Satellite Subsystems Research Articles

State-of-the-Art DC-DC Converters for Satellite Applications: A Comprehensive Review

Future manned and deep space missions require an Electrical Power System (EPS) that can deliver high power while overcoming challenges like weight and volume constraints and the harsh space environment. A variety of DC-DC converters are employed to supply, store, and transmit power to various satellite subsystems. This paper identifies the design specifications of DC-DC converters for a range of satellite applications and offers a state-of-the-art review of non-isolated, isolated, and integrated topologies. Foreseeing the future of electric propulsion, various sources for electric propulsion are compared, and converters for electric propulsion are studied. The topologies are compared regarding practical parameters like reliability, modularity, redundancy, efficiency, and power density. Furthermore, an application-wise comparison of the topologies and the type of satellite they are suitable for is provided. Finally, the research gaps pertaining to various space applications, such as the design of DC-DC converters, electric propulsion, deep space exploration, electronic component selection, and space-based power satellites, are presented.

Labyrinth seal design for space applications

Labyrinth seals, extensively used in space applications, serve to prevent the loss of liquid lubricants and shield satellite subsystems from contamination. These seals are essential for the reliable functioning of bearings and for protecting satellite subsystems from contamination. This study compares analytical predictions of lubricant loss against experimental measurements and computer simulations to optimize labyrinth seal configurations. Analytical models tend to overestimate mass loss by 5–8 times compared to experimental data, indicating limited reliability for complex seal geometries. Simulations using MolFlow+ and COMSOL Multiphysics align closely with experimental results, providing accurate mass loss predictions. Key findings highlight that labyrinth length, width, and surface roughness are critical factors in minimizing evaporative mass loss. Notably, stepped labyrinth seals with relief grooves and optimized step positioning effectively reduce molecular beaming effects and improve sealing performance compared to straight geometries. Effective sealing not only reduces mission failures but also helps to minimize space debris, thereby promoting safer satellite missions.

Multi-granularity negotiation correction method for satellite digital twin model

Affected by uncertainty, there are errors between the digital twin model and the real system, which need to be corrected and the uncertainty of the model quantitatively evaluated as the basis for selecting the model when using it. However, the satellite digital twin model has the characteristics of multi-dynamic, multi-spatial scale, and multi-physical field coupling. The rigidity problem of differential equations and the multi-scale problem of partial differential equations will appear during numerical solution. If many telemetry parameters are corrected at the system level at the same time, the results will not converge. A multi-granularity negotiation correction framework for satellite digital twin models is proposed. The parameters are grouped by analyzing the correlation and frequency domain characteristics of telemetry parameters. Models of different granularities of satellite subsystems and components are established, and multi-granularity digital twin models are constructed on demand. The coupling relationship between different levels of satellite components is studied, and a negotiation correction method is proposed. The framework is verified using real on-orbit telemetry data. The research results show that the negotiation correction method proposed in this paper improves the RMSE accuracy by more than that of the unused one , and the correction results are more systematic and complete.

LOW-COST PHOTOVOLTAIC EMULATOR WITH A HIGH-DYNAMIC RESPONSE FOR SMALL SATELLITE APPLICATIONS

In recent years, growing interest from academic institutions and emerging countries in small satellite missions has led to a need for photovoltaic emulators (PVEs) during subsystem testing. Unfortunately, the market lacks suitable PVEs with adequate power and characteristics for these applications. To fill this gap, this proposal introduces a low-cost, flexible, and high-dynamic response PVE for testing small satellite subsystems. The proposed PVE includes an analog electronic circuit that amplifies the reference current-voltage (I-V) curve from a space reference solar cell. It is characterized by accurate amplification of solar cell curves under various conditions, achieving a maximum output power of 124 W. This capability enables assessment under diverse space application scenarios with rapidly changing climatic conditions. The emulator's remarkable flexibility is demonstrated through the use of various solar cell technologies for space applications as references. Experimental results effectively confirm the practical feasibility of the proposed PVE.

Proposal of a Process for selection solar cells Nanosatellite

By the PEDAGOSAT project we aim to democratize all educational activities related to CubeSat-class: nanosatellite, from physics through engineering, technical achievements, integration, to testing and operations to the greatest number of students. The key idea is to eventually have our academic nanosatellite training platform offering an open source opportunity to Algerians universities, and having the capacity to cover all engineer training areas relating to "small satellites". As part of this project, some satellite subsystems, test and emulation facilities will be realized, processes and procedures for testing and integration related to space technology will be addressed, implemented and even mastered. The presented work is part of the development of the on-board power system, and covers the selection of solar cells for the manufacture of solar panels of this satellite. The main source of energy present in space is solar energy, it a continuous and inexhaustible source that a satellite can. In satellite we use a solar panel to ensure its operation. In the dimensioning of a satellite, it is essential to identify these electrical power requirements named “power budget analysis”. Indeed, this makes it possible to determine the number of cells and/solar panels to be installed to guarantee the power continuity of the satellite in sunlight phase of its orbit by recharging its batteries and feeding equipment’s. During all the mission duration; from the beginning of life (BOL) after the launch to it deorbits (EOL) to disintegrate in the atmosphere. For the PEDAGO-SAT as for other satellites, it will be necessary to verify the parameters and physical characteristics of the solar cells/panels according to certified procedures and methodologies in order to be able to pronounce on their qualification for aerospace use. In this context, we propose a low-cost process revision to be able to carry out qualification tests with an accessible facility in the university labs. This revision will also concern the development of homemade means and software that fit the investments that may be made by the Algerian research and academic facilities. As illustrated in this paper a performance evaluation of low-cost solar cells was done using the developed solution and the selected cells will be integrated in the solar panels of PEDAGOSAT.

