共查询到20条相似文献，搜索用时 15 毫秒
1.
We consider transfers with low thrust in an arbitrary field of forces. The modified method of transporting trajectory [1–4] is used for optimization of the transfers. The complexity of finding the transporting trajectory of a preset type can be the main obstacle to application of this method. This challenge is solved for the three-body problem in the Hill motion model. Numerical analysis of the method is performed using an example of the transfers to halo-orbits around the solar-terrestrial libration points. 相似文献
2.
A system of two-degree-of-freedom force gyroscopes (gyrodynes) is considered to be used for spacecraft attitude control. Possible values of its total angular momentum form some finite region P in the frame of reference rigidly connected with the spacecraft. Near the boundary of this region and singular surfaces located inside it the control of the angular momentum is complicated or impossible. The program angular momentum of the gyrodynes, realizing the law of variation of the spacecraft orientation, should lie inside P and outside some singular surfaces, and due to this fact the boundary and internal singular surfaces should be studied. This work is dedicated to the numerical construction of region P and its internal singular surfaces by the method of parameter continuation. Using the results by E.N. Tokar’ we formalize sufficient conditions which in some cases allow one to determine the type of the singular surface. As an example, a system of six gyrodynes is considered, for which the regions of variations of the intrinsic angular momentum and singular surfaces are constructed. The possibilities of the system are demonstrated for the case when one gyrodyne fails. 相似文献
3.
A review of the last results of UV observations in the interplanetary space of neutral hydrogen and neutral helium in resonance lines HI λ1215.7 Å and HeI λ584 Å is presented. The history of discovery of the interstellar wind effect is expounded in the review, and interaction of the solar wind with the interstellar medium is briefly described. Models of the inner-heliospheric distribution of emissivity in the lines HI λ1215.7 Å and HeI λ584 Å are discussed, and possibilities of getting the solar wind parameters from UV observations in the L α line are considered. Currently accepted parameters of the local interstellar medium are presented. The parameters obtained are compared with those derived from non-optical measurements. 相似文献
4.
We have made estimations of climatic changes in the 21st century at different scenarios of changes in the solar and volcanic activities using ensemble calculations with the help of a three-dimensional climatic model taking the carbon cycle into account. This model was developed in the Oboukhov Institute of Atmospheric Physics, Russian Academy of Sciences. An ensemble of scenarios is used for possible changes of the solar radiation flux in the 21st century, based on different methods of extrapolation of the data for the period 1610–2000. Along with this, different scenarios of volcanic activity in the 21st century are used. The results of thus made calculations are indicative of a rather small role played by the solar activity variations in changes of the global mean annual near-surface temperature in the 21st century as compared to the expected anthropogenic impact. Model changes of the global near-surface temperature in the 21st century (possible variations of the solar radiation and volcanic activity included) are characterized by a general increase determined in the main by anthropogenic SRES scenarios. 相似文献
5.
V. N. Platonov 《Cosmic Research》2009,47(3):235-242
The problem of maintaining spacecraft attitude during the loss of information from attitude sensors and inertial sensors is considered. The problem is solved on the basis of the force gyro stabilization principle with producing an angular momentum in the plane of orbit. The redundant mode of attitude maintenance is developed for spacecraft of the Yamal series. The results of testing the mode during the in-flight tests of the Yamal-200 spacecraft are presented. 相似文献
6.
7.
Basic conditions of observation of IMF tubular-loop structures are considered on the basis of experimental data of studying the fluxes of solar cosmic ray protons in the interplanetary medium. Lifetime of these structures, when their sources disappear on the Sun, is estimated. 相似文献
8.
We study the influence of additive and parametric slowly varying harmonic (at the Chandler frequency and doubled frequency) and stochastic Gaussian broadband perturbations on mathematical expectations, variances, and covariations of oscillations of the Earth’s pole. The influence of perturbations on both regular and irregular stochastic oscillations is considered in detail. Results of numerical experiments are presented. The developed models and software are included into information resources on the fundamental problem “Statistical dynamics of the Earth’s rotation” of Russian Academy of Sciences. 相似文献
9.
B. I. Rabinovich 《Cosmic Research》2009,47(4):287-298
A mathematical model of the non-steady-state magnetosphere of the ocean of Jupiter’s moon Europa is described. This magnetosphere is induced by the magnetic field of Jupiter, and its interaction with the Europa ocean is considered. Rotation of the ocean and its icy crust with respect to the hard core is described by a system of integro-differential equations with singular kernels, the values of the Reynolds number and magnetic Reynolds number being large for the system. The solution to these equations obtained by the methods of operational calculus is analyzed quantitatively and compared with a model experiment. 相似文献
10.
