By Jean-Louis Tison
Hello everybody ! Here are the fresh news of the drilling tent to tell you more about the second phase of the process in which we were obliged to move to a wet drilling mode.
As mentioned in one of my previous posts, starting at a depth of about 90-100m, just after the transformation of snow (density of 0.5 g/cm3) in firn (density 0.5-82 g/cm3) and then in ice (density 0.82-0.92 g/cm3) is finished, the pressure difference between the ice and the air in the drilling hole becomes too high.
The mechanical chocks from the cutting by the drilling head produce ice in small disks, a few centimeters wide, that makes further analyses extremely hard or even impossible in some cases (such as for instance the analysis of the gas composition of the ice because of the contamination from the actual atmosphere along the fractures).