The Spectra mission aims to create a 3U Cubesat demonstrator for monitoring the civil radiofrequency spectrum. In particular, it seeks to detect and locate targets emitting within a frequency band (to be determined) and to transmit the obtained spectrum to the ground. Phase 0/A studies have been conducted by CSUT in partnership with the National School of Advanced Techniques of Brittany (ENSTA Bretagne). They have enabled a preliminary definition of the space system including a reference orbit, a pre-dimensioned 3U Cubesat (equipment choices, layout, power budget, etc.), a ground segment, and a range of potential launchers.