On a possibility of delivery of samples of primordial matter from asteroids of the main belt by a spacecraft with electric propulsion

The possibilities of an expedition to asteroids of the Main belt with the goal of obtaining samples of their matter using a spacecraft with a small-thrust electric propulsion, which is under development as a part of the Fobos-Grunt project, are considered. Obtaining matter from different regions of the Solar system is necessary in order to understand its origin and the structure of the Earth. Approximate estimates are made for the flights of spacecraft with electric propulsion and different power of solar batteries, and with perturbation maneuver near Mars for expeditions to the Main asteroid belt, including its middle part.     

Forecasting the velocity of quasi-stationary solar wind and the intensity of geomagnetic disturbances produced by it

A brief review is given of contemporary approaches to solving the problem of medium-term forecast of the velocity of quasi-stationary solar wind (SW) and of the intensity of geomagnetic disturbances caused by it. At the present time, two promising models of calculating the velocity of quasi-stationary SW at the Earth’s orbit are realized. One model is the semi-empirical model of Wang-Sheeley-Arge (WSA) which allows one to calculate the dependence V(t) of SW velocity at the Earth’s orbit using measured values of the photospheric magnetic field. This model is based on calculation of the local divergence f _S of magnetic field lines. The second model is semi-empirical model by Eselevich-Fainshtein-Rudenko (EFR). It is based on calculation in a potential approximation of the area of foot points on the solar surface of open magnetic tubes (sources of fast quasistationary SW). The new Bd-technology is used in these calculations, allowing one to calculate instantaneous distributions of the magnetic field above the entire visible surface of the Sun. Using predicted V(t) profiles, one can in EFR model calculate also the intensity of geomagnetic disturbances caused by quasi-stationary SW. This intensity is expressed through the K _p index. In this paper the EFR model is discussed in detail. Some examples of epignosis and real forecast of V(t) and K _p (t) are discussed. A comparison of the results of applying these two models for the SW velocity forecasting is presented.     

Peculiarities of long-wave radio bursts from solar flares preceding strong geomagnetic storms

Radio bursts in the frequency range of 100–1500 kHz, recorded in 1997–2000 on the INTERBALL-1 satellite during the solar flares preceding the strong geomagnetic storms with D _st < ?100 nT, are analyzed in this paper. The observed long-wave III-type radio bursts of solar origin at frequencies of 1460 and 780 kHz were characterized by large values of the flux S _f = 10^?15 ?10^?17 W/m² Hz and duration longer than 10 min. The rapid frequency drift of a modulated radio burst continued up to a frequency of 250 kHz, which testified that the exciting agent (a beam of energetic electrons) propagated from the Sun to the Earth. All such flares were characterized by the appearance of halo coronal mass ejections, observed by the LASCO/SOHO, and by the presence of a southward B_z-component of the IMF, measured on the ACE and WIND spacecraft. In addition, shortly after radio bursts, the INTERBALL-1 satellite has recorded the fluxes of energetic electrons with E > 40 keV.     

Numerical simulation of effects of the August 11, 1999 solar eclipse in the outer ionosphere

The results of a numerical simulation of such parameters of the topside ionosphere as concentration N _e and temperature T _e of electrons, and concentration n(H⁺) and fluxes along the magnetic field lines Φ(H⁺) of H⁺ ions at an altitude of ～2000 km for the conditions of the August 11, 1999 solar eclipse are presented. The calculations were performed using the Global Self-consistent Model of the Thermosphere, Ionosphere, and Protonosphere of the Earth (GSM TIP). It is shown that during the eclipse, in addition to a region of decreased values of T _e in the Northern Hemisphere and in the magnetically conjugate region in the Southern Hemisphere, regions of electron heating emerge in both hemispheres. Simultaneously, an extended region of decreased values of N _e comes into existence and moves behind the Moon’s shadow. Regions with decreased (down to ～30%) and enhanced (up to ～50%) concentrations of H⁺ ions are detected in the global distribution of these ions.     

