Detection and characterization of instrumental transients in LISA Pathfinder and their projection to LISA

On a new LISA dynamics feedback control scheme: Common-mode isolation of test mass control and probes of test-mass acceleration

“…Injecting guidance signals induces no change on Θ S/C , H S/C and Φ S/C , while producing an apparent change to the measured test mass position and angle relative to the housing. Suspension forces and torques will then be triggered as expected, while S/C jitter around the nominal working point will be rejected by the combinations shown in Equation ( 16) and (25). This important exception to the isolation is true both for longitudinal and angular suspension of the test masses.…”

“…One can also verify that an attitude guidance on the spacecraft will still trigger suspension forces and torques on the test masses, ensuring that they will follow the spacecraft while it orbits the Sun. In this case Θ S/C , H S/C and Φ S/C shown in Equation ( 16) and (25) are by definition error signals and not sensing outputs: they are inputs of the DFACS. Injecting guidance signals induces no change on Θ S/C , H S/C and Φ S/C , while producing an apparent change to the measured test mass position and angle relative to the housing.…”

“…Differential mode along the sensitive axes: a local measurement of the differential acceleration noise -At low-frequency, test-mass acceleration noise limits the performance of LISA. Understanding noise behavior is critical to identifying transient events [25], extracting the maximum number of continuous gravitational waveforms and stochastic gravitational wave signals [26,27]. A number of instrument-noise characterization experiments and calibrations also rely on applying and measuring direct forces on the test masses [28].…”