First Analysis of Ground-Level Enhancement (GLE) 72 on 10 September 2017: Spectral and Anisotropy Characteristics

Using data obtained with neutron monitors and space-borne instruments, we analyzed the second ground-level enhancement (GLE) of Solar Cycle 24, namely the event of 10 September 2017 (GLE 72), and derived the spectral and angular characteristics of associated GLE particles. We employed a new neutron-monitor yield function and a recently proposed model based on an optimization procedure. The method consists of simulating particle propagation in a model magnetosphere in order to derive the cutoff rigidity and neutron-monitor asymptotic directions. Subsequently, the rigidity spectrum and anisotropy of GLE particles are obtained in their dynamical evolution during the event on the basis of an inverse-problem solution. The derived angular distribution and spectra are discussed briefly.     

The Impact Effect Callculator of Celestial Body Impacts to the Earth: The Constructor of Hazardous Orbits

Quick assessment of hazardous effects from impacts of large celestial bodies is achieved through the development of a new consequence calculator. A distinctive feature of this calculator is a new block, the Hazardous-Orbit Constructor, which simulates the conditions of entry of a celestial body into the Earth’s atmosphere and determines the orbital parameters of the body based on given atmospheric entry conditions. This block is used to simulate the atmospheric entry conditions of known asteroids and meteoroids and to determine the orbital parameters of known bolides leading to meteorite fall events. For the case of asteroid 2008 TC3 and the P?ibram meteorite, it is shown that within the potential impact area of the celestial body, the atmospheric entry angle may vary considerably.     

Design Experience of a Demonstrator Descent Vehicle Introducing Aeroelastic Deployable Structural Elements to Space Engineering

The development project of a prototype demonstrator for a descent vehicle and the possibilities of descent from orbit using aero-elastic braking devices deployable in space and in the atmosphere is considered. The project was carried out jointly by the Lavochkin Scientific Production Association and the Moscow Aviation Institute teams in 2013–2015. The results are evaluated for both the project itself and the cooperation of the two organizations.     

On Increasing the Accuracy of Star Trackers to Subsecond Levels

Modern star trackers are based on photodetector arrays such as CCD or CMOS arrays. The accuracy of commercially available devices is ~1–3 arcseconds. However, the development of the space industry calls for higher orientation accuracies, which are needed in laser space communications, monitoring of near-Earth space and space debris, high-precision global mapping, and remote sensing of the Earth. The problems associated with enhancing the accuracy of modern star trackers are discussed.     

About Superrotation in Venus

In this work we study in a general view slow rotating planets as Venus or Titan which present superrotating winds in their atmospheres. We are interested in understanding what mechanisms are candidates to be sources of net angular momentum to generate this kind of dynamics. In particular, in the case of Venus, in its atmosphere around an altitude of 100 km relative to the surface, there exists winds that perform a full rotation around the planet in four terrestrial days, whereas the venusian day is equivalent to 243 terrestrial ones. This phenomenon called superrotation is known since many decades. However, its origin and behaviour is not completely understood. In this article we analise and ponderate the importance of different effects to generate this dynamics.     

Why chromatic imaging matters

During the last two decades, the first generation of beam combiners at the Very Large Telescope Interferometer has proved the importance of optical interferometry for high-angular resolution astrophysical studies in the near- and mid-infrared. With the advent of 4-beam combiners at the VLTI, the u ? v coverage per pointing increases significantly, providing an opportunity to use reconstructed images as powerful scientific tools. Therefore, interferometric imaging is already a key feature of the new generation of VLTI instruments, as well as for other interferometric facilities like CHARA and JWST. It is thus imperative to account for the current image reconstruction capabilities and their expected evolutions in the coming years. Here, we present a general overview of the current situation of optical interferometric image reconstruction with a focus on new wavelength-dependent information, highlighting its main advantages and limitations. As an Appendix we include several cookbooks describing the usage and installation of several state-of-the art image reconstruction packages. To illustrate the current capabilities of the software available to the community, we recovered chromatic images, from simulated MATISSE data, using the MCMC software SQUEEZE. With these images, we aim at showing the importance of selecting good regularization functions and their impact on the reconstruction.     

On the energy integral for first post-Newtonian approximation

The post-Newtonian approximation for general relativity is widely adopted by the geodesy and astronomy communities. It has been successfully exploited for the inclusion of relativistic effects in practically all geodetic applications and techniques such as satellite/lunar laser ranging and very long baseline interferometry. Presently, the levels of accuracy required in geodetic techniques require that reference frames, planetary and satellite orbits and signal propagation be treated within the post-Newtonian regime. For arbitrary scalar W and vector gravitational potentials \(W^j (j=1,2,3)\), we present a novel derivation of the energy associated with a test particle in the post-Newtonian regime. The integral so obtained appears not to have been given previously in the literature and is deduced through algebraic manipulation on seeking a Jacobi-like integral associated with the standard post-Newtonian equations of motion. The new integral is independently verified through a variational formulation using the post-Newtonian metric components and is subsequently verified by numerical integration of the post-Newtonian equations of motion.     

Geochronology of Alkaline Rocks of the Aryskan Rare Metal Deposit,East Sayan

Doklady Earth Sciences - The temporal relations between alkaline rocks of the Aryskan rare metal (Y, REEs, Nb, Ta) deposit are determined using metamict zircon with high U and Th contents, which...     

Thermodynamic characteristics of water in natural water bodies with a high mineralization

To adequately describe the hydrophysical processes in water bodies with a high mineralization, it is necessary to take into account the dependence that the thermodynamic characteristics of water have on the amount of salts contained in it. This work investigates some widely known formulas for calculating a number of thermodynamic parameters of mineralized water. The density, freezing temperature, specific heat of evaporation, and relative pressure of saturated vapor over the surface are considered. The possibilities of using these formulas when modeling hydrophysical processes in water bodies with salinity in the range of 0–250 pro mille are analyzed. It is shown that the formulas under consideration should be used when the salinity does not exceed 100 pro mille. If the mineralization is higher, it is necessary to elaborate more suitable formulas on the basis of an approximation of in situ data or data from handbooks.