The Swarm Absolute Scalar Magnetometer magnetic cleanliness program

The Swarm mission selected by the European Space Agency (ESA) as the 3^rd Opportunity mission of the Earth Explorer Program will operate a constellation of three satellites dedicated to the most advanced survey of the Earth´s magnetic field and its temporal evolution. The magnetic payload aboard each satellite will consist of a Vector Field Magnetometer (VFM) developed by the Danish National Space Center and an Absolute Scalar Magnetometer (ASM) [1] developed by CEA-LETI in partnership with CNES. This instrument shall provide scalar measurements of the magnetic field for the calibration of the fluxgate vector instrument. As a consequence, its accuracy is crucial for the mission´s success, and all the parameters affecting it have been consequently thoroughly investigated. This paper focuses on the magnetic cleanliness program that has been implemented throughout the ASM development phases to guarantee its conformity with the performance requirements, from the instrument´s design and manufacture to its final qualification tests.