Geostationary Spacecraft Research Articles

Statistical Study of Uncontrolled Geostationary Satellites near an Unstable Equilibrium Point

The growth of the population of space debris in the geostationary ring and the resulting threat to active satellites require insight into the dynamics of uncontrolled objects in the region. A Monte Carlo simulation analyzed the sensitivity to initial conditions of the long-term evolution of geostationary spacecraft near an unstable point of the geopotential, where irregular behavior (e.g., transitions between long libration and continuous circulation) occurs. A statistical analysis unveiled sudden transitions from order to disorder, interspersed with intervals of smooth evolution. There is a periodicity of approximately half a century in the episodes of disorder, suggesting a connection with the precession of the orbital plane, due to Earth’s oblateness and lunisolar perturbations. The third-degree harmonics of the geopotential also play a vital role. They introduce an asymmetry between the unstable equilibrium points, enabling the long libration mode. The unpredictability occurs just in a small fraction of the precession cycle, when the inclination is close to zero. A simplified model including only gravity harmonics up to degree 3 and the Earth and moon in circular coplanar orbits is capable of reproducing most features of the high-fidelity simulation.

Method of determining the coordinates of the radio signal source in satellite communication systems

Telecommunications have penetrated deeply into all spheres of human activity. Due to the use of digital technologies, it has become possible to transmit and receive information of various kinds in one stream (not separately). Three geostationary satellites are sufficient to provide data transmission from anywhere in the world to another point using artificial Earth satellites. Data transmission systems using the satellite should contain at least two Earth Stations and a repeater of the communication satellite. There are no means of combating any types of artificial interference in the Earth Stations equipment. The jammer, an illegitimate user, can emit a signal from any point in space within a telecommunications satellite system. The paper provides an analysis of existing methods for determining the coordinates of a radio signal source, describes a method for determining the coordinates of an radio signal source (illegitimate user) in satellite telecommunications systems using a geostationary spacecraft. The development was based on a three-position virtual antenna array, the positions of which determined the base of an irregular tetrahedron, and the radio signal source itself was its vertex. In the course of the solution, canonical equations of straight lines in space were compiled, at the intersection point of which the source of the radio signal is located. The coordinates of the radio signal source were the roots of the system, when finding the unit vectors lying on these lines.

Optimization of the launch profile of geostationary spacecraft with electric propulsion system using Falcon-9 launch vehicle

A combined flight profile is being considered, in which the Falcon 9 launch vehicle launches the spacecraft into elliptical intermediate orbit from the Cape Canaveral launch site. In the process of analyzing the problem, the value of the height of the perigee and the inclination of the intermediate orbit are fixed, and the height of the apogee of the intermediate orbit varies. After separation from the last stage of the launch vehicle, the spacecraft carries out transfer to geostationary orbit using electric propulsion system. At the stage of insertion spacecraft from intermediate orbit to geostationary orbit using electric propulsion system, the problem of minimizing the mass of the propellant, multi-revolutionary transfer is considered. The number of revolution and the height of the apogee of the intermediate orbit vary in order to analyze the effect of these parameters on the duration of the transfer and the delivered mass of the spacecraft into geostationary orbit. The main purpose of this paper is to calculate the optimal values of the apogee height of the intermediate orbit and the optimal number of revolution that ensure the delivery of the maximum mass of the spacecraft to the geostationary orbit in a given time delta(t)*. To solve the optimization problem, the Pontryagin maximum principle is applied. After apply ing the maximum principle, the optimization problem is reduced to solving the boundary value problem, which is solved by the continuation method by parameter. The paper presents the results of the optimization problem of multi-revolutionary transfer and analysis of the energy characteristics of combined flight profile for insertion of spacecraft into geostationary orbit.

Rapid Suboptimal Low-Thrust Space Trajectory Design

The finite Fourier series shape-based approach for fast initial trajectory design satisfies the equations of motion and other problem constraints at discrete points by using a nonlinear programming solver to design the Fourier coefficients. In this paper, the finite Fourier series approach is extended to account for the necessary conditions for optimality during the Fourier coefficient design. The proposed method uses the approximate trajectories to analytically estimate the costates at these discrete points by employing a finite difference technique on the adjoint differential equations. Lagrange multipliers associated with any terminal state constraints are determined using an auxiliary function. Residual errors in the stationarity condition are reduced through the objective function, with the Legendre–Clebsch condition enforced as a nonlinear inequality constraint; applying these two conditions finds suboptimal solutions without an excessive loss of computational efficiency. Test cases use steering angle and thrust acceleration magnitude controls and span Earth-escape spirals, geostationary spacecraft rendezvous, and phasing maneuvers. The presented results demonstrate the proposed method’s ability to achieve trajectories closer to the optimal solution.

