Abstract: The paper presents machine-learning models for predicting powerful solar flares and background X-ray fluxes in the range of 1–8 Å. To predict solar flares for the next day, information was used on the current level of solar activity obtained from ground-based synoptic observations, such as characteristics of sunspots and radio fluxes at wavelengths of 10.7 and 5 cm, as well as the level of the background flux and the number of solar flares of the current day obtained from the GOES satellite. To predict the background fluxes of X-ray radiation, only data from ground-based telescopes were used. The high efficiency of the forecast for the next day is shown. The neural network was trained on data available since 2002. PubDate: 2020-11-01
Abstract: When spacecraft cross the heliospheric plasma sheet (HPS) that separates large-scale magnetic sectors of opposite directions in the solar wind, multiple rapid fluctuations in the sign of the magnetic radial component are often observed. These fluctuations indicate the change of the sign of the azimuth electric current density within the HPS. Possible mechanisms of formation of the multilayered current structure of the HPS are proposed. Within the context of a stationary magnetohydrodynamic solar wind model, we test one of the most popular hypotheses regarding an extension of multiple current sheets from the streamer belt oriented along the neutral line of the solar magnetic field into the solar wind. Properties of self-consistent distributions of the solar wind key characteristics are investigated as function of the fine structure of streamers. The results show that both single and multiple streamers can be the source of the set of a multilayered structure with alternating azimuthal currents. The significance of the results for the interpretation of solar wind data is discussed. PubDate: 2020-11-01
Abstract: A self-consistent hybrid model of a thin current sheet (TCS) with a thickness of the order of several ion gyroradii is proposed that takes into account the multicomponent nature of collisionless space plasma. Several plasma components can be present in the tails of the magnetospheres of terrestrial planets (for example, the Earth, Mercury, Mars, and Venus). Variations in the current sheet (CS) structure in magnetospheric plasma in the presence of heavy oxygen ions with different characteristics are analyzed. It is shown that high relative concentrations of oxygen ions, as well as their relatively high temperatures and drift velocities, lead to significant thickening of CS and the formation of an additional embedded scale. In this case, on the profiles of the main characteristics—current density and magnetic field—symmetric breaks appear, which correspond to a sharp change in the gradients of variation in values. A comparison is performed and a qualitative agreement is shown between the simulation results and observational data in the tail of the Martian magnetosphere. PubDate: 2020-11-01
Abstract: This work is devoted to the study of properties of spectra of turbulent solar wind fluctuations in plasma compression regions, such as CIR (the plasma compression regions in front of high-speed streams from coronal holes) and SHEATH (the compression regions in front of interplanetary manifestations of coronal mass ejections EJECTA and magnetic clouds MC). The spectra of ion flux fluctuations, on both magnetohydrodynamic and ion-kinetic scales, are considered on the basis of data from the BMSW spectrometer on the SPEKTR-R spacecraft with a high (up to 31 ms) time resolution. The comparison of turbulent characteristics in the plasma compression regions and in the undisturbed solar wind is carried out both on a separate example and using extensive statistical material. It is shown in the paper that the turbulent cascade characteristics on the kinetic interval can significantly change in the plasma compression regions, and the signatures of a change in the main processes that determine the energy dissipation are revealed in them, which may cause increased heating in the regions under consideration. PubDate: 2020-11-01
Abstract: The magnetosheath is an integral element of solar–terrestrial relations. The paper analyzes the influence of the solar wind parameters and their variability, as well as the topology of the bow shock on the characteristics of plasma turbulence in the magnetosheath on scales corresponding to the transition from the inertial region of a turbulent cascade to the dissipative one. The analysis is based on extensive statistics of measurements of the BMSW instrument with high time resolution on board the Spektr-R satellite in the magnetosheath in 2011–2018. It is shown that the variability of the solar wind plasma density and the interplanetary magnetic field magnitude, as well as the angle between the normal to the bow shock and the interplanetary magnetic field has the greatest influence on the form of the turbulent cascade directly behind the bow shock. PubDate: 2020-11-01
