Estimation of dynamic characteristics of the <Emphasis Type="Italic">International Space Station</Emphasis> from measurements of microaccelerations

We describe the results of determining the mass of the International Space Station using the data of MAMS accelerometer taken during correction of the station orbit on August 20, 2004. The correction was made by approach and attitude control engines (ACE) of the Progress transporting spacecraft. The engines were preliminary calibrated in an autonomous flight using the onboard device for measuring apparent velocity increment. The method of calibration is described and its results are presented. The error in station mass determination is about 1%. The same data of MAMS and similar data obtained during the orbit correction on August 26, 2004 were used for the analysis of high-frequency vibrations of the station mainframe caused by operation of the ACE of Progress. Natural frequencies of the ACE are determined. They lie in the frequency band 0.024–0.11 Hz. ACE operation is demonstrated to result in a substantial increase of microaccelerations onboard the station in the frequency range 0–1 Hz. The frequencies are indicated at which disturbances increase by more than an order of magnitude. The study described was carried out as a part of the Tensor technological experiment.     

Geomagnetic effect of launches and flights of large spacecraft

The results of observations of variations in the geomagnetic field that accompanied launches and flights of rockets of different types have been analyzed. The launches were performed in 2002–2010 from different space launch facilities of the world (237 events in total), and variations in the range of periods 1–1000 s were studied. Measurements were performed near the city of Kharkov (distance from the spaceports ranges from 1500 to 9500 km). Statistical analysis and spectral estimations have been made, and three groups of disturbances were revealed. Time delays and disturbance durations increased with increasing distance from spaceports. Typical periods were equal to 6 to 14 min, while amplitudes varied in the range 1–3 nT.     

Planetary waves according to simultaneous observations of <Emphasis Type="Italic">GPS</Emphasis> satellites and ground-based magnetic stations

On the basis of measurements made at Japanese magnetic stations and using GPS satellites for the 12 months of 2003, a comparison of simultaneous variations of three components of the magnetic field and total electron content (TEC) was carried out in the range of the planetary waves period. The correlation analysis has shown that almost synchronous variations exist within this range of periods at the ground-based magnetometer stations and in the TEC measurements both during strong magnetic disturbances and in quiet periods. The strong magnetic disturbances could be considered as a possible independent source of ionospheric variations within the planetary waves range, while the accompanying ionospheric storms could be a possible factor changing the conductivity of the lower ionosphere plasma. In quiet periods, the correlation of magnetic variations and disturbances in TEC is caused by the direct impact of atmospheric planetary waves on the lower ionosphere and can be related to variations of ionospheric currents due to the dynamo mechanism.     

Vertical distribution of the power of short- and long-period oscillations in a sunspot and in surrounding magnetic elements

We present the results of processing three 256-min series of observations of quasi-periodic oscillations of the field of line-of-sight velocities in three sunspots. The Doppler shifts were determined simultaneously for six spectral lines formed at different heights in the solar atmosphere. In addition to the well-known high-frequency (periods of 3–5 min) oscillations, a band of low-frequency oscillations with periods of 60–80 min is revealed in the spectra of the sunspot umbra and magnetic elements located in immediate proximity of the sunspot. Unlike the short-period modes, the power of the long-period mode of line-of-sight velocity oscillations in the sunspot decreases sharply with height: these oscillations are distinctly seen in the line formed at a height of 200 km and almost are not seen in the line with the formation height of 500 km. This is indicative of different physical nature of the short-period and long-period oscillations of a sunspot. If the former are caused by slow magnetosonic waves within the field tube of the spot, the latter are representative of global vertical-radial oscillations of a magnetic element (spot, pore) as a whole near the position of a stable equilibrium.     

