The JEM-EUSO Program

Abstract

The Extreme Universe Space Observatory on-board the Japanese Experiment Module (JEM-EUSO) of the International Space Station (ISS), is a space mission that aims to unveiling the nature and the origin of the Ultra High Energy Cosmic Rays (UHECRs) and to address basic problems of fundamental physics at extreme energies. The instrument is designed to measure the arrival direction, the energy and, possibly, the nature of these particles. Basically, it consists of a wide Field of View (FoV) telescope, based on Fresnel lenses, that looks down from the ISS during night-time to detect UV photons (fluorescence and Cherenkov photons) emitted from air showers. An infrared camera and an atmosphere monitoring system improve the performance of the instrument. The program is proceeding in different steps. While the JEM-EUSO mission is being improved to allow the use of the new carrier Space-X Dragon, the project K-EUSO, a mirror-based telescope to be placed on the Russian module of the ISS, conceived as an improvement of the KLYPVE experiment already approved by the Russian Space Agency Roscosmos, modified with EUSO technology, is in the stage of final definition. Meanwhile, a program of test experiments, pathfinders of the main mission, has been developed: the first, EUSO-Balloon, successfully flew on board a stratospheric balloon in Canada to measure the fluorescence background from the top of the Atmosphere; a second, EUSO-TA on ground, is in operation at the Telescope Array site in Utah. Next steps include: a) Mini-EUSO, approved by Roscosmos and the Italian Space Agency ASI, a small, compact UV telescope to be installed inside the Russian Module of the ISS to measure the UV background from Earth and b) a long duration Super Pressure Balloon Flight (EUSO-SPB) to be flown from New Zealand to observe EAS (Extensive Air Showers) from stratospheric atmosphere altitudes. Scientific, technical and programmatic aspects of all these EUSO-like projects are described.