The Gravity Probe B gyroscope readout system Original Research Article

We describe the superconducting gyroscope readout system to be used for measuring to a precision of 1 marcsecond in 10 hours of integration time the spin axis orientation of the Gravity Probe B (GP-B) gyroscope. The cryogenic portion of the readout system uses a dc SQUID to measure the gyroscopeʹs London magnetic moment. Room temperature electronics appropriately bias the dc SQUID, allowing the detection and amplification of the gyroscope signal. We will describe recent advances in the system hardware including improved electronics and packaging. We will show flight quality noise performance and will discuss measurements of the systemʹs rejection of simulated on-orbit environmental influences.