Band 31, Heft 1

Machine learning is an efficient method for analysing and interpreting the increasing amount of astronomical data that are available. In this study, we show a pedagogical approach that should benefit anyone willing to experiment with deep learning techniques in the context of stellar parameter determination. Using the convolutional neural network architecture, we give a step-by-step overview of how to select the optimal parameters for deriving the most accurate values for the stellar parameters of stars: T eff {T}_{{\rm{eff}}} , log g \log g , [M/H], and v e sin i {v}_{e}\sin i . Synthetic spectra with random noise were used to constrain this method and to mimic the observations. We found that each stellar parameter requires a different combination of network hyperparameters and the maximum accuracy reached depends on this combination as well as the signal-to-noise ratio of the observations, and the architecture of the network. We also show that this technique can be applied to other spectral-types in different wavelength ranges after the technique has been optimized.

The equilibrium cold dark matter halos show the almost universal inner r − 1 {r}^{-1} cusps, whose physical origin is still not completely clear. This work tries to further clarify this problem by the Landau–Ginzburg (LG) theory, which is often used to study the long-range correlation of the fluctuations in the critical phenomenon, and we will first introduce it in detail. The order parameter in this work is the density fluctuation, and the external perturbation is denoted by its gravitational effects on the particles. Then we discuss the availability of the aforementioned method for the cold dark matter halos and show that the universal r − 1 {r}^{-1} cusp may even form at the early age of the halo formation and can be expected for the dark matter halos with all the scales, which is also consistent with recent works. This article suggests that the r − 1 {r}^{-1} cusp may originate from the long-range correlations of the gravitating system. This correlation also exists in the short-range system near the critical point, and the difference is that the correlation length in the gravitating system is much longer than that of the short-range system.

In this work, cosmological solutions based on the time-dependent cosmological ( Λ \Lambda ) and Newtonian ( G G ) running “constants” in the Bianchi type- I spacetime are investigated vis-à-vis known cosmological data. The observationally known values of Ω m , Ω r {\Omega }_{{\rm{m}}},{\Omega }_{{\rm{r}}} and Ω Λ {\Omega }_{\Lambda } have been used to solve the Einstein field equations for the model and the resulting behaviours of the physical and dynamical quantities, with particular emphasis on late-time cosmology, are discussed. Our analysis indicates that certain choices of the defining model parameters give results consistent with the observed behaviour of the universe, such as accelerated expansion and an early anisotropy that vanishes at late times.

This article is devoted to the discovery of comets at the Vilnius Observatory together with the orbital analysis of dynamically interesting comets, namely 322P. We studied the orbital evolution of comet 322P with and without non-gravitational effects. It turned out that many of the comet’s orbital clones go into and out of retrograde orbits, sometimes repeatedly. The reason for such dramatic changes in the inclination of the orbit is the origin of comet 322P close to mean motion resonance 3:1 with Jupiter, ejecting them from there and, consequently, bringing the clones closer to the terrestrial group of planets. In this way, the clones of comet 322P enter retrograde orbits and reside there several ky to several My.

We have proposed a generalized King’s model for the observed density of stars in globular clusters (GC). Using two methods of minimizing the functional, composed in the form of the square of the difference between the theoretical and observed density values, we obtained the behavior of the degree of concentration for 26 GC. We have taken the observational data for these clusters from the work of Miocchi et al. (2013), which is a combination of ground-based and space-based observations. The minimized functional depends on three free parameters and one of them clearly characterizes the concentration of stars towards the center of the cluster. The two research methods used here give almost the same results with reasonably good accuracy. In contrast to the work of Nuritdinov et al. (2021), the χ 2 method is used to determine the degree of concentration. In addition, we analyzed data from de Boer et al. (2019). However, these data do not contain information for the central regions of the clusters. The lack of these data does not allow finding the degree of concentration with the required accuracy.

This paper discusses the disordering of the principle of cosmology on a small scale, i.e. the possibility of interpreting the observational data of type Ia Supernovae (SNe Ia) through the inhomogeneity and anisotropy of the Universe. The expansion of the Universe may appear to be accelerating due to “dark flows”, changes in the wavelength of light passing through “voids” and clusters, or anisotropy. Different sets of cosmological data are also considered without the need for a dark energy component.

In order to process and visualise the monochromatic images of regions of the Sun obtained with the CCD multichannel spectroheliograph, the freely distributed programs ImageJ and ParaView were chosen and then fine-tuned. This reduced the time required to develop the data processing and visualization software for this instrument and also made it easier to make further corrections and additions to it.

