  JEM-EUSO, on board of the Japanese Exploration Module of the International
Space Station, is being proposed as the first space observatory devoted to
UHECR. Its privileged position at 430 km above the Earth surface, combined with
a large field of view, innovative optics and a high efficiency focal surface,
results in an unprecedented exposure which significantly surpasses that of the
largest ground observatories. The large number of events expected above the GZK
threshold for photo-pion production by protons will allow the directional
identification of individual sources and the determination of their spectra,
i.e., doing astronomy and astrophysics through the particle channel. Similar
goals can be achieved in the case of light UHECR nuclei. Furthermore, the
atmospheric target volume ($\sim 10^{12}$ ton) makes the possibility of
neutrino observation a highlight of the mission. Other exploratory objectives
include the detection of extreme energy gammas and the study of Galactic
magnetic fields as well as global observations of the earth's atmosphere,
including clouds, night-glows, plasma discharges, and meteors. In this
contribution we will describe the scientific objectives of JEM-EUSO.

High Energy Astrophysical Phenomena