Tilt-to-Length Coupling in the GRACE Follow-On Laser Ranging Interferometer

Henry Wegener, Vitali Müller, Gerhard Heinzel, Malte Misfeldt
2020 Journal of Spacecraft and Rockets  
The Laser Ranging Interferometer onboard the Gravity Recovery and Climate Experiment Follow-On satellites is the first laser interferometer in space measuring satellite-to-satellite distance variations. One of its main noise sources at low frequencies is the so-called tilt-to-length coupling, caused by satellite pointing variations. This error is estimated by fitting a linear coupling model, making use of the so-called center-of-mass calibration maneuvers. These maneuvers are performed
more » ... for the original purpose of center-of-mass determination. Here, the results of the tilt-to-length estimations for the Laser Ranging Interferometer are presented in terms of coupling factors, which are all within 200 μm ⋅ rad −1 and thus meet the requirements. From these parameters, estimations of nadir and cross-track components of the spacecraft center-of-mass positions with respect to the interferometer reference point are derived, providing an additional method to track center-of-mass movement over time. Nomenclature p = spacecraft positions, m q = spacecraft attitude quaternions X = spacecraft state vector θ = intersatellite pointing angles, rad λ = tilt-to-length coupling factors, m ⋅ rad −1 ρ = intersatellite range, m ω = spacecraft angular velocities, rad ⋅ s −1
doi:10.2514/1.a34790 fatcat:cvttj7fj35hgjb6p4tzpt7y4wq