Abstract: An experiment on radio sounding of the circumsolar plasma by signals from the Mars Express spacecraft in 2013 was carried out in the period from March 4 through May 31. The investigated characteristics were the frequency of signals in the centimeter and decimeter ranges and the differential frequency. A number of events were recorded in which the intensity of the frequency fluctuations of the signals probing the plasma was several times higher than the background values. As shown by the analysis of observations of solar activity, such as an increase in the flux of X-rays and SOHO LASCO coronagraph data, this is explained by the passage of disturbed plasma streams generated in the solar corona through the spacecraft radio communication path with the Earth. The comparison of the radio transmission data with the results of measurements of the parameters of the near-Earth plasma using the Wind spacecraft in adjacent periods of time. As a result of the analysis of the data on the proton concentration, it became clear that sharp increases in both the average values and fluctuations of this characteristic were also observed near the Earth. The time lag between the events observed in the circumsolar and near-Earth plasma shows that the cause of the disturbances is the increased activity of the same coronal region rotating with the Sun. PubDate: 2020-11-01
Abstract: One perturbed type of solar wind and magnetospheric disturbance drivers is the compression region in front of fast ICMEs—the Sheath region. In front of this region, an interplanetary shock is observed in approximately half of cases. However, the parameters and their time profiles in these two types of the Sheath region differ comparatively little. Therefore, the Sheath region without a shock is as geoeffective as the Sheath region with a shock: the Sheath region in the first case generated almost 10% of magnetic storms with a minimum Dst < –50 nT of all the magnetic storms for 1976–2017 with identified interplanetary drivers. Many authors do not analyze this driver (for this reason, we call it the “lost driver”); therefore, their studies contain incorrect conclusions on solar–terrestrial physics. PubDate: 2020-11-01
Abstract: — The structure of interplanetary shock fronts was studied based on the data from the BMSW plasma spectrometer, installed on the SPEKTR-R spacecraft, supplemented by magnetic field measurements on the WIND spacecraft. Special attention was paid to periodic growths (overshoots) in the value of the ion flux or magnetic field relative to their mean values outside the ramp. A comparison was performed with the overshoot in the magnetic field, with the Mach number, and with the β parameter. Based on an analysis of 18 intersections of interplanetary shock fronts, in which the overshoots in the ion flux and magnetic field value were observed, it was shown that the value of the magnetic field overshoot is, on the average, less than a similar value in the solar wind’s ion flux, which is associated with different time resolution of measurements. The ion flux overshoot value is found to grow with the growth of the Mach number, in the same way, as the value of the magnetic field overshoot. It is shown that overshoots are formed not only in the supercritical shocks, but also in those with Mach numbers that are less than the value of the first critical Mach number. It is also found that the estimates of the wavelength of the ion flux and magnetic field oscillations behind the ramp well correlate with the value of a gyroradius of captured ions. PubDate: 2020-11-01
Abstract: A critical review of the hypothesis of the Big Bang and accompanying expansion of the Universe is presented. A conclusion is drawn that proof of it is absent. Explanations of the redshift of galaxies and the relic background without involving relativistic ideas are proposed. PubDate: 2020-11-01
Abstract: The characteristics and course of development of the current 24th solar activity (SA) cycle allow it to be considered a cycles in an epoch of lowered SA. Comparison of evolutionary changes in the cycles of different epochs in the phases of the minimum made it possible to distinguish two groups by the rate of decline. The first group with a relatively fast decline (~15 months) includes all cycles of epochs of increased SA, transition periods, and cycle 16 from the epoch of lowered SA. The second, with a slow decline (~40 months), contains the rest of the cycles of epochs of lowered SA, including the current 24th one, the minimum of which can be expected in the first half of 2020. PubDate: 2020-11-01
Abstract: We investigate a procedure for determining the shadow cone of the Earth in the course of the motion of a satellite in the ecliptic plane. The average time spent by the satellite in the Area of the Earth’s shadow is estimated depending on the orbit parameters in the outer sphere of the Earth’s gravitational influence. The obtained estimate of the average time spent by the satellite in the shadow allows us not to take the shadow into account in the qualitative analysis of satellite motion. The results obtained for a conical shape of the shadow are compared with the results obtained for a cylindrical shape, and a choice is made in favor of the conical one. PubDate: 2020-11-01
Abstract: This article presents the results of experimental studies of properties that are resistant to abnormal high and abnormally low temperatures of samples of the radio-absorbing material VTMV-1C. Based on the studies, it was concluded that the radar-absorbing material can be used to attenuate reflected waves of electromagnetic fields from various parts of the spacecraft structure and to reduce the levels of resonance phenomena of the electromagnetic field in the modules and cases of onboard instruments and devices of spacecraft. PubDate: 2020-09-01