The paper presents study the 11-year dynamics of solar activity on the basis of new observational material on coronal holes (CHs) and sunspots in the period from May 13, 2010 to May 13, 2021. We used the Heliophysics Event Knowledgebase (HEK) to obtain information on CHs areas. For 11 years of observations, we processed about 18000 CHs. Slightly more than 8000 are polar, the rest are nonpolar CHs. The statistical volume of the presented material is quite extensive and gives grounds for the study of the dynamics of different types of CHs during the cycle. Our research has shown: in the 24th solar activity cycle, the South led for polar CHs and the North led for nonpolar ones. We established a relationship between the number and area of CHs and the phase of the solar cycle. The number and daily total area of polar CHs increases at the minima of solar activity and decreases at the maximum of the cycle. This is consistent with the general concept of polar CHs as the main source of the solar dipole magnetic field. An asymmetry in both the number and areas of polar coronal holes in the northern and southern hemispheres is observed. It is shown that the areas of nonpolar CHs change quasi-synchronously with sunspot activity, which suggests a physical connection between these two phenomena.

The observed primordial energy release of solar flare in the corona is explained by the mechanism of S. I. Syrovatskii, according to which the flare energy is accumulated in the current sheet. The flare release of the current sheet energy causes the observed manifestations of the flare, which are explained by the electrodynamical model of a solar flare proposed by I. M. Podgorny. According to this model, hard X-ray beam radiation on the solar surface is explained by the acceleration of electrons in field aligned currents caused by the Hall electric field in the current sheet. The study of the flare mechanism is impossible without performing magnetohydrodynamic (MHD) simulations above a real active region (AR), in which the calculation begins several days before the appearance of flares. When setting the problem, no assumptions were made about the flare mechanism. An absolutely implicit finite-difference scheme, conservative with respect to the magnetic flux, has been developed, which is implemented in the PERESVET code. MHD simulation in the real scale of time can only be carried out, thanks to parallel computations using compute unified device architecture (CUDA) technology. Methods have been developed that made it possible to stabilize the numerical instability arising near the boundary of the region. Calculation above AR 10365 for low viscosities ( Rm = 1 0 9 {\rm{Rm}}=1{0}^{9} , Re = 1 0 7 {\rm{Re}}=1{0}^{7} , ν Art Phoosphere = ν Magn Art Phoosphere = 1 0 − 4 {\nu }_{\text{Art Phoosphere}}={\nu }_{\text{Magn Art Phoosphere}}=1{0}^{-4} ) showed the appearance of a singular X-type line, in the vicinity of which a current sheet with accumulated magnetic energy for a flare can form. Also, by means of MHD simulation the appearance of singular lines above a real AR is shown, in which the magnetic field is a superposition of an X-type field and a diverging magnetic field. In such a superposition of configurations, even if the diverging field predominates, the formation of a current sheet is possible, which can explain the appearance of a flare of not very high power. The coincidence of the position of the source of the flare thermal X-ray radiation with the places of appearance of the current sheets confirms the mechanism of the solar flare, based on the accumulation of energy in the magnetic field of the current sheet.

As shown in the first results of MHD simulations in the real scale of time, above the active region (AR) 10365, during the first flare M 1.9 (05/26/2003 05:34) at a height of 16–18 mm (lower corona), a singular line of magnetic field appears. The local maximum of the current density is situated on this singular line. The magnetic field in the vicinity of this singular line is the superposition of an X-type magnetic configuration and a divergent magnetic field. The accumulation of magnetic energy for solar flare with current sheet creation takes place near this singular line due to magnetic field deformation by disturbances in the X-type configuration in spite of the presence of overlaid diverging magnetic configuration. The magnetic configuration is so complicated that the singular line can be found only by using specially developed graphical system of search. The position of singular line coincides with position of source of flare radio emission at the frequency 17 GHz above AR 10365 measured by Nobeyama Radioheliograph (NoRH). Also, MHD simulation shows appearance of the singular line, in the vicinity of which X-type configuration dominates. However, apparently due to small disturbance, propagating from the photosphere, sufficient magnetic energy was not accumulated in this configuration, so the NoRH does not show the flare source of emission at the frequency 17 GHz in the place, where this singular line is situated.

Eclipses of UX Ori stars by compact gas–dust clouds and large-scale circumstellar disk perturbations are modeled. A flared disk and a disk with a puffing-up in the dust sublimation zone are considered. The disk puffing-up explains several observed features of eclipses. The linear polarization degree can remain unchanged during the eclipse. There might be no star reddening in the blue and ultraviolet spectral regions. Strong changes (up to 90 ° 90\text{°} ) in the positional angle of the linear polarization may happen when passing from one spectral band to another. An eclipse by a large-scale disk perturbation can be noticeably deeper than an eclipse by a compact gas–dust cloud. The polarization degree in such an eclipse can also be significantly higher. In addition, an eclipse by a large-scale perturbation of a star with a puffed-up disk explains the significant scatter of eclipse parameters at the same fading level. A significant change in the positional angle of the linear polarization may occur during a large-scale disk perturbation eclipse minimum and after it. We attempted parametric identification of long-lasted deep minima of UX Ori and WW Vul. The considered simple model can only partially explain the observed phenomena and need further development.