Ionization losses of the Earth’s radiation belt protons according to the radial diffusion theory

Using modern models of the plasmasphere and exosphere, radial profiles of the rates of ionization losses of protons with μ = 0.3–10 keV/nT (μ is the first adiabatic invariant) of the Earth’s radiation belts (ERBs) have been constructed. To calculate Coulomb losses of protons, we used the ISEE-1 satellite data at L = 3–9 and CRRES satellite data at L ≤ 3 (L is the McIlwain parameter). The relation of contributions of Coulomb losses and charge exchange in the rate of ionization losses of protons has been considered. We have discovered the effect of subtracting Coulomb losses from charge exchange of ERB protons for small μ and L, which can imitate a local particle source. It has been demonstrated that, with decreasing L, the rate of ionization losses of ERB protons decreases as a whole. The radial dependence of this rate only has a negative gradient in the narrow range (ΔL ~ 0.5) in the region of the plasmapause and only for protons with μ > 1.2 keV/nT.     

Short increases of the fluxes of electrons with energies > 0.08 MeV at low-latitude (<Emphasis Type="Italic">L</Emphasis> < 2) regions of near-Earth space

We present the characteristics of short (duration less than 1 min) increases of the counting rate of electrons with energies >0.08 MeV observed in low-latitude (L < 2.0) regions of near-Earth space in the course of the GRIF experiment on the Spektr module of the Mir orbital station. The measurements were carried out using a set of instruments including X-ray and gamma-ray spectrometers, as well as detectors of electrons, protons, and nuclei with large and small geometrical factors, which allowed one to detect the fluxes of charged particles both in the region of the Earth’s radiation belts and in regions close to the geomagnetic equator. As a result of more than 1.5 years of observation, it is demonstrated that short increases in the intensity of electrons of subrelativistic energies are detected not only in the regions of the near-Earth space known as “precipitation zones” (1.7 < L < 2.5), but in high-latitude regions (up to the geomagnetic equator, L < 1.1) as well. Two types of increases of the electron counting rate are found: either fairly regular increases repeating on successive orbits or increases local in time. The latter type of increases can be caused by a short enhancement of electron flux on a given drift shell. The results of our measurements have shown that the duration of the detected increases in intensity can be rather short, as little as 20–30 s. Therefore, in the case of large amplitudes, such increases of the counting rate of electrons can imitate astrophysical events of the type of cosmic gamma-ray bursts in the detectors of hard X-ray and gamma radiation.     

Observations of corotating solar wind structures at radio sounding by signals of the <Emphasis Type="Italic">Rosetta</Emphasis> and <Emphasis Type="Italic">Mars Express</Emphasis> spacecraft

In the implementation of the space projects Rosetta and Mars Express, a large-scale series of experiments has been carried out on radio sounding circumsolar plasma by decimeter (S-band) and centimeter (X-band) signals of the Rosetta comet probe (from October 3 to October 31, 2010) and the Mars Express satellite of Mars (from December 25, 2010 to March 27, 2011). It was found that in the phase of ingress the spacecraft behind the Sun, the intensity of the frequency fluctuations increases in accordance with a power function whose argument is the solar offset distance of radio ray path, and when the spacecraft is removed from the Sun (the egress phase), frequency fluctuations are reduced. Periodic strong increases in the fluctuation level, exceeding by a factor of 3–12 the background values of this value determined by the regular radial dependences, are imposed on the regular dependences. It was found that increasing the fluctuations of radio waves alternates with the periodicity m × T or n × T, where m = 1/2, n = 1, аnd T is the synodic period of the Sun’s rotation (T ≈ 27 days). It was shown that the corotating structures associated with the interaction regions of different speed fluxes are formed in the area of solar wind acceleration and at distances of 6–20 solar radii already have a quasi-stationary character.     

Determination of the density and percentage of metal oxides in the lunar soil based on radar data

Results of laboratory measurements of the dielectric characteristics of lunar soil samples returned to the Earth by the Luna and Apollo missions have been analyzed. The feasibility of determining the density of the upper cover of the Moon from the permittivity, which is restored as a result of solving the inverse problem of radiolocation, has been discussed. A formula has been proposed for approximating the frequency dependence of the loss tangent for the regolith and bedrock. Relationships have been deduced for estimating the percentage of metal oxides in the lunar soil.     

