Design of the plasma spectrometer BMSW (Fast Monitor of the Solar Wind, possessing high temporal resolution) is described in the paper, as well as its characteristics and modes of operation. Some examples of measurements of various properties of the solar wind, made with this instrument installed onboard the high-apogee satellite Spektr-R, are presented.
Results of modeling the time behavior of the D (st) index at the main phase of 93 geomagnetic storms (-250 < D (st) a parts per thousand currency sign -50 nT) caused by different types of solar wind (SW) streams: magnetic clouds (MC, 10 storms), corotating interaction regions (CIR, 31 storms), the compression region before interplanetary coronal ejections (Sheath before ICME, 21 storms), and "pistons" (Ejecta, 31 storms) are presented. The "Catalog of Large-Scale Solar Wind Phenomena during 1976-2000" (ftp://ftp.iki.rssi.ru/pub/omni/) created on the basis of the OMNI database was the initial data for the analysis. The main phase of magnetic storms is approximated by a linear dependence on the main parameters of the solar wind: integral electric field sumEy, dynamic pressure P (d) , and fluctuation level sB in IMF. For all types of SW, the main phase of magnetic storms is better modeled by individual values of the approximation coefficients: the correlation coefficient is high and the standard deviation between the modeled and measured values of D (st) is low. The accuracy of the model in question is higher for storms from MC and is lower by a factor of 2 for the storms from other types of SW. The version of the model with the approximation coefficients averaged over SW type describes worse variations of the measured D (st) index: the correlation coefficient is the lowest for the storms caused by MC and the highest for the Sheath- and CIR-induced storms. The model accuracy is the highest for the storms caused by Ejecta and, for the storms caused by Sheath, is a factor of 1.42 lower. Addition of corrections for the prehistory of the development of the beginning of the main phase of the magnetic storm improves modeling parameters for all types of interplanetary sources of storms: the correlation coefficient varies within the range from r = 0.81 for the storms caused by Ejecta to r = 0.85 for the storms caused by Sheath. The highest accuracy is for the storms caused by MC. It is, by a factor of 1.5, lower for the Sheath-induced storms.
The paper describes the first results of all-sky polarization measurements of the twilight background started in central Russia in the very beginning of summer 2011. Time-frequency data of the sky intensity and polarization over a wide range of sky point zenith distances are used to separate single and multiple scattering and construct the altitude dependence of the scattering coefficient and polarization in the mesosphere (altitudes from 60 to 90 km) at different angles. The undisturbed structure of the mesosphere without noticeable aerosol stratification on observation days makes it possible to estimate the temperature of the atmosphere at these altitudes.
At present, the Institute of Nuclear Physics of Moscow State University, in cooperation with other organizations, is preparing space experiments onboard the Lomonosov satellite. The main goal of this mission is to study extreme astrophysical phenomena such as cosmic gamma-ray bursts and ultra-high-energy cosmic rays. These phenomena are associated with the processes occurring in the early universe in very distant astrophysical objects, therefore, they can provide information on the first stages of the evolution of the universe. This paper considers the main characteristics of the scientific equipment aboard the Lomonosov satellite.
Regularization problems in celestial mechanics and astrodynamics are considered. The fundamental regular quaternion models of celestial mechanics and astrodynamics are presented. It is shown that the efficiency of analytical investigation and numerical solution of boundary problems of optimal trajectory motion control of spacecraft may be increased using quaternion astrodynamics models. The regularization problem of celestial mechanics and astrodynamics that implies eliminating the feature, which arises in the equations of the two-body problem in case of impact of the second body with the central body, is considered in the first section of the paper. The quaternion method for regularizing the equations of the perturbed spatial two-body problem suggested by the author is presented; the method is compared with Kustaanheimo-Stiefel (KS) regularization. Demonstrative geometric and kinematic interpretations of regularizing transformations are provided. Regular quaternion equations for the two-body problem, which generalize the regular Kustaanheimo-Stiefel equations, as well as regular equations in quaternion osculating elements and quaternion regular equations for perturbed central motion of a material point, are considered. The papers on quaternion regularization in celestial mechanics and astrodynamics are briefly analyzed.
One of the goals of the Lomonosov satellite designed by scientists of Moscow State University is to study the prompt emission of cosmic gamma-ray bursts. This paper describes the gamma-ray burst monitor in the gamma-ray range (the BDRG instrument) and the wide-field optical cameras (the SHOK instrument) for detecting both the gamma-ray burst prompt emission and its precursors.
An active magnetic control synthesis for attitude guidance of “Chibis-M” microsatellite is considered. The only information required is the data from the sun sensor. Applicability of a control to achieve solar panels sun-pointing is studied. Equations of motions are analytically solved using averaging technique. The behavior of a system with respect to initial conditions and orbit parameters is studied.