Multiphase astrochemical modeling presents a numerical challenge especially for the simulation of objects with the wide range of physical parameters such as protoplanetary disks. We demonstrate an implementation of the analytical Jacobian for the numerical integration of the system of differential rate equations that govern chemical evolution in star-forming regions. The analytical Jacobian allowed us to greatly improve the stability of the code in protoplanetary disk conditions. We utilize the MONACO code to study the evolution of abundances of chemical species in protoplanetary disks. The chemical model includes 670 species and 6,015 reactions in the gas phase and on interstellar grains. The specific feature of the utilized chemical model is the inclusion of low-temperature chemical processes leading to the formation of complex organic molecules (COMs), included previously in the models of chemistry of COMs in prestellar clouds. To test the impact of analytical Jacobian on the stability of numerical simulations of chemical evolution in protoplanetary disks, we calculated the chemical composition of the disk using a two-phase model and four variants of the chemical reaction network, three values of the surface diffusion rates, and two types of the initial chemical composition. We also show a preliminary implementation of the analytical Jacobian to a three-phase model.

In this work, we consider small-scale sectorial perturbation modes in a disk-like model of a radially nonstationary spiral galaxy in order to study the gravitational instabilities of these modes. Calculations of horizontal sectorial small-scale perturbation modes, such as ( m ; N ) = ( 10 ; 10 ) \left(m;\hspace{0.33em}N)=\left(10;\hspace{0.33em}10) , (11; 11), (12; 12), (13; 13), (14; 14), and (15; 15), against the background of a nonlinearly nonequilibrium anisotropic model of the self-gravitating disk have been carried out. For each of these perturbation modes, critical diagrams are plotted between the virial parameter and the degree of rotation. The growth rates of instability are calculated and compared for different values of the rotation parameter. The results of calculations and comparisons of instability regions show that with an increase in the degree of small scale, the instability region narrows as the wave numbers increase.

Extraplanar structures of ionized gas are detected in numerous edge-on galaxies. Whether HII regions or supernovae (SNe) responsible for its ionization is still debated. Here, we consider the H α {\rm{H}}\alpha emissivity from shells of superbubbles driven by SNe explosions in a stellar cluster located either in the midplane or above the midplane of the disc. We found that these shells form filamentary structures emitting brightly in H α {\rm{H}}\alpha line at height of ∼ 0.6 \sim 0.6 – 1.6 kpc 1.6\hspace{0.33em}{\rm{kpc}} above the disc depending on cluster location and gas metallicity. The H α {\rm{H}}\alpha surface brightness ranges within ∼ 1 0 − 17 \sim 1{0}^{-17} – 1 0 − 16 erg s − 1 cm − 2 arcsec − 2 1{0}^{-16}\hspace{0.33em}{\rm{erg}}\hspace{0.33em}{{\rm{s}}}^{-1}\hspace{0.33em}{{\rm{cm}}}^{-2}\hspace{0.33em}{{\rm{arcsec}}}^{-2} are close to the values observed in edge-on galaxies. We conclude that the H α {\rm{H}}\alpha emission of extraplanar structures can be explained by recombination in collisionally ionized gas of unstable shells driven by multiple SNe.

One of the important sources for independent determination of stellar masses is eclipsing binaries with components on the main sequence, and with observable spectral lines of both components. The parameters of such stars are used to construct the mass–luminosity relation for stars of high and intermediate masses. Among them, the type of long-period eclipsing binaries stands out, the parameters of which are currently not fully determined, which is associated with the difficulties caused by the need for long-term observations. In this article, we will review the currently available observational data for such objects and discuss the prospects for their use to determine stellar masses.

We compare the results on the chemical composition of four globular clusters (GCs) in M31 (Bol 6, Bol 20, Bol 45, and Bol 50) (Maricheva M. 2021. Study of integrated spectra of four globular clusters in M 31. Astrophys. Bull. 76:389–404. doi: https://doi.org/10.1134/S199034132104009X) to the available literature data on integrated-light spectroscopy of GCs with similar ages and chemical abundances in our Galaxy and M31 and on the chemical abundances of stars in two galaxies. The clusters and their literature analogues are of moderate metallicity − 1.1 < [ Fe/H ] < − 0.75 -1.1\lt \left[\hspace{0.1em}\text{Fe/H}\hspace{0.1em}]\lt -0.75 dex and old (10 Gyr). Mg, Ca, and C abundances of four GCs are higher than literature estimates for the GCs in M31 with [ Fe/H ] ∼ − 1 \left[\hspace{0.1em}\text{Fe/H}\hspace{0.1em}] \sim -1 dex obtained using high-resolution integrated-light spectroscopy methods. Using literature data, we did not find complete analogues for the studied clusters in our Galaxy and M31 in terms of age, helium mass fraction ( Y Y ), and chemical composition. The alpha-element abundances in four clusters are about 0.2 dex higher than the average for stars in the Galactic field at [ Fe/H ] ∼ − 1 \left[\hspace{0.1em}\text{Fe/H}\hspace{0.1em}] \sim -1 dex. We suggest that these and M. Maricheva’s (Maricheva M. 2021) findings about lower metallicities of the studied objects than the average metallicity of red giants in the M31 halo and about the abundances of alpha-process elements in them corresponding to the average value for stars in the M31 inner halo likely indicate that the star formation process in the vicinity of M31 at the time of our sample cluster formation was complex with the inflow of fresh gas from the intergalactic medium and violent star forming events associated with SNe II bursts.

