The JEM-EUSO Mission to Explore the Extreme Universe

The JEM-EUSO mission will explore the origin of the extreme energy comic-rays (EECRs) above 1020eV and and can shed new light on some topics of fundamental physics. It is planned to be launched by a H2B rocket on 2017 and transferred to ISS by the H2 Transfer Vehicle (HTV), where it will be attached to the external experiment platform of KIBO. The super-wide-field of view (60 degrees) telescope, with a diameter of about 2.5m looks down the night-side atmosphere of the Earth from ∼400 km of altitude, to detect near UV photons (330–400nm, both fluorescent and Cherenkov) emitted by giant air-showers produced by EECRs. The instrument is design to observe between 500 and 800 events above 55 EeV in its first 3 yr of operation, as well as an exposure larger than 1 million km2 str yr at 3×1020eV 5 yr after launch. At these energies cosmic rays carry directional information and the arrival direction map will allow the identification of point sources of EECR, in case they exist, and of their astronomical counterparts. The comparison among the energy spectra of the spatially resolved individual sources will clarify the acceleration/emission mechanism, and also probe the Greisen-Zatsepin-Kuzmin process for the validation of Lorentz invariance up to γ∼1011. Neutral components (neutrinos and gamma rays) can also be detected if their fluxes are high enough. In fact, few cosmogenic neutrinos per year can be expected under conservative assumptions.