"Chasing the most energetic particles in the Universe by looking down: the POEMMA-Balloon with Radio mission"
Ultra-high-energy cosmic rays (UHECR) and Very-high-energy neutrinos (VHEN) are the most energetic particles known, exceeding those of human-made accelerators by several orders of magnitude and they provide us with a unique window into the most extreme astrophysical sources. However, their low fluxes and, for neutrinos, their weak interaction, make detection challenging, leaving fundamental question still open. Answering these questions requires far greater exposure than current ground-based detectors provide. A space-based multi-messenger observatory with full-sky coverage, such as the proposed POEMMA mission, would address these challenges.
The super pressure balloon mission, POEMMA-Balloon with Radio (PBR), is being prepared for launch from Wanaka, New Zealand, in Spring 2028. It will circle the Southern Ocean for more than 20 days, searching for extensive air shower signatures in the atmosphere. PBR is the most advanced pathfinder towards a space observatory pursuing its scientific objectives: (1) fluorescence detection of UHECR from suborbital space, (2) optical Cherenkov and radio observations of high-altitude horizontal air showers, and (3) follow-up of astrophysical alerts in the search for VHEN.