The Calet Space Observatory For JEM-EF On the International Space Station

The CALorimetric Electron Telescope, CALET, is a new Space Observatory being developed for the Japanese Experiment Module Exposed Facility, JEM-EF, of the International Space Station. Major scientific objectives are to search for nearby cosmic ray sources and dark matter by carrying out a precise measurement of the electron spectrum from 10's of GeV - 10 TeV and of gamma rays in the range 20 MeV - several TeV. CALET has a unique capability to observe electrons and gamma-rays over 1 TeV, with a hadron rejection power better than 105 and an energy resolution of a few % beyond 100 GeV. Moreover, CALET will follow PAMELA, GLAST and other experiments and can both extend and refine the observations made by those missions. The main instrument, to be described, consists of an imaging calorimeter combined with a total absorption calorimeter. With auxiliary detectors, the CALET Observatory will also monitor solar activity and study gamma-ray bursts. The phase A/B study is underway for a proposed 2013 launch on the H-II Transfer Vehicle (HTV) for 3- 5 years of observation on JEM-EF.