Time-resolved measurements of differential fluxes of low energy charged particles, trapped in the magnetosphere, are interesting for Space Weather characterization and to study the coupling between the lithosphere and magnetosphere, allowing the investigation of the possible correlations between seismic events and particle precipitations from Van Allen Belts. The project of a compact (10x10x10cm$^3$) particle spectrometer, the Low Energy Module (LEM) as part of the Zirè instrument on board the NUSES space mission is shown.
The LEM will be able to perform measurements of energy, direction, and composition of low energy charged particles down to 0.1 MeV kinetic energy. The particle identification capability of the LEM relies on the $\Delta$E-E technique performed by thin silicon detectors. To fulfill the size and mass requirements of the whole mission, the particle direction measurement is based on the "active collimation" technique. The detection concept and the expected LEM performances will be summarized.