Measurement results are presented for the velocity of density irregularities in solar wind plasma, which modulate the frequency of coherent radio signals from the Galileo spacecraft in the S-band. The measurements have been performed by the spaced receiving technique at ground monitoring stations. The data cover a range of heliocentric distances from 7 to 72 solar radii at low heliolatitudes near solar minimum. It is shown that acceleration of slow solar wind continues up to distances of about 30 solar radii. In the overlapping ranges of distances from the Sun, the results are qualitatively consistent with LASCO SOHO data for the same periods, with the previous results obtained by analyzing the amplitude fluctuations of signals from the Venera 15 and 16 spacecraft, and with the more recent measurements acquired using the Mars Express spacecraft.
The results of studies of proton flux dynamics of the ring current and magnetic field in the middle of radiation belts during two strong magnetic storms in 2015 (March 17–18, 2015 and June 22–23, 2015) with a close amplitude of Dst-variations (∣Dst max∣ ~ 200 nT) are presented. An analysis of the experimental data obtained on board two space vehicles named Van Allen Probes (earlier: Radiation Belt Storm Probes, RBSP), located at an orbit close to equatorial is performed. Modeling of the ring current and magnetic field in the frames of the paraboloid model of Earth’s magnetosphere А2000 is conducted. Confirmation of the existence of a mechanism for ring current development and, respectively, geomagnetic storm under the action of a strong pulse of solar-wind pressure is obtained as a result of comparative analysis of ring current dynamics and the magnetic field in the middle of radiation belts during the main phases of two storms in 2015. It is found that during the magnetic storm of June 22–23, 2015, the development of the ring current during the main phase continued despite the northward turn of the interplanetary magnetic field (IMF) and the following period with positive B z in the solar wind. The effect observed during June 22–23, 2015 is explained by the intensification of storm ring current due to a long and powerful pulse of the solar wind pressure that led to a nonadiabatic transport of the ring current particles to lower L shells.
The vertical profiles of temperature and pressure obtained from radio occultation measurements made by satellites Venera-15 and -16 from October 1983 to September 1984 are used for the analysis of wind speed in Venus’s atmosphere. The altitude and latitude dependences of zonal wind speed in the middle atmosphere of the planet’s northern and southern hemispheres are identified at altitudes from 50 to 80 km over the latitude interval of 60°–85°. Zonal speeds were determined assuming cyclostrophic atmosphere balance. The existence of jet flows, whose maximal speed is ~100 m/s and axis is placed at an altitude near 60 km within the latitude zone of 73°–75° N, is confirmed in the northern polar atmosphere of the planet. The results of wind speed measurements in the southern hemisphere clearly show that the jet flows exist at an altitude around 62 km at latitudes from 70° to 72° S, and their zonal speed reaches a maximum of ~115 m/s. It is found that these jets at high latitudes are stipulated by negative latitudinal temperature gradients at altitudes below the jet flow axes in Venus’s polar atmosphere.
The paper is devoted to studying processes of plasma particle acceleration in the process of magnetic dipolarizations in a current sheet of Earth's magnetotail. A numerical model is constructed that allows evaluation of particle acceleration in three possible scenarios: (A) Proper dipolarization; (B) Passage of multiple dipolarization fronts; (C) Passage of fronts followed by high-frequency electromagnetic oscillations. The energy spectra of three types of accelerated particles are obtained: hydrogen H+ and oxygen O+ ions and electrons e(-). It is shown that, at different time scales, predominant acceleration of various particle populations occurs in scenarios (A)-(C). Oxygen ions are accelerated most efficiently in single dipolarization process (A), protons (and, to some extent, electrons), in scenario (B), whereas scenario (C) is most efficient for acceleration of electrons. It is shown that accounting for high-frequency electromagnetic fluctuations, accompanying magnetic dipolarization, may explain the appearance of streams of particles with energies on the order of hundreds of keV in Earth's magnetotail.
