for the JEM-EUSO CollaborationThe Extreme Universe Observatory onboard the Japanese Experiment Module (JEM-EUSO) is a mission being developed to observe ultra high energy cosmic rays (UHECRs) from space. JEM-EUSO consists of a wide field of view UV-telescope, assisted by an atmospheric monitoring system, designed to be mounted oboard the International Space Station. JEM-EUSO will observe the extensive air showers (EAS) induced by UHE cosmic particles with energies above 3 × 10 19 eV by using the earth's atmosphere as a large detector. Due to the amount of monitored target volume JEM-EUSO is expected to reach an effective aperture of approx. 2 × 10 5 km 2 sr. During its lifetime, the mission will measure several hundred events with E > 5 × 10 19 eV significantly improving the statistics of the most energetic part of the spectrum above the observed cut-off. In the context of the JEM-EUSO Collaboration different mission profiles are being explored. A configuration actively investigated is a telescope, mainly based on the same technologies already employed in the baseline instrument, which can be launched with the SpaceX Falcon 9 rocket and transported to the ISS by the Dragon spacecraft. This new mission configuration allows a circular design of the optics which improves the performances. In this paper we present a brief study of the expected angular resolution of this new configuration.

Cosmic rays with energies exceeding 10 18 eV, usually defined as Ultra High Energy Cosmic Rays (UHECRs), allow the possibility to study physics at energies well beyond man made accelerators. State of the art UHECR detectors have reached unprecedented exposures and have pioneered the field of Extreme Energy Cosmic Rays (EECR), cosmic rays with energies exceeding 5 × 10 19 eV. The EECR flux is extremely small, of the order of 1 particle per square kilometer per century. The next generation of UHECR and EECR detectors are expected to increase the exposure by at least one order of magnitude. The JEM-EUSO mission, currently designed to be hosted onboard the JEM module of the ISS, consists of a ultra wide field of view UV-telescope orbiting the earth at an altitude of about 400 km. JEM-EUSO will look for fluorescent UV tracks produced by Extensive Air Showers (EAS) on the night side of the earth. According to the most recent studies, the JEM-EUSO mission, can be transported onto the ISS by using the SpaceX's Dragon spacecraft. In this work we present preliminary studies on the angular and energy reconstruction performances for different types of primaries (protons, iron nuclei and gamma rays). We compare our results with previously published results for the JEM-EUSO mission in a different configuration, and find a slight improvement.

Extreme Universe Space Observatory on-board the Japanese Experiment Module (JEM-EUSO) is a mission devoted to the observation of ultra-high energy cosmic rays (UHECRs) around and above the Greisen-Zatseptin-Kuzimin energy at ∼ 5 × 10 19 eV. The origin of these enigmatically energetic cosmic rays remain an open question since their discovery more than 50 years ago. High statistics on UHECRs are essential to provide key information to answer this question and necessitate very large exposures to overcome their extremely low flux of an order of a few events per square kilometer per century. JEM-EUSO is designed to measure the air showers induced by UHECRs using a super-wide field-of-view ultra-violet fluorescence telescope pointed downwards on Earth's nighttime atmosphere. Orbiting onboard the International Space Station (ISS), JEM-EUSO rather uniformly covers the entire Celestial Sphere, allowing a thorough analysis of the UHECR arrival direction distribution. In the present work, we introduce a design of the JEM-EUSO telescope suitable for using the Space-X Falcon 9 rocket and the Dragon spacecraft for transport to the ISS. This design allows for accommodation of the telescope with equivalent or slightly improved performance than that studied for H-II Transport Vehicle option. We then discuss the expected performance, in particular the scientific objective of searching the arrival direction distribution of UHECRs for their origin through simulation studies.

Similarly to extreme energy cosmic rays (EECRs), neutrinos at energies exceeding 5×10 19 eV are expected to interact in the Earth's atmosphere and create extensive air showers. The JEM-EUSO mission, developed to be hosted onboard the JEM module of the International Space Station, aims at detecting these extensive air showers from space by means of the fluorescent and diffusively reflected Cherenkov light they produce. In the present paper we investigate the capability of JEM-EUSO to trigger and detect neutrino induced events in the H-II Transfer Vehicle (HTV) configuration. We also discuss the status of their reconstruction feasibility considering JEM-EUSO's most recent design, which will be launched with Falcon 9 and delivered to the ISS by the SpaceX Dragon free-flying spacecraft.

JEM-EUSO (The Extreme Universe Observatory onboard the Japanese Experiment Module) is a space borne UV-telescope for the observation of UHECR induced extensive air showers (EAS). Currently in the development phase it will be attached to the ISS (International Space Station) to use the earth's atmosphere as a large detector. Due to the large target volume it gains an effective aperture of approx. 2 × 10 5 km 2 sr-sufficient for the CR observation above an energy of 3 × 10 19 eV. During the mission lifetime, JEM-EUSO will observe several hundred of events above E = 5 × 10 19 eV, significantly improving the statistics in this part of the UHECR spectrum. The default operation mode of the instrument is envisaged to be along its nadir direction. However, in a later stage of the mission, a tilting of the telescope, away from its nadir direction, is discussed as a potential strategy to further increase the exposure at the highest energies. In the tilted mode operation the exposure would significantly increase. Hence, the regime of extreme energies above 10 20 eV could be explored in a reasonable amount of time. Naturally, in this setup the angular resolution of the instrument is expected to decrease. In the scope of this work we evaluate the expected angular resolution performance of the JEM-EUSO instrument in dependence of the tilting angle.