Abstract To meet various requirements of the future deep space missions of China, State Key Laboratory of Astronautic Dynamics constructs a new orbit determinatin software with parallel observations process. By using 32 threads, the computational efficiency per iteration (including spacecraft’s integration) could be promoted to 10 times as that of single-threaded orbit determination. Suppose the number of observations is p p , the number of estimated parameters (including spacecraft’s state) is q q , the amount of computation of one observation is x x , the amount of computation of one Givens transformation is y y and the best number of threads is proved to be [ p ⋅ ( x + y ) / ( q ⋅ y ) ] 1 / 2 {\left[p\cdot \left(x+y)\text{/}\left(q\cdot y)]}^{1\text{/}2} for one-step threads combination. The root mean square of the postfit residuals of China’s deep space monitoring network (CDSMN) and China’s Very Long Baseline Interferometry (VLBI) network (CVN) observations in the Earth-Mars transfer phase and the Mars-orbiting phase are almost the same: about 0.3 m for Ranging, about 0.3 mm/s for Doppler, about 3 cm for VLBI delay and about 0.5 mm/s for VLBI delay rate. It is also found that all the four types of observations of CDSMN and CVN are needed in orbit determination for deep space maneuver and braking at periareion calculation. In the Mars-orbiting phase, the position accuracy after orbit determination under CDSMN-only tracking mode can reach about 1 km.

Abstract Polytropic equations (Lane–Emden [LE] equations) are valuable because they offer a simple explanation for a star’s interior structure, interstellar matter, molecular clouds, and even spiral arms that can be calculated and used to estimate various physical parameters. Many analytical and numerical methods are used to solve the polytropic LE equation. The series expansion method played an essential role in many areas of science and has found application in many branches of physical science. This work uses the series expansion method to examine N-dimensional polytropes (i.e., slab, cylinder, and sphere). To solve LE-type equations, a computational method based on accelerated series expansion (ASE) is applied. We calculate several models for the N-dimensional polytropes. The numerical results show good agreement between the ASE and numerical and analytical models of the N-dimensional polytropes.

Abstract We report the Korean records for comet C/1652 Y1, which have not been introduced in previous studies on historical comets. According to Korean historical documents, this comet, described as bai xing (white star, in literal) or ke xing (guest star, in literal), was observed with the naked eye for 22 days from December 19, 1652 to January 9, 1653. In this study, we first cross-checked the records of comet C/1652 Y1 among Korean documents and presented the translations in the Appendix for future reference. We then compared the Korean observations with the orbital path determined from calculations using the orbital elements provided by Marsden (1983. Catalog of cometary orbit. Hillside: Enslow Publishers). We also compared the illustrations depicted by Weigelius and Schiltero (1653. Commentatio astronomica de cometa novo qui sub finem anni 1652 lumine sub obscuro nobis illuxit. Jenae: Typis Georgii Sengenvvaldi) and by Hevelius (1668. Cometographia, Totam Naturam Cometarum; Exhibens. Gedani: Typis Auctoris, & Sumptibus, Simon Reiniger). We found that the Korean observations show discrepancies with the orbital path calculated by Marsden and the illustration of Weigelius and Schiltero, particularly near the end of the observation period. In conclusion, we believe that this study will contribute to improving the orbital path calculation of comet C/1652 Y1.

Abstract With the deployment of global navigation systems such as GPS, GLONASS, GALILEO, and BeiDou, and the construction of the global observation network, global navigation satellite system (GNSS) data have greatly expanded. Traditional relational databases and file systems can no longer efficiently store and process GNSS data. In addition, multidimensional, in-depth visual analysis methods for such data are lacking. In this paper, we provide a solution and implement a GNSS data visualization system based on MapV and cesium running on the Hadoop platform, which can effectively solve the problems of the lack of storage and computing resources for these massive multisource heterogeneous data. The proposed system provides multidimensional presentations to show how the space and ground segments of the entire system are organized by analyzing GNSS data.

Abstract The increasing amount of massive data generated by commercial spacecraft in orbit puts forward higher and higher requirements for the stability, reliability, and computing power of computer systems for commercial aerospace data center. Data center computer systems are gradually transforming from X86 architecture and IP network model to a platform model with cloud computing and software-defined network (SDN) technology. This article proposes a new network architecture based on a unicast/multicast protocol for data interaction between the SDN and IP network. There are three main contributions of this article. The first is that the architecture proposed in this article aims to reduce end-to-end transmission latency and packet loss. The second is to improve the flexibility of system configuration and precise control when the SND controller state changes. The third is to verify the feasibility of deploying network architecture in a real data center environment.

