JEM-EUSO will make the first all-sky survey of extreme energy cosmic rays (E>50 EeV) to study the highest energy cosmic accelerators. EECRs result from extreme conditions in the extragalactic universe that are beyond our present understanding.
The JEM-EUSO instrument will be the first spaced based observatory to study ultra high energy cosmic rays. By looking down from the International Space Station, JEM-EUSO will use the earth's atmosphere as an enormous astroparticle detector. During night sky periods, it will record UV light from extensive particle air showers that are produced by the interactions of ultra high energy particles in the atmosphere. The instrument will also have sensitivity to atmospheric optical transients, for example elves and certain meteorites.