"JEM-EUSO, POEMMA, and PBR: Hunters of UHECRs and VHENs from Orbital and Suborbital Altitudes" 

Presented by Dr. Johannes Eser, Associate Research Scientist, from Columbia University

Ultra-high-energy cosmic rays remain one of the major open questions in astroparticle physics. Answering these questions requires next-generation instruments, which can be divided into high-accuracy and high-exposure observatories, the latter providing far greater exposure than current ground-based detectors. The long-term goal of the JEM-EUSO and POEMMA programs is to maximize exposure at the highest energies by building a space-based multi-messenger observatory capable of detecting ultra-high-energy cosmic rays and very-high-energy neutrinos with full-sky coverage.

A major step toward this goal is the POEMMA-Balloon with Radio mission, PBR, an ultra-long-duration balloon payload planned for launch from Wanaka, New Zealand, in Spring 2028. As the latest and most advanced pathfinder designed and built by the JEM-EUSO collaboration, PBR will validate key elements of the instrument design and observation strategy. While circling over the Southern Ocean during an expected flight of more than 20 days, PBR will pursue three main scientific objectives: (1) fluorescence detection of ultra-high-energy cosmic rays (E>1EeV) 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 very-high-energy neutrinos (E>1PeV). In this talk, we will discuss the motivation why going to space is advantages, present the design of POEMMA  followed by close look at its latest pathfinder PBR.