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(E0) >7×1019eV. 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 7×1019eV) in 5 years observation. The JEM-EUSO telescope has a Field of View(FoV) of °60×°48 and a cumulative exposure of >4×105km2⋅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).