Test-bed development and testing of the electrostatic positioning system for the satellite test of the equivalence principle

The Satellite Test of Equivalence Principle (STEP) is a NASA experiment to test the Equivalence Principle (EP) in space to at least 5 orders of magnitude beyond the current state of art. To achieve precision of 1 part in 10 18, many engineering subsystems have been developed to reduce disturbance and forces other than gravity.; Testing is essential in order to generate confidence that the engineering systems will perform as expected in space. For this purpose, an Accelerometer Test Facility (ATF) has been built. The ATF simulates the environment that the test mass will 'see' in space. To facilitate testing, a six degrees of freedom (DOF) test-bed, in the form of a cryogenic-probe, has been designed, implemented and tested. The 6 DOF test-bed is innovatively broken down in a 4 DOF stage at room temperature and 2 DOF cryogenic tilt table. The test-bed is used to test one of the STEP systems, called the Electrostatic Positioning System (EPS). This subsystem employs capacitive electrodes and facilitated measurement of five of the DOFs of the STEP test mass.; Before testing in the facility, an end to end simulation is performed. This simulation imitated the STEP accelerometer electrostatically and produced capacitance matrices as output. The simulation generated expectations for the test results and also allowed further analysis of the 'ideal' STEP accelerometer such as forces and nonlinearities which are difficult to measure directly. These results will be useful for the next generation STEP prototype. The simulations are followed by testing of the EPS subsystem in the ATF facility and the results show acceptable matching of experimental and simulated values. Some improvements in the STEP design, the prototype and the test facility are suggested for future implementation.; Roll of the test mass around the science data direction is important as it may produce systematic errors and degrade the science experiment. An analysis, for measuring and controlling this roll rate with current EPS design is presented in the last chapter. It uses the imperfections in test mass design e.g. non-cylindricity and mass center offset to sense and create torques on the test mass. Feasibility of this method, needed pre-flight measurements and control effort are also discussed.