 Subjects -> AERONAUTICS AND SPACE FLIGHT (Total: 124 journals)
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- Erratum to: High-Cadence Observations of Magnetic Field Dynamics and
Photospheric Emission Sources in the Eruptive Near-the-Limb X4.9 Solar
Flare on 25 February, 2014: Evidences for Two-Stage Magnetic Reconnection
during the Impulsive Phase-
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Abstract: An Erratum to this paper has been published: https://doi.org/10.1134/S0010952523330031
PubDate: 2023-10-01
- Erratum to: Space–Time Structures in the Auroral Oval: Approaches to
Modeling-
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Abstract: An Erratum to this paper has been published: https://doi.org/10.1134/S001095252333002X
PubDate: 2023-10-01
- Erratum to: Stability of a Magnetically Actuated Satellite towards the Sun
on a Sun-Synchronous Orbit-
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Abstract: An Erratum to this paper has been published: https://doi.org/10.1134/S0010952523330018
PubDate: 2023-10-01
- Optimization of the Maneuver to Ensure a High Velocity of the Spacecraft
Entry into the Atmosphere-
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Abstract: The transfer scheme that provides a parabolic entry of the spacecraft into the Earth’s atmosphere has been optimized. Such a maneuver can be of interest in experimental testing of the spacecraft reentry from the Moon or after interplanetary missions. It is assumed that the spacecraft is inserted into a low Earth orbit and is equipped with a chemical propulsion system and a limited-thrust engine, which should provide a maneuver to bring the spacecraft into the Earth’s atmosphere. The optimization criterion takes into account the characteristic velocity of the maneuver. The developed method of optimizing the transfer scheme and the spacecraft trajectory itself is based on the maximum principle. Single-revolution and multi-revolution transfer trajectories are analyzed. It is shown that for single-revolution trajectories there is an optimal time and an optimal angular distance of flight. Their values and the minimum characteristic velocity of the maneuver are evaluated. Unlike single-revolution trajectories, the characteristic velocity for multi-revolution trajectories monotonically decreases with increasing transfer duration. The dependence of the characteristic velocity on the transfer duration for single-, two-, three- and four-revolution trajectories is given. The transfer duration ranges in which it is advisable to use each type of trajectory are analyzed.
PubDate: 2023-10-01
- Statistical Characteristics of Emission from Stationary Plasma Thrusters
Operating with Various Propellants-
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Abstract: The procedure of experimental determination of statistical characteristics of own electromagnetic radiation of a laboratory mock-up of an SPT-70 stationary plasma thruster developed by the Research Institute of Applied Mechanics and Electrodynamics of the Moscow Aviation Institute is described. The study investigated the temporal complex implementation of the processes of radiation of the SPT-70 with a sampling duration of 1 ms and an analysis band of 140 MHz for characteristic central frequencies of 0.9, 1.050, 1.200, and 1.350 GHz (discharge power of 600 W, horizontal polarization) when working on various working bodies. The conducted studies allowed to obtain estimates of the statistical characteristics of the SPT-70 radiation for prospective working bodies The new results should be attributed to the fact that the obtained distribution laws for the common-phase and quadrature components of the complex envelope process of radiation differ significantly from the Gaussian one. As for the distribution of the amplitude envelope process, in general, there is a difference from the Rayleigh distribution law. In the transition from xenon to krypton, the degree of negativity and the difference from Rayleigh’s law increase. At the same time, the law of phase distribution of the complex envelope process is close to uniform and invariant to the type of working body.
