JEM-EUSO observes extreme energy cosmic rays (EECRs) by measuring the fluorescence and Cherenkov photons produced in the extensive air shower (EAS). When a EECR reaches the Earth’s atmosphere it interacts with the atmospheric nuclei producing secondary particles that in turn collide with the air atoms giving rise to a propagating cascade of hundreds of billions of particles.

JEM-EUSO MissionThe origin of Ultra-High Energy Cosmic Rays (UHECRs) remains a great mystery. The extremely energetic sources that produce them are still unidentified. Recent data have confirmed their extragalactic nature but have questioned their composition and increased the mystery behind it. To identify the first source a significant increase in the observed cosmic rays of extreme energies (around 1020 eV) is needed. JEM-EUSO is designed to increase the number of observed Extreme Energy Cosmic Rays (EECRs) by an order of magnitude during its mission.
JEM-EUSO Collaboration13 Countries, 77 Institutes and about 280 researchers are collaborating in JEM-EUSO, with the support of the most important International and National Space Agencies and research funding institutions. NASA began supporting the mission in 2013.