SYSTEM-DESIGN FOR THE CONTROL OF LIQUID-HELIUM BY ELECTROSTATIC FORCES FOR THE SATELLITE TEST OF EQUIVALENCE PRINCIPLE (STEP) MISSION

Since the equivalence principle is a fundamental postulate of Einstein 's general theory of relativity, a precise test is of great scientific interest. An improved test of the equivalence of inertial and gravita tional mass by a factor of 10(6) is non possible, using superconductin g measurement technology in an earth-orbiting spacecraft. Superfluid l iquid helium must be used as a cryogen to maintain the temperature of the four gravimeters at 1.8 K. Because of the extreme sensitivity of t he measurement, the gravitational disturbance caused by the motion of the liquid helium in the local gravity-gradient field if of concern. I t is proposed to use electrostatic forces to provide the necessary con trol. We present a description of the design and performance of a prop osed flight system.