  JEM-EUSO is a space science mission to explore extreme energies and physics
of the Universe. Its instrument will watch the dark-side of the earth and will
detect UV photons emitted from the extensive air shower caused by an Ultra-High
Energy Cosmic Rays (UHECRs above 10^18 eV), or Extremely High Energy Cosmic Ray
(EHECR) particle (e.g., above about 10^20 eV). Such a high-rigidity particles
as the latter arrives almost in a straight-line from its origin through the
magnetic fields of our Milky Way Galaxy and is expected to allow us to trace
the source location by its arrival direction. This nature can open the door to
the new astronomy with charged particles. In its five years operation including
the tilted mode, JEM-EUSO will detect at least 1,000 events with E>7x10^19 eV
with the GZK cutoff spectrum. It can determine the energy spectrum and source
locations of GZK to super-GZK regions with a statistical accuracy of several
percent. JEM-EUSO is planned to be deployed by H2 Transfer Vehicle (HTV) and
will be attached to the Japanese Experiment Module/ Exposure Facility (JEM/EF)
of International Space Station. JAXA has selected JEM-EUSO as one of the
mission candidates of the second phase utilization of JEM/EF for the launch in
early-to-mid 2010s.
