  CALET (CALorimetric Electron Telescope) is a high energy astroparticle
physics experiment planned for a long exposure mission aboard the International
Space Station (ISS) by the Japanese Aerospace Exploration Agency, in
collaboration with the Italian Space Agency (ASI) and NASA. The main science
goal is high precision measurements of the inclusive electron (+positron)
spectrum below 1 TeV and the exploration of the energy region above 1 TeV,
where the shape of the high end of the spectrum might unveil the presence of
nearby sources of acceleration. CALET has been designed to achieve a large
proton rejection capability (>10$^5$) with a fine grained imaging calorimeter
(IMC) followed by a total absorption calorimeter (TASC), for a total thickness
of 30 X$_{0}$ and 1.3 proton interaction length. With an excellent energy
resolution and a lower background contamination with respect to previous
experiments, CALET will search for possible spectral signatures of dark matter
with both electrons and gamma rays. CALET will also measure the high energy
spectra and relative abundance of cosmic nuclei from proton to iron and detect
trans-iron elements up to Z$\sim$40. The charge identification of individual
nuclear species is performed by a dedicated module (CHD) and by multiple dE/dx
measurements in the IMC. With a large exposure and high energy resolution,
CALET will be able to verify and complement the observations of CREAM, PAMELA
and AMS-02 on a possible deviation from a pure power-law of proton and He
spectra in the few hundred GeV region and to extend the study to the multi-TeV
region. CALET will also contribute to clarify the present experimental picture
on the energy dependence of the boron/carbon ratio, below and above 1 TeV/n,
thereby providing valuable information on cosmic-ray propagation in the galaxy.
Gamma-ray transients will be studied with a dedicated Gamma-ray Burst Monitor
(GBM).
