Dr. Meike List
ZARM, Universität Bremen

MICROSCOPE: A space-based test of the Weak Equivalence Principle

In 2016, April 25th the French space mission MICROSCOPE was launched. The mission's goal is to test General Relativity by determining the validity of the Weak Equivalence Principle (WEP) at the 1E-15 precision level. The MICROSCOPE space mission implements a new approach to test the WEP by taking advantage of the very quiet space environment. Non-gravitational forces acting on the satellite are counteracted by cold gas thrusters making it possible to compare the accelerations of two test masses of different compositions (titanium and platinum alloys) “freely falling” in the same orbit around Earth. This is done by accurately measuring the force required to keep the two test masses in relative equilibrium.

The T-SAGE (Twin Space Accelerometers for Gravitation Experiment) scientific payload, provided by ONERA, is integrated within a CNES microsatellite. Among the German scientific cooperation partners, the Center of applied space technology and microgravity (ZARM), University of Bremen, has been involved in the mission with two different tasks. The accelerometer payload was qualified in ZARMs drop tower by means of free fall tests. Furthermore, the whole mission was simulated by using the high precision orbit propagation tool HPS (developed together with the DLR institute of space systems in Bremen) for preparing the scientific data analysis during the mission's phases C and D as well as during commissioning phase.  

After shutting down drag-free control in February 2018, the high precision accelerometers are still working and are currently used to perform technical experiments, e.g. instrument, platform, and propulsion experiments. The system will be decommissioned in November 2018 and the satellite will be set to de-orbit mode.

In this talk the mission's milestones including a detailed description of the scientific payload as well as the satellite itself will be presented. Furthermore, the current result of still ongoing data analysis will be shown.