Observations of electromagnetic emissions inside the Earth’s plasmasphere from the <Emphasis Type="Italic">Interball-1</Emphasis> satellite

The spectrum analyzer AKR-X onboard the Interball-1 satellite at the beginning (August–October 1995) and at the end (August–October 2000) of satellite operation in perigees of its orbital motion recorded and analyzed electromagnetic emissions of the inner regions of the Earth’s plasmasphere in the frequency band 100–1500 kHz at distances of 1.1–1.8 R _E. The observations have shown that the electromagnetic modes (the Z and LO modes escaping the magnetosphere) which are formed at the altitudes 600–4000 km are associated with the subauroral nonthermal continuum and with the recently discovered kilometric continuum. There are noticeable differences in the spectral character of these emissions during the minimum (1996) and maximum (2000) solar activity, when, as a rule, the LO mode escaping the plasmaphere and the continua are not present.     

Large-scale irregularities of the winter polar topside ionosphere according to data from <Emphasis Type="Italic">Swarm</Emphasis> satellites

An analysis of the electron density measurements (Ne) along the flyby trajectories over the high-latitude region of the Northern Hemisphere under winter conditions in 2014 and 2016 has shown that the main large-scale structure observed by Swarm satellites is the tongue of ionization (TOI). At the maximum of the solar cycle (F_10.7 = 160), the average value of Ne in the TOI region at an altitude of 500 km was 8 × 10⁴ cm^–3. Two years later, at F_10.7 = 100, Ne ~ 5 × 10⁴ cm^–3 and Ne ~2.5 × 10⁴ cm^–3 were observed at altitudes of 470 and 530 km, respectively. During the dominance of the azimuthal component of the interplanetary magnetic field, the TOI has been observed mainly on the dawn or dusk side depending on the sign of B _y . Simultaneous observations of the convective plasma drift velocity in the polar cap show the transpolar flow drift to the dawn (B_y < 0) or dusk side (B _y < 0). Observations and numerical simulation of the Ne distribution have confirmed the significant role of the electric field of the magnetospheric convection in the generation of large-scale irregularities in the polar ionosphere.     

Turbulent fluctuations of plasma and magnetic field parameters in the magnetosheath and the low-latitude boundary layer formation: Multisatellite observations on March 2, 1996

The results of simultaneous analysis of plasma and magnetic field characteristics measured on the INTERBALL/Tail Probe, WIND and Geotail satellites on March 2, 1996, are presented. During these observations the INTERBALL/Tail Probe crossed the low-latitude boundary layer, and the WIND and Geotail satellites measured the solar wind’s and magnetosheath’s parameters, respectively. The plasma and magnetic field characteristics in these regions have been compared. The data of the Corall, Electron, and MIF instruments on the INTERBALL/Tail Probe satellite are analyzed. Fluctuations of the magnetic field components and plasma velocity in the solar wind and magnetosheath, measured onboard the WIND and Geotail satellites, are compared. The causes resulting in appearance of plasma jet flows in the low-latitude boundary layer are analyzed. The amplitude of magnetic field fluctuations in the magnetosheath for a studied magnetosphere boundary crossing is shown to exceed the magnetic field value below the magnetopause near the cusp. The possibility of local violation of pressure balance on the magnetopause is discussed, as well as penetration of magnetosheath plasma into the magnetosphere, as a result of magnetic field and plasma flux fluctuations in the magnetosheath.     

Energy dependence of the characteristic decay time of proton fluxes in solar cosmic ray events

Energetic solar proton events within the energy interval 1–48 MeV at the stage of their decay are considered over the period of 1974–2001. The dependence of the characteristic decay time on the proton energy in the assumed power-law representation τ(E) =E ^?n is analyzed for the events with an exponential decay form. The dependence of n on the heliolongitude of the flare (the particles source on the Sun) is studied.     

Peculiarities of the formation of a thin current sheet in the Earth’s magnetosphere

We investigate the process of the self-consistent formation of a thin current sheet with a thickness close to the ion Larmor gyroradius in the presence of decreasing magnetic field’s normal component B_n. This behavior is typical of the current sheet of the Earth’s magnetospheric tail during geomagnetic substorms. It has been shown that, in a numerical model of the current sheet, based on the particle-in-cell method, the appearance of self-consistent electric field component E_y in the current sheet vicinity can lead to its significant thinning and, eventually, to the formation of a multiscale configuration with a thin current sheet (TCS) in the central region supported by transient particles. The structure of the resulting equilibrium is determined by the initial parameters of the model and by the particle dynamics during the sheet thinning. Under certain conditions, the particle drift in the crossed electric and magnetic fields leads to a significant portion of ions becoming trapped near the neutral sheet and, in this way, to the formation of a wider configuration with an embedded thin current sheet. The population of trapped particles produces diamagnetic negative currents that manifest in the form of negative wings at the periphery of the sheet. Correspondingly, in the direction perpendicular to the sheet, a nonmonotonic coordinate dependence of the magnetic field appears. The mechanisms of the evolution of the current sheet in the Earth’s magnetotail and the formation of a multiscale structure are discussed.     