Robust algorithm of control for a maneuver in the Martian atmosphere to insert a spacecraft into the planet’s satellite orbit

When inserting a satellite into an orbit around Mars with the use of aerodynamic drag, it is required to apply a robust algorithm which is capable of being adapted to the actual conditions of the planet’s atmosphere. We suggest a method of adaptation taking into account the specific features of the maneuver including descending and ascending legs of the trajectory. It is demonstrated that the algorithm is efficient when disturbances of the density of the Martian atmosphere increase by a factor of 2–3.     

Galactic cosmic rays and parameters of the interplanetary medium near solar activity minima

The time behavior of intensity of cosmic rays with relatively low (~1–6 GeV) and high (>10 GeV) energies are considered together with characteristics influencing the modulation of cosmic rays in the heliosphere. The periods under study are close to solar activity minima in cycles 21/22, 22/23, and 23/24. Diffusion and convection in small-scale magnetic fields of the heliosphere are demonstrated to play some role only at sufficiently weak disturbances of the field (B/δB > 1.3). In this case, a negative correlation is observed between B/δB and a tilt of the surface of the heliospheric current sheet. The analysis of characteristics of the interplanetary medium in periods of solar activity minima shows that the energy anomaly of cosmic rays in the minimum of cycles 23/24 is caused by deficit of high energy particles rather than by an excess of particles of relatively small energies.     

Study of vibration microaccelerations onboard the International Space Station

The results of studying vibration microaccelerations aboard the International Space Station are presented. The study was performed using the measurement data of the MAMS low-frequency and the SAMS high-frequency accelerometers. For the study, six intervals of measurements were selected, performed in 2005. During these intervals the station was flying in the standard orbital orientation, attitude control engines were not switched on, and the crew rested. Discrete and continuous spectra were analyzed on selected intervals. The most significant disturbances with the discrete spectrum (cyclic trends) have been found. Using the second order autoregression model, parameters of the most significant disturbances with the continuous spectrum were determined. This study was carried out as a part of the technical experiment “The ISS environment”.     

Design of satellite constellations with continuous coverage on elliptic orbits of <Emphasis Type="Italic">Molniya</Emphasis> type

New methods of choosing the structures of satellite constellations (SC) on elliptical orbits of the Molniya type are presented. The methods, using critical inclination and putting the orbit apogee in the Earth’s hemisphere with an area of continuous coverage, are based on geometrical analysis of two-dimensional representation of the coverage conditions and SC motion in the space of inertial longitude of the orbit ascending node and time. The coverage conditions are represented in the form of a certain region. Dynamics of all satellites in this space is represented by uniform motion along a straight line approximately parallel to the ordinate axis, while the satellite system forms a grid. The problem of choosing a minimal (as far as the number of satellites is concerned) SC configuration can be formulated as a search for the most sparse grid. The contemporary advanced methods of computational geometry serve as an algorithmic basis for the problem solution. Design of SC for continuous coverage of latitude belts with the use of kinematically regular systems is considered. A method of analyzing single-track systems for continuous coverage of arbitrary geographic regions is described, which makes a region at any time instant observable by at least one satellite of the system. As an example, SC on elliptical orbits are considered with periods of ～4, 12, and 24 hours.     

Effects of the geomagnetic storm on October 29–31, 2003, on mid-latitude short-wave radio paths (the data of Doppler measurements)

We present the results of spectral analysis of a signal of oblique sounding of the ionosphere. This signal was received at the Doppler phase-angle measuring facility of Kazan University during the geomagnetic storm on October 29–31, 2003. On various short-wave (SW) radio paths, intense variations of Doppler frequency shift were observed. These variations exceeded variations observed on days without geomagnetic disturbances by an order of magnitude (and by two orders of magnitude during some short periods). Relatively short periods (1–3.5 min) are predominant on these days in variations of the Doppler frequency shift. It should be noted that, while for weak geomagnetic disturbances the response in the form of distortions of SW signal parameters was observed, as a rule, only for the paths coming from high-latitude regions, in the given case the effect was observed for all radio paths.Translated from Kosmicheskie Issledovaniya, Vol. 42, No. 6, 2004, pp. 640–644.Original Russian Text Copyright © 2004 by Bochkarev, Petrova, Teplov.     

