The drag-free experiment on-board LISA Pathfinder, the LISA Technology Package (LTP), has for its main science mission the proof of a low disturbance noise level. It is measured differentially between two test-masses whose relative motion is perturbed by their respective capacitive actuator noise. In order to suppress this noise source the drift mode actuation scheme uses very short impulses to produce kicks. This way the test-masses motion between two kicks is a free parabolic flight and can be used for a spectral estimation of the remaining noise sources, allowing us to distinguish between external noise sources and actuation noise. This mode will be helpful in the case of a high actuation noise or to investigate some unexpected external noise source, but the foremost reason being that this experiment is closer to the ultimate LISA experiment in terms of actuation noise. It must be implemented on-board taking into account the constraints of a space-borne experiment in terms of robustness, usability and existing software and hardware architecture.
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