Abstract: This article discusses the resolution of an optical lidar for measuring the background concentration of methane in the Earth’s atmosphere. Using simulation and experimental studies, it has been shown that a resolution the width of the absorption line of which is ~0.006 nm and that has a concentration of methane of ~6% of the background can be obtained with a signal-to-noise ratio for received signals of ~200. When extrapolating the results to orbital measurements, the horizontal resolution will be ~8 km and the vertical resolution will be ~1.5 km. A broadening of the emission line of the lidar transmitter by a factor of 2–3 does not significantly reduce the resolution of the lidar, which makes it possible to increase the radiated power at the considered wavelength of ~1653 nm and improve the energy potential of the device as a whole. PubDate: 2020-09-01
Abstract: Ground-truth experiments are needed to calibrate and validate satellite microwave data and to improve the quality and utilization efficiency of satellite data in solving problems of hydrometeorological support. This paper considers the arrangement of specialized test observatories in the satellite data validation subsystem exemplified by the geophysical observatory in Lehtusi (a town in Leningrad oblast), describes the state and prospects of its equipping with modern tools of contact and remote measurements of meteorological parameters, and indicates directions of scientific research. PubDate: 2020-09-01
Abstract: The paper considers the problem of the optimal thrusters arrangement aboard a geostationary spacecraft. It is necessary to simultaneously ensure orbit correction and reaction wheels desaturation. A formalization for thrusters optimal arrangement problem is proposed. Examples of the minimal thrusters arrangement are given, taking into account the given limitations and requirements both in the case of regular operation and in the case of a possible failure of one of the thrusters. The influence of possible installation errors and the center of mass displacement is taken into account. PubDate: 2020-09-01
Abstract: A technique for assessing the market of advanced global telecommunication networks, including the space segment, as global coverage communication megaconstellations is considered. According to our results, the worldwide traffic consumption by 5G mobile devices by 2022 will be almost 8.5 EB/month. The possible cost of deploying a megaconstellation of communications to provide broadband Internet access at any place in the world can range from $5 to $50 billion, depending on service requirements. We have shown that modern and prospective space communications constellations can be integrated into a new-generation global telecommunication infrastructure. Deployment of a constellation of 600 or more devices with a cost of almost $10 billion can provide traffic transit from base stations in remote areas delivering the population with broadband Internet through 5G networks. PubDate: 2020-09-01
Abstract: This paper presents an analysis of the possibility of performing VLBI (Very Long Base Interferometry) observations in the halo-orbit near the L2 libration point of the Sun–(Earth + Moon) system. This orbit is intended to be used by the Millimetron ground–space radio interferometer. This orbit is shown to provide a slow evolution of UV-coverage, and the majority of sources do not have small baseline projections throughout the mission. The problem of effective use of observational time is also revealed. The obtained results are generalized to the entire family of halo-orbits, as well as to the Lissajous family of orbits. PubDate: 2020-09-01
Abstract: 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. PubDate: 2020-09-01
Abstract: An original technique is proposed for determining the overlap of visibility zones of auroral imagers from two spacecrafts: Meteor-MP and Probe. The peculiarity of the method is that it takes into account the orientation of the Probe spacecraft relative to the Sun and the angle of slope of the satellite imager Laetitia. Other conditions of the space experiment are also considered related to the shadow parts of the satellite orbits and the Moon phases. The method is an integral part of the software package for studying the polar ionosphere characteristics and monitoring its state. It has been experimentally shown that in order to obtain the maximum number of overlapping visibility zones for the imagers, the space experiment must be started during the spring or autumn equinox. PubDate: 2020-09-01
Abstract: This paper is a continuation of our works [1, 2], in which we discussed some incorrect approaches to identifying large-scale types of solar wind and related incorrect conclusions drawn when analyzing the solar-terrestrial physics data. In this paper, we analyze the sets of CME-induced, CIR-induced, and multistep magnetic storms for the period of 1996–2004 from the list by Kataoka and Miyoshi [3]. It is shown that a significant number of the events in this list were identified incorrectly and that their interpretation differs, both from our catalog (Yermolaev et al. [4], ftp://ftp.iki.rssi.ru/pub/omni/) for the Sheath, ICME, and CIR and from the catalog by Richardson and Cane [5] for ICME. The use of the uncorrected list of Kataoka and Miyoshi leads to incorrect identification of the interplanetary drivers of magnetic storms and to erroneous conclusions, for example, in paper [6]. PubDate: 2020-09-01
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