Experiment on the <Emphasis Type="Italic">Vernov</Emphasis> satellite: Transient energetic processes in the Earth’s atmosphere and magnetosphere. Part I: Description of the experiment

The program of physical studies on the Vernov satellite launched on July 8, 2014 into a polar (640 × 830 km) solar-synchronous orbit with an inclination of 98.4° is presented. We described the complex of scientific equipment on this satellite in detail, including multidirectional gamma-ray detectors, electron spectrometers, red and ultra-violet detectors, and wave probes. The experiment on the Vernov satellite is mainly aimed at a comprehensive study of the processes of generation of transient phenomena in the optical and gamma-ray ranges in the Earth’s atmosphere (such as high-altitude breakdown on runaway relativistic electrons), the study of the action on the atmosphere of electrons precipitated from the radiation belts, and low- and high-frequency electromagnetic waves of both space and atmospheric origin.     

Families of periodic solutions in three-dimensional restricted three-body problem

Planar orbits of three-dimensional restricted circular three-body problem are considered as a special case of three-dimensional orbits, and the second-order monodromy matrices M (in coordinate z and velocity v _z ) are calculated for them. Semi-trace s of matrix M determines vertical stability of an orbit. If |s| ≤ 1, then transformation of the subspace (z, v _z ) in the neighborhood of solution for the period is reduced to deformation and a rotation through angle φ, cosφ = s. If the angle ? can be rationally expressed through 2π,φ = 2π·p/q, where p and q are integer, then a planar orbit generates the families of three-dimensional periodic solutions that have a period larger by a factor of q (second kind Poincareé periodic solutions). Directions of continuation in the subspace (z, v _z ) are determined by matrix M. If |s| < 1, we have two new families, while only one exists at resonances 1: 1 (s = 1) and 2: 1 (s = ?1). In the course of motion along the family of three-dimensional periodic solutions, a transition is possible from one family of planar solutions to another one, sometimes previously unknown family of planar solutions.     

Study of notches in the Earth’s plasmasphere based on data of the <Emphasis Type="Italic">MAGION-5</Emphasis> satellite

Depleted narrow (localized in longitude) regions (field tubes) in the plasmasphere, recently discovered in He⁺ radiation measurements on the IMAGE spacecraft, were first directly observed by the Magion-5 satellite. The low-density regions (notches) occupy <～ 10–30° in longitude and extend from L ～ 2–3 to the plasmasphere boundary in neighboring plasmasphere regions with larger densities. The Magion-5 data give evidence that in the low-density regions temperature is enhanced as compared to the neighboring denser plasmasphere regions. Formation of notches in the plasmasphere is, apparently, associated with AE intensification during weak magnetic storms, while strong magnetic storms usually result in the overall reduction of plasmasphere dimensions. However, even a strong magnetic storm on April 6–7, 2000 (max K _p = 9-and min D _st ～ ?290 nT), but accompanied by an isolated AE impulse, resulted in a density decrease only in the longitudinally limited post-midnight sector of the plasmasphere.     

Large-size space debris flyby in low earth orbits

the analysis of NORAD catalogue of space objects executed with respect to the overall sizes of upper-stages and last stages of carrier rockets allows the classification of 5 groups of large-size space debris (LSSD). These groups are defined according to the proximity of orbital inclinations of the involved objects. The orbits within a group have various values of deviations in the Right Ascension of the Ascending Node (RAAN). It is proposed to use the RAANs deviations' evolution portrait to clarify the orbital planes’ relative spatial distribution in a group so that the RAAN deviations should be calculated with respect to the concrete precessing orbital plane of the concrete object. In case of the first three groups (inclinations i = 71°, i = 74°, i = 81°) the straight lines of the RAAN relative deviations almost do not intersect each other. So the simple, successive flyby of group’s elements is effective, but the significant value of total ΔV is required to form drift orbits. In case of the fifth group (Sun-synchronous orbits) these straight lines chaotically intersect each other for many times due to the noticeable differences in values of semi-major axes and orbital inclinations. The intersections’ existence makes it possible to create such a flyby sequence for LSSD group when the orbit of one LSSD object simultaneously serves as the drift orbit to attain another LSSD object. This flyby scheme requiring less ΔV was called “diagonal.” The RAANs deviations’ evolution portrait built for the fourth group (to be studied in the paper) contains both types of lines, so the simultaneous combination of diagonal and successive flyby schemes is possible. The value of total ΔV and temporal costs were calculated to cover all the elements of the 4th group. The article is also enriched by the results obtained for the flyby problem solution in case of all the five mentioned LSSD groups. The general recommendations are given concerned with the required reserve of total ΔV and with amount of detachable de-orbiting units onboard the maneuvering platform and onboard the refueling vehicle.     

