NetSat-4G A four nano-satellite formation for global geomagnetic gradiometry

This paper proposes a concept for a Global GeomaGnetic Gradiometry (4G) nano-satellite mission. The proposed concept makes use of a formation of four nano-satellites carrying vector magnetometers and flying in a Cartwheel-Helix formation at low altitude. The use of four satellites makes possible the simultaneous measurement of the geomagnetic gradients in all three directions (east-west, north-south and radial), and thus the realisation of a full gradiometry mission. The concept foresees the use of a miniaturised propulsion system for formation acquisition and maintenance, allowing not only to setup optimal formation geometries for optimal gradient retrieval but also to extend the mission lifetime at the targeted low altitude. The preliminary results of an end-to-end simulation are presented, and the gradient concept for NetSat-4G demonstrated. Given the constraints inherent to a nano-satellite platform, measurement performance is still, as expected, inferior to what can nowadays be achieved with larger and more expensive missions. Despite the disadvantages, the proposed concept is still considered pertinent as it would allow, for the first time, to implement a full geomagnetic gradiometry mission.