Small Spacecraft Research Articles

Estimating the design parameters of a space-based radio surveillance system

Currently, small spacecraft with both optoelectronic and radar imaging equipment are becoming increasingly common. The purpose of the work is to improve the efficiency of preliminary assessment of achievable characteristics of radio surveillance payloads at the initial stages of design of small spacecraft. The paper describes the advantages of using radar imaging equipment, as well as the main trends in its development. The main areas of application of spacecraft with radar of different frequency ranges are given; the advantages of each frequency range are described. The methodology of determining the parameters of the trajectory signal when the platform moves in a circular orbit, taking into account the assumptions associated with estimating the size of the irradiation zone in azimuth is considered. Based on the considered methodology, a program is developed in Python programming language that makes it possible to estimate the length of synthesized aperture, synthesis time and azimuthal resolution of the target equipment on the basis of mass and dimensional characteristics of the antenna and spacecraft orbit parameters. A graphical user interface has been developed for the program which allows the user to interactively vary the initial data for calculation and evaluate the graphical representation of the result. The developed software system can be used for calculation of the main design parameters of small spacecraft with radar imaging equipment at the preliminary design stage.

Technologies for Increasing the Control Efficiency of Small Spacecraft with Solar Panels by Taking into Account Temperature Shock

The problem of the effective control of a small spacecraft is very relevant for solving a number of target tasks. Such tasks include, for example, remote sensing of the Earth or the implementation of gravity-sensitive processes. Therefore, it is necessary to develop new technologies for controlling small spacecraft. These technologies must take into account a number of disturbing factors that have not been taken into account previously. Temperature shock is one such factor for small spacecraft with solar panels. Therefore, the goal of the work is to create a new technology for controlling a small spacecraft based on a mathematical model of the stressed/deformed state of a solar panel during a temperature shock. The main methods for solving the problem are mathematical methods for solving initial/boundary value problems, in particular, the initial/boundary value problem of the third kind. As a result, an approximate solution for the deformation of a solar panel during a temperature shock was obtained. This solution is more general than those obtained previously. In particular, it satisfies the symmetrical condition of the solar panel. This could not be achieved by the previous solutions. We also observe an improvement (as compared to the previous solutions) in the fulfillment of the boundary conditions for the whole duration of the temperature shock. Based on this, a new technology for controlling a small spacecraft was created and its effectiveness was demonstrated. Application of the developed technology will improve the performance of the target tasks such as remote sensing of the Earth or the implementation of gravity-sensitive processes.

Upcoming MSU cubesats for space weather and astrophysical research

The program of space exploration using small spacecraft, implemented at Moscow State University, involves the installation of a set of instruments for detecting energetic particles and gamma rays on cubesat satellites. Currently, cubesats equipped with DeCoR scintillation spectrometers designed to study space weather factors and astrophysical phenomena are operating in orbit. The use of two-layer scintillation detectors makes it possible to register gamma quanta and electrons separately, which gives the possibility to study the dynamics of radiation belts and electron precipitation simultaneously with solar and astrophysical gamma ray bursts in an experiment in a solar-synchronous orbit. The results of ground-based calibrations, as well as monitoring measurements in orbit using DeCoR instruments on cubesats launched in June 2023, demonstrate good opportunities for conducting the above-mentioned studies. In order to further improve the ability to conduct detailed studies of space radiation, MSU plans to use detector suites composed of two units: a position-sensitive detector based on the set of GAGG:Ce crystals and one detector-spectrometer based on the CsI(Tl) crystal. Computer modeling shows the possibility of implementing such a suite on small satellites. In 2024, it is planned to launch two satellites with prototypes of an enhanced instrumental suite in order to test the methodology of detailed measurements.

A search for Planet Nine with small spacecraft: Three-body, post-Newtonian, non-gravitational, planetary and Kuiper Belt effects

