Calorimetric Electron Telescope

Alternative names	CALET
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TheCALorimetric Electron Telescope (CALET) is aspace telescope being mainly used to perform high precision observations ofelectrons andgamma rays. It tracks the trajectory of electrons,protons,nuclei, and gamma rays and measures their direction,charge and energy, which may help understand the nature ofdark matter or nearby sources of high-energyparticle acceleration.^[2]

The mission was developed and sponsored by theJapan Aerospace Exploration Agency (JAXA), involving teams from Japan, Italy, and the United States. CALET was launched aboard JAXA's H-II Transfer VehicleKounotori 5 (HTV-5) on 19 August 2015, and was placed on theInternational Space Station's JapaneseKibo module.

CALET is anastrophysics mission that searches for signatures ofdark matter and provides the highest energy direct measurements of thecosmic ray electron spectrum in order to observe discrete sources of high-energyparticle acceleration in our local region of thegalaxy.^[4][5] The mission was developed and sponsored by theJapan Aerospace Exploration Agency (JAXA), involving teams from Japan, Italy, and the United States. It seeks to understand the mechanisms of particle acceleration and propagation of cosmic rays in our galaxy, to identify their sources of acceleration, their elemental composition as a function of energy, and possibly to unveil the nature of dark matter.^[2] Such sources seem to be able to accelerate particles to energies far higher than scientists can achieve on Earth using the largestaccelerators. Understanding how nature does this is important to space travel and has possible applications here on Earth.^[2] The CALETPrincipal Investigator is Shoji Torii from theWaseda University, Japan; John Wefel is the co-principal investigator for the US team; Pier S. Marrocchesi, is the co-investigator from the Italy team.

Unlikeoptical telescopes, CALET operates in a scanning mode. It records each cosmic ray event that enters its field of view and triggers its detectors to take measurements of the cosmic ray in the extremely high energy region of teraelectronvolts (TeV, onetrillionelectronvolts).^[5] These measurements are recorded on the space station and sent to aground station atWaseda University for analyses.^[6] CALET may also yield evidence of rare interactions betweenmatter and dark matter by working in synergy with theAlpha Magnetic Spectrometer (AMS) – also aboard theISS – that is looking atpositrons andantiprotons to identify dark matter.^[2] Observations will be carried out more than 5 years.^[7]

CALET contains a sub-payload CIRC (Compact Infrared Camera) to observe the Earth's surface in order to detectforest fires.^[8]

The objectives are to understand the following:^[9]

1. origin and mechanisms of acceleration of high-energycosmic rays andgamma rays
2. propagation mechanism of cosmic rays throughoutthe Galaxy
3. identity ofdark matter

As a cosmic ray observatory, CALET aims to clarify high energy space phenomena and dark matter from two perspectives; one isparticle creation andannihilation in the field ofparticle physics (ornuclear physics) and the other is particle acceleration and propagation in the field ofspace physics.

CALET first published data on half a million electron and positron cosmic ray events in 2017, finding aspectral index of −3.152 ± 0.016 above 30 GeV.^[10][11]

• List of X-ray space telescopes

• [1]^{[permanent dead link]} "Status and performance of the Calorimetric Electron Telescope (CALET) on the International Space Station". (PDF) By Roberta Sparvoli.
• [2] CALET brochure in English (PDF) at JAXA.

• Astrophysics
• Dark matter
• Space telescopes
• Gamma-ray telescopes

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