The scientists on these two projects drop sensors into holes like that to search for astrophysical neutrinos, using the Antarctic Ice shelf as a giant target.
Neutrinos are basic particles that are nearly massless and only interact with other particles by a "weak" nuclear force. As a consequence, they can sail through dusty regions of our galaxy and universe and, in principle, let us see things that we never could with light that would get scattered away. This is particularly true with Supernovae- stars that exhaust their fuel, collapse under their own weight, and then explode. The electrons, protons, and photons in collapsing stars get so hot that they effectively bind together and cannot escape; only the neutrinos can get out, and as a result carry away 99% of the star's radiant energy. This makes neutrinos an alluring way to study stellar collapse.
|Picture of the 1987A supernova (with photons, not neutrinos), from Hubble Space Telescope|
Oh wait! I've spent the past two weeks living on one that holds 60% of the Earth's fresh-water! The idea behind the Ice-Cube Observatory is to drop strings of the sensors (photo-multiplier tubes) in the picture below into holes that are 2km deep and look for evidence of neutrinos scattering off a cubic kilometer section of ice. In principle, one can even use the multiple detectors to infer where the neutrino came from. They haven't seen anything yet, although the project only finished construction a year ago.
|Detector for Ice-Cube (on display in the station)|
|An antenna for the Askaryan Radio Array, being dropped into a hole.|
There's reason for optimism for the ARA folks- a balloon borne version called ANITA-2, which flew from McMurdo a few years back, saw evidence for one ultra-high-energy neutrino event. With time on their side, ARA may have the chance to see more than one.