An analysis of low-frequency component in microacceleration measurements made onboard the <Emphasis Type="Italic">Foton M-2</Emphasis> satellite

The low-frequency component is investigated in the data of measurements performed onboard the Foton M-2 satellite with the three-component accelerometer TAS-3. Investigations consisted in comparison of this component with its calculated analog found from a reconstruction of the satellite’s attitude motion. The influence of the Earth’s magnetic field on the accelerometer readings is discovered by way of spectral analysis of the functions representing the results of determining the low-frequency microacceleration by two methods. After making correction for this influence, the results obtained by these two methods coincided within a root-mean-square error of less than 10^?6 m/s².     

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.     

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.     

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.     

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.     

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.     

Proton fluxes measured by low-orbit satellites

In this paper we consider the fluxes of protons in the energy range from 30 keV to 140 MeV recorded by instruments onboard the Russian satellites KORONAS-F and UNIVERSITETSKII and on the American satellites GOES-11 and NOAA-17. In order to estimate the reliability of the obtained data, the comparison of measurements of separate energy channels of these instruments between themselves is performed. Experimental fluxes of trapped protons are compared with the fluxes predicted by the AP8 model.     

Specific features of motion of geosynchronous satellites in the neighborhood of unstable stationary points

A study of peculiarities of the motion of equatorial circular geosynchronous satellites is performed in the neighborhoods of unstable stationary points with longitudes of 165° and 345°. The maps of initial conditions are constructed on the phase plane “longitude of subsatellite point-semi-major axis of orbit” corresponding to various types of regular motions and to quasi-random solutions. The dimensions of zones of the quasi-random solutions are within the limits from decimal fractions of a degree to a few degrees (in longitude) and from hundreds of meters up to several kilometers (along the semi-major axis).     

Application of information criteria to control the structurally uncertain navigation system of a reusable spacecraft

The problem of attitude control of a gyro-stabilized platform with the structurally uncertain drift model is solved. The solution is realized in two stages. At the first stage, on the basis of the obtained stochastic model of the reusable spacecraft navigation system, the drift model of gyro-stabilized platform is identified. At the second stage, the control of its spatial orientation is synthesized with regard to the found drift model. The results of numerical simulation are presented in conclusion.     

The use of solutions to problems of spacecraft trajectory optimization in impulse formulation when solving the problems of optimal control of trajectories of a spacecraft with limited thrust engine: I

In this first part of our paper, it is suggested to use solutions to boundary value problems in the optimization problems (in impulse formulation) for spacecraft trajectories in order to obtain the initial approximation, when boundary value problems of the maximum principle are solved numerically by the shooting method. The technique suggested is applied to the problems of optimal control over motion of the center of mass of a spacecraft controlled by the thrust vector of jet engine with limited thrust in an arbitrary gravitational field in a vacuum. The method is based on a modified (in comparison to the classic scheme) shooting method computation together with the method of continuation along a parameter (maximum reactive acceleration, initial thrust-to-weight ratio, or any other parameter equivalent to them). This technique allows one to obtain the initial approximation with a high precision, and it is applicable to a wide range of optimal control problems solved using the maximum principle, if the impulse formulation makes sense for these problems.     

One method of controlling the motion of an aerospace vehicle during its long flight in the atmosphere

Based on the methods of the theory of optimum control of dynamic systems, as well as the methods of inverse problems of dynamics and the energy principle, a combined method is developed for control of the motion of a flying vehicle of the Aerospace plane type during the long flight in the atmosphere. The disturbed motion is considered under the conditions when there are constraints on the values of control actions and on functions of phase coordinates.     

Manifestation of configurations of magnetic clouds of the solar wind in geomagnetic activity

On the basis of an analysis of the data of multi-satellite observations of magnetic clouds at the path Venus-Earth, the dependence of their geoeffectiveness on the orientation in the ecliptic plane and position relative to the Sun-Earth line is determined in the paper. The cloud parameters were determined on the basis of the model of a force-free cylindrical flux rope. The search for magnetic clouds in the flow of data from the monitoring space vehicle was performed using a special-purpose computer program.     

Optimization of passive orbit with the use of gravity maneuver

A high-precision method of calculating gravitational interactions is applied in order to determine optimal trajectories. A number of problems, necessary for determination of optimal parameters at a launch of a spacecraft and during its flyby near celestial bodies, are considered. The spacecraft trajectory was determined by numerical integration of the equations of passive motion of the spacecraft and of the equations of motion for planets, the Sun, and the Moon. The optimal trajectory of the spacecraft approaching the Sun is determined by fitting its initial conditions.     

The use of radio images for analyzing the results of narrow-band radio location of asteroids

We investigate a method of getting radio images of asteroids by single-position radar with narrowband sounding signal. A model is presented for calculation of power spectra of echo signals of a rotating rough ellipsoid. This model is a useful tool for analyzing the results of radio-location experiments. The accuracy of determination of the shape of an asteroid and its roughness is estimated based on the analysis of two-dimensional radio images.     

The family of potentials admitting integration of the perturbed two-body problem in regular coordinates

An infinite system of potentials is presented that admits separation of regular variables in the perturbed two-body problem. The regular coordinates are constructed using a specially selected L-matrix. An explicit solution to the problem in the elliptical case is constructed. In the general case the solution is reduced to inversion of hyper-elliptic integrals. The cases of motion with and without constraints are considered. The results of numerical experiments are presented.     

Multiple continuous coverage of the earth based on multi-satellite systems with linear structure

A new and wider definition is given to multi-satellite systems with linear structure (SLS), and efficiency of their application to multiple continuous coverage of the Earth is substantiated. Owing to this widening, SLS have incorporated already well-recognized “polar systems” by L. Rider and W.S. Adams, “kinematically regular systems” by G.V. Mozhaev, and “delta-systems” by J.G. Walker, as well as “near-polar systems” by Yu.P. Ulybyshev, and some other satellite constellations unknown before. A universal method of SLS optimization is presented, valid for any values of coverage multiplicity and the number of satellites in a system. The method uses the criterion of minimum radius of a circle seen from a satellite on the surface of the globe. Among the best SLS found in this way there are both systems representing the well-known classes mentioned above and new orbit constellations of satellites.