<title>A Superconducting Gyroscope to Test Einstein's General Theory of Relativity</title>

In 1960 L.I. Schiff suggested a new test of Einstein&apos's General Theory of Relativity based on measuring the precessions of the spin axes of gyroscopes in orbit around the Earth. Since 1963 a research group in Stanford Physics and Aeronautics Departments has been developing an experiment to measure the two effects calculated by Schiff. The gyro-scope consists of a uniform sphere of fused quartz 38 mm in diameter, coated with super-conductor, electrically suspended and spinning at about 170 Hz in a vacuum. Readout is by magnetic observation of the London moment in the spinning superconductor. The paper describes the proposed flight apparatus and the current state of development of the gyroscope, including techniques for manufacturing and measuring the gyro rotor and housing, generating ultra-low magnetic fields, and mechanizing the readout. The torque analysis, which indicates a limiting gyro drift-rate of 2 x 10-11 deg/hour in space, is briefly summarized.