Statistical investigation of Heliospheric conditions resulting in magnetic storms: 2

This work is a continuation of investigation [1] of the behavior of the solar wind’s and interplanetary magnetic field’s parameters near the onset of geomagnetic storms for various types of solar wind streams. The data of the OMNI base for the 1976–2000 period are used in the analysis. The types of solar wind streams were determined, and the times of beginning (onsets) of magnetic storms were distributed in solar wind types as follows: CIR (121 storms), Sheath (22 storms), MC (113 storms), and “uncertain type” (367 storms). The growth of variations (hourly standard deviations) of the density and IMF magnitude was observed 5–10 hours before the onset only in the Sheath. For the CIR-, Sheath-and MC-induced storms the dependence between the minimum of the IMF B _z-component and the minimum of the D _st -index, as well as the dependence between the electric field E _y of solar wind and the minimum of the D _st -index are steeper than those for the “uncertain” solar wind type. The steepest D _st vs. B _z dependence is observed in the Sheath, and the steepest D _st vs. E _y dependence is observed in the MC.     

Study and comparison of the parameters of five hot flow anomalies at a bow shock front

Five hot flow anomalies (HFA) recorded by the Tail Probe of the INTERBALL satellite in 1996 are analyzed in present work. For the five chosen events the authors determined the characteristics of current sheets whose interaction with the bow shock front led to formation of an HFA, as well as the directions of external electric fields and the directions of motion of these HFAs over a shock front. The analysis of plasma convection in an HFA body is carried out; the average velocities of plasma motion in the HFA are determined in a coordinate system linked with the normal to a current layer and with the normal to the bow shock. According to the character of plasma convection in an HFA body, these five events may be divided into two types, which also differ in the direction of the motion over the front of the bow shock. In the first-type HFAs, the convection of plasma has a component directed from the intermediate region confirming its identification as a source of energy for the formation of an HFA. In the second-type HFAs, plasma motion from the intermediate region in leading and trailing parts is less expressed. This fact, as well as the great variation of peculiar velocities in the body of anomalies, allowed the assumption that second-type anomalies are nonstationary. Evidence is presented that the anomalies considered in the paper are bordered with shocks formed in solar wind passing a large-scale, decelerated body of heated plasma.     

Empirical model of the high-latitude boundary of the Earth’s outer radiation belt at altitudes of up to 1000 km

An empirical model of the high-latitude boundary of the outer Earth’s radiation belt (ERB) has been presented, which is based on the measurement data of electron fluxes on the polar low-orbit CORONAS-Photon, Meteor-M1, and Meteor-M2 satellites. The boundary was determined by a sharp decrease to the background level of the flux of trapped electrons with energies of 100 or 200 keV in the polar part of the profile of the outer radiation belt. A numerical algorithm has been implemented to determine the time moment, when the fastest flux changes are recorded. The primary search was carried out, first, on 30 s averaged data, then repeated on data with a higher resolution. A functional dependence was obtained in order to approximate the obtained set of intersections of the boundary by elliptical curve. The empirical model constructed using the CORONAS-Photon measurement data in the epoch of anomalously low geomagnetic activity reflects the longitude structure of the high-latitude boundary of the outer radiation belt associated with the internal Earth’s magnetic field (MF), as well as its dependence on the universal time. Based on the data of intersections of the high-latitude boundary of the outer ERB (OERB) in the epoch of 2014–2016, the latitudinal shift of the boundary to the equator dependent on geomagnetic activity has been determined, as well as the nightside shift of the boundary due to the diurnal rotation of the Earth.