LISA Pathfinder Performance Confirmed in an Open-Loop Configuration: Results from the Free-Fall Actuation Mode

Area of Science:

• Space physics
• Gravitational wave detection
• Precision measurement

Background:

• The LISA Pathfinder (LPF) mission aims to measure minute acceleration noise between test masses.
• Traditional methods involve continuous actuation forces, which can introduce noise and calibration errors.
• An alternative free-fall mode offers a way to measure acceleration noise in the absence of actuation.

Purpose of the Study:

• To report on the results of the LPF free-fall mode experiment.
• To validate the LPF's noise measurements through an independent method.
• To assess the effectiveness of intermittent actuation for noise reduction.

Main Methods:

• Implementing a free-fall mode where control forces are applied intermittently as impulses.
• Measuring differential acceleration noise during periods of true free fall.
• Conducting additional measurements with larger actuation forces.

Main Results:

• The differential acceleration noise measured in free-fall mode aligns with results from the continuous actuation scheme.
• This agreement serves as an independent confirmation of the LPF's overall noise performance.
• The technique effectively eliminates actuation noise when it is a dominant factor, even with larger forces.

Conclusions:

• The LISA Pathfinder free-fall mode provides a valid and independent method for measuring acceleration noise.
• This approach successfully eliminates actuation noise and calibration errors, confirming previous findings.
• The intermittent actuation technique is a viable strategy for noise reduction in precision measurements.