't take too long to figure out that the radio portion of the EM spectrum is really useful, especially if their physiology remotely resembles anything on Earth. We can't naturally detect radio waves so we don't hear a buzzing sound when talking on cell phones and we can't see it so we're not blinded by an FM reparter on a hilltop. Radio travels quite far in all sorts of media and can be generated and detected with relatively simple electronics. Lower frequencies are also much easier to broadcast omnidirectionally so multiple receivers can pick up a signal simulteneously. Suffice to say that radio is something a technological civilization is probably going to make good use of. Because of radio's propogation characteristics it is possible to detect signals at extreme distances.

Because of this our solar system is surrounded by a bubble of radio chatter about a hundred light years in diameter, expanding a bit farther every year. A technological civilization within this bubble of radio noise is quite likely to see us. A thousand years from now a technological civilization within a two thousand light year bubble could potentially see us. Therefore it is assumed that we could see another civilization's radio noise. This is SETI's general search criteria, evidense of a technological civilization outside of our solar system.

Now if a technological civilization were deliberately trying to send us a message. Maybe not us specifically but anyone out in the galaxy who might be able to find such a signal. How might that civilization send out a signal? There's lots of different ways but there's a really good chance they would send it via radio. As mentioned, it has excellent propogation characteristics. Radio signals reach us from the edges of the visible universe, it wouldn't be terribly difficult to get a signal a few hundred or thousand lightyears. It is also something the universe is teeming with. There's radio sources all over the place yet also quite a few empty bands. A civilization that figures out how radio works and happens to point an antenna at the sky will find this out quickly.

Now it is possible advanced civilizations might communicate via some extremely high tech means. SETI's notion is twofold, we will be able to see random noise generated by a civilization or we'll get a deliberate signal from one. Under premise one we might see radio traffic of some super technological civilization, they might be broadcasting gravity wave signals but we might be able to see their radar. Under the second premise a civilization wanting to be seen by others would attempt to communicate in the most fundamental way possible. Radio waves are pretty fundamental. It takes a modest command of physics and electronics to detect them and understand what you're actually seeing.

So yes it has been considered.