Geostationary Orbital Debris Collision Hazard after a Collision

Many space objects are densely distributed in the geostationary (GEO) band, and the long-term impact of the collision of GEO spacecraft and space debris on the GEO environment has attracted more and more attention. After summarizing the advantages and disadvantages of the long-term evolution model based on the “Cube” collision probability calculation model, the “Grid” model, a long-term evolution model especially suitable for GEO band, was established. For four types of collision and disintegration events, the “Grid” model was used to study the space environment in the GEO band after collisions between GEO spacecraft and space debris. Future collisions were simulated, and the number of space objects in the next 100 years was counted. Once space debris and massive spacecraft were completely disintegrated after collision, the number of space objects and the collision probability increased sharply, and this caused a collision cascading syndrome. Even if there was no initial disintegration event, collision and disintegration events occurred in the long-term evolution of the GEO band, which led to an increase in the number of space objects. However, the collision probability was much lower, and the number of space objects grew much more slowly without the initial collision.

Procedures for cognitive and synergetic observation and proactive control of power capacity of nickel-hydrogen storage batteries onboard a geostationary spacecraft

The paper presents methods of providing power resources for the mission of the Yamal-100 spacecraft from the secondary onboard power supply sources — nickel-hydrogen storage batteries. For the first time in the world practice of using metal-hydrogen electrochemical batteries installed in a common gas manifold a ~10-years operational life in orbit has been achieved for batteries operated onboard a geostationary satellite. A decline in power capacity of storage batteries could result in early termination of the spacecraft mission. Therefore, the energy resource of the storage battery was maintained through proactive management consisting of prediction and active control. The methods that were developed for continuous observation in the form of monitoring and diagnostics of the storage batteries status including estimation of the current discharge energy capacity made it possible to predict further degradation loss under conditions of insufficient power for the storage batteries cooling equipment. The active control consisted in using methods aimed at providing optimal operating conditions, fending off a potential development of an anomalous thermal situation within the electrochemical reaction zone, and regenerating the energy capacity. The control furthermore used the synergy effect produced by secondary energy interrelationships between onboard systems. This made it possible to meet the batteries operational life requirements under exposure to an unfavorable external factor in the form of an increasing heat impact on the batteries temperature control equipment. The increase in thermal load was caused by re-reflection of a portion of the luminous flux from structural elements of the spacecraft and an increase in solar absorption factor (aging) of thermal control coatings. Key words: spacecraft, control process, nickel-hydrogen battery, provision of resources, energy capacity, proactive control, synergy.

Первые результаты работы аппаратуры МСУ-ГС/ВЭ на КА «Арктика-М» № 1

The hydrometeorological spacecraft Arktika-M No. 1 was successfully launched in February 2021. The Arktika-M series spacecraft are used in the highly elliptical orbit Molniya, which allows regular imaging of the Earth’s polar regions that are inaccessible for observation from the geostationary orbit. Information from these satellites is applied to solve problems of operational meteorology, hydrology, climate, and environmental monitoring in the Arctic region. The MSU-GS/VE equipment deployed on these spacecraft is slated for receiving images of the Earth in the visible and infrared ranges of the electromagnetic spectrum with the periodicity of up to 15 minutes. The MSU-GS/VE equipment is the analogue of the MSU-GS equipment developed for geostationary spacecraft and upgraded for use in imaging from a highly elliptical orbit. The paper presents the first results of the MSU-GS/VE equipment operation. Modernization of the MSU-GS equipment, which allows using it on the Arktika-M series spacecraft, is described. Further development of the MSU-GS and MSU-GS/VE equipment is also discussed.

Pressure measurement inside non-sealed equipment bay of the geostationary spacecraft

Pressure measurement inside non-sealed equipment bay of the geostationary spacecraft

Trajectory Planning for Optical Satellite’s Continuous Surveillance of Geostationary Spacecraft

This paper focuses on the trajectory planning that optical satellites approach the geostationary (GEO) spacecraft and the trajectory planning that the optical satellite flies around the GEO spacecraft for continuous surveillance of the GEO spacecraft The optical satellite approaches the GEO spacecraft with continuous thrust and flies around the GEO spacecraft without thrust. The observation angles of the optical satellite to the GEO spacecraft are less than 30 degrees throughout the entire fly-around mission. Two methods are used in fly-around trajectory planning: trajectory planning based on classical orbital elements and trajectory planning based on CW equations. The advantage of trajectory planning based on classical orbital elements is that the position of the optical satellite relative to the GEO spacecraft is clear in earthcentered-inertial frame and the calculation method of fly-around orbital elements is simple. If the orbital inclination of the GEO spacecraft is less than 0.02 degrees and the semi-major axis of the elliptical relative trajectory of the fly-around formation is greater than 60 km, fly-around trajectory planning based on classical orbital elements is more efficient and easier than that based on CW equations. Optimal control theory is used in the trajectory planning for optical satellites approaching GEO spacecraft and the trajectory optimization is a two-point boundary-value problem. Simulations have proved that this method is feasible, which is highly effective in engineering. This method can be used for space situational awareness and on-orbit servicing missions of GEO spacecraft.