PubDate: 2023-10-01
- Propellant Influence on Electromagnetic Environment Generated by
Stationary Plasma Thrusters-
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Abstract: Possible aspects of violation of the functional safety of spacecraft in terms of electromagnetic compatibility with electric rocket thrusters in their work on alternative working substances are considered. The procedure of experimental determination of spectral–time characteristics of own electromagnetic radiation of laboratory model of stationary plasma thruster SPT-70 developed by the Research Institute of Applied Mechanics and Electrodynamics of the Moscow Aviation Institute is described. Measurements of noise emissions were carried out on a vacuum installation with a “radiotransparent” compartment and a shielded echo-free camera in the frequency range of 1–12 GHz for typical discharge capacities (600, 800, and 1000 W), vertical and horizontal polarization, and various working substances used (krypton and xenon). The conducted studies have allowed obtaining new comparative results of the assessment of spectral characteristics of SPT-70 radiation for standard modes and prospective working bodies within the orthogonal polarization bases. The new results should include information about the radiation characteristics of SPT-70 in the time area. It is shown that the transition from xenon to krypton retains the pulsed nature of the radiation of a stationary plasma thruster, leading not only to an increase in the amplitude of pulses, but also to an increase in the frequency of repetition of “bursts” and an increase in their duration, which requires additional measures to ensure electromagnetic compatibility in order to preserve the functional safety of the spacecraft.
PubDate: 2023-10-01
- Study of Cosmic Ray Intensity (CRI) along with Solar Wind Parameters and
Geomagnetic Indices from Different Stations-
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Abstract: In this study, the variations of cosmic ray intensity (CRI) and their correlations with solar wind parameters and geomagnetic indices from different stations are investigated. In this work, CRI data obtained from the neutron monitor database over the MWSN, DOMC, and HRMS stations was used. The findings of this study indicate that the CRI over the MWSN station was greater than over the DOMC and HRMS stations. However, the CRI over DOMC is much lower than for MWSN and HRMS stations. Interestingly, the CRI values at all stations decreased during a strong geomagnetic storm period in May 2017 compared to January 2020. Also, the continuous wavelet transform (CWT) result showed that a higher power spectrum in CRI was clearly seen in May 2017 than in January 2020. This is because cosmic ray intensity is more highly modulated by the strength of geomagnetic storms (strong storms) than weak storms and the southward shifts of the interplanetary magnetic field (IMF Bz) component. Noticeably, CRI is found to decrease in a pattern similar to Earth’s magnetic field, and the Dst-index indicates that disturbances of the ring current cause the value of CRI to decrease upon reaching Earth. The correlation analysis of CRI over DOMC, MWSN, and HRMS stations along with the solar wind parameters and geomagnetic indices for both strong and moderate events found that the coefficients of interplanetary electric field (IEF Ey), f10.7-index, Kp, and Ap-indices peak with a very high value of 1 for a zero lag, which shows a good positive correlation between the parameters. However, the coefficients of the IMF Bz, solar wind speed, and Dst-index peak with very high values of 0.2 and 0.5 for a zero lag, indicating weaker and stronger correlations between the parameters that were taken into account for the study.
PubDate: 2023-10-01
- An Experimental Study of an Ion Thruster with Electrodes of an
Ion-Extraction System Made of a Fine-Structure Carbon–Carbon Composite-
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Abstract: This article presents the results of 1000-h tests of a radiofrequency ion thruster (RFIT) with electrodes of an ion-extraction system made of carbon–carbon composite material based on the non-woven carbon frame. The quality of the surface of the thruster IES accelerating electrode being the key element of the RFIT from the lifetime point of view was assessed by visual examination and scanning electron microscopy. The maximum depth of erosion cavity on the accelerating electrode surface was determined. Electrode-surface elemental analysis was performed by the method of electron-probe microanalysis.
PubDate: 2023-10-01
- A Method for Calculating the Trajectory of a Single-Impulse Flight to a
Halo Orbit around the L2 Libration Point of the Earth–Moon System-
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Abstract: The problem of calculation of low-energy impulse trajectories to halo orbits in the vicinity of the L2 point of the Earth–Moon system is considered. A new method for calculating the trajectories of a single-impulse low-energy flight to a halo orbit is presented. The limited problem of four bodies is analyzed, within which the attraction of the Earth, Moon, and Sun is taken into account, and their position and speed are calculated using high-precision ephemeris support. Particular attention in the development of the method is paid to ensuring its computational stability for calculating trajectories with a long stay of a spacecraft (SC) in the zone of weak stability near the boundary of the Hill sphere of the Earth. The results of the calculation of single-impulse transfer trajectories from low Earth orbit to halo orbit around the L2 point of the Earth–Moon system are given. The analysis of the dependence of the main characteristics of single-impulse trajectories from the date of approach to the halo orbit is carried out.
