The Spectra mission aims at producing a Cubesat 3U demonstrator for the survey of the civilian radiofrequency spectrum. In particular, it aims to detect and locate targets emitting in a frequency band (to be determined) and to reduce the spectrum obtained on the ground. Phase 0/A studies were conducted by CSUT in partnership with the Ecole Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne). They allowed a preliminary definition of the spatial system including a reference orbit, a pre-sized cubesat 3U (choice of equipment, layout, power budget, …), a ground segment and potential launchers.