The EUSO-SPB2 mission and first results

The Extreme Universe Space Observatory on a Super Pressure Balloon 2 (EUSO-SPB2) payload flew two astroparticle telescopes. A Fluorescence Telescope (FT) pointed in nadir to search for the first Ultra-High Energy Cosmic Ray (UHECR) induced extensive airshower (EAS) signatures observed in fluorescence light from above with an energy threshold of >3E18 eV. A Cherenkov Telescope (CT) searched for Cherenkov light signatures from EAS. These EAS can be induced by Cosmic Rays (CRs) with energies ~10PeV above the horizon and by PeV-scale Earth-Emergent neutrinos that use Earth as a tau-neutrino to tau-lepton converter. The EUSO-SPB2 mission launched from Wanaka NZ on May 13, 2023 but terminated about 36h later over the Pacific Ocean due to a balloon leak.

Analysis of the FT data did not find any UHECRs but did demonstrate the instrument's reliability. The first analysis of the CT data identified about ten above-the-limb CR candidates and demonstrated the ability of the CT to measure Earth-skimming neutrino signatures. Searches for diffuse neutrino signatures and searches for neutrino signatures in coincidence with astrophysical targets of opportunity have been performed. No candidate events were identified over the curtailed mission.