MICROSCOPE, testing the equivalence principle in space

The test of the equivalence principle can be performed in space with orders of magnitude better resolution than in the laboratory, because of the outstanding steady and soft environment of the in-orbit experiment. The expected new experimental results will contribute to the unification of the four interactions, demonstrate the existence of extra scalar interaction or participate in the research for a quantum gravity theory. The MICROSCOPE space mission is being developed within the framework of the Cries scientific program with the objective of testing the universality of free fall with a 10(-15) accuracy. The concept and the design of the experiment are discussed and the major performance drivers of the room temperature instrument are pointed out. The launch of the drag-free satellite is scheduled for late 2004. By its specific technology demonstration, the mission will open the way to even more accurate acceleration measurements for other space missions in fundamental physics. (C) 2001 Academic des sciences/Editions scientifiques et medicales Elsevier SAS.