The dynamics of magnetic flux tubes (MFTs) in the accretion disk of typical Herbig Ae/Be star (HAeBeS) with fossil large-scale magnetic field is modeled taking into account the buoyant and drag forces, radiative heat exchange with the surrounding gas, and the magnetic field of the disk. The structure of the disk is simulated using our magnetohydrodynamic model, taking into account the heating of the surface layers of the disk with the stellar radiation. The simulations show that MFTs periodically rise from the innermost region of the disk with speeds up to 10–12 km  s − 1 {{\rm{s}}}^{-1} . MFTs experience decaying magnetic oscillations under the action of the external magnetic field near the disk’s surface. The oscillation period increases with distance from the star and initial plasma beta of the MFT, ranging from several hours at r = 0.012 au r=0.012\hspace{0.33em}{\rm{au}} up to several months at r = 1 au r=1\hspace{0.33em}{\rm{au}} . The oscillations are characterized by pulsations of the MFT’s characteristics including its temperature. We argue that the oscillations can produce observed IR-variability of HAeBeSs, which would be more intense than in the case of T Tauri stars, since the disks of HAeBeSs are hotter, denser, and have stronger magnetic field.

The results of observations of selected stars orbiting the central body of our Galaxy, which, according to the latest data, has a mass of about 4 million of solar mass, are considered. Using the methods of observation and processing of binary stars used at the Pulkovo Observatory and the published exact relative positions of the star-central body obtained with the Keck and VLT telescopes, we checked the possibility of determining the preliminary orbits of the above objects in some cases from observations covering sufficient short arc in relation to the turnover period. Examples are the stars S02 and S102 with published positions and the graphical data for S27 and S4711. We attempted to calculate the assumed relativistic effects in accordance with the orbital elements obtained by Pulkovo methods. In this case, the estimates of the O–C errors for these orbits turned out to be comparable with the O–C errors for the orbits published by the Keck and VLT observers, in some cases about several milliarcseconds. The theoretical relativistic parameters also turned out to be of the same order of value with the results of these authors.

We investigate spectral and photometric properties of extragalactic star-forming complexes (SFCs). The SFCs were selected in 17 nearby galaxies of a spiral or irregular type, having inclinations less than 45° and distances less than 15 Mpc. To identify SFCs, we developed a method based on matching sources of emission at 160 μ m 160\hspace{0.33em}{\rm{\mu }}{\rm{m}} (cold dust) and 8 μ m 8\hspace{0.33em}{\rm{\mu }}{\rm{m}} (polycyclic aromatic hydrocarbons). Using photometry in different spectral bands, correlations between SFC properties for spiral and irregular galaxies were considered. Spectral and kinematic analysis was carried out for several SFCs, and a method to detect gas motion patterns in these SFCs was suggested.

I present a detection of four new triple-mode high-amplitude Delta Scuti variables, pulsating in the fundamental, first, and second overtone modes. This is a new addition to the ten known cases in the Galaxy. I used the data of ASAS-SN and analyzed them using the WinEfk code by V. P. Goranskij. Light elements and parameters of the light curves were obtained.

Supernovae explosions (SNe) in a stratified interstellar disc can create large scale structures and outflows perpendicular to the disc. Their morphology and emission characteristics depend on interrelations between the number of exploded SNe, the ISM vertical scale height, the height above the ISM disc at which SNe are located, and the mid-plane density of ambient gas. When observed such out-of-plane gas structures do characterize properties of the driving SNe and reveal the presence of underlying stellar clusters. Even though the morphology and emission properties of such structures are sensitive to characteristics of ambient gas they might be used for rough estimates of the clusters’ mass.

The analysis of radio emission of three new pulsars discovered at the Pushchino Radio Astronomy Observatory is presented. The detailed observations were carried out at a frequency of 111 MHz using the large phase array and the standard digital receiver with a total bandwidth of 2.245 MHz and a time resolution of 2.46 or 5.12 ms. All pulsars exhibit features of their radiation, the subpulse drift is observed in J0220+3622, the flare activity is exhibited in J0303+2248, and the nulling phenomenon has been detected in J0810+3725.