The vertical profiles of temperature and pressure obtained from radio occultation measurements made by satellites Venera-15 and -16 from October 1983 to September 1984 are used for the analysis of wind speed in Venus's atmosphere. The altitude and latitude dependences of zonal wind speed in the middle atmosphere of the planet's northern and southern hemispheres are identified at altitudes from 50 to 80 km over the latitude interval of 60 degrees-85 degrees. Zonal speeds were determined assuming cyclostrophic atmosphere balance. The existence of jet flows, whose maximal speed is 100 m/s and axis is placed at an altitude near 60km within the latitude zone of 73 degrees-75 degrees N, is confirmed in the northern polar atmosphere of the planet. The results of wind speed measurements in the southern hemisphere clearly show that the jet flows exist at an altitude around 62 km at latitudes from 70 degrees to 72 degrees S, and their zonal speed reaches a maximum of 115 m/s. It is found that these jets at high latitudes are stipulated by negative latitudinal temperature gradients at altitudes below the jet flow axes in Venus's polar atmosphere.
The paper is devoted to studying processes of plasma particle acceleration in the process of magnetic dipolarizations in a current sheet of Earth’s magnetotail. A numerical model is constructed that allows evaluation of particle acceleration in three possible scenarios: (A) Proper dipolarization; (B) Passage of multiple dipolarization fronts; (C) Passage of fronts followed by high-frequency electromagnetic oscillations. The energy spectra of three types of accelerated particles are obtained: hydrogen H+ and oxygen O+ ions and electrons e–. It is shown that, at different time scales, predominant acceleration of various particle populations occurs in scenarios (A)–(C). Oxygen ions are accelerated most efficiently in single dipolarization process (A), protons (and, to some extent, electrons), in scenario (B), whereas scenario (C) is most efficient for acceleration of electrons. It is shown that accounting for high-frequency electromagnetic fluctuations, accompanying magnetic dipolarization, may explain the appearance of streams of particles with energies on the order of hundreds of keV in Earth’s magnetotail.
On the basis of satellite observations obtained with the help of X-ray and gamma-ray detector units (BDRG/Lomonosov in Russian), using digital filtering methods, the analysis of time delays between the second pulsations of time profiles of hard X-ray radiation of different frequency bands from the solar flare that occurred on July 21, 2016 has been made. It is shown that the count rate in energy channels of 10–20, 20–35, and 35–60 keV detected by BDRG/Lomonosov are correlated with an accuracy up to 0.1 s. The result agrees well with the observations of the Gamma-ray Burst Monitor on board the Fermi satellite and supposes an effective acceleration of charged particles over the entire length of the flare magnetic arc.
Within the self-consistent hybrid model based on the quasi-adiabatic approximation of the proton dynamics, a fine structure of strong current sheets (SCSs) in the solar wind has been investigated, including the heliospheric current sheet. The motion of electrons is fast and considered in the Boltzmann approximation. The simulation results have been shown that the SCS profiles have a multiscale enclosed structure with a narrow central current sheet that is enclosed in a wider sheet, similar to the heliospheric current sheet surrounded by the plasma sheet. The features of the SCS structure are determined by the relative contributions of the current of demagnetized protons in serpentine orbits and drift currents of electrons. The model predicts and describes the properties of SCSs observed by spacecraft. It has been shown that the multiscale structure of current sheets is an inherent intrinsic property of current sheets in the solar wind.
This paper analyzes the correlation between planetary indices of geomagnetic activity Dst, ap, and AE and the values of coupling functions, calculated from data on plasma and magnetic field parameters during four types of solar wind (SW) streams: the regions of interaction of streams with different velocities (co-rotating interaction region—CIR), interplanetary manifestations of coronal mass ejections ICMEs (MC and Ejecta), and the Sheath compression regions in front of MC and Ejecta. To select SW types, we used data from ftp://ftp.iki.rssi.ru/pub/omni/ for 1995–2016, in which 744 CIR, 118 MC, 501 Sheath, and 843 Ejectaevents were identified. The coupling functions were calculated based on the OMNI data base. The analysis has shown low values of correlation coefficients (R < 0.5) between the coupling functions and Dst index for all SW types. For the ap and AE indices, a rather strong correlation with coupling functions (0.6 < R < 0.82) was obtained for all SW types. The geoeffectiveness of coupling functions, estimated from the values of linear regression coefficients, has the highest values for the ap index for the Sheath and MC SW types. For the auroral AE index, the highest values of coupling function efficiencies were obtained for the CIR and Ejecta SW types.