PubDate: 2023-10-01
- Designing Low-Energy Low-Thrust Flight to the Moon on a Temporary Capture
Trajectory-
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Abstract: The study considers the problem of calculating the low-energy trajectories of a low-thrust spacecraft to the Moon during the ballistic capture. The transfer is carried out using a transit trajectory in the vicinity of one of the collinear libration points L1 or L2 of the Earth-Moon system. Using a transit trajectory allows us to reduce fuel consumptions for the transfer by applying spacecraft dynamic in the Earth-Moon system. After exit from the orbit of ballistic capture, depending on the goal of mission the required lunar orbit can be formed, or the maneuver can be completed for inserting into the required interplanetary trajectory. A method for solving the problem is proposed, which consists in selecting the suitable transit trajectory to ensure sufficiently long duration of staying a spacecraft in the sphere of influence of the Moon, and in calculating the optimal low-thrust trajectories from initial lunar orbit to the transit trajectory to the Moon. To solve the problem of optimal control and calculate the optimal exit point to the transit trajectory, the Pontryagin’s maximum principle is used in combination with the continuation method by parameter. Numerical examples are given for calculating low-energy trajectories to the Moon during the ballistic capture with the optimization of exit point to the transit trajectory.
PubDate: 2023-10-01
- Optimization of a Low-Thrust Heliocentric Trajectory between the Collinear
Libration Points of Different Planets-
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Abstract: The aim of this study is to optimize a low-thrust interplanetary trajectory using collinear libration points L1 and L2 as the junction points of the geocentric or planetocentric segments of the trajectory with the heliocentric segment. The problem of optimizing the heliocentric segment of perturbed low-thrust interplanetary transfer is considered in the four-body ephemeris model, which includes the Sun, Earth, target planet, and spacecraft. To optimize the trajectories, an indirect approach is used based on Pontryagin’s maximum principles and the continuation method. The possibility of reducing the characteristic velocity in comparison with the estimates obtained through the method of zero sphere of influence is shown.
PubDate: 2023-10-01
- The Problem of Optimal Discharge Energy in an Ablative Pulsed Plasma
Thruster-
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Abstract: One promising trend in small-spacecraft development is the development of small electric propulsion systems (EPSs) based on ablative pulsed plasma thrusters (APPTs). The problem of optimal discharge energy in APPT that provides a minimal total mass of the EPSs has been considered. It has been shown that, at a given total impulse, discharge energy of an APPT has an optimal value that depends on the specific energy intensity of power capacitors, the specific thrust impulse of the engine, mass of electronic units, and other elements of the propulsion system circuit. It has been concluded that the calculation of the optimal discharge energy allows reducing the total mass of the propulsion system during the design of an APPT-based EPSs.
PubDate: 2023-10-01
- Optimization of the Spacecraft Transfer Maneuver from a Point of the
Elliptical Orbit to Another Point of the Same Orbit-
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Abstract: The problem of changing the orbital position of the spacecraft located in some elliptical orbit in the Newtonian gravitational field is analyzed. It is assumed that the spacecraft is equipped with a non-adjustable engine that can be activated multiple times. An algorithm for determining the optimal (according to the criterion of the minimum characteristic velocity) transfer scheme has been developed. Special attention is paid to the analysis of the number of active segments on the trajectory and their location on the trajectory revolutions. The algorithm is based on the maximum principle and the method of parameter continuation. The initial approximation for the transfer scheme is found using the trajectory of the optimal transfer of the spacecraft with a perfectly adjustable propulsion system (engine of limited power). This trajectory is then continued for the spacecraft with a non-adjustable engine, introducing a smoothing parameter for the thrust function. In the final stage, the characteristics of the optimal transfer pattern are determined for the spacecraft with a non-adjustable engine involving a relay thrust function. The properties of the optimal scheme of the maneuver as a function of the angular distance of transfer (the number of revolutions of the trajectory) and a function of the phasing angle (the angle characterizing the angular distance between the points of the orbit where the transfer takes place) are analyzed. It is shown that an increase in the angular distance of the transfer significantly reduces the characteristic velocity of the maneuver even at large phasing angles.