A hypothetical gravitating body in the outer Solar System, the so-called Planet Nine, was proposed to explain the unexpected clustering of the Kuiper Belt Objects. As it has not been observed via telescopes, it was conjectured to be a primordial black hole (of the size of a quince) that could be gravitationally detected by laser-launching or solar sailing many small spacecraft. Here, we study various aspects that will affect such a search for Planet Nine. Our basic observable is the angular displacement in the trajectory of a small spacecraft which will be mainly affected by the gravity of Planet Nine, augmented with several other 3-body, non-gravitational, post-Newtonian, planetary and Kuiper Belt effects. First, we calculate the effect of the Sun in the framework of the circular restricted three-body problem of the Sun–Planet Nine-spacecraft for the two particular initial conditions. Then, we study the effects of Kuiper Belt and outer planets, namely Jupiter, Saturn, Uranus, Neptune, as well as non-gravitational perturbations such as magnetic and drag forces exerted by the interstellar medium; and the solar radiation pressure. In addition, we investigate the post-Newtonian general relativistic effects such as the frame-dragging, Schwarzschild effect, and geodetic precession on the spacecraft trajectory. We show that the leading order angular displacement is due to the solar radiation pressure for the lower spacecraft velocities, and the drag force for the higher spacecraft velocities. Among the general relativistic effects, the frame-dragging has the smallest effect; and the Schwarzschild effect due to Sun has the largest effect. However, none of the general relativistic effects produces a meaningful contribution to the detection.

STUDY OF TECHNOLOGY FOR THE RELIABILITY AND SURVIVABILITY MODELLING OF ONBOARD CONTROL SYSTEM OF SMALL SPACECRAFT OPERATING IN COMPLEX MODES

The technology of system modeling of reliability and survivability of the onboard control system (OCS) of the spacecraft is presented in the study of various options for the activation of operating modes. The technology of spacecraft functioning based on the concept of digital twins currently takes a leading position. That’s concept allows you to create realistic virtual copies of spacecraft, to simulate not only the objects themselves, but also the processes of their design and operation in various conditions of a priori uncertainty. Such conditions, first of all, should include the destructive effects of an aggressive external environment (outer space) and the multi-mode nature (sequence and intensity of the modes involved) of the functioning of onboard spacecraft systems. The implementation of the requirements of multi-purpose and multi-mode control in these conditions is closely related to the study of the reliability and survivability of such objects from the standpoint of considering their structural construction. The proposed article discusses an approach to assessing the reliability and survivability of onboard systems of small spacecraft (SS), which is based on the concept of a parametric genome structure, taking into account the multi-mode operation in an aggregated form.

Using the principle of gravitational stabilization and orientation in the design of small spacecraft

Currently, most small spacecraft (MCAS) are becoming increasingly relevant in the modern space industry. To successfully complete the tasks assigned to them, the ICS must be oriented in some way in space relative to the Earth. The orientation and stabilization system (SOS) is responsible for this task, which is necessary for monitoring and controlling the position of the MC in space. At the moment, the tasks for the MCA basically do not require complex turning maneuvers and high orientation accuracy, therefore passive and combined SOS have become widespread for them. Such systems have a long service life, are characterized by simplicity, high reliability and low weight. One of the typical systems used in modern space technology is gravity systems. The principle of gravitational SOS is based on the use of gravity acting on a body and moments of inertia relative to three mutually orthogonal axes. This article proposes a 3U CubeSat ICA project with a gravitational orientation system. The design of such a satellite requires a gravitational stabilization device, which is necessary to deploy the ICA after separating it from the launch vehicle, as well as to create a restoring moment. The gravitational device is supposed to be placed between the rigidly bonded 2U MC and the third U MCA. The advantage of this design is the fact that it becomes possible to place more payload on the MC without overloading it with various devices for the orientation and stabilization system.

Optical and electrophysical properties of nitride TiAlSiN and carbonitride TiAlSiCN coatings: influence of reactive magnetron deposition regimes

The development of thin-film thermal control coatings for small spacecraft is relevant. Coatings based on titanium nitride are capable of functioning in unfavorable conditions of near and deep space, due to their high resistance to the irradiation by high-energy particles. Using the reactive magnetron sputtering method, the nanostructured TiAlSiN and TiAlSiCN coatings were formed on the substrates of silicon oxide (SiO2), glass-ceramic CT-1 and single-crystalline silicon (Si(100)). A study of the electrophysical and optical properties of the formed coatings was carried out. The deposited coatings demonstrate a good reflectivity in the infrared range of spectrum (700–2000 nm), what is important for reducing the overheating of the spacecraft (SC) under the influence of the direct sunlight. In the visible range of spectrum (400–700 nm), a low level of total Rtotal reflection is observed. This is promising for satellites designed to observe the Earth’s surface. The values of solar absorption coefficients αs, emissivity coefficients ε0, ratios αs/ε0, as well as the equilibrium temperature Tр for the samples under study were obtained. The values of resistivity ρ and surface resistance R□, electron concentration N and electron mobility μ were determined. It has been discovered that TiAlSiN, TiAlSiCN films are electrically conductive: ρTiAlSiN = (92÷4260) ∙ 10–7 Ω ∙ m, ρTiAlSiCN = (51÷2360) ∙ 10–7 Ω ∙ m. It has been found that adding carbon to the coating composition reduces the resistance. The obtained nanostructured coatings of TiAlSiN nitride and TiAlSiCN carbonitride can be used as temperature control coatings for small spacecrafts.

