[en] A project of the OLVE-HERO space detector for measurement of the cosmic rays in the range 10¹²–10¹⁶ eV is proposed. It will include a large ionization-neutron 3D calorimeter with a high granularity and geometric factor of ∼16 m² sr. The main OLVE-HERO detector is expected to be an image calorimeter with boron loaded plastic scintillator and a tungsten absorber. Such a calorimeter allows to measure an additional neutron signal that should improve the detector energy resolution and also the rejection power between electromagnetic and nuclear components of cosmic rays. Improvement by factor 30–50 is expected. The OLVE-HERO detector prototype was designed and tested at SPS CERN beam during Pb ion run in 2018. Test results and the corresponding Monte-Carlo simulation are presented.