PubDate: 2023-10-01
- On Libration Points in the Asteroid–Research Probe System
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Abstract: This paper is dedicated to a study of relative motion in the field of homogeneous spheroid bodies. It is assumed that an asteroid’s satellite does not affect its translational and rotational motion by inertia. The latter motion has the form of rotation in the mode of regular precession. The case in which the asteroid is an ellipsoid of revolution is considered. A system of conditions that the libration points must satisfy is constructed; it is shown that its solution is two types of libration points, which differ in their location with respect to the constant vector of the angular momentum and the axis of symmetry of the ellipsoid. Thereafter, the stability of libration points is investigated numerically and analytically in the first approximation.
PubDate: 2023-08-01
DOI: 10.1134/S0010952523700211
- High-Cadence Observations of Magnetic Field Dynamics and Photospheric
Emission Sources in the Eruptive Near-the-Limb X4.9 Solar Flare on 25
February, 2014: Evidences for Two-Stage Magnetic Reconnection during the
Impulsive Phase-
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Abstract: — We present an analysis of the pre-limb eruptive X4.9 solar flare on February 25, 2014, by means of which we confirm a hypothesis of the two-stage energy release corresponding to two magnetic reconnection regimes in the flare impulsive phase. This flare is selected, firstly, because of its morphological peculiarities suggesting the presence of the two energy release stages. Secondly, the flare was very suitably located near the solar limb and it was well-observed by many instruments. We performed an analysis of multiwavelength observational data of this flare region to find a connection between changes of the photospheric magnetic field, morphology of hard and soft X-ray sources, dynamics of the photospheric optical emission sources, metric radio bursts, and kinematics of an eruptive structure. The simultaneous usage of the line-of-sight and vector Helioseismic Magnetic Imager (HMI) magnetograms allowed us to trace magnetic field changes during the flare impulsive phase with high temporal resolution. HMI filtergrams allowed to trace displacement of the photospheric emission sources, associated with the magnetic reconnection, with very high temporal resolution up to 2 s. Using all observational results, we argue that the found flare stages are characterized by the following magnetic reconnection regimes. The first stage is predominantly characterized by the three-dimensional zipping reconnection in the strong sheared magnetic field assuming the tether-cutting geometry. The second stage corresponds to the so-called “standard” model of eruptive flares with the quasi-two-dimensional reconnection below the eruptive flux-rope. All observational peculiarities of these two stages are discussed in details.
PubDate: 2023-08-01
DOI: 10.1134/S0010952523090010
- A Lunar Printer Experiment on Laser Fusion of the Lunar Regolith in the
Luna-Grunt Space Project-
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Abstract: This paper presents the results of laboratory studies on the use of a new technology of selective laser melting to obtain experimental products from the lunar regolith without special additives. The main properties of the natural regolith, which significantly affect the fusion process, are determined. The first samples of a given geometry were obtained from labradorite and gabbro-diabase powders, which are natural analogues of lunar regolith, using this technology. The research results are planned to be used in the preparation of initial data for the development of the Lunar Printer space device as part of the complex of scientific equipment of the promising lunar project Luna-Grunt.