Abstract We present the results of numerical simulations focused on the accretion of intergalactic gas onto a gas-rich S-type disc galaxy. Our investigation explores the conditions favouring the emergence of counterrotating stellar and gaseous components within the galaxy, leading to the inflow of gas towards the central kiloparsec of the galaxy. Notably, we find that the most substantial reservoir of gas, serving as fuel for galactic nucleus activity, resides within the central region during the retrograde infall of gas at an incident angle of approximately 2 0 ° 2{0}^{^\circ } relative to the galactic plane. Departures from this angle significantly diminish the gas flow rate towards the galactic centre. Conversely, the prograde infall of intergalactic gas makes a marginal contribution to the gas content in the central region and cannot supply fuel to the active galactic nucleus. An intriguing characteristic of the observed retrograde impact is the emergence of a rotating polar ring at the galaxy’s periphery, primarily originating from intergalactic gas.

Abstract A generalized super-twisting second-order sliding mode adaptive fixed-time control law, which is used for spacecraft pose tracking in the presence of internal and external uncertainties, is proposed. Lie group SE(3) (for special Euclidean group), which is the configuration space for rigid body motion, is used for modeling the six-degrees-of-freedom dynamics of spacecraft. A fixed-time sliding mode surface is proposed and applied to design an generalized super-twisting sliding mode control law. A novel dual-layer adaption law for the controller is proposed to the ensure the gains varying rapidly with the disturbance. The adaptive second-order sliding mode controller guarantees a uniform exact convergence for the closed-loop tracking control system with less energy consumption. Numerical simulations are performed to demonstrate the excellent performances of the control law.

Abstract A comprehensive photometric study and evolutionary state for the systems V0487 Lac, V0566 Hya, and V0666 Lac were carried out by means of their first photometric observations. New times of minima were estimated from the observed light curves, and first (O–C) curves were established for all systems. The radiative treatment was carried out using a Windows interface version of the Wilson and Devinney programme (W–D). The adopted models provide some absolute characteristics for the systems under study, which are used to determine the spectral type of the system’s constituents and their evolutionary stage. Distances to each system were calculated, and physical properties were estimated. All system components, with the exception of the secondary component of the system V0487 Lac, showed good fit when the systems were positioned on the theoretical mass–luminosity and mass–radius relations.

Abstract The main belt asteroids 4747, 5255, 11411, 15433, and 17866 were studied at the Baldone Astrophysical Observatory in the time span range 2018–2022. The obtained light curve data together with published Minor Planet Center data are analyzed with Fourier series, Lomb-Scargle periodogram, and phase dispersion minimization methods. A plan of analysis is given. The results computed from different observatories’ data are compared, and mean-weighted periods are obtained.

Abstract In 2007, Storti predicted that the value of the cosmic microwave background radiation (CMBR) temperature may be improved: from the particle data group (PDG) value of [T 0 = 2.725 ± 0.001 K] to [T 0 = 2.7254 K]. In 2011, the PDG revised their value of CMBR to [T 0 = 2.7255 ± 0.006 K]. In 2008, Storti predicted a ΛCDM Hubble constant of [H 0 = 67.0843 km/s/Mpc]. In the same year, the PDG published their value as being [H 0 = 73 ± 3 km/s/Mpc]. In 2013, the PDG published a revised value of [H 0] as being considerably lower [H 0 = 67.3 ± 1.2 km/s/Mpc]. These predictions and experimental confirmations, in particular the value of [H 0] being successfully predicted 5 years in advance of the Planck collaboration and without Planck satellite instrumentation, demonstrate the power of the technique applied. We utilize the same technique to calculate the present values of ΛCDM [H 0], [ΩΛ], [ΩM], [q], and [Λ]. Subsequently, we describe the complete history of the cosmos from the instant of the Big Bang to the present epoch, in complete agreement with the standard model of cosmology. Moreover, we explicitly demonstrate that the Hubble tension does not exist, in a companion publication to this research article. This is achieved by utilizing a single equation to calculate both values of Hubble constant associated with the Hubble tension.