Estimation of the Magnetic Noise Contribution to LISA Pathfinder Differential Acceleration

The payload of LISA Pathfinder (LPF) is the LISA Technology Package (LTP), which is designed to measure relative accelerations between two test masses in nominal free fall placed in a single spacecraft. The differential acceleration reading will be perturbed by disturbances such as thermal fluctuations or magnetic effects. The Magnetic Diagnostics System is one of its modules and it will perform two main tasks: (1) estimate the magnetic properties of the test masses, i.e., their remanent magnetic moment and susceptibility, and (2) infer the magnetic field and its gradient at the location of the test masses. The present paper describes the first task and how an estimation accuracy of 1% relative error is attained.