The TRACERS Fluxgate Magnetometer (MAG)

The NASA Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites (TRACERS) mission is a two-spacecraft mission designed to explore the temporal and spatial signatures of magnetic reconnection as observed at the low altitude dayside cusp. The instrumentation on each TRACERS spacecraft includes a three-axis vector fluxgate magnetometer (MAG). The MAG sensor design heritage is from Magnetospheric Multiscale (MMS), while the electronics heritage is from the InSight mission to Mars. Testing as part of the MAG instrument delivery verified that the MAG dynamic range exceeded ±60,000 nT with a resolution of ∼9 pT to provide margin. The fluxgate magnetometers have been calibrated on the ground, but as is typical for fluxgates they will be re-calibrated using on-orbit data. The TRACERS spacecraft are spinning spacecraft in an orbit at 590 km altitude. Absolute gains, orientation, and spin-axis offsets will be determined through comparison with the International Geomagnetic Reference Field (IGRF) with an underlying orbit-period cadence. Additionally, spin-tones allow determination of relative angular orientation and gain and spin-plane offsets at spin-period temporal resolution. To meet the TRACERS mission science objectives MAG will measure magnetic field perturbations from large scale field-aligned currents, and shorter scale Alfvén waves. The electromagnetic energy flux associated with these magnetic field perturbations has major impacts on particle acceleration along the flux tube and ionospheric heating through Joule dissipation. This conversion from electromagnetic to particle energy is a primary driver for the escape of ionospheric plasma into the magnetosphere, making this an important secondary science objective for the TRACERS mission.