South Pole Cryogenics Various astrophysical projects at the South Pole use cryogens to reduce instrument noise.  Liquid nitrogen (LNN2) is used to calibrate and liquid helium (LHe) is used to cool circuits to four degrees above absolute zero.  Liquid helium is a critical part of some experiments, and it is also volatile; therefore the volume of this cryogenic fluid on station is monitored closely. Liquid Helium Tracking Spreadsheets The South Pole Cryogenics web page posts updates of the Liquid Helium Tracking Spreadsheets as they become available. Total Volume Liquid Helium on Station—3K Volumes (PDF 24 KB) Total Volume Liquid Helium in Dewars—Wessington Volumes (PDF 24 KB) Actual vs Projected Liquid Helium in Transport (PDF 24 KB)