Multimodal electrospray thruster for small spacecraft: design and experimental characterization

Electrospray thrusters are a promising electric micropropulsion technology which could be used to meet the propulsion needs of nanosatellites, or for fine attitude control of larger spacecraft. Multimodal propulsion is the integration of two or more propulsion modes into a system which utilizes a common propellant. Indeed, spacecraft mission simulations and models have shown that this type of multimode propulsion capacity is exciting because of the flexibility and adaptability it provides mission designers and planners. A single spacecraft would have potential to execute drastically different mission profiles, and the exact mission could even be determined post-launch. The current paper investigates a micro-propulsion system which combines a droplet and ion mode electrospray emitter into a unified multimodal system (using an ionic liquid as the common propellant for both systems). The high relative thrust droplet mode emitter was fabricated from P3 borosilicate glass while the high efficiency ion mode emitter, Carbon Xerogel dense porous substrate, was fabricated in-house. To characterize the multimodal thruster, a full beam and time-of-flight (ToF) experimental setup were developed at the RMC Advanced Propulsion and Plasma Exploration Laboratory (RAPPEL) and experiments were conducted using a custom vacuum chamber. The ion mode emitter, with a beam comprised purely of ions had an onset voltage around 1400 V with an estimated thrust performance of 0.14 μN\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu N$$\\end{document} and specific impulse of 4040 s. For droplet mode, with a mixed beam comprised of around 17%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\%$$\\end{document} droplets and 83%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\%$$\\end{document} ions, an onset voltage of 1375 V with an estimated performance of thrust at 14 μN\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu N$$\\end{document} and specific impulse of 140 s were measured. The prototype thruster demonstrates how various electrospray emitters could be combined into a multimodal system to provide flexibility and adaptability in providing effective thrust for small satellites.

Development of a simulation model and adjustment of hyperparameters of a neural network for predicting possible states of a network of small space carriages

The purpose of the research is to develop a simulation model and tune the hyperparameters of a neural network to predict possible states of a network of small spacecraft.The research methods are based on the concepts of the theory of artificial intelligence to control a group of small spacecraft (SSV) – the use of adaptive methods and tools to make decisions, similar to the mechanisms of human thinking. In relation to space communication systems with a heterogeneous structure, artificial intelligence methods and technologies are aimed at predicting the state of communication channels between network nodes and automatically reconfiguring a network of devices based on neural network learning processes. One of the most important functions of network software for the application of cognitive algorithms is to predict the quality of communication between pairs of SSVs.Results. A method has been developed for using the Transformer architecture neural network to predict possible states of the SSV network, which provides aggregation and time synchronization of data on the state of the SSV network, their use for training the neural network, as well as using the neural network to predict the quality of communication. The data format for the training sample has been created, based on the representation of the state of the SSV network, which ensures the generation of the initial state of the network, modeling the proactive mode of its operation, collecting SSV network state markers to generate training data sets in the form of chronological sequences grouped into frames, and allowing to reduce the amount of data transferred between SSVs when creating a training set. A simulation model of the SSV network has been developed, which provides generation of the initial state of the network, modeling of the proactive mode of its operation, and collection of information about the state of the SSV network to generate sets of synthetic training data.Conclusion. The article develops a simulation model of the SSV network for generating synthetic training data and predicting possible states of the SSV network, as well as a method for using a neural network to predict possible states of the SSV network.

Control strategy for trading off solar power and control input while rendezvous and docking

This paper presents a novel strategy for decoupling the attitude and orbit equations of a CubeSat for rendezvous and docking with an uncontrollable cooperative target. For computing a safe trajectory, the proposed control algorithm takes into account the solar energy received by the CubeSat. The CubeSat is equipped with a thruster for orbit maneuvers, magnetic coils for attitude control, and four fixed single-sided rectangular solar panels. The coupled dynamics arising from the dynamical model of the spacecraft is solved using a novel weighted vector-based approach. This paper presents a linearized nonlinear optimal control problem arising in small spacecrafts while trying to maximize solar energy input in the rendezvous and docking process. An intermediate orbit is defined and used to divide the problem into two different optimal control problems: rendezvous optimization and docking optimization problems. A geometrical approach based on the shape of the chaser and the target is contemplated for collision avoidance while docking. The proposed controller design is modified whenever the sunlight is obstructed by the Earth, and the maneuvering controls are redesigned accordingly for optimal rendezvous and docking. Numerical simulations have been carried out to show the efficacy of the proposed concept for steering the trade-off between solar energy and control input during the rendezvous and docking of CubeSat with a tumbling target.

