It all starts with a hole in the ice. A really big hole in the ice...and getting that hole into the ice is an adventure in and of itself. In order to drill a hole in the huge block of ice that the South Pole is composed of, we use an enhanced hot water drill, or "the drill" to drill holes more than 2.5km deep.
We start by using what's known as a firn drill. The firn drill is used to drill through the firn layer (i.e. compacted snow) down to the actual ice, normally about 50 meters down. We do this before we start the hot water drilling because otherwise the water would disappear into the snow. We circulate and re-circulate hot water through the firn drill so it can melt its way through the ice, just spraying a small amount to the sides for lubrication.
After this, we then continue the drilling using hot water. The basic idea behind this process is to heat up water and then pump it down the ice hole we've just started with the firn drill. This hot water melts the ice, resulting in cooler water. This cooler water flows back up the hole that is being drilled to the surface where it is reclaimed, reheated, and reused. The drill system is made up of many components that were separated to make shipping and moving easier; shipping to the South Pole is no easy task! All of the components had to fit into the cargo hold of a C-130 (plane). At the South Pole two distinct sites comprise the drill system: the Seasonal Equipment Site (SES) and the Tower Operations Site (TOS).
After each hole is drilled the hose is removed to another location and the drilling operations begin again at the second TOS. It is possible to drill a new hole every 3-4 days using two towers. Once we've drilled the hole, we need to find out if it's big enough for us to put in a string of Digital Optical Modules (DOMs). The drill head itself has a set of calipers as part of the drill head that sends a serial data string to the surface in addition to a pressure sensor that lets us figure out the drill depth. Our drillers then analyze the data that is sent back to decide whether or not the hole has met the required dimensions. This data looks something like this:
