MICROSCOPEmisjonen

MICROSCOPEmisjonen was a European Space Agency (ESA) mission that studied the equivalence principle of general relativity. The mission was launched in 2016 aboard a Russian Rockot rocket. The primary instrument on board was the MICROSCOPE (Micro-Satellite à Composants Optiques et Électroniques) satellite, which carried a highly sensitive accelerometer to measure the motion of two pairs of test masses. These test masses were made of different materials and were placed in free fall within the satellite.

The fundamental idea behind the experiment was to test whether objects of different compositions fall at the same rate in a gravitational field, regardless of their internal structure. According to Einstein's equivalence principle, they should. MICROSCOPEmisjonen aimed to verify this principle to an unprecedented level of accuracy. By precisely measuring the accelerations of the test masses, scientists could detect even tiny deviations from the expected behavior, which would indicate a violation of the equivalence principle.

The mission collected data for several years, performing rigorous analysis to account for all potential sources of error, such as thermal effects, electrostatic forces, and atmospheric drag. The results, published in 2017 and subsequent years, showed no violation of the equivalence principle within the mission's limits of precision. This confirmed the validity of Einstein's theory of gravity with enhanced confidence. MICROSCOPEmisjonen represented a significant advancement in our experimental understanding of fundamental physics.