Global registration by optical radiation of lightning discharges on aboard a low-orbit spacecraft

Registration of the coordinates of lightning by their optical radiation has already been implemented on geostationary spacecraft in the wavelength range of 777.4 nm. However, the algorithms for processing the registered signals, as well as the volumes of information flows, have not yet been sufficiently studied. The choice of the sensor for the global registration of optical radiation of lightning on board a low-orbit spacecraft is substantiated. The prospects of using photodiodes in the difference-ranging method for determining coordinates are shown.The characteristics of lightning detection using matrices and LEDs have been studied. The prospects of using photodiodes in the differential-range-finding method for determining coordinates are shown. It is shown that the registration of optical lightning radiation on board the spacecraft by photodiodes provides the characteristics of detection and false alarms of a higher quality compared with the use of CCD matrices.

Методика оптимизации энергомассовых характеристик системы электропитания геостационарного космического аппарата

This article determines a methodology to maximize a specific power of the electrical power system of a geostationary spacecraft, using the EPS simulation model. A typical (for GEO spacecraft) fully-regulated EPS structure is considered. The advantages of using the full bridge quasi-resonant converters with galvanic isolation are considered. The results of the energy efficiency estimation of power converters at various ranges of input voltages, as well as the criteria and conditions for calculating the positive energy budget of a GEO spacecraft are presented. The application of the EPS simulation model is shown and the results of optimization of the proposed EPS energy and mass characteristics for 6 and 13 kW payloads are described

Minimal Thrusters Configuration for Simultaneous Orbit Correction and Reaction Wheels Desaturation for GEO Satellite

The paper considers the problem of the optimal thrusters arrangement aboard a geostationary spacecraft. It is necessary to simultaneously ensure orbit correction and reaction wheels desaturation. A formalization for thrusters optimal arrangement problem is proposed. Examples of the minimal thrusters arrangement are given, taking into account the given limitations and requirements both in the case of regular operation and in the case of a possible failure of one of the thrusters. The influence of possible installation errors and the center of mass displacement is taken into account.

Radio links from low-orbit satellites

In this article, methods of transmitting the information from low-orbit satellites to the Earth are considered. Transferring the information from a low-orbit satellite to geostationary spacecraft at millimeter-wave frequencies that strongly attenuate in the atmosphere is proposed. The possibility of transmitting information from a low-orbit satellite transmitter with a power no more than 1–2 W and small-sized antenna arrays on the communication line is shown.

Application of the approximation method in the algorithm for determining the position of a geostationary satellite

The article is devoted to the study of the features of the movement of geostationary satellites. The relevance lies in the possibility of more accurate determination of the position of the geostationary spacecraft for the correct performance of target tasks, as well as to increase the efficiency and improve the performance of satellites. The issues of using non-singular elements are considered to determine the satellite position in detail. Non-singular elements solve the problem of increasing the approximation error at very small values of eccentricity and inclination. As a result of the work performed, a program code and an algorithm were drawn up for calculating coordinates, a velocity vector and modeling the movement of a geostationary satellite at any time. The application of the results of the program code will make it possible to determine with high accuracy and further simulate the satellite’s orbital movement, which will lead to a decrease in dangerous situations in near-earth space. The topic under consideration will be of interest to specialists studying the issues of spacecraft ballistics.

Design of the structural arrangement for a space reflector via parametric and topology optimization

Development of the optimal structural arrangement for a reflector with the aim to improve its mass and design is of importance due to the necessity to increase areal density and decrease rigidity of the modern space antennas vehicles. Currently, CAE-systems allow to design reflectors using both traditional methods, for example, parametric optimization, and methods which are innovative in this field, such as topology optimization. The paper compares two methods of the structural arrangement design for a thin dimensionally stable reflector operating as part of a geostationary spacecraft: parametric and topology optimization. The algorithms of the structural arrangement development which include the statement of the optimization problem, geometry design and a number of check analyses are presented. A number of structural of a space reflector design under the action of loads at the stage of launch, temperature gradients at the exploitation conditions and modal analysis is performed. The designed reflectors are compared. The studies performed allowed us to develop the optimal structural arrangement for a space reflector using the parametric and topology optimization. The optimal structural arrangement for a space reflector using the optimization could be produced surface figure error (estimated in RMS) with respect to the theoretical paraboloid.