Design optimization of a low response time thruster control valve for small satellite missions

Small satellites and spacecrafts use propulsion systems to stabilize their attitude, control orientation and deorbit it at the end of the mission life. The flow and thrust of the liquid propulsion system are controlled by the control valve, typically operated by solenoid. According to recent literature, space-qualified solenoid valves are expensive and financially non viable, especially for small satellite missions. In this paper, a detailed methodology is presented to design the solenoid valve dedicated for small satellites. This study includes design criteria focusing on geometrical configuration. The dynamic, and electro-magnetic models are used to characterize the solenoid valve. Dynamic modelling helps to determine the response time of valve, affecting the thruster minimum impulse bit. The physical dimensions of the designed solenoid valve are smaller than those available in commercial off-the shelf (COTS) solenoid valves. However, the efficacy of the proposed design is proven effective with the COTS space grade valve specifications, and it shows that the proposed valve consumes less power than the conventional valves. Finally, it is worth noting that despite their modest and compact physical dimensions, the proposed valve are ideal for small satellite missions.

Analysis of Suitability of Fixed-wing Aircraft for Launching Satellites into Low Earth Orbit

The use of near-Earth space for scientific and commercial purposes has skyrocketed in recent years. However, progress continues to be hampered by the cost and availability of vehicles relied upon for delivering payloads to the Earth’s orbit. The Riga Technical University (Latvia), with the assistance of the Technological University in Kielce (Poland), is developing a concept of a novel payload launch system. The implications of such a system for launching payloads into low Earth orbit (LEO) are presented in the article. The system, intended for launching small spacecraft, comprises the A319 MPA transport airplane used as a platform aircraft and a three-stage payload carrier, codenamed LatLaunch. The first and second stages of the three-stage launch vehicle are unmanned winged aircraft. The third stage is a classic rocket which, once dropped from the launch platform, takes the payload to a specific height, at a given rate of speed and at a predetermined trajectory angle. The article presents the results of a study focusing on designing this system.

Smart Ground Support Equipment—The Design and Demonstration of Robotic Ground Support Equipment for Small Spacecraft Integration and Verification

In order to reduce the costs of integration and verification processes and to optimize the assembly, integration and verification (AIV) flow in the prototype development of small- and medium-sized spacecrafts, an industrial six-axis robot was used as a universal mechanical ground support equipment instead of a tailored prototype specific ground support equipment (GSE). In particular, a robotic platform offers the possibility of embedding verification steps such as mass property determination into the integration process while offering a wider range of ergonomic adaption due to the enhanced number of degrees of freedom compared to a classical static Mechanical GSE (MGSE). This reduces development costs for projects and enhances the flexibility and ergonomics of primarily mechanical AIV operations. In this paper, the robotic MGSE system is described, the operational prospects for in-line verification are elaborated and an example is given showing the possibilities and challenges of its operational use as well as its in-line mass determination capabilities. For this purpose, a method has been developed that allows for the precise measurement of the spacecraft mass using the robot’s existing technology without the need for additional hardware. Subsequent work will extend this to determine the center of gravity and the moments of inertia of the payload on the robotic MGSE.

Modeling, Simulation and Control of a Spacecraft: Automated Rendezvous under Positional Constraints

The aim of this research paper is to propose a framework to model, simulate and control the motion of a small spacecraft in the proximity of a space station. In particular, rendezvous in the presence of physical obstacles is tackled by a virtual potential theory within a modern manifold calculus setting and simulated numerically. The roto-translational motion of a spacecraft as well as the control fields are entirely formulated through a coordinate-free Lie group-type formalism. Likewise, the proposed control strategies are expressed in a coordinate-free setting through structured control fields. Several numerical simulations guide the reader through an evaluation of the most convenient control strategy among those devised in the present work.

