It tracks the trajectory of electrons, protons, nuclei, and gamma rays and measures their direction, charge and energy, which may help understand the nature of dark matter or nearby sources of high-energy particle acceleration.

CALET was launched aboard JAXA's H-II Transfer Vehicle Kounotori 5 (HTV-5) on 19 August 2015, and was placed on the International Space Station's Japanese Kibo module.

CALET is an astrophysics mission that searches for signatures of dark matter and provides the highest energy direct measurements of the cosmic ray electron spectrum in order to observe discrete sources of high-energy particle acceleration in our local region of the galaxy.

[7] CALET contains a sub-payload CIRC (Compact Infrared Camera) to observe the Earth's surface in order to detect forest fires.

CALET first published data on half a million electron and positron cosmic ray events in 2017, finding a spectral index of −3.152 ± 0.016 above 30 GeV.