Colloquium: From Swarm to NanoMagSat, optically pumped helium magnetometers for Earth observation
Since Magsat in 1980, the payload of the missions dedicated to the study of the Earth magnetic field generally consists of a combination of a vector magnetometer co-mounted with star trackers on an optical bench plus a scalar magnetometer used as an absolute reference to calibrate the vector data. Now the Absolute Scalar Magnetometer flown on Swarm has demonstrated the feasibility to simultaneously deliver calibrated vector data in addition to the field amplitude, thus opening the way for a simplification of the traditional Earth Observation magnetic payload. Moreover this instrument could also be regularly operated at higher frequency (burst mode, with a 250 Hz sampling rate), which led to the detection of Extremely Low Frequency whistlers providing useful information on the ionospheric plasma. Building on the Swarm ASM’s results, the NanoMagSat mission will include a Miniaturized Absolute Magnetometer directly derived from the ASM-V but also a High Frequency Magnetometer similarly based on helium optical pumping but exploiting parametric resonances. Preliminary performance characterization results of both instruments will be discussed, as well as the mission development status.