JEM-EUSO Mission

JEM-EUSO (Extreme Universe Space Observatory on-board Japanese Experiment Module)
is a new type space-borne observatory for ultra-high energy cosmic rays (UHECR).


The origin and existence of the extreme energy cosmic rays (i.e. E ≥ 1020eV) remain an open puzzle in contemporary astroparticle physics. Existing ground-based experiments - HIRES, Telescope Array and Auger - have claimed existence of a cutoff in the cosmic ray energy spectrum at energy ∼ 1020 eV. Such a suppression of the highest energy particles was theoretically predicted by Greisen, Zatsepin and Kuzmin (GZK cutoff), on the basis of the fact that the highest energy cosmic rays collide with Cosmic Microwave Background - filling the Universe remnant of the Big Bang - loosing energy on their path from sources to the Earth vicinity. JEM-EUSO was planned to clarify the origin of the highest energy particles and to definitly resolve GZK-suppression problem.

The JEM-EUSO telescope will be accommodated on the Japanese Experiment Module of the International Space Station (ISS) at an orbit altitude ∼400 km. It will use huge amount of the Earth atmosphere as a detector of ultra-high energy cosmic rays measuring their primary energy, arrival direction and composition with accuracy and statistics not achievable in ground-based experiments. The main scientific objective of the mission is to innovate astronomy and astrophysics through UHECR channel.

JEM-EUSO science and exploratory goals

  • identification of the highest energy cosmic ray sources
  • study of UHECR acceleration and emission processes
  • measurement of the trans-GZK spectrum
  • discovery of UHE neutrinos
  • discovery of UHE Gamma-rays
  • study of the galactic and local extragalactic magnetic field
  • particle physics beyond LHC
  • verification of special relativity and quantum gravity effects at extreme energies
  • global atmospheric observation - transient luminous events (TLE),
    nightglow and lightnings, meteors and meteoroids

JEM-EUSO is planned to be launched in 2017 by the Japanese heavy liftrocket - H2B, and then conveyed to ISS by HTV (H-II Transfer Vehicle). It will orbit around the Earth every 90 min at the ISS altitude of ∼400 km. The mission will last at least 5 years.

About 270 researchers from 78 institutes in 13 countries are working actually in JEM-EUSO Collaboration.