Buried a mile deep in the Antarctic ice, the AMANDA or Antarctic Muon and Neutrino Detector Array heralds a new kind of astronomy. AMANDA occupies a volume of ice three times the size of the Eiffel Tower, transforming the polar ice cap into a detector capable of sampling the high-energy neutrinos that emanate from some of the most distant and violent phenomena in the cosmos - colliding black holes, galaxies with super violent cores and mysterious gamma ray bursts. Like ghostly messengers, high-energy neutrinos traverse huge distances, passing through stars, planets, magnetic fields and entire galaxies without skipping a beat.
To distinguish neutrinos from a background of cosmic ray muons, the Earth is used as a filter, with only neutrinos able to pass through the planet unchecked.
Strings of optical sensors 500 meters long are dropped into wells in the Antarctic ice one and a half kilometers below the surface.
Slightly larger than a basketball, the optical sensors at the heart of AMANDA are arranged on fiber-optic cables. Deployed deep in the ice like beads on a necklace, the sensors work like light bulbs in reverse. They capture light - even the faint and fleeting Cherenkov light traced by muons - convert it to electricity, amplify it and turn it into an optical signal that is sent to the surface where it is stored, read and interpreted.
A trail of Cherenkov light is created when a neutrino, on very rare occasions, crashes head-on into another particle such as a proton or neutron. From the wreckage of those collisions emerges a muon which creates a fleeting trail of blue light on a path identical to that of the originating neutrino, allowing scientists to follow it back to a point of origin.