Its main purpose was to collect and map signals intelligence around the world.
The Direction générale de l'armement (DGA) described it as a "vacuum cleaner for [radio] waves".
Essaim was a constellation of four 120 kg microsatellites (one of which was a spare) in low Earth orbit (LEO).
Missions were designed by the Celar (Centre d'électronique de l'armement) in Bruz, near Rennes and were uploaded from CNES in Toulouse to the constellation.
The flight was shared with Helios 2A and two other auxiliary payloads: Parasol and Nanosat 01.