I stopped in at the visitor center and had a look around. Theres not much there for the visitor but you do get the basics.
There are 27 of the radio dishes and they are each 25 metres in diameter. The 27 dishes are arranged in a "Y" pattern with 9 on each leg of the Y. The legs of the Y can each be up to 20 Km long and this gives the combined array an effective resolving power of a 27Km sized dish. They use "interferometry" (some cleaver mathematics) to combine the signals from each dish so that they effectively get a single signal to work with for their astronomy.
The resolving power of the array is the equivalent of the "zoom" function on your camera. When the dishes are all spaced out over the three 20Km legs, it gives a very high resolving power (maximum zoom) and you get a detailed look at a very small piece of the sky.
But, when I was there, all the dishes were quite close together (within about 1 square Km) which lets the scientists get a "wide angle" look at the sky but with a very large antenna size to detect very weak or faint signals. The up-side of this for me is that it makes some nice pictures with all the dishes being so close together.
One of the things that this array of dishes has let scientists (astro-physicists actually) figure out is how black holes manage to accelerate particles up to near-light speeds and "squirt" them out in narrow beams from their poles. These beams of extremely high energy particles are in fact rather deadly and if you just happen to be on the receiving end of one of them then, well, its all over! There is apparently some speculation that the earth may have got a "blast" of this sort that caused the dinosaur extinction etc...
Not that there is much that we could do about that sort of situation, but I do believe that this sort of research is incredibly valuable in understanding the physical universe. The physics involved in stars and black holes is the same physics that lets us build computers and cell phones and all sorts of every-day things too.
More knowledge is always a better thing as far as Im concerned... though the uses that we humans sometimes put that knowledge to are dubious to say the least!
Apparently there is also another array of this sort being built (on-line in 2012) with 50 dishes in the Atacama desert of Northern Chile....
Perhaps I will have a look at that one too when I get there...
