11 February 2010
I had a tour last month of the world’s strangest telescope. Not many have seen it, much less taken the tour. Why?
It’s at the South Pole. Only about 4,000 people have ever been to the South Pole. Most were there before construction began!
It’s called ICE CUBE.
A telescope in the shape of (and made of in reality too) a giant ice cube. I mean a big cube too. Think of an ice cube 1000 meters long, wide and tall. One cubic kilometer.
What are they looking for with it? Read on.
Imagine a particle so small that it could pass through the entire Earth and not run into anything. That particle exists and it is called a NEUTRINO. It has no charge and very little mass. There are a lot of them around. Many trillions pass through you every second but they don’t hit anything either.
So why use a telescope to detect them and why do astronomers care?
I wanted to say something like- It’s simple!
Frankly though, it’s not.
It gets into particle physics very quickly, but I spent some time on my trip to Antarctica talking with very smart people. One of them was Kyle Story who is working on the other South Pole Telescope. He kindly explained things to me at dinner one evening, so here goes, as far as I understand it.
Neutrinos have a big advantage over other things we build telescopes to see. They travel in a straight line and they ignore everything they pass through! We cannot see through our Milky Way Galaxy because of clouds of dust. Neutrinos pass right through with no affect. They can pass through almost anything with little or no affect.
They come in 3 types, but more importantly they come in high energy and low energy types. Cosmic rays hitting the atmosphere produce the lower energy neutrinos and our sun produces the trillions per second that pass through us. Even when the sun is down! (remember they pass through the Earth easily)
Astronomers are most interested in the high energy neutrinos. Those produced in supernova explosions, or the ones coming from the Big Bang when the universe was about two seconds old.
They are excited for good reason. Mark Krasberg of Ice Cube, who gave us the tour, says every time in history we have looked at the universe with a new kind of telescope, great discoveries were made. No reason to doubt that it will happen again this time.
So what happens when a neutrino does hit something? It produces another particle that continues in exactly the same direction and it produces a flash of blue light! That we can see.
( I shot the video above just before taking the pic at the top of this post)
To detect them and trace where they come from, you need to block out as many of the low energy neighbourhood neutrinos as possible, and you need a nice dark place full of something for the neutrino to hit, that is clear so we can see them!
How about a 1 kilometer cube of ice, 1km below the South Pole??
The ice is very dark at that depth but it’s also perfectly clear! If you look down toward the North Pole then you will get more of the high energy neutrinos you want and less of the local ones. It’s perfect!
Really! I kid you not.
Who is going to build it? Who has the money and the faciltiies at the bottom of the World to even try?
The National Science Foundation.
They are rightfully proud of this. Pure science for one reason. We want to know.
We are curious!
It is being constructed now. Scientists are digging holes around 2,500 meters deep and installing an array of detectors on a series of lines dropped into the hole. They dig the holes using heated water. Once they place the sensors, called DOM’s, (Digital Optical Modules) they will be frozen in the ice for thousands of years. A whole array of these DOMS will be used to track the blue light produced by those very unlucky neutrinos that do happen to hit something.
What’s even neater is that they let me sign my name to one. It’ll be there long after I’m gone. The ice at the pole is moving slowly toward the edge of Antarctica, and my signed DOM will pop out the edge of Antarctica in 25,000 years or so. Even better, my DOM may also discover what dark matter is.
A telescope buried in ice at the South Pole, looking down toward the North Pole, to detect particles so small they can pass through the Earth without hitting anything. If that doesn’t qualify for the world’s strangest telescope, nothing does!
I have just given a very brief explanation. Ice Cube has a great site online. You can find out a lot more there. Check out the FAQ too.
If you got the idea in high school that science was boring. You were told wrong. Way wrong.