Disturbance of the upper atmosphere after crash launch of the <Emphasis Type="Italic">Proton</Emphasis> carrier rocket

The data of inclined sounding obtained on July 5, 1999 after explosion of the Proton carrier launcher in the upper atmosphere are discussed. A comparative analysis is performed of the detected disturbances with disturbances recorded during explosion of the Soyuz rocket in the middle atmosphere and with disturbances typical for the standard mode of the rocket flight.     

Instability of entropy waves in cosmic plasma

A dispersion equation is derived for small disturbances of the magnetohydrodynamic type in optically transparent plasma with cosmic abundance of elements. The electron heat conductivity along the magnetic field and proton heat conductivity across the field are taken into account. It is shown that entropy waves increase exponentially in wide ranges of temperatures and densities of the cosmic plasma. Manifestations of instability of the entropy waves in the cosmic plasma are discussed.     

Protons with energy of E P ≥ MeV under the earth’s radiation belts

Variations in fluxes of quasi-trapped energetic protons were studied on the basis of the data of the CORONAS-I satellite. These variations are characterized by an increase in the proton fluxes with E _P ≥ 1 MeV both in the vicinity of the geomagnetic equator and in the high-latitude region of the magnetosphere. The analysis of structural features of the proton distributions in the regions at L ～ 1–1.1; 3 < L < 4; and L > 4, was performed and made it possible to detect reliably the type of the proton flux increase in this region. The mechanisms of particle scattering leading to the precipitation of energetic protons under conditions of various types of geomagnetic disturbances are considered.     

Antenna radiation effects on the orbits of GPS and INTELSAT satellites

A large number of disturbances add to the main force exerted by Earth's gravitational field and affect the actual orbital trajectory of artificial satellites. They possess antennas with specific purposes, such as telecommunication systems operating at specific ranges of frequencies and radiated power. For instance, the antennas used in the GPS and INTELSAT satellites are quadrifilar helix and parabolic reflectors respectively. The radiation emitted by the antennas produces a radiation reaction force on the satellite making its orbital elements deviate from their expected values. Using a mathematical model for the radiation reaction force caused by the antenna, derived from the electromagnetic theory and the energy-momentum conservation law, the perturbation effects on the orbits of the GPS and INTELSAT satellites were studied. The numerical integrator used to solve the satellite equations of motion is based on the Runge–Kutta method of fourth and fifth orders. The theoretical model of antenna radiation reaction takes into account the satellite mass, antenna radiated power and maximum gain of the antenna.     

Effect of geomagnetic field disturbances on the adaptive stress reaction of cosmonauts

Investigations of the effect of geomagnetic activity factors on the cardiac rhythm regulation and arterial pressure of cosmonauts during the expeditions onboard the Soyuz spacecraft, and the MIR and ISS orbital space stations was carried out for various durations of flight in weightlessness and, under control. Groups of cosmonauts were inspected under flight conditions outside the geomagnetic disturbances and in ground preflight conditions, during disturbances without them. The presence of specific effect of geomagnetic disturbances on the system of vegetative regulation of blood circulation of cosmonauts during the flight was demonstrated for the first time. The response of cosmonauts’ cardiac rhythm on the magnetic storm is definitely revealed; however, it depends on the initial functional background and, in particular, on the state of mechanisms of vegetative regulation (the duration of flight and adaptation to it).     

