TY - JOUR

T1 - Scale Factor Determination for the GRACE Follow-On Laser Ranging Interferometer Including Thermal Coupling

AU - Misfeldt, Malte

AU - Müller, Vitali

AU - Müller, Laura

AU - Wegener, Henry

AU - Heinzel, Gerhard

N1 - Funding Information: This work has been supported by: The Deutsche Forschungsgemeinschaft (DFG, German Research Foundation, Project-ID 434617780, SFB 1464); Clusters of Excellence “QuantumFrontiers: Light and Matter at the Quantum Frontier: Foundations and Applications in Metrology” (EXC-2123, project number: 390837967); the European Space Agency in the framework of Next Generation Geodesy Mission development and ESA’s third-party mission support for GRACE-FO; the Chinese Academy of Sciences (CAS) and the Max Planck Society (MPG) in the framework of the LEGACY cooperation on low-frequency gravitational-wave astronomy (M.IF.A.QOP18098).

PY - 2023/1/18

Y1 - 2023/1/18

N2 - The GRACE follow-on satellites carry the very first interspacecraft Laser Ranging Interferometer (LRI). After more than four years in orbit, the LRI outperforms the sensitivity of the conventional Microwave Instrument (MWI). However, in the current data processing scheme, the LRI product still needs the MWI data to determine the unknown absolute laser frequency, representing the “ruler” for converting the raw phase measurements into a physical displacement in meters. In this paper, we derive formulas for precisely performing that conversion from the phase measurement into a range, accounting for a varying carrier frequency. Furthermore, the dominant errors due to knowledge uncertainty of the carrier frequency as well as uncorrected time biases are derived. In the second part, we address the dependency of the LRI on the MWI in the currently employed cross-calibration scheme and present three different models for the LRI laser frequency, two of which are largely independent of the MWI. Furthermore, we analyze the contribution of thermal variations on the scale factor estimates and the LRI-MWI residuals. A linear model called Thermal Coupling (TC) is derived, which significantly reduces the differences between LRI and MWI to a level where the MWI observations limit the comparison.

AB - The GRACE follow-on satellites carry the very first interspacecraft Laser Ranging Interferometer (LRI). After more than four years in orbit, the LRI outperforms the sensitivity of the conventional Microwave Instrument (MWI). However, in the current data processing scheme, the LRI product still needs the MWI data to determine the unknown absolute laser frequency, representing the “ruler” for converting the raw phase measurements into a physical displacement in meters. In this paper, we derive formulas for precisely performing that conversion from the phase measurement into a range, accounting for a varying carrier frequency. Furthermore, the dominant errors due to knowledge uncertainty of the carrier frequency as well as uncorrected time biases are derived. In the second part, we address the dependency of the LRI on the MWI in the currently employed cross-calibration scheme and present three different models for the LRI laser frequency, two of which are largely independent of the MWI. Furthermore, we analyze the contribution of thermal variations on the scale factor estimates and the LRI-MWI residuals. A linear model called Thermal Coupling (TC) is derived, which significantly reduces the differences between LRI and MWI to a level where the MWI observations limit the comparison.

KW - GRACE follow-on

KW - laser ranging interferometer

KW - scale factor

KW - thermal coupling

KW - tone error

UR - http://www.scopus.com/inward/record.url?scp=85147896973&partnerID=8YFLogxK

U2 - 10.48550/arXiv.2207.11470

DO - 10.48550/arXiv.2207.11470

M3 - Article

AN - SCOPUS:85147896973

VL - 15

JO - Remote sensing

JF - Remote sensing

SN - 2072-4292

IS - 3

M1 - 570

ER -