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The Japanese CALET (Calorimetric Electron Telescope) is cosmic ray observatory for the International Space Station (ISS).

To ascertain the existence of dark matter, electromagnetic waves flying about in space, as well as cosmic rays and high energy gamma rays (both rays hold energy with much higher than these of ultraviolet rays and X-rays) should be closely examined. Therefore, CALET will be installed to the Kibo’s Exposed Facility (EF) to conduct a long-term observation.

The objectives are to understand the following:

  • origin and mechanisms of acceleration of high-energy cosmic rays and gamma rays
  • propagation mechanism of cosmic rays throughout the galaxy
  • identity of dark matter.

As a cosmic ray observatory, CALET aims to clarify high energy space phenomena and dark matter, etc. from two perspectives; one is particle creation and annihilation in the field of particle physics (or nuclear physics) and the other is particle acceleration and propagation in the field of space physics.

CALET carries two instruments:

  • CAL - Calorimeter
  • CGBM - Gamma-ray Burst Monitor

CALET was installed to the Kibo’s EF. CALET is equipped with the latest detection technology and electronics called “CALorimeter” to determine the kind and flying directions of particles flying in space.

The CALorimeter has been developed through balloon experiments which can measure electrons and gamma rays of very high energy, protons, and nuclear components. In addition, it measures gamma-ray bursts that emit huge gamma rays in a short time outside our Milky Way galaxy and the influence of solar activity on the Earth environment.

Observation will be carried out for 2-5 years to elucidate high energy space phenomenena on in a wide area of space, from interplanetary space to the outside our Milky Way galaxy.

Nation: Japan
Type / Application: Astronomy, cosmic rays
Operator: JAXA
Contractors: JAXA
Equipment: CAL, CGBM
Configuration: Attached ISS payload
Propulsion: None
Power: Via ISS
Lifetime: 2-5 years
Mass: 650 kg
Orbit: 400 km × 400 km, 51.6° (typical)
Satellite COSPAR Date LS Launch Vehicle Remarks
CALET N/A 19.08.2015 Ta YLP-2 H-2B-304 with HTV 5, Flock-2b 1, ..., 14, SERPENS, S-CUBE, GOMX 3, AAUSAT 5


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