Within the axisymmetric MHD model of the solar wind, the magnetic field of the Sun has been analyzed in two phases of the solar cycle: the minimum activity, when the dipole magnetic field dominates and the maximum activity, when the quadrupole field predominates. It has been shown that during the period of maximum solar activity, the heliospheric current sheet acquires a conical shape and shifts to high latitudes up to 30° above the ecliptic plane. In the opposite hemisphere, at the same latitudes, a second current sheet of conical shape with an azimuth current of the opposite direction is established. It has been shown that the profiles of the main characteristics of the solar wind become steeper with distance from the Sun, and their amplitudes decrease, in this case, for the quadrupole field, the dependences of the main characteristics of the solar wind are more complex. A comparison of the results of the model with averaged characteristics of the solar wind shows a good match between the observed values and model parameters.
The results of experiments onboard the Lomonosov satellite on observing natural and technogenic space hazards including electromagnetic transients and space debris are discussed. A new space project Universat-SOCRAT being developed by Moscow State University is also discussed. The project aims to create a constellation of small satellites for real-time monitoring of the radiation environment and potentially hazardous objects of natural (asteroids, meteoroids) and technogenic origin (space debris) in near-Earth space, and such phenomena as cosmic and atmospheric gamma-ray bursts and optical and ultraviolet radiation flashes from Earth’s atmosphere.
Temporal variations in the relative number of failed rocket launches in Russia (Soviet Union) and the United States have been compared to reveal that these variations are antipersistent. The accident rates of rocket and space equipment launches have been analyzed as a function of the level and phase of solar activity cycle. The relative number of failed launches in Russia (Soviet Union) and the United States for the growth phase of solar activity has been shown to exceed the number for the phase of solar activity decline, although no clear correlation between solar activity and the number of failed launches has been detected.
This paper investigates the possibility of predicting the time series of the geomagnetic index Dst. The prediction is based on parameters of the solar wind and interplanetary magnetic field measured at Lagrange point L1 within the Advanced Composition Explorer (ACE) spacecraft experiment using machine learning methods—artificial neural networks: classical perceptrons, recurrent networks of long short-term memory (LSTM), and committees of predictive models. Ultimately, the best results have been obtained using heterogeneous committees based on neural networks of both types.
The precession of Saturn under the effect of the gravity of the Sun, Jupiter and planet’s satellites has been investigated. Saturn is considered to be an axisymmetric (A = B) solid body close to the dynamically spherical one. The orbits of Saturn and Jupiter are considered to be Keplerian ellipses in the inertial coordinate system. It has been shown that the entire set of small parameters of the problem can be reduced to two independent parameters. The averaged Hamiltonian function of the problem and the integrals of evolutionary equations are obtained disregarding the effect of satellites. Using the small parameter method, the expressions for the precession frequency and the nutation angle of the planet’s axis of rotation caused by the gravity of the Sun and Jupiter are obtained. Considering the planet with satellites as a whole preceding around the normal to the unmovable plane of Saturn’s orbit, the satellites effect on the Saturn rotation is taken into account via the corrections in the formula for the undisturbed precession frequency. The satellites are shown to have no effect on the nutation angle (in the framework of the accepted model), and the disturbances from Jupiter to make the main contribution to the nutation angle evolution. The effect of Jupiter on the nutation angle and the precession period is described with regard to the attraction of satellites.
The results of radiation tests of microcontrollers of the ATmega-128 type in a wide range of dose rates and temperatures have been used to estimate the probability of no-failure operation of microcontrollers in real operating conditions. The Eyring function has been used to take into account the temperature effect.