Sporadic structures and small-scale irregularity in the nighttime polar ionosphere in the period of high solar activity according to the data of radio occultation measurements on satellite-to-satellite paths

Results of the analysis of 327 sessions of radio occultation on satellite-to-satellite paths are presented. The data are taken in the nighttime polar ionosphere in the regions with latitudes of 67°–88°, and in the period of high solar activity from October 26, 2003 to November 9, 2003. Typical ionospheric changes in the amplitude and phase of decimeter radio waves on paths GPS satellites-CHAMP satellite are presented. It is demonstrated that these data make it possible to determine characteristics of the sporadic E _s structures in the lower ionosphere at heights of 75–120 km. Histograms of distribution of the lower and upper boundaries, thickness, and intensity of the E _s structures are presented. Dispersion and spectra of amplitude fluctuations of decimeter radio waves caused by small-scale irregularity of the ionospheric plasma are analyzed. The relation of the polar E _s structures and intensity of small-scale plasma irregularity to various manifestations of solar activity is discussed. The efficiency of monitoring the ionospheric disturbances caused by shock waves of the solar wind by the radio occultation method on satellite-to-satellite paths is demonstrated.     

惯导系统可观测性及最佳可观测子空间的定量研究

应用结构分解理论及奇异值分解法对惯导系统（INS）误差模型的可观测性进行了全面分析。研究了一种基于可观测性定义及奇异值分解法结合的定量确定惯导系统可观测性及可观测度的方法，明确了惯导系统的三个最佳不可观测状态组合；应用线性控制系统的Kalman典范结构分解定理，确定了惯导系统的最佳观测子系统。此项研究成果，为进一步研究INS的快速精确对准及标定技术奠定了理论基础。     

Pathophysiology of motor functions in prolonged manned space flights.

The influence of weightlessness on different parts of the motor system have been studied in crew members of 140 and 175 days space flights. It has been shown that weightlessness affects all parts of the motor system including (i) the leg and trunk muscles, in which severe atonia, a decrease of strength and an increase of electromyographic cost of contraction have been observed, (ii) the proprioceptive elements and the spinal reflex mechanisms in which decreased thresholds accompanied by decreases of maximal amplitude of reflexes and disturbances in cross reflex mechanisms have been found. and (iii) the central mechanisms that control characteristics of postural and locomotor activities. The intensities and durations of disturbances of different parts of the motor system did not correlate to each other, but did correlate with prophylactic activity during space flight. The data suggest a different nature of disturbances caused by weightlessness in different parts of the motor system.     

Satellite Measurements of Plasma Disturbances and Electric Currents Induced in the Midlatitude Ionosphere Modified by High-Power HF Radio Waves

Cosmic Research - We have analyzed the experimental data obtained in 2016–2019 from the measurements of plasma disturbances and electric currents induced at ionospheric altitudes upon the...     

Theory of type III radio bursts in the interplanetary space. II. Study of instability of the electron beam-solar wind plasma system in a linear approximation

Frequency characteristics of disturbances of a one-dimensionally inhomogeneous electron beam-solar wind plasma system are studied in the geometrical optics approximation on the basis of the Maxwell equations closed by the material equation obtained earlier. The corresponding dispersion equation is derived and solved. It is found that resonance interaction of a wave with an electron beam can occur only at two spatial points. Perhaps, such a short-time (point-like) mechanism of the resonance clarifies one of the main problems of physics of electron beams generated by solar flares: their time of existence is much longer than the time following from the previous theoretical estimates of the beam energy loss rate due to radiation.     

A comparison of polarization jet characteristics at the greatly separated stations Yakutsk and Podkamennaya Tunguska

Characteristics of the polarization jet (PJ) are considered on the basis of measurements made in 1989–1992 at the ionospheric stations Yakutsk (L = 3.0, λ = 129.6°) and Podkamennaya Tunguska (L = 3.0, λ = 90.0°) separated in longitude. Using the data of these stations, the result obtained earlier (that the formation of PJ during disturbances in the near-midnight sector occurs at the expansion phase of a substorm) is confirmed. At isolated magnetic disturbances with AE > 500 nT in the 11:00–16:00 UT interval, the PJ band covers an MLT sector of 3 h between the Yakutsk and Podkamennaya Tunguska stations. The time of the PJ beginning at the Podkamennaya Tunguska station for the majority of events is 45–60 min behind the PJ beginning at the Yakutsk station. This corresponds to the westward motion of a PJ source with a velocity of ～3 MLT h per hour.