Abstract
Abstract The role of the Absolute Scalar Magnetometer (ASM) in the European Space Agency (ESA) Swarm mission is to deliver absolute measurements of the magnetic field’s strength for science investigations and in-flight calibration of the Vector Field Magnetometer (VFM). However, the ASM instrument can also simultaneously deliver vector measurements with no impact on the magnetometer’s scalar performance, using a so-called vector mode. This vector mode has been continuously operated since the beginning of the mission, except for short periods of time during commissioning. Since both scalar and vector measurements are perfectly synchronous and spatially coherent, a direct assessment of the ASM vector performance can then be carried out at instrument level without need to correct for the various magnetic perturbations generated by the satellites. After a brief description of the instrument’s operating principles, a thorough analysis of the instrument’s behavior is presented, as well as a characterization of its environment in flight, using an alternative high sampling rate (burst) scalar mode that could be run a few days during commissioning. The ASM vector calibration process is next detailed, with some emphasis on its sensitivity to operational conditions. Finally, the evolution of the instrument’s performance during the first year of the mission is presented and discussed in view of the mission’s performance requirements for vector measurements.
Highlights
ASM payload, operating principle description, and standalone performances As the magnetic scalar reference of the European Space Agency (ESA) Swarm mission (Friis-Christensen et al 2006), the Absolute Scalar Magnetometer (ASM) developed by CEA-LETI with the support of CNES provides continuous absolute measurements of the Earth’s magnetic field strength B0 for science purposes and in-flight vector calibration of the Vector Field Magnetometer (VFM) fluxgate instruments
The maximum ASM accuracy error after all level 1b corrections is of 65 pT (1 σ) (Jager et al 2010, Fratter et al 2015), well below the 150 pT (1 σ) budget allocated to the instrument
A scalar noise analysis in the [35- to 40-Hz] frequency band performed on corrected burst mode noise spectrograms for all instruments during commissioning reveals scalar resolutions of respectively 1.1, 1.0, and 1.5 pT/Hz for the ASM nominal instruments on Swarm Alpha, Bravo, and Charlie, in full agreement with on-ground characterizations
Summary
ASM payload, operating principle description, and standalone performances As the magnetic scalar reference of the ESA Swarm mission (Friis-Christensen et al 2006), the Absolute Scalar Magnetometer (ASM) developed by CEA-LETI with the support of CNES provides continuous absolute measurements of the Earth’s magnetic field strength B0 for science purposes and in-flight vector calibration of the Vector Field Magnetometer (VFM) fluxgate instruments. A scalar noise analysis in the [35- to 40-Hz] frequency band performed on corrected burst mode noise spectrograms for all instruments during commissioning reveals scalar resolutions of respectively 1.1, 1.0, and 1.5 pT/Hz for the ASM nominal instruments on Swarm Alpha, Bravo, and Charlie, in full agreement with on-ground characterizations.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