A. G. Tuchin 《Cosmic Research》2008,46(6):506-516
The problem of selecting quasi-synchronous orbits of a spacecraft around Phobos is considered. These quasi-synchronous orbits are far (with respect to the Hill’s sphere) quasi-satellite orbits with retrograde rotation in the restricted three body problem. The orbit should pass through a given point at a specified time instant. It should also possess a property of minimum distance from the Phobos surface at every passage above the region of planned landing. The equations of dynamics are represented in the form describing the orbit as a combination of motions in two drifting ellipses, inner and outer ellipses. The center of the outer ellipse is located on the inner ellipse. A formula is derived that relates averaged values of half-axes of the inner and outer ellipses. It is used for construction of the first approximation of numerically designed orbit, which makes it possible to simplify and speed up the computing process. The tables of initial conditions obtained as a result of calculations are presented. 相似文献
11.
E. L. Akim R. N. Arkhangelsky Yu. K. Zaiko S. M. Lavrenov A. L. Poroshin E. G. Ruzsky V. A. Stepaniants A. G. Tuchin D. A. Tuchin V. P. Fedotov V. S. Yaroshevsky 《Cosmic Research》2009,47(4):299-309
Basic concepts and algorithms laid as foundations of the scheme of landing on the Martian moon Phobos (developed for the Phobos-Grunt project) are presented. The conditions ensuring the landing are discussed. Algorithms of onboard navigation and control are described. The equations of spacecraft motion with respect to Phobos are considered, as well as their use for correction of the spacecraft motion. The algorithm of estimation of the spacecraft’s state vector using measurements with a laser altimeter and Doppler meter of velocity and distance is presented. A system for modeling the landing with a firmware complex including a prototype of the onboard computer is described. 相似文献
12.
On the basis of generalization of the results of extensive trajectory calculations for trial charged particles moving in the geomagnetic field the method of calculation of effective vertical cutoff rigidity, taking into account the values of K p -index and local time, is developed. The IGRF and Tsyganenko-89 models are used for the geomagnetic field. A comparison of the results of model simulations with the experimental data on penetration of charged particles into near-Earth space is made, and penetration functions for typical spacecraft orbits are calculated. 相似文献
13.
Diurnal variation of cosmic ray intensity for the period of 1989 to 2000 at Kiel, Haleakakla, Rome, Hermanus, Calgary, and Goose Bay neutron monitors has been studied. Frequency histograms are generated for each year by using the daily values of amplitudes and phases. In the present analysis we have derived the yearly mean amplitude and phase of the diurnal variation of cosmic ray intensity. It has been concluded from the analysis that the diurnal amplitude is mostly concentrated in between the amplitude values of 0.1% and 0.4%, whereas the phase of diurnal anisotropy is concentrated in the belt of 100 to 225 degrees. As such, the various characteristics of long-term diurnal variation of cosmic ray intensity for the maxima of solar activity cycle 22 to the next maxima of solar activity cycle 23 have been studied. The minimum amplitudes are apparent for the minimum solar activity periods starting from 1995 and up to 1997 at Kiel, Haleakakla, Rome, Hermanus, Calgary and Goose Bay stations. The diurnal amplitude has been found to have almost recovered to its values observed during 1989 to 1990. It is also seen that the diurnal amplitudes are much larger by a factor of two at high/middle latitude stations as compared to that for low latitude stations, where the amplitudes are even ～01% or less during 1996. The phase is significantly earlier during 1996 and 1997 with some significant change starting in 1995. As such, competitive is a continuous decreasing trend in the diurnal phase with smaller change at high/middle latitude and significantly much larger change at low latitudes. 相似文献
14.
G. G. Fedotov 《Cosmic Research》2007,45(2):156-166
An efficient scheme of the use of the Earth’s gravity in interplanetary flights is suggested, which opens up new opportunities for exploration of the solar system. The scheme of the gravitational maneuver allows one to considerably reduce the spacecraft mass consumption for a flight and the time of flight. An algorithm of the gravitational maneuver is suggested that takes into account the restriction on the altitude of a planet flyby. Estimates are made of transport capabilities for delivery of a spacecraft to the orbits of Jupiter, Saturn, and Uranus. The spacecraft is based on a middle-class carrier launcher of the Soyuz type and includes chemical and electric plasma jet engines of the SPD-140 type, which use solar energy. 相似文献
15.
