Abstract: A system for the modification of the rigidity and damping properties of structural joints comprises at least an intermediate structure (3) to receive, on both sides, two structures (1, 2) to be coupled; releasable blocking means (6) to immobilize, in a coupled condition, said two structures to be coupled and said intermediate structure; first and second sets of bistable components (7, 8), the structural resistance features of the components of the first set being different from those of the second set; the components of the first set being internally connected to one of said structures to be coupled and to said intermediate structure; the components of the second set being internally connected to one and other of said structures to be coupled; said bistable components being in an unstable condition when all the mentioned structures are coupled together. The invention is applicable to the field of space vehicles.