The task of keeping the experimental payload near the 1.8 degrees kelvin fell to a vacuum-jacketed device called a dewar.
The task of keeping the experimental payload near the 1.8 degrees kelvin fell to a vacuum-jacketed device called a dewar. Invented by James Dewar (1854-1928) the dewar is basically a large “thermos bottle” designed to hold liquified gases, which in the case of Gravity Probe B, meant holding liquid helium in a superfluid state (below 2.16 degrees kelvin) for nearly two years. The 650-gallon, nine-feet tall dewar also served as the main structural element of the spacecraft.
Image credit: Stanford University/Barron Storey