📝 SummarXiv

Abstract

The POEMMA-Balloon with Radio (PBR) is an Ultra Long Duration Balloon payload scheduled for launch in Spring 2027 from Wanaka, New Zealand. It will circle over the Southern Ocean for a mission duration as long as 50 days, serving as a precursor to the dual satellite mission, Probe of Extreme Multi-Messenger Astrophysics (POEMMA). The PBR mission represents a significant step towards establishing a space-based multi-messenger observatory. Observations from space will enhance the statistics of the highest-energy cosmic rays and complement ground-based observatories by enabling simultaneous observations of both hemispheres with a single instrument. Additionally, POEMMA will facilitate the measurement of Very-High-Energy Neutrinos (VHENs) following multi-messenger alerts of astrophysical transient events, such as gamma-ray bursts. PBR is an adaptation of the POEMMA mission, featuring three primary science goals: 1. Observe Ultra-High-Energy Cosmic Rays (UHECRs) via the fluorescence technique from suborbital space. 2. Observe horizontal high-altitude air showers (HAHAs) with energies exceeding the cosmic ray knee (E > 3 PeV) using optical and radio detection for the first time. 3. Follow astrophysical event alerts in the search for VHENs. This contribution provides an overview of the PBR payload and discusses the expected performance of its various detectors.