Circumlunar Spacecraft Navigation Using the Measurements from Global Navigation Satellite Systems GLONASS, GPS, Galileo and BeiDou

The study makes an approach to the problem of circumlunar spacecraft navigation using the measurements from the global navigation satellite systems (GNSS) GLONASS, GPS, Galileo and BeiDou. Algorithms have been developed for determining the orbits of low- and high-orbit circumlunar spacecraft, based on the method of dynamic filtering of pseudo-range measurements from “reverse” navigation satellites (NS). The solution to the navigation problem has been simulated by the measurements from four GNSS, and by those from the NS of GLONASS and GPS only. Accuracy and dynamic characteristics of the obtained solutions have been determined and compared to similar solutions for geostationary spacecraft.

Half a century of satellite remote sensing of sea-surface temperature

Sea-surface temperature (SST) was one of the first ocean variables to be studied from earth observation satellites. Pioneering images from infrared scanning radiometers revealed the complexity of the surface temperature fields, but these were derived from radiance measurements at orbital heights and included the effects of the intervening atmosphere. Corrections for the effects of the atmosphere to make quantitative estimates of the SST became possible when radiometers with multiple infrared channels were deployed in 1979. At the same time, imaging microwave radiometers with SST capabilities were also flown. Since then, SST has been derived from infrared and microwave radiometers on polar orbiting satellites and from infrared radiometers on geostationary spacecraft. As the performances of satellite radiometers and SST retrieval algorithms improved, accurate, global, high resolution, frequently sampled SST fields became fundamental to many research and operational activities. Here we provide an overview of the physics of the derivation of SST and the history of the development of satellite instruments over half a century. As demonstrated accuracies increased, they stimulated scientific research into the oceans, the coupled ocean-atmosphere system and the climate. We provide brief overviews of the development of some applications, including the feasibility of generating Climate Data Records. We summarize the important role of the Group for High Resolution SST (GHRSST) in providing a forum for scientists and operational practitioners to discuss problems and results, and to help coordinate activities world-wide, including alignment of data formatting and protocols and research. The challenges of burgeoning data volumes, data distribution and analysis have benefited from simultaneous progress in computing power, high capacity storage, and communications over the Internet, so we summarize the development and current capabilities of data archives. We conclude with an outlook of developments anticipated in the next decade or so.

Проектирование радиационной защиты комплекса научной аппаратуры космического аппарата дистанционного зондирования Земли

In the course of operation spacecrafts are exposed to ionizing radiation from outer space. The electronic component base (ECB) used in creating onboard radio-electronic equipment of universal space platforms does not always correspond to the external operating conditions in terms of radiation resistance for some spacecraft orbits due to a number of technical and/or economic reasons. One method to increase the radiation resistance of onboard equipment is to install additional mass protection in the form of screens on the whole equipment or local screens on individual critical radio and electronic components. The article describes the design of additional radiation protection of the geostationary spacecraft scientific equipment complex for adaptation to the radiation conditions of operation in orbits of the “Molniya” type. The solution of the problem involves several preliminary steps, namely: determining the radiation conditions for the spacecraft operation in the target orbit, estimating the local absorbed doses at the locations of the onboard equipment, estimating absorbed doses directly in the electronic component base of the equipment and analyzing the radiation resistance. Designing the radiation complex of scientific equipment was based on the values of the radiation resistance of the equipment and its components, as well as the calculated values of the local absorbed doses in the components

Minimum energy coplanar orbit transfer of geostationary spacecraft using time-averaged Hamiltonian

In this study, an analytical solution of the minimum-energy orbit transfer problem is derived under the assumption that the orbital motion is in the same plane throughout the transfer and that the transfer time is given. In order to solve the optimal control problem, the averaged canonical equations are derived using the time-averaged Hamiltonian. The corresponding two-point boundary-value problems are analytically integrated to form a set of nonlinear algebraic equations and the procedure to obtain the optimal trajectory and control input is presented. The analytical solutions are compared with the numerical solutions by the pseudospectral method and are found to be in good agreement.

Design and Realization of Dual Frequency C-Band Telemetry Transmitter for Geostationary Spacecrafts

Design and Realization of Dual Frequency C-Band Telemetry Transmitter for Geostationary Spacecrafts