Results from the First Missions of the JEM-EUSO Program
2019 August 28
The origin of Ultra-High Energy Cosmic Rays (UHECRs) remains unsolved in contemporary astroparticle physics. The objective of the JEM-EUSO program is the realization of a space mission devoted to UHECR physics. Several detectors have been developed in this framework or are under development. EUSO–TA, installed at the Telescope Array site in Utah in 2013, is in operation. It has detected 9 UHECRs in coincidence with Telescope Array fluorescence detector at Black Rock Mesa. EUSO–Balloon flew on board a stratospheric balloon in August 2014. It measured the UV intensity on forests, lakes and cities as well as proved the observation of UHECR–like events reproduced by laser tracks. EUSO–SPB1 was launched on board a super pressure balloon on April 24th 2017 and flew for 12 days. It proved the functionality of all the subsystems of the telescope on a long term and observed the UV emission on oceans. TUS, on board the Lomonosov satellite, in orbit since April 28th 2016, is now included in the JEM–EUSO program and has detected so far in the UHECR trigger-mode a few interesting signals. Mini–EUSO is in its final phase of integration in Russia, and is scheduled for launch on August 22 nd. The main results obtained so far by these missions are summarized and put in the perspective offuture space detectors such as K–EUSO and POEMMA.