JEM-EUSO: Extreme Universe Space Observatory on JEM/ISS

EUSO is a super-wide field UV telescope to detect Ultra-High Energy Cosmic-Rays (UHECRs) with energy above 1020eV. It is attached to the International Space Station (ISS) and observes fluorescence photons emitted by giant air showers produced by UHECR. The three dimensional development of the shower is reconstructed from a series of images of the shower. Phase-A study of EUSO under the European Space Agency (ESA) has successfully finished in July 2004. The phase-B study, however, has been postponed for a long time because of financial problems in ESA and Italy. Then, Japanese and U.S. teams re-defined EUSO as a mission attached to the Japanese Experiment Module/Exposure Facility of ISS. They renamed it as JEM-EUSO and started the preparation targeting the launch in 2012 in the framework of second phase of JEM/EF utilization. The outline of the mission is presented.