PubDate: 2023-08-01
DOI: 10.1134/S0010952523700302
- Simultaneous Ground and Satellite Measurements of the Polarization Jet at
the Yakutsk Station Meridian-
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Abstract: The data of simultaneous measurements of the polarization jet from the Yakutsk ground-based vertical radio sounding station and satellite observations of narrow electron density dips or fast westward drifts of the ionospheric plasma from satellites of the Defense Meteorological Satellite Program (DMSP) series. The events are based on ground-based ionospheric measurements and cover the time interval from March 1989 to December 2015, i.e. about 26 years. The simultaneity of observations is ensured by a time period of approximately ±1.5 h from the time of registration of signs of a polarization jet according to the data of a ground-based ionospheric sounding station or by the an orbital period of DMSP satellites around the Earth. Based on data of long-term simultaneous satellite and ground-based measurements (126 events), it was shown and confirmed that the presence of characteristic additional traces of reflections on ionograms indicates the presence of narrow and fast drifts of ionospheric plasma or a polarization jet near the zenith of the observation station. It is also shown that the quasi-instantaneous longitude extent of a polarization jet at subauroral latitudes can in some cases reach 8 h or 120° by longitude.
PubDate: 2023-08-01
DOI: 10.1134/S0010952523700314
- The Effect of Products Released from the Structural Materials of a
Spacecraft on the Optical Properties of Its Thermal Control Coatings-
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Abstract: In this paper, we report on our experimental findings regarding the release of easily condensing substances from certain structural materials utilized in spacecraft, and we evaluate the impact of thin condensate films on the integral optical coefficients of external thermal control coatings (TCCs) of spacecraft. To simulate the space environment and solar radiation, the experiments were conducted in a vacuum. We found that the flux densities of the components released from the materials’ surfaces reach 5.4 × 10–7 g cm–2 s–1 and exhibit an exponential decrease over time. Furthermore, thin condensate films with a thickness of 100 Å can significantly degrade the integral optical coefficients of TCCs by tens of percent. These effects can alter the heat balance of the spacecraft. The experimental research methods used in this study can be applied to a broad range of materials, and the results have implications for the design and construction of various types of spacecraft.
PubDate: 2023-08-01
DOI: 10.1134/S0010952523700284
- Predicting the Parameters of the Orientation of the Earth in Problems of
Navigation Taking into Account the Phenomenon of the Development of
Irregularity in the Earth’s Rotation-
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Abstract: This article discusses the application of a previously proposed [1] methodology for predicting the Earth’s orientation parameters (EOPs) that provides high accuracy as a result of optimizing a special procedure of processing historical data using the least-mean-squares method. The results of investigating the accuracy characteristics of the obtained EOP estimations are presented in relation with a predictive task in the interval from 2019 to 2022, when, for the first time in the history of observing the Earth’s daily rotation, a change was recorded in the difference trend between Universal Time and Coordinated Universal Time was recorded, caused by the length of day decreasing. The influence of the length of the day trend changing and related problems on the accuracy of EOP prediction in various navigation tasks using classical polynomials describing EOP evolution is discussed. A comparative analysis of the EOP prediction made by the International Earth Rotation and Reference Systems Service for a similar time period is carried out.
PubDate: 2023-08-01
DOI: 10.1134/S0010952523220021
- Time Series of Space Observations: Analysis of Local Meteorological and
Solar Series-
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Abstract: A range of issues related to the results of the analysis of some meteorological and solar series of satellite observations in the Kara-Dag area (Crimea) is considered. A qualitative and quantitative picture of changes in the total insolation falling on the Earth’s surface, air temperature at a height of 2 m, and the Earth’s surface temperature in Kara-Dag over the past 38 years is presented. A numerical model has been constructed that makes it possible to predict the most powerful fluctuation with a period of 1 year in the analyzed data. The following methods were used in the work: the method of wavelet analysis, statistical methods for extracting Gaussian and non-Gaussian noise, an iterative method for constructing and estimating the accuracy of model approximations. Coherent variations in the analyzed and some global geodynamic and solar time series were established using two-channel autoregressive analysis. A qualitative characteristic of the process of changing the main variations in the analyzed time series was obtained using the analysis of phase trajectories on the Poincaré plane.
PubDate: 2023-08-01
DOI: 10.1134/S0010952523700326
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