We numerically model the collapse of magnetic rotating protostellar clouds with mass of 10 M ⊙ {M}_{\odot } . The simulations are carried out with the help of 2D MHD code Enlil. The structure of the cloud at the isothermal stage of the collapse is investigated for the cases of weak, moderate, and strong initial magnetic field. Simulations reveal the universal hierarchical structure of collapsing protostellar clouds, consisting of the flattened envelope with the qausi-magnetostatc disk inside and the first core in its center. The size of the primary disk increases with the initial magnetic energy of the cloud. The magnetic braking efficiently transports the angular momentum from the primary disk into the envelope in the case, when the initial magnetic energy of the cloud is more than 20% of its gravitational energy. The intensity of the outflows launched from the region near the boundary of the first core increases with initial magnetic energy. The “dead” zone with small ionization fraction, x < 1 0 − 11 x\lt 1{0}^{-11} , forms inside the first hydrostatic core and at the base of the outflow. Ohmic dissipation and ambipolar diffusion determine conditions for further formation of the protostellar disk in this region.

A characteristic property of pulsars is pulsed periodic radio emission, which has a high stability of periods. Despite the high stability of the emission periods of pulsars, monitoring the time of arrival of pulses (timing) shows the presence of different types of irregularities: variations of residual deviations, changes in the shape of the pulse, switching on and off of radio emission, and rotation discontinuities. Numerous observations of the radio emission of pulsars indicate that they are caused mainly by processes occurring in the pulsar’s magnetosphere. The special interest causes the observations of a pulsar in the Crab Nebula, performed, in particular, at Jodrell Bank and Pushchino Radio Astronomy Observatory of Lebedev Physical Institute. The connection between the scattering of radio pulses and the measure of the pulsar dispersion, which was established earlier in Pushchino together with Jodrell Bank, has been confirmed. The observed variations in the scattering of radio pulses and their partial correlation with the dispersion measure are explained by the eclipse of the pulsar by plasma clouds with electron density fluctuations significantly exceeding the corresponding fluctuations in the interstellar medium. The question of a possible connection between glitches, dispersion measure variations, radio pulses scattering, and gamma-ray flares is discussed.

We have the estimated masses of components of visual binaries from their spectral classification. We have selected pairs in which the less massive component looks more evolved. Spectral observations of some of these pairs were made, and at least one pair, HD 156331, was confirmed to have components of different ages. Since mass exchange is excluded in wide binaries, it means that HD 156331 can be formed by capture.

The European Space Agency’s ANALOG-1 experiment is the culmination of 12 distinct METERON experiments carried out since 2011. These all address aspects of teleoperating a robotic asset from an orbital platform, i.e., technical implementation, user interfaces, autonomy and operations. The ANALOG-1 technology demonstration and operations concept experiment is based upon the surface mission scenario segment of the notional EL3 sample return mission. This segment focuses on the control of a lunar surface robotic asset from the Earth and from the Lunar Gateway. The experiment is taking place in two parts, with the first successfully completed from the ISS in November 2019. It assessed the effectiveness of a state-of-the-art robotic control interface to control a complex mobile robot from orbit, as well as evaluating the scientific interactions, during robotic-assisted geology exploration, between crew in orbit and scientists on the ground. Luca Parmitano operated the robot while he was on the ISS. For this experiment, a complex control station had been installed on the ISS. The experiment demonstrated the advantage of having an immersive control station and high level of robotic dexterity, with Luca finishing all his assigned and secondary geology targets ahead of time.

The revived interest of many countries and the growing number of ongoing and scheduled missions to the Moon increases the significance of supporting navigation system development. A number of publications are based on multi-Global Navigation Satellite System (GNSS) signal reception from the opposite side of the Earth using high-gain antennas and lunar augmentation constellations. While the accuracy of such systems could be sufficient, the positioning, navigation, and timing (PNT) service dependency on circumterestrial navigation sources prevents the use of advanced navigation technologies honed in circumlunar space for further Mars and other celestial body missions, which is one of the major goals of lunar exploration. Moreover, orbit determination and time synchronization (ODTS) method descriptions and estimations are usually skipped in the studies of lunar augmentations. An alternative concept of the Lunar Navigation Satellite System (LNSS) is proposed based on Earth-dependency reduction principal and on-board ODTS. The advantage of the proposed approach is that LNSS-like systems could be adapted for other celestial bodies taking into account aspects such as their shape, dynamics, perturbations, as well as exploration priority regions. The baseline LNSS constellation of three circular orbits with three satellites each has been chosen as the result of multicriterion analysis of orbital stability and geometry. Station keeping requires less than 15 m/s for 10 years without significant changes in navigation performance in the prioritized Polar Regions. The full cycle of LNSS operation from ODTS and signal generation to its reception, processing, and obtaining navigation solutions has been simulated to obtain positioning accuracy for different types of users. Positioning accuracy of space users in approach/departure phases, in near-lunar orbits, as well as static users on a lunar surface is confirmed on a level of a few tens of meters. The same accuracy is achievable by dynamic users on a lunar surface during route stops or also in motion in case of LNSS constellation expansion or deployment of ground-based augmentation beacons in on-site exploration zones.

