Our planet is surrounded by the Earth's magnetic field, which is generated by core movements and protects us from solar winds and cosmic rays. However, this field is subject to many variations from numerous sources: movements within the Earth's core (responsible for long-term changes in the magnetic field and even pole reversals), interactions with solar winds, tides, human activity and more. In the event of a magnetic storm, the instability caused by solar wind can lead to disruptions in power transmission networks and positioning systems, as well as increased exposure of satellites to ionizing particles.
The analysis of the Earth's magnetic field is therefore of prime importance in many sectors.
“Above all, this study is of major scientific interest,” emphasizes Jean-Michel Léger, Head of the “Space Applications” program at CEA. “The aim is to better understand our planet and its evolution through the lens of its magnetic field, and to use these measurements for magnetic navigation or to deduce information about ocean temperature and salinity.”
From the Swarm mission to NanoMagSat
This field is currently studied using ground magnetic observatories, magnetometers on board airliners and the European Space Agency's (ESA) Swarm space mission. Launched in 2013, Swarm comprises three mini-satellites, each equipped with magnetometers already developed by CEA-Leti
“We drew on the initial feedback from Swarm to identify a path for further analysis,” says Jean-Michel Léger. “This is what led us to propose a new mission."
Back in 2014, the NanoMagSat project was spearheaded by CEA-Leti and the Institut de Physique du Globe de Paris (IPGP), with support from the Centre National d'Etudes Spatiales (CNES). In 2019, the consortium successfully responded to an ESA call for tenders for a three-year program with a budget of thirty million euros.
A constellation of three nanosatellites in low-Earth orbit
The NanoMagSat mission consists of three “16U Cubesat” satellites, in other words nanosatellites weighing approximately 25 kg compared to the 470 kg for each Swarm satellite. Half the volume of the nanosatellite will be occupied by a deployable boom, leaving little room for instrumentation.
“CEA-Leti teams have worked on miniaturizing the magnetometers to adapt them to these conditions,” says Jean-Michel Léger. “The on-board instruments will not only extend the measurements carried out as part of Swarm, but will also enable us to gather information on space weather. The magnetometers have been improved, both in terms of resolution and data acquisition frequency. They will be accompanied by star cameras and an optical bench within the payload as well as a multi-needle Langmuir probe, to be managed entirely by CEA-Leti."
“In addition to optimizing the instruments, we have also optimized the configuration of the constellation,” adds Jean-Michel Léger. “Unlike Swarm, two satellites will be positioned in low orbit, at an inclination of 60°, to improve space-time coverage by more quickly revisiting geographical areas at various local times.”
In 2022, ESA asked the NanoMagSat consortium to carry out a risk-reduction study, in particular around the deployable boom. With the success of this phase, the agency approved the continuation of the project, thus effectively kicking off the mission. This is good news for the teams involved, who are already looking ahead to the final deadline: satellite launches are scheduled for the end of 2027.