Observation of ELVES from the International Space Station with the Mini-EUSO telescope

<p>Mini-EUSO is a telescope that observes the Earth from the International Space Station by recording ultraviolet emissions (290 ÷ 430 nm) of cosmic, atmospheric and terrestrial origin with a field of view of 44◦, a spatial resolution of 6.3 km and a temporal resolution of 2.5 mus.</p><p>The instrument is based on an optical system composed of two Fresnel lenses and a focal surface composed of 36 multi-anode photomultiplier tubes, 64 channels each, for a total of 2304 channels with single photon counting sensitivity.</p><p>Mini-EUSO is a UV telescope launched in 2019   and observing the Earth from the inside the Russian Zvezda module, through a nadir-facing UV-transparent.</p><p>It is composed of a Fresnel optics (25 cm diameter, 44 deg field of view) and a Multi Anode Photomultiplier focal surface (2304 pixels, 6km on the surface) with a single-photon counting capability and a sampling rate of 400kHz.</p><p>Its scientific objectives include the search for ultra-high energy cosmic rays (E>1e21eV), the study of  meteors and search for interstellar objects and Strange Quark Matter, the  mapping   of the Earth's night-time ultraviolet emissions, the search for space debris.</p><p>The characteristcs of the detector make it also well suited for the detection of TLEs, especially ELVES and the study of its development to extract spatial and temporal evolution.  In this article we will focus our attention on the observation of single and multi-ringed elves.</p>

Photoelectron transport and associated Far Ultraviolet emissions: Model simulation and comparison with observations

<p>Photoelectrons are produced by solar Extreme Ultraviolet radiation and contribute significantly to the ionization and heat balances in planetary upper atmospheres. They are also the source of dayglow emissions, whose intensities may become comparable to weak or moderate dayside auroras. Proper modeling of photoelectrons and dayglow components is desirable for global auroral imaging, one of the core objectives of the SMILE mission. In many previous studies and model simulations, the transport effects of photoelectrons are neglected, so that the photoelectron distribution is controlled by a balance between local production and energy degradation. However, photoelectrons, when generated, can move along the magnetic field line. In particular, some of the photoelectrons may precipitate into the conjugate dark hemisphere and induce auroral-like emissions there, which was reported in realistic observations [Kil et al., 2020]. As a part of the SMILE Ultraviolet imager (UVI) model platform, we have recently developed an auroral/dayglow model that takes into account the interhemispheric transport of photoelectrons and/or secondary electrons, as well as their interaction with the ionosphere/thermosphere. In this study, we report the model simulation of the photoelectron generation and transport, and their induced UV emissions in both the dayside and nightside atmosphere. The simulation results are found to be in reasonable agreement with the realistic SSUSI/GUVI observations.</p>

Covid-19 Virus Sterilization Oven Based on Combination Between Ultraviolet and Infrared Emissions

The world is countering an unexpected wide spread of Covid-19 virus. Among the procedures used to prevent spreading the virus are classical and modern sterilization methods. In this paper, we combine the use of ultraviolet emissions, as a modern method, with the infrared emissions that generates high temperature, as a classical method, to design and implement a sterilization oven. Ultraviolet emissions have the ability to destroy the RNA of the virus while the infrared emissions destroy the virus membrane. Test was performed on indicators contains +ve gram rod bacteria which is stronger than the Covid-19 virus in high temperature and UV emission tolerant. Results showed that the UV emissions killed the microorganism in 15 minutes. However, combination between the UV and IR emissions in a sterilization oven succeeded to kill the under test microorganism in five minutes. The combination between the two sources of emission guarantees an effective sterilization process against bacteria, fungus, and viruses. Moreover, it speeds up the sterilization process time.

A terrestrial gamma-ray flash and ionospheric ultraviolet emissions powered by lightning

Terrestrial gamma-ray flashes (TGFs) are transient gamma-ray emissions from thunderstorms, generated by electrons accelerated to relativistic energies in electric fields. Elves are ultraviolet and optical emissions excited in the lower ionosphere by electromagnetic waves radiated from lightning current pulses. We observe a TGF and an associated Elve using the Atmosphere-Space Interactions Monitor on the International Space Station. The TGF occurs at the onset of a lightning current pulse that generates an Elve, in the early stage of a lightning flash. Our measurements suggest that the current onset is fast and has a high amplitude, a prerequisite for Elves, and that the TGF is generated in the electric fields associated with the lightning leader.