Accurate and rapid prediction of reentry trajectory and landing point is the basis to ensure the reentry vehicle recovery and rescue, but it has high requirements for the continuity and stability of real-time monitoring and positioning data and the fidelity of the reentry prediction model. In order to solve the above contradiction, based on the theory of relative entropy and closeness in fuzzy learning, research on real-time evaluation of reentry reachability is presented in this article. With the Monte Carlo analysis data during the design and evaluation of the reentry vehicle control system, the reentry trajectory feature information base is designed. With the matching identification decision strategy between the identified trajectory and trajectory feature base, the reachability of the reentry vehicle, reachable trajectory, and landing point can be predicted. The simulation results show that by reasonably selecting the time window and using the evaluation method designed in this article, making statistics of the trajectory sequence number and frequency identified based on relative entropy and closeness method, the reachability evaluation results can be given stably, which is suitable for the real-time task evaluation of TT&C system.

The basic concepts, technical implementation, and application scenarios of computer simulation, virtualization, and cloud computing are intertwined and each has its characteristics. In this article, the basic concepts, necessity, feasibility, and core difficulties of computer simulation, virtualization, and cloud computing are analyzed. Also, the application prospects of the three technologies are expounded, the technical differences are analyzed, and the application of some key technologies in the data center is introduced. The generalization of computer simulation technology, the specialization of virtualization technology, and the systematization of cloud computing technology are expounded, which represent the mainstream direction of technology development in the field of information and communication at this stage. The application examples of the three in the aerospace telemetry, tracking, and command field are taken to illustrate that information technology essentially serves the business logic of their respective fields, which also well reflects the basic characteristics of demand-oriented, safety-oriented, innovation, and long-term development. It has guiding significance for the technical orientation, technical selection, and engineering implementation of information system architecture design.

High-accuracy orbit prediction plays a crucial role in several aerospace applications, such as satellite navigation, orbital maneuver, space situational awareness, etc . The conventional methods of orbit prediction are usually based on dynamic models with clear mathematical expressions. However, coefficients of perturbation forces and relevant features of satellites are approximate values, which induces errors during the process of orbit prediction. In this study, a new orbit prediction model based on principal component analysis (PCA) and extreme gradient boosting (XGBoost) model is proposed to improve the accuracy of orbit prediction by learning from the historical data in a simulated environment. First, a series of experiments are conducted to determine the approximate numbers of features, which are used in the following machine learning (ML) process. Then, PCA and XGBoost models are used to find incremental corrections to orbit prediction with dynamic models. The results reveal that the designed framework based on PCA and XGBoost models can effectively improve the orbit prediction accuracy in most cases. More importantly, the proposed model has excellent generalization capability for different satellites, which means that a model learned from one satellite can be used on another new satellite without learning from the historical data of the target satellite. Overall, it has been proved that the proposed ML model can be a supplement to dynamic models for improving the orbit prediction accuracy.

To ensure the safety of the power supply for an in-orbit satellite, it is of great significance to accurately predict the end-of-discharge time of lithium-ion batteries for making a reasonable flight plan. Constrained by development time and experimental environment, it is usually difficult to obtain many full discharge voltage curves of satellite batteries from ground experiments as historical data. Because of insufficient data, the prediction accuracy of the single time series prediction method is low. To solve this problem, this paper takes the voltage of the discharge process as the time series and uses the evidential reasoning rule algorithm to fuse the outputs of three typical prediction models to improve the prediction accuracy. The result can be expressed as a form of belief degree distribution with the ability to express uncertainty. Using the NASA battery dataset, the effectiveness of the proposed method is verified, and the end-of-discharge of an in-orbit satellite battery is predicted by the telemetry data.

High-altitude satellites are visible to more ground station antennas for longer periods of time, its requests often specify an antenna set and optional service windows, consequently leaving huge scheduling search space. The exploitation of reinforcement learning techniques provides a novel approach to the problem of high-altitude orbit satellite range scheduling. Upper sliding bound of request pass was calculated, combining customized scheduling strategy with overall antenna effectiveness, a frame of satellite range scheduling for urgent request using reinforcement learning was proposed. Simulations based on practical circumstances demonstrate the validity of the proposed method.

The continuous full operation of the constellation of BeiDou navigation satellite system (BDS) provides favorable conditions for the performance evaluation of the BDS inter-satellite links (ISLs). The primary features of ISLs that affect the precision of precise orbit determination (POD) and time synchronization include (i) the spatiotemporal coverage or continuity of observations; (ii) the observational accuracy, such as observation noise and bias; and (iii) the observational geometry represented by dilution of precision. After comparing some technical features and the current status of the Global Navigation Satellite Systems ISLs, the measurement principle of dual one-way ISLs for BDS and its data processing methods are presented. The performance evaluation involving the above three aspects was carried out using 14 days of ISL data, with some typical indicators derived. POD based on data fusion of ISLs and ground-based L-band monitoring stations was conducted, with root-mean-square of posterior residuals of about 5.0 cm, and MEO radial accuracy better than 1.0 cm. The results show that ISLs offer crucial support for BDS to provide global high-precision services under regional monitoring network conditions.

