The results of the TUS experiment on search and study ultra high-energy cosmic rays with energies E > 70 EeV are analyzed. The TUS detector registered several unusual events of the unclear origin. The analysis of not similar to EAS and unique anomalous events is the subject of the study presented in this paper.

The NUCLEON space observatory was developed to measure the spectra of cosmic ray nuclei with individual charge resolution in the energy range of several TeV to 1 PeV per particle. The NUCLEON was launched into a heliosynchronous orbit as an additional load on the Resurs-2P production satellite on December 28, 2014, and it is still in operation (2019). This work is a brief review of the results from the NUCLEON observatory over three years of operation in orbit. The spectra of the main primary abundant nuclei and product nuclei of cosmic rays (CRs) are presented. Some new interesting features of the CR spectra found in the NUCLEON data are discussed.

TUS (Tracking Ultraviolet Set-up) is the world's first orbital detector of ultra-high-energy cosmic rays (UHECRs). It was launched into orbit on 28th April 2016 as a part of the scientific payload of the Lomonosov satellite. The main aim of the mission was to test the technique of measuring the ultraviolet fluorescence and Cherenkov radiation of extensive air showers generated by primary cosmic rays with energies above ∼100 EeV in the Earth atmosphere from space. During its operation for 1.5 years, TUS registered almost 80,000 events with a few of them satisfying conditions anticipated for extensive air showers (EASs) initiated by UHECRs. Here we discuss an event registered on 3rd October 2016. The event was measured in perfect observation conditions as an ultraviolet track in the nocturnal atmosphere of the Earth, with the kinematics and the light curve similar to those expected from an EAS. A reconstruction of parameters of a primary particle gave the zenith angle around 44̂ but an extreme energy not compatible with the cosmic ray energy spectrum obtained with ground-based experiments. We discuss in details all conditions of registering the event, explain the reconstruction procedure and its limitations and comment on possible sources of the signal, both of anthropogenic and astrophysical origin. We believe this detection represents a significant milestone in the space-based observation of UHECRs because it proves the capability of an orbital telescope to detect light signals with the apparent motion and light shape similar to what are expected from EASs. This is important for the on-going development of the future missions KLYPVE-EUSO and POEMMA, aimed for studying UHECRs from space.

Tracking Ultraviolet Setup (TUS) detector is a detector of ultraviolet (UV) radiation of the atmosphere in the wavelength range of 300–400 nm (near-ultraviolet) with high sensitivity (tens of photons emitted within the solid angle of 10–4 sr in 0.8 μs), which operated for a year and a half aboard the Lomonosov satellite. The TUS telescope had a multipurpose operational program, which made it possible to detect UV flashes from the shortest ones created by extensive air showers generated by cosmic rays to long ones, up to 1 s, created by meteors. Among these various phenomena, most often are flashes from lightning strikes, both directly creating a glow and causing the development of secondary discharges in the atmosphere, in the upper atmosphere and in the ionosphere. These discharges differ in both nature and phenomenology—in particular, they have different durations and luminosities.

The TUS (Tracking Ultraviolet Setup) detector aboard the Lomonosov satellite was launched into a Sun-synchronous orbit with an altitude of ~500 km on April 28, 2016. The main purpose of the TUS orbital experiment is to search for ultra-high energy cosmic rays (UHECRs) with Е > 70 EeV by measuring the fluorescence and Cherenkov radiation of extensive air showers (EASes) in the Earth’s atmosphere. The design and operating principles of the TUS detector are briefly described. A multilevel algorithm developed to search for and reconstruct EAS events (candidates) in the region of UHECRs is used to analyze the TUS data. Preliminary results from the TUS in orbit, including the results from the search for and study of identified EAS candidates, are presented.

