The EUSO Data Simulation and Analysis Tree

The “Extreme Universe Space Observatory – EUSO” is the first Space mission devoted to the exploration of the outermost bounds of the Universe through the investigation of the Extremely-High Energy Cosmic Rays, EECR, using the Earth atmosphere as a giant detector. The objective is to obtain a detailed description of the Cosmic Ray spectrum beyond 5×10 19 eV together with a map of the arrival directions. EUSO will detect EECR looking at the streak of fluorescence light produced when such a particle interacts with the atmosphere. The signal will be detected after its propagation upward from the dark Earth atmosphere to the EUSO telescope accommodated, as external payload, on the International Space Station. EUSO is a mission of the European Space Agency ESA, and it is now completing the “Phase A” study with a goal for a three year mission starting in 2010. The various peculiarities of the EUSO space-based observational approach imply a dedicated effort for the evaluation of the expected features of the detected signals and for the reconstruction of its space-time development, energy and composition, namely from simulation and data analysis point of view. A complete software infrastructure named ESAF (EUSO Simulation and Analysis Framework) is under development suitable for event simulation, detector response simulation, event reconstruction and scientific data analysis.