Proportional navigation guidance law (PNG) is widely used for passive homing missiles. But PNG often suffers from inaccurate tracking of target or even failure when the target is maneuvering quickly or releasing artificial decoys. In order to solve this problem, the angular acceleration compensation guidance law (AACG) is constructed by using line of sight (LOS) angular velocity and LOS angular acceleration. The stability analysis with Lyapunov stability theory shows that AACG system is asymptotically stable on a large scale under certain stability constraint conditions. AACG command is designed to be perpendicular to the LOS and optimized by gravity compensation. AACG is neither dependent on target acceleration nor the distance between the missile and the target. The numerical simulation results indicate that AACG has good guidance performance on air-to-air missiles when the target maneuvers violently or releases artificial decoys in the endgame term.

With the development of human space technology, more and more astronauts fly into space. With the rapid development of commercial aerospace, more ordinary people will go to space for sightseeing. However, it should not be ignored that microgravity, space radiation, relative geometry, and orbit of space stations have various effects on the health of astronauts. In recent years, scholars in various countries have made considerable research progress in this field. This article analyzes the research history and current situation of this field, including the individual effects of space radiation, microgravity, orbit, and relative geometry, as well as their comprehensive effects. In addition, various nursing measures have been investigated.

Ever-increasing space debris poses a great threat to spacecraft safety; its removal debuts as an innovative technology and will be in demand in the future. This article proposes a design for micro/nano joint satellites composed of four micro/nanosatellites with high maneuverability to clear space debris. The design incorporates two operating modes with typical applications, and the joint satellite features and essential key technologies are introduced. With the aim to demonstrate well-performed image data fusion and processing of the design, four cameras with different spectral and optical properties are installed for each micro/nanosatellite to acquire images and spectral characteristics for multifeatured identification of debris based on comprehensive analysis. Due to the different remote sensing payloads of the four micro/nanosatellites, the joint satellite is also capable of remote sensing. Compared with a single micro/nanosatellite, the joint satellite is more accurate for debris identification and rapid on-orbit maneuverability in addition to the superior flexibility brought by a touch-and-unfold separating removal mechanism.

This study presented a mathematical description of an arbitrary shape area, and after analyzing the characteristics of the near-polar orbital co-ground trajectory constellation that satisfies the revisit interval constraint, an optimization model of the orbital parameters design of reference satellites in regional coverage constellations was constructed. Then based on the designed area covering the constellation of common ground trajectories, a simple and effective two-pulse maneuvering scheme was adopted for the needs of sudden tasks, and an existing satellite scheduling optimization model using the golden section method to constrain the boundary of substellar point coverage was constructed. Finally, the optimal design of regional coverage constellations and existing satellite dispatches was carried out for the sea areas with the most frequent tropical cyclone activities in the northwest Pacific Ocean, and the simulation results verified the effectiveness of the proposed optimization model and have certain practical use value.

Satellite anomaly is a process of evolution. Detecting this evolution and the underlying feature changes is critical to satellite health prediction, fault early warning, and response. Analyzing the correlation between telemetry parameters is more convincing than detecting single-point anomalies. In this article, principal component analysis method was adopted to downscale the multivariate probability model, T 2 {T}^{2} statistic was checked to determine the data anomaly, without the trouble of threshold setting. After an anomaly was detected, time-domain visualization and dimension reduction methods were introduced to visualize the satellite anomaly evolution, where the dimensions of telemetry or features were reduced and presented in two- or three-dimensional coordinates. Engineering practice shows that this method facilitates the early detection of satellite anomalies, and helps ground operators to respond in the early stages of an anomaly.

BeiDou navigation satellite system (BDS) receivers on-board cannot give real-time positioning precision in tracking missile and carrier rocket. In this article, the dynamic filtered optimal estimation theory is applied to the highly dynamic on-board BDS ballistic parameter solution, an optimally constrained geometric dilution precision (GDOP) constellation selection strategy is proposed, a mathematical model based on dynamic filtered estimation for the ballistic determination and precision estimation of the on-board BDS is established, and an analysis of the on-board BDS positioning precision is carried out using the observed data. The calculation results show that the dynamic filter positioning algorithm is simple, practical, and reliable, which can effectively suppress and reduce the random errors of ballistic parameters and significantly improve the positioning precision, fully satisfying the needs of high dynamic and high precision navigation and positioning users, and has good application prospects.

