In particular, the team:
- has been developing, testing and validating the disturbance noise budget for the almost free-falling test masses that serve as the reference end-mirrors for the laser beams in both missions.
- designed and tested the Gravitational Reference Sensor (GRS) that surrounds the test-masses and works as an active shield against external disturbances, is used both to sense the relative displacement of the spacecraft with respect to the test masses, and to actuate them so to force the system of bodies (spacecraft and test masses) to minimize their relative displacement. The key requirement is doing all this without introducing force noise exceeding the very stringent requirement imposed by the need of guaranteeing the quality of the free fall of the test masses.
- Plays the role of Principal Investigator (PI) of the LISA Pathfinder, the demonstration mission which main goal is to demonstrate the possibility of achieving the purity of free fall required for LISA.
The noise model is validated by testing the disturbances on the LPF and LISA test masses introduced by the GRS itself, within less than an order of magnitude from the LISA requirements in the Trento torsion pendulum facilities, where lightweight versions of the test masses are suspended inside replicas of the LISA GRS. This technique allows characterization of the individual noise sources (e.g. coupling to electrostatic spurious interactions, residual gas damping, thermal gradients), as well as evaluation of the overall residual noise originated in the sensor themselves. The study of the noise sources drives then the design of the GRS (or even the whole system) for LPF and LISA, so to minimize the impact of the disturbance source itself. Additionally, the HW can be tested in operative condition, so that the facilities serve as a fundamental test bench to develop and validate the experimental sequences that will be implemented in the LISA Pathfinder mission.
The head of the Trento group, Prof. Stefano Vitale, is the Principal Investigator of the LISA Pathfinder mission, and in this role his team:
- collaborates and coordinates with all the entities (Universities, institutions, industry) building LPF
- tests flight-representative HW at a level comparable with the LPF requirements
- together with the other institutions involved in LPF defines, validates and optimizes of the pattern of experimental sequences that will be carried on aboard LPF
- develops, together with the other institutions involved in LPF, the software of the quasi-real time analysis of the LPF experimental data
Team staff members:
William J. Weber