The CALorimetric Electron Telescope (CALET) landed at the International Space Station on Aug. 24, signalling the start of its years-long mission to search for cosmic rays.

The observatory was launched from the Tanegashima Space Center on Aug. 19, on board the HTV-5 Transport Module, which is run by JAXA, the Japan Aerospace Exploration Agency. Within just a couple of days after it docked, the CALET has already been able to transmit its first signals back from the ISS.

CALET will be embarking on various activities while in space. The observatory will conduct measurements of the electron energy spectrum, which will most probably give an insight about the potential signatures of dark matter, says John Wefel, co-principal investigator of the CALET project and lead of the American crew involved in CALET, from the Louisiana State University.

The observatory has the ability to determine cosmic nuclei from hydrogen to iron and beyond, and possesses "excellent energy resolution" features, says Pier Simone Marrocchesi, co-principal investigator of the CALET and leader of the Italian team. With this, the observatory may also aid in explaining the aberrations from the pure-power law that was recently identified by the Alpha Magnetic Spectrometer (AMS-02) of the ISS in the spectra of energy of light nuclei. Information about higher energies, details of spectrum deflections, as well as the positions where the spectral break-points for each nuclear species occuurred may also be provided by CALET. The telescope had undergone numerous calibrations at the European Council for Nuclear Research or Conseil Européen pour la Recherche Nucléaire (CERN) as the correct adjustment of the calorimetric equipment is the key for the control of the energy scale.

NASA and the Italian Space Agency have also participated in the CALET space mission, which is a CERN-recognized experiment. After the AMS-02, the CALET is the second high-energy astroparticle mission attached to the ISS. "One of the main scientific objectives of CALET is to measure the detailed shape of the electron spectrum above 1 tera-electronvolt," says Shoji Torii, principal investigator of CALET from Waseda University in Tokyo.

Following the Japanese H-II transfer vehicle's (HTV5) attachment to the ISS, the observatory was removed by a robotic arm and installed on the Japanese Experiment Module - Exposed Facility (JEM-EF), also called Kibo, where it will obtain data for five years.

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