1. A system for detecting a posture of a moving object in space comprising: a fixed electro-optical device of known orientation comprising at least one emission source, an image sensor and a processing system that performs image analysis; and an optical assembly comprising at least one optical retroreflector arranged on the moving object, wherein: the optical retroreflector is an optical sphere of variable index comprising a transparent hemisphere and a reflecting hemisphere such that a light ray, refracted by the transparent hemisphere, reflected by the reflecting hemisphere and refracted a second time by the transparent hemisphere re-emerges parallel to its direction of incidence, the optical retroreflector comprises a meshing comprising at least three opaque wires, of a thickness and known geometrical arrangement, an image of the optical retroreflector lit by the source forms a reflection on the image sensor, said reflection comprising at least two images of a shadow of one of the at least three opaque wires by the optical retroreflector, and the processing system performs the image analysis to detect at least an orientation of a leak line given by said images, said orientation being representative of a first parameter of the posture of the moving object.