A new method for recording planets and searching for minor planets (asteroids), AISs, and satellites passing along the solar disk—an advanced method of Doppler tomography—has been developed. This method, due to its high sensitivity, will also allow one to detect exoplanets and specify elements of planetary orbits and the parameters of their stars. It can be used to determine the shape of stars and the distribution of surface brightness, as well as analyze the rotation of the star surface and its active regions (spots, flares, etc.). Finally, it will allow one to establish the shape of planets, AISs, and satellites passing along the star disk. It is based on analysis by high-resolution spectral devices of variations in the profiles of the emission and absorption lines of stars, broadened due to the rotation of stars or flows of emitting gases. For the use of high-resolution spectroscopies, new types of telescopes–spectrographs of record luminosity and a scheme of a mirror collimator–condenser are proposed. Possible manifestations of the Ritz effect in these measurements are considered.
This paper considers the problem of the optimum interplanetary transfer of a spacecraft equipped with an uncontrolled electric propulsion system (EPS). The control-optimization criterion is considered the fuel consumption value or the transfer time, which are minimized. The maximum-principle formalism is used to find the optimum control law. Using the problem of transfer to Mars as an example, the structure and relationship of various locally optimum solutions belonging to various families of extremals is revealed.
This work is a continuation of paper , in which we discussed some incorrect approaches to the identification of large-scale types of solar wind and associated incorrect conclusions in the analysis of solar–terrestrial physics data. In this paper, we analyze the lists of 28 events of coronal mass ejection (CME) and 31 events of corotating interaction region (CIR) in 2013–2016 used by Shen et al.  to compare the responses of the Earth’s radiation belts to various interplanetary drivers. The interpretation of solar wind types in these lists differs both from our catalog  for Sheath, ICME, and CIR and from the catalog by Richardson and Cane  for CME. In addition, the authors of paper  do not distinguish the Sheath- and ICME-induced magnetic storms and include them in the general type of CME-induced storms. Our analysis has shown that, among the 28 events of CME-induced storms mentioned, 16 events belong to Sheath, 2 events to MC, 4 events to Ejecta, 2 events to CIR, and 4 events to undisturbed solar wind with shocks. The catalog , which also does not distinguish the Sheath and ICME, contains 18 of the 28 events presented in paper . Among 31 CIR events presented by the authors of paper , according to our analysis, 25 events belong to CIR, 2 events to Sheath, and 4 events to undisturbed solar wind. In catalog , one of the 31 CIR events from paper  is presented as CME. Since the properties of CIR and Sheath compression regions are close, the conclusions of the authors of paper  on the properties of CIR-induced storms are only slightly distorted by the incorrect identification of stream types, whereas the conclusions concerning the CME-induced storms, which more than by a half represent the Sheath-induced storms, seem incorrect to us.
This paper highlights the features of modeling the process of mechanical contamination of near-Earth space (NES), gives a brief description of existing models for predicting the mechanical contamination of NES, and analyzes the influence of uncertainty in the initial data on the accuracy of predictions of the mechanical contamination of NES by modern models. It has been proposed to predict the deadline of the "ecological life" of near-Earth orbit based on a description of increasing the density of mechanical contamination in NES with logistic dependences. The analytic function has been obtained and presented for the first time, allowing one to obtain the predicted value of the deadline of the near-Earth orbit in the form of an equation that includes the value of the maximum permissible contamination density given in the form of a fuzzy value. The solution of this fuzzy equation in the case of a triangular shape of the membership function of the maximum possible contamination density has been presented. The possibility of transforming the fuzzy prediction to a crisp interval form has been shown by finding the interval crisp alpha-level set closest to the considered fuzzy set (FS).
A solution is found for the nonlinear problem of the passage of a three-rotor gyrostat through a given angular position in space under uncontrollable external disturbances. The equivalent linearization method for nonlinear controlled systems is utilized, making it possible to reduce the solution of the problem to the solution of a linear antagonistic game problem with a nonfixed end time. An estimate is obtained for permissible disturbance levels depending on given constraints on control moments.