CALET: A calorimeter-based orbital observatory for High Energy Astroparticle Physics

CALET is an advanced experiment that will be installed on the Exposure Facility of the Japanese Experiment Module (JEM-EF) on the International Space Station (ISS) with a launch window in 2014. The instrument consists of three main sub-systems: a charge module using plastic scintillators to identify the charge of the particle, a thin imaging calorimeter (3X0) with tungsten plates interleaving scintillating fiber planes, and a thick calorimeter (27X0) composed of lead tungstate logs. It has sufficient depth, imaging capabilities and excellent energy resolution to allow for a clear separation between hadrons and electrons and between charged particles and gamma-rays. The charge module will be able to identify cosmic nuclei from H through Fe as well as trans-Fe elements at least up to Zr (Z=40). With extended observations, over a period of 5 years, CALET will be able to unveil the presence of possible nearby sources of high energy electrons, study the details of particle propagation in the galaxy and search for signatures of dark matter. In this paper, we will review the main features of the CALET instrument and the present status of the mission.