The attitude dynamics of a fast rotating triaxial satellite under gravity-gradient is revisited. The essentially unique reduction of the Euler-Poinsot Hamiltonian, which can be performed in different sets of variables, provides a suitable set of canonical variables that expedites the perturbation approach. Two canonical transformations reduce the perturbed problem to its secular terms. The secular Hamiltonian and the transformation equations of the averaging are computed in closed form of the triaxiality coefficient, thus being valid for any triaxial body. The solution depends on Jacobi elliptic functions and integrals, and applies to non-resonant rotations under the assumption that the rotation rate is much higher than the orbital or precessional motion.
Results of the comparative analysis of the dynamics of SCR fluxes with energies of 1-100 MeV in the interplanetary environment according to the data of the ACE and Wind spacecraft and within the Earth's magnetosphere according to the data of the GOES-15 and Electro-L satellites in the region of geostationary orbits, and POES-19 and Meteor-M1 in the region of polar caps during two increases in SCR of January 19-31, 2012, are presented. It is shown that the decrease in the efficiency of SCR penetration into the Earth's magnetosphere in the region of the orbits under study on January 28, 2012, is related to the passage of the Earth's magnetosphere through the interplanetary environment structure with a quasi-radial interplanetary magnetic field and a small pressure of the solar wind.
We investigated periodic motions of the axis of symmetry of a model satellite of the Earth, which are similar to the motions of the longitudinal axes of the Mir orbital station in 1999–2001 and the Foton-M3 satellite in 2007. The motions of these spacecraft represented weakly disturbed regular Euler precession with the angular momentum vector of motion relative to the center of mass close to the orbital plane. The direction of this vector during the motion was not practically changed. The model satellite represents an axisymmetric gyrostat with gyrostatic moment directed along the axis of symmetry. The satellite moves in a circular orbit and undergoes the action of the gravitational torque. The motion of the axis of symmetry of this satellite relative to the absolute space is described by fourth-order differential equations with periodic coefficients. The periodic solutions to this system with special symmetry properties are constructed using analytical and numerical methods.
The laws of distribution of the space angle of attack are analyzed for a light descent capsule on the atmosphere's conventional boundary and on the segment of motion in dense layers of the atmosphere until the moment of reaching the maximum velocity head. It is assumed that upon detachment from a base spacecraft the angular velocity components of the descent capsule represent independent random quantities distributed according to the normal law. The shape of the descent capsule is close to a body of revolution whose instantaneous aerodynamic characteristic has a sufficiently simple form (one stable and one unstable positions of static equilibrium). It is demonstrated that there is a possibility to approximate the distribution densities by well-known laws and by approximate functions constructed on the basis of simplified models. Evolution of the distribution laws at increasing mass-inertia asymmetry of the descent capsule is studied.
This paper analyzes the accuracy of orbit determination calculated by observations of short arcs. In this case, we imposed the condition that the arc length and/or the distribution of arc observations should provide a confident classification of the orbit of a small celestial body allowing one to distinguish a potentially hazardous body, also including a threat of collision.
An algorithm for studying the families of symmetric periodic orbits using their generating solutions, whose structure was presented in the first part of this paper , is described. The algorithm is essentially based on symmetry of the generating solution and on its initial approximation. More than 20 new families of symmetric periodic solutions of the Hill's problem have been found and investigated with the use of this algorithm. The families including trajectories for orbital injection into the vicinity of collinear libration points L (1,2) are described.
The planar circular Hill's problem is considered, as well as its limiting integrable variant called the H,non problem, for which the original Hill's problem is a singular perturbation. Among solutions to the H,non problem there are a countable number of generating solutions-arcs that are uniquely determined by the condition of successive passage through the origin of coordinates-singular point of equations of motion of the Hill's problem. Using the generating solutions-arcs as "letters" of a certain "alphabet", one can compose, according to some rules, the "words": generating solutions of families of periodic orbits of the Hill's problem. The sequence of letters in a word determines the order of orbit transfer from one invariant manifold to another, while the set of all properly specified words determine the system's symbolic dynamics.
The nonlinear game problem of the three-axis reorientation of an asymmetric solid body with three flywheels (rotors) has been solved. Acceptable levels of uncontrollable noise depending on given constraints of control moments have been estimated.
The paper deals with a choice of the rational trajectory of motion of a landing module designed for the Moon landing, from the moment of its de-orbiting from the near-lunar orbit up to landing. An integrated conceptual basis is used to develop multistep terminal algorithms for guidance for the three segments of the descent.
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.
A novel method of virtual trajectories is proposed for the design of multiple gravity assist trajectories. The database of virtual trajectories can be tabulated for any planetary sequence and used in subsequent calculations. Requirements for the mission duration and the launch date are taken into account during the iterative procedure of database screening and refinement. The results of applying the virtual trajectories method to the design of a mission to Uranus are presented.