Identification and Removal of Reaction Wheel Interference From In‐Situ Magnetic Field Data Using Multichannel Singular Spectrum Analysis. Issue 2 (10th February 2023)

• Record Type: Journal Article
• Authors: Finley, Matthew G.; Broadfoot, Robert M.; Shekhar, Sapna; Miles, David M.
• Is Part Of: Journal of geophysical research. Volume 128:Issue 2(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-02-10
• Subjects: magnetic interference -- gradiometer -- reaction wheel interference -- magnetic field data -- interference suppression -- magnetometer; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1029/2022JA031020
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: In situ magnetic field measurements are critical to our understanding of a variety of space physics phenomena including field‐aligned currents and plasma waves. Unfortunately, high‐fidelity magnetometer measurements are often degraded by stray magnetic fields from the host spacecraft, its subsystems, and other instruments. One dominant source of magnetic interference on many missions are reaction wheels—spinning platters of varying rates used to control spacecraft attitude. This manuscript presents a novel approach to the mitigation of reaction wheel interference on magnetometer measurements aboard spacecraft where multiple magnetometer sensors are deployed. Specifically, multichannel singular spectrum analysis is employed to decompose multiple time series simultaneously. A technique for automatic component selection is proposed that classifies the decomposed signals into common geophysical signals and disparate locally generated signals enabling the robust estimation and removal of the local interference without requiring any assumptions about its characteristics or source. The utility of this proposed method is demonstrated empirically using in situ data from the CASSIOPE/Swarm‐Echo mission, and a data interval with near‐constant background field was shown to have its local reaction wheel interference reduced from 1.90 nT RMS, for the uncorrected outboard sensor, to 0.21 nT RMS (an 89.0% reduction). This technique can be generalized to arrays of more than two sensors, and should apply to additional types of magnetic interference. Plain Language Summary: In order to observe and study the magnetic fields near Earth, high‐quality magnetic field measurements are necessary. However, the spacecraft carrying magnetic field sensors are often magnetically noisy—they produce stray magnetic fields that contaminate the measurements. One dominant noise source on many spacecrafts are the systems that control the orientation of the spacecraft. This manuscript presents a novel approach to the suppression of magnetic interference caused by these systems, improving the quality of acquired data. Specifically, a technique for the simultaneous separation of multiple measurements into physically meaningful components is combined with an automated component selection technique. This allows for a high‐quality estimate of the spacecraft noise to be generated and subsequently removed from magnetic field measurements, greatly improving the data quality. For example, an interval of data captured by the CASSIOPE/Swarm‐Echo satellite was shown to have its local interference reduced by an average of 89%. Key Points: In situ magnetic field measurements are often degraded by stray magnetic fields from the host spacecraft, such as from reaction wheels Decomposing magnetic field data from multiple sensors simultaneously using multichannel singular spectrum analysis allows separation of geophysical fields and local noise Automated component selection procedure allows for robust estimation and subtraction of local magnetic noise, improving data quality