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Mini-EUSO ("UV atmosphere" in Russian Space Program) will observe Earth night side atmosphere from ISS in the UV band. The observed light consists mainly of light produced by airglow. We investigate the feasibility to observe airglow dynamics by Mini-EUSO detector. The investigation focuses on observability of two effects. One is the observability of magnetic storms in airglow light, where we expect decreasing light production in UV during storms. The other is the possibility to detect patterns created by atmospheric gravity waves induced by tsunami waves.

EUSO-TA is a ground-based cosmic ray fluorescence detector, pathfinder of the JEM-EUSO experiment, installed in 2013 at the Telescope Array (TA) site, in front of a TA fluorescence detector station, and completed with the focal surface in 2015, when it started to be operative. The data acquisition works in coincidence with TA, and this guarantees an easy identification of the cosmic ray events detected by EUSO-TA thanksto the reliability of the TA event detection and reconstruction methods. Up to now, a few cosmic ray events have been identified. Two simulation software are developed for the JEM-EUSO detectors: ESAF and Offline. ESAF is the simulation software developed in the framework of the JEM-EUSO collaboration; Offline was originally developed and successfully tested for years by the Auger Collaboration, and it has recently been adapted for the JEM-EUSO detectors. Thanks to the first events detected by EUSO-TA, ESAF and Offline have been improved in order to have a good comparison between data and simulations. This made the evaluation of the EUSO-TA detection threshold possible, with an Offline study based on the simulation of similar cosmic ray air showers as those detected and which crossed EUSO-TA FOV according to TA reconstruction. In parallel, an independent simulation of the expected number of detectable events by EUSO-TA has been conducted using ESAF code. The simulation methods are described in this work, as well as the comparison between the number of actual detected events and the number of expected ones.

We present an update of the cosmic ray energy spectrum measured from $3{\times}10^{17}$ eV to over $10^{20}$ eV at the Pierre Auger Observatory. This energy range is covered by combining data from the surface detector (subdividing the events into a vertical and a horizontal data set), from a denser array of stations and from hybrid events simultaneously recorded by the surface and the fluorescence detectors. Data collected to date, with a total exposure exceeding 67,000 $\rm km^2$ sr yr, rely on the energy scale provided by the fluorescence detector. The spectral features, and the impact of systematic uncertainties on their significance, are discussed in detail.

The Mini-EUSO instrument is an UV telescope to be placed aboard the International Space Sta-tion (ISS) in the framework of the JEM-EUSO project. Mini-EUSO will map the Earth in the UV range (300 - 400 nm) with a spatial resolution of 5 km and a temporal resolution of 2.5 μs. Therefore, Mini-EUSO offers an excellent opportunity to study a variety of physics phenomena such as transient luminous events and meteors, as well as searching for strange quark matter and test the detection of space debris. Mini-EUSO will serve also as a pathfinder for the study of Extreme Energy Cosmic Rays from space. A review on the expected performance of Mini-EUSO in detecting a variety of physical phenomena simulated with the EUSO Simulation and Analysis Framework (ESAF) package is described.