We describe here the realization and tests of a two stage torsion pendulum facility (nicknamed
PETER, from Italian PEndolo Traslazionale E Rotazionale, namely translational and Rotational
Pendulum) for the measurement of the Gravitational Reference Sensor (GRS) actuation Cross
Talks (CT) for LISA-Pathfinder and its possible evolution. This project started within the ground
testing activities for the characterization, before flight, of the GRS of LISA-Pathfinder, where
it showed results consistent with what observed on flight. The apparatus could easily evolve to
a facility to test small forces/torques on free falling instrumented masses, for future next generation
space missions. Here, we will discuss the principle of operation of the double torsion
pendulum and the initial goal of the activity, the description of the PETER apparatus, cross -talk
measurement technique and results and possible extension to more than 2 DoF