Modelling an Ion Thruster for a Small Spacecraft in Very Low Earth Orbit

A gridded ion thruster running on two different propellants (Xenon and Iodine) and sited within a 3U CubeSat satellite, is modelled in a Low-Earth-Orbit (altitude 400 km), using a Particle-in-Cell approach. Charged exchange collisions cause a plume backflow, which results in erosion or contamination of external spacecraft surfaces. In particular, this research is motivated by evaluating the risks to solar panel arrays from plume backflow. At low altitudes there is a wide range of ambient species able to interact electrostatically with the ion plume. In particular one must consider the plasma potential of the incoming particle flux at the solid boundaries as well as a sheath comparison and the temperature of the solar panel surfaces. This enables evaluation of the effect of temperature on the charged exchange region. A Particle-in-Cell is used, with a hybrid approach where electrons are treated as a fluid and the propellant as kinetic particles. Our results compare surface ablation for two propellants, focusing on solar panel arrays which are considered to be especially vulnerable to the backflow of ions from the plume expansion. It is found that the flux of incoming particles increases for lower satellite surface temperatures. Furthermore, Xenon results in having a lower overall effect on the sensitivity of the particle flux in comparison to Iodine.

Solution to the problem of detecting a malfunction of the position sensor of small spacecraft

The classic scheme for constructing a modern system for controlling the parameters of the angular motion of a spacecraft involves the use of high-precision gyroscopes, periodically adjusted according to the readings of optoelectronic devices. The most widely used in orientation and navigation systems are precision angular velocity sensors and gyroscopes on an electrostatic suspension, which determine the angles of rotation of the aircraft around its center of mass; Angular and linear accelerometers are also used, mounted in a certain way on the body of the aircraft.

Selection of a Neural Network Architecture for Implementation of Cognitive Functions of Network Software for Control of a Group of Interacting Small Space Vehicles

The purpose of the research is to substantiate and select the architecture of a neural network for the possibility of implementing the cognitive functions of network software for controlling a grouping of interacting small spacecraft.Methods are based on the concepts of AI theory for managing the grouping of small spacecraft - the use of adaptive methods and tools that allow making decisions, similar to the mechanisms of human thinking. With regard to space communication systems with a heterogeneous structure, AI methods and technologies are aimed at the processes of predicting the state in communication channels between network nodes and automatic reconfiguration of the network of devices based on the learning processes of a neural network (NN).Results. In the learning and forecasting mode, it is necessary to use time series of parameters and coordinates of specific pairs of small spacecraft with non-zero line of sight. Especially for time series analysis, recurrent neural networks (RNN) are used, in particular, LSTM. The idea of RNN operation is to use as input data for the current forecast not only the state vectors of the SVs and their coordinates, but also the previous value of the communication quality, actual or predictive. The paper shows that the onboard computing power of a separate MSC does not allow performing forecasting and training on board. Therefore, a dedicated ground segment of forecasting and monitoring is required, which will collect a posteriori information, periodically train the cognitive model, use it to predict the quality of communication, and transmit the results to the network nodes to build data transmission routes.Conclusion. The analysis of modern solutions and the choice of neural network architecture for the implementation of the cognitive functions of the network software for controlling the grouping of interacting small spacecraft showed that the neural networks of the Transformer architecture, which are based on the mechanism of internal attention, most fully meet the requirements of the project. The Transformer architecture allows using the entirety of a priori data, has a high learning and forecasting speed.

Terrestrial complex for receiving information from small spacecrafts

The work is devoted to the development of a terrestrial complex for receive and process information from small spacescrafts. The main requirement for these stations is their simplicity and maximum availability both in terms of cost and operating capabilities. Such stations provide a two-way exchange of information with spacecrafts in the frequency range 435-438 MHz, receive and process data transmitted in the VHF band by amateur and student satellites, and receive communications from the international space station crew and radio amateurs on Earth.

Application of small spacecraft for automatic identification of vessels

The work is devoted to the development of a specialized complex based on a CubeSat 3U nanosatellite for receiving and processing signals from the AIS system. With the help of such system, it is planned to form a domestic AIS space constellation. The urgency is connected with the current absence of the Russian Federation’s own satellite means of obtaining AIS data for monitoring the movement of ships in the world’s oceans and in its own water area. Access to this data is becoming critical in connection with the development of the Northern Sea Route and the development of shipping in the Azov, Black Seas and the Far East.

Development of automated system for receiving and analysing telemetry data from small spacecrafts

The system presented in the study is designed to increase the share of automation in the process of interaction with small spacecraft (SSС) at all stages of operation. Automatic operation of the system will reduce the cost of human resources, the number of errors in management, and increase the time of uninterrupted and continuous operation. The system independently calculates the time of all possible sessions of a group of small spacecrafts with a ground station; forms on its basis a schedule for the operation of a ground station, taking into account historical and future calculation sessions; implements control of the rotary antenna according to the compiled session schedule; decodes telemetry data, writes it to the database, carries out preprocessing and visualization. The system was developed taking into account possible scaling to several receiving stations.