This article presents a study on the design of high-speed inter-satellite links for the global navigation satellite system, which consists of 24 middle earth orbit, 3 inclined geosynchronous orbit, 3 geostationary orbit satellites, and 4 typical ground stations based on the laser link of slowly varying continuous system and high-speed Ka link. Pre-allocation of node connections in inter-satellite link construction is conducted by employing the optimized Dijkstra algorithm using finite-state automata. In addition, topological design and routing planning principles are utilized for high-speed inter-satellite links. Based on full constellation orbit data of a regression period and locations of the ground station nodes, an hourly link construction program is obtained using the scheme described above. The calculation result of the position dilution of precision values of all satellites, the average inter-satellite transmission delay, and the inter-satellite link switching meet the requirements of measurement, data transmission, and management for navigation constellation.

An integrated ranging and differential one-way range (DOR) signal design is implemented. The design utilizes the regenerative pseudo-noise ranging scheme and one pair of dedicated DOR tones for the deep space United X Band system. To demonstrate its effectiveness, it was applied to China’s Tianwen-1 orbiter and compared with the classic and normal designs. Using the link budget and error analysis methods, the measurement accuracy and communication ability were assessed. Results show that the novel design achieves better performance compared with that of the classic and normal designs. In the applied case, the power efficiency improved by > 30 % \gt 30 \% , two-way ranging precision improved from 0.50 to 0.09 m, and the two-way Doppler precision improved by 20% compared with those of the classic one. In addition, the spacecraft thermal noise during Delta-DOR measurements was slightly reduced. Owing to the higher downlink residual carrier, the supported telemetry data rate increased by 50%. Compared with the normal one, a higher downlink residual carrier (by 0.35 dB) was achieved by the novel design and resulted in slightly better ranging and Doppler accuracies. The novel design has a good technical foundation and is expected to be adopted in China’s future lunar and deep space explorations.

Based on the characteristics of near-circular orbits and close-range leader–follower flights, the relative dynamics equations of the eccentricity/inclination ( e/i ) vector method are introduced herein. Additionally, the constraint terms in the design of the leader–follower flight formation are found to satisfy the conditions of the line-of-sight angle and inter-satellite distance. The control box algorithm is proposed under the flying task’s constraints, such as the line-of-sight angle and distance between the satellites according to the e/i vector and Gauss perturbation equations. The algorithm comprehensively takes into account the relationship between the relative motion variations in the satellite formation in near-circular orbits as well as their relationship with the velocity increment applied to the satellites. The example simulated in this study not only illustrates the existence of a coupling relationship between the flight-following distance and flight-following line-of-sight angle but also verifies the influence of the relative eccentricity of the two satellites on the leader–follower flight stability. The simulation results show that when the control box algorithm was used to maintain the leader–follower flight, this method was simple, intuitive, and may be feasibly introduced as a flight-following control strategy.

In this article, we study the orbital dynamics with the gravitational potential of the asteroid 93 Minerva using an irregular shape model from observations. We calculate its physical size, physical mass, surface height, and zero-velocity surface. Meanwhile, we recognize that there are five equilibrium points around Minerva, four of which are external, and one is internal. Two of the external equilibrium points are stable and near the y y -axis, while two external equilibrium points are unstable and near the x x -axis. In addition, we study the changes in the number, position, and topological case of the equilibrium points when changing the spin speed and the density. We calculate the gravitational force acceleration of the polyhedron model, and we back up our calculations by simulating the orbit of one moonlet under the gravitational force acceleration of Minerva. With the simulation result, we demonstrate the existence of stable orbits around Minerva.

In order to deal with the shortage of spacecraft telemetry, tracking, and command (TT&C) resources and the high complexity of planning and scheduling in the future, based on the current situation of the TT&C network in China, the construction requirements of space–ground integration TT&C network are put forward, and the basic framework is constructed. Referring to the random access mechanism of ground cellular mobile communication system, access once encountered TT&C mode is designed. This work introduces its basic idea, gives an example of the implementation process in the new form, designs the protocol stack system of random access TT&C, and probes into the key technologies, such as spacecraft access optimization selection strategy and panoramic (airspace) multi-beam and multi-target simultaneous TT&C technology, for reference of further research.

Considering that some tasks will require the consistency of the position and attitude of the end-effector, multi-space-robot cooperative capture also needs to consider the synchronization of the two capture arms. Taking the dual-space robots as example, the trajectory planning problem before cooperative capture is focused. First, a drive-transform method based on trapezoidal velocity interpolation is proposed, which combines the advantages of these two methods to obtain the SE(3) motion trajectory, in which the attitude and position are planned synchronously. Then, the trajectory optimization model of cooperative capture is established, which takes the optimal time and the minimum attitude disturbance of the base as the optimization goals, and simultaneously satisfies that the two capture arms reach the capture point synchronously. In order to solve this multi-objective optimization problem, a dual-population multi-objective fruit fly algorithm based on non-dominated sorting was proposed. Finally, the simulation example of dual-space robots shows that the proposed algorithm is effective, and the analysis of the optimal solution set demonstrates that the optimized cooperative capture trajectory is smooth and synchronous.