JEM-EUSO mission on the ISS with the aim of performing particle astronomy

The Extreme Universe Space Observatory (EUSO) is a science mission to investigate the nature and origin of Extremely-High-Energy Cosmic Rays (EHECRs) with primary energy(E 0 ) > 7 × 10 19 eV . It will be installed in the Japanese Experiment Module (JEM) on the International Space Station (ISS). This mission is aimed to perform charged-particle astronomy in this energy region with large statistics of EHECRs (>1000 events above 7 × 10 19 eV ) in 5 years observation. The JEM-EUSO telescope has a Field of View(FoV) of 60 ° × 48 ° and a cumulative exposure of > 4 × 10 5 km 2 ⋅ sr ⋅ yr . It consists of high-transmittance Fresnel lenses (a side-cut shape with a 2.65 m major axis), a cluster of multi-anode photomultipliers(MAPMT) as a photo-sensitive detector at the focal surface and suitable electronics. JEM-EUSO has been selected as one of the mission candidates of the second phase utilization of JEM expected in early 2010s, by the Japan Aerospace eXploration Agency(JAXA).