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From astrophysics to Earth observation: first science results of the Atmosphere-Space Interaction Monitor (ASIM) mission onboard the International Space Station.
Martino Marisaldi (Birkeland Centre for Space Science, University of Bergen)
Thursday 31/01/2019 @ 11:30, Sala IV piano Battiferro
Terrestrial Gamma-ray Flashes (TGFs) are submillisecond bursts of photons with energies up to several tens of MeV originating from thunderstorms and lightning, and are the manifestation of the most energetic natural particle acceleration processes occurring on Earth. The Atmosphere-Space Interaction Monitor (ASIM) is a mission of the European Space Agency (ESA) dedicated to the observation of optical and high-energy transient emissions associated to thunderstorm and lightning activity: TGF and Transient Luminous Events (TLE). ASIM overall main science goals are the understanding of the physics of TLEs and TGFs, their relation to lightning and their global impact to the high-altitude atmosphere and the geospace. ASIM was launched on April the 2nd 2018 and installed on the external facility of the Columbus module of the International Space Station, and is in nominal operations since June 2018. Two detector concepts and measurement techniques widely employed in high-energy astrophysics (coded mask system for X-ray imaging, and scintillation detectors for gamma-ray spectroscopy) are now employed for the first time for Earth observation in the ASIM payload. The ASIM scientific payload consists of two main instruments: the Modular X- and Gamma-ray Sensor (MXGS), for X-ray imaging and gamma-ray spectroscopy of TGFs, and the Modular Multi-Spectral Imaging Assembly (MMIA), consisting of two cameras and three high-speed photometers in optical bands. In this presentation I will first set the stage on TGF science and observations, and show how a small successful high-energy astrophysics mission like AGILE became one of the major players in a scientific field far away from the original main science goals of the mission. Then I will review the ASIM payload and mission objectives and present the first scientific results after six months of nominal operations concerning TGF morphology and imaging, and the TGF / lightning / TLE relationship.