— The TAIGA (Tunka Advanced Instrument for cosmic ray physics and Gamma-ray Astronomy) experiment aims at observing gamma-rays in the energy range from 1 TeV to several 100 TeV. The operation of the observatory is based on a new hybrid approach that combines imaging air Cherenkov telescopes (IACTs) and wide-angle Cherenkov detectors (TAIGA-HiSCORE) for measuring times of extensive air shower (EAS) light front arrival. Monte Carlo simulations are compared to real data to determine the performance of the detector setup. Dedicated software and algorithms are described, model parameters are given, and an overview of the current status of model-based performance studies is presented.

TUS (Tracking Ultraviolet Set-up) is the world’s first orbital detector of ultra-high-energy cosmic rays (UHECRs). It was launched into orbit on April 28, 2016, as a part of the scientific payload of the Lomonosov satellite. The main aim of the mission was to test the technique of measuring the ultraviolet fluorescence and Cherenkov radiation of extensive air showers generated by primary cosmic rays with energies above ∼ 100 EeV in the nocturnal atmosphere of the Earth from space. During its operation period, TUS registered almost 80,000 events, with a few of them satisfying the criteria expected for UHECR candidate events. Here we discuss the phenomenology and possible interpretations of an outstanding event registered in perfect observational conditions on October 3, 2016.

The Tunka-133 Cherenkov complex for recording extensive air showers (EAS) collected data over seven winters from 2009 to 2017. The differential energy spectra of all particles was acquired in the 6 × 10 15 –3 × 10 18 eV range of energies over 2175 h. The TAIGA-HiSCORE complex is continually being expanded and upgraded. Data acquired by 30 first-line stations over 35 days during the period 2017–2018 is analyzed in this work. As at the Tunka-133 setup, the primary particle energies above 10 15 eV are measured using the density of the Cherenkov light flux at a distance of 200 m from a shower’s axis. Data on lower energies are collected by determining the energy of the light flux near a shower’s axis. This results in a spectrum of 2 × 10 14 –10 17 eV. The combined spectrum for the two systems covers a range of 2 × 10 14 –2 × 10 18 eV.

Work is currently under way in the Tunka Valley, 50 km from Lake Baikal, to create the TAIGA gamma observatory for studying gamma radiation and cosmic ray fluxes in the 10 13 –10 18 eV range of energies. To detect gamma rays with energies above tens of TeV, a hybrid method of detecting showers is implemented. It is based on data obtained by the TAIGA Imaging Atmospheric Cherenkov Telescope (IACT) and the wide-angle TAIGA-HiSCORE array. The preliminary results from processing the telescope’s data for the low-energy region (>2–3 TeV) are presented. Joint events with energy more than 50 TeV are analyzed and compared to Monte Carlo calculations.

TUS (Tracking Ultraviolet Set-up) is the world’s first orbital detector of ultra-high-energy cosmic rays (UHECRs). It was launched into orbit on April 28, 2016, as a part of the scientific payload of the Lomonosov satellite. The main aim of the mission was to test the technique of measuring the ultraviolet fluorescence and Cherenkov radiation of extensive air showers generated by primary cosmic rays with energies above $\sim$100 EeV in the nocturnal atmosphere of the Earth from space. During its operation period, TUS registered almost 80,000 events, with a few of them satisfying the criteria expected for UHECR candidate events. Here we discuss the phenomenology and possible interpretations of an outstanding event registered in perfect observational conditions on October 3, 2016.

The NUCLEON experiment is aimed at measuring the spectrum and the elemental composition of cosmic rays (CR) in the 1011–1015 eV energy range. The energy spectrum, the charge, and the mass of CR particles provide additional data on CR sources and the mechanisms of CR acceleration and propagation in the Galaxy. The NUCLEON detector was launched into orbit aboard the Resurs-P No. 2 satellite in December 2014. Statistics in the range up to 5 × 1014 eV, exceeding the available statistics of the ATIC and CREAM balloon experiments, were obtained in the course of measurements. The NUCLEON experiment relies on modern detectors used in high-energy physics experiments. The design of its trigger system, which is based on plastic scintillator multistrip detectors, is presented. The results of tests conducted at the CERN SPS accelerator are discussed.