Swarm: ESA’s magnetic field mission

ESA’s Swarm mission is dedicated to identifying and measuring precisely the different magnetic signals that make up Earth’s magnetic field.
Swarm is ESA’s first constellation of Earth observation satellites. The three identical satellites have a rather unusual shape: trapezoidal with a long boom that is deployed once they are in orbit. Including the boom, each satellite is about 9 m long. In orbit, the boom trails at the back of the satellite. Magnetic cleanliness is of paramount importance to the mission, hence the sensitive scalar magnetometer is housed at the end of each boom, far away from any magnetic disturbance the electrical units on the satellite body may cause. The optical bench, holding the vector field magnetometer and the three startrackers, is mounted half-way along the boom. The electric field instrument is fixed to the front of the satellite.