V. I. Kurkin N. M. Polekh O. M. Pirog I. N. Poddel’skii A. E. Stepanov 《Cosmic Research》2008,46(4):339-346
Ionospheric disturbances in the equinox periods of 2005–2006 are considered on the basis of the ionosondes of vertical and oblique sounding located in the north-east region of Russia. It is found that the X-ray flares observed in the first half of September 2005 caused an additional increase in the ionization of the lower ionosphere in the daytime, this fact leading to a development of absorption and an increase in the lowest observable frequencies at the Magadan-Irkutsk and Noril’sk-Irkutsk radio paths. Wave-like changes in the maximum observable frequencies and critical frequencies with periods of about 2–2.5 h were detected during the magnetic disturbances. Oscillations of the planetary wave type with periods of 4–5 days were also revealed. 相似文献
16.
The problem of stabilization of a rotating spacecraft with a flexible spike antenna located along the axis of spacecraft rotation is considered. A magnetohydrodynamic element is used as a final-control element in the control loop of spacecraft attitude, and the solar direction sensor serves as a measuring device. At the first stage of investigation, the problem of stability is considered for stationary and non-stationary modes of rotation of the spacecraft with a flexible antenna and with a cavity partially filled with a low-viscosity liquid. 相似文献
17.
A. V. Mordvinov 《Cosmic Research》2008,46(4):314-319
A comparative analysis of variations of the mean solar magnetic field and the interplanetary magnetic field over all history of their measurements is performed. Asymmetry of the solar magnetic field and its manifestation in the heliosphere is investigated. Long-term variations of the solar magnetic field and the heliosphere, which manifest themselves in alternation of dominating magnetic polarities of different sign, are discovered. On the basis of the analysis of cumulative sums of the IMF components, long-term variations of the IMF geometry and of the solar wind spiral angle are found. The cumulative sum of the IMF B z component perpendicular to the ecliptic plane also shows long-term variations. Time intervals are revealed, in which negative values of the IMF B z component dominate, and an increased geomagnetic activity is observed. 相似文献
18.
I. V. Mingalev V. S. Mingalev O. V. Mingalev B. Kazeminejad H. Lammer H. K. Birnat H. I. M. Lihteneger K. Schvingenschu H. O. Ruker 《Cosmic Research》2009,47(2):114-125
The results of numerical simulation of the general circulation in the Titan’s atmosphere at heights from 0 to 250 km are presented, obtained using a new model based on numerical solution of complete equations of motion of viscous compressible gas at the temperature distribution given by an empirical model. The model uses no hydrostatic equation and, as compared with traditional models, has higher resolution in vertical and over horizon. The results presented differ from results of other models and agree with the vertical profile of the zonal component of wind velocity measured by the Huygens spacecraft. Interpretation of this profile is given, including its main peculiarity consisting in a nonmonotonic behavior at heights from 60 to 75 km. 相似文献
19.
The paper is devoted to an analysis of observational manifestations of the aerosol layer in the Earth’s stratosphere and to a method of determining their optical properties. It is based on polarization measurements of the twilight sky background in the zenith vicinity and in a broad spectral band with an effective wavelength of 5250 Å. An increased abundance of the stratosphere aerosol was found in December 2006 for the first time in several years of observation. The suggested method allows one to determine the ratio of radiation scattering coefficients by the stratosphere aerosol and by air molecules, as well as the degree of polarization of aerosol scattering in the stratosphere. The appearance of the stratosphere aerosol is associated with explosive eruption of Rabaul volcano having occurred in the beginning of October 2006. 相似文献
20.
O. V. Kholostova 《Cosmic Research》2008,46(3):264-272
In a central Newtonian gravitational field, the motion of a dynamically symmetrical satellite along an elliptical orbit of arbitrary eccentricity is considered. The particular motion of the satellite is known when its axis of symmetry is perpendicular to the orbit plane, and the satellite rotates about this axis with a constant angular velocity (cylindrical precession). A nonlinear analysis of stability of this motion has been performed under the assumption that the geometry of the satellite mass corresponds to a thin plate. At small values of orbit eccentricity e the analysis is analytical, while numerical analysis is used for arbitrary values of e. 相似文献