Multidisciplinary design and optimization of intelligent Distributed Satellite Systems for EARTH observation

Recent advances in small, connected and intelligent satellite systems have created a wide range of opportunities for the adoption of intelligent Distributed Satellite Systems (iDSS) in communication, navigation and Earth Observation (EO) missions. iDSS are goal-oriented systems comprising of multiple satellites or modules that interact, communicate and/or cooperate with each other to accomplish the desired mission goals. The ability to mass-produce low-cost small satellites and contemporary developments in avionics/astrionics technology have spurred interest in iDSS, especially for Low Earth Orbit (LEO) satellite constellations and regional clusters. The SmartSat Cooperative Research Centre (CRC) and Australian space roadmap, as well as the landmark National Space Programme strategy and priorities, encompass EO. To date, insufficient progress and no conclusive outcome was made in terms of how contemporary Multidisciplinary Design Optimization (MDO) models and tools can be best tailored to the new capabilities and specificities of iDSS. The MDO of iDSS is challenging because it introduces new variables and highly non-linear interactions. In this context, we propose an MDO methodology to optimize an iDSS for persistent coverage over the entire Australian landmass. Several aspects of the iDSS are considered in this work, including the constellation model, subsystem models and the coupling interactions between different satellite subsystems and constellation design parameters. The constellation configuration, as well as the subsystems, are modelled using OpenMDAO, which is used to analyze and visualize the planned iDSS EO mission. The iDSS is then optimized using the Multidisciplinary Feasible (MDF) architecture approach and the iDSS interdependencies are numerically treated using the Nonlinear Block Gauss-Seidel (NLBGS) iterative solver. The resulting N2 diagrams are presented and the proposed solution is both spatially and temporally optimized, demonstrating that the proposed iDSS will enable near real-time persistent coverage over the entire Australian continent.

System-Level Total Ionizing Dose Testing of Satellite Subsystems: EagleEye Microsatellite Case Study

A system-level total ionizing dose test method of satellite subsystems is discussed in the context of the radiation qualification of a satellite. System-level tests are performed with high-energy X-rays, and the irradiation results of the key subsystems, including the on-board computer, attitude- and orbit-control-system computer, and battery management system, are presented and analyzed in terms of the repeatability of the results, the observability issues, and the importance of the test conditions. Furthermore, the main benefits of the system-level total ionizing dose tests of the given subsystems are discussed, as well as the risks related to performing tests at the system level.

Thermal control of a small satellite in low earth orbit using phase change materials-based thermal energy storage panel

Thermal control of small satellites in low earth orbit (LEO) is not easy due to the intermittent heating conditions. The satellites in LEO are sometimes present in the illumination zone and other times in the eclipse zone, which imposes difficulties keeping their temperatures within the safe range. The present study investigates a thermal energy storage panel (TESP) integrated with phase change materials (PCM) to control the temperatures of satellite subsystems. The TESP was made of aluminium with outer dimensions of 100 mm long, 71 mm wide, and 25 mm high. The PCMs used were organic-based materials, which were RT 12, RT 22, and RT 31. The TESP was tested under two thermal powers of 11 W and 14 W. These powers are typical of satellite subsystems. The finite volume method was adopted for thermal analysis of the TESP. The significance of this study is that it provides a detailed computational analysis of the TESP for microsatellites' temperature management under typical LEO conditions. The research outcomes show a significant advancement in the thermal managing performance of PCM-based TESP. RT 22 could reduce the highest temperature by 4.7 % and raise the lowest by 9.5 %. It was observed from the analysis that the PCM with intermediary melting temperature provided better thermal control efficiency. RT 12 reported a lower extreme temperature difference (ETD) and could decrease it by 63.9 % relative to the case with no PCM. At the same time, RT 22 reported an ETD of 23 min and could reduce it by 63 % relative to the case with no PCM at 14 W. The present study concluded that PCMs show great potential as a viable approach for effectively thermally managing devices that experience cyclic thermal fluctuations, such as the subsystems of satellites operating in LEO.

Experimental study of space lubricant evaporation in a high vacuum environment

The liquid lubricant evaporation in space applications poses significant challenges, raising the risk of inaccurate estimation of lubricant implementation and the potential contamination of satellite subsystems. The study of vacuum evaporation becomes highly relevant with the increasing use of liquid lubricants in satellite constellations. This research presents a novel methodology for assessing the lubricant evaporation rate, focusing on establishing a correlation between existing analytical models and experimental measurements. The obtained experimental results clearly demonstrate a disparity between the existing analytical models and the measured evaporated mass of vacuum base oils. Importantly, these results indicate higher evaporation rates predicted by the analytical approach. This emphasises the importance of refining the analytical models to accurately predict the amount of liquid lubricant evaporated.

Analysis and Design of a Diplexing Power Divider for Ku-Band Satellite Applications.

In dual-band RF front-end systems, to transmit different frequency signals in different paths, each path requires the power to be divided along two transmission channels. In such systems, a circuit is created in which the input ports of power dividers with different frequency bands are connected to the output ports of a diplexing circuit in a cascade form. These circuits often contain different band filters in their schemes and have a complicated design. In this paper, an innovative technique for designing a diplexing power divider for Ku-band applications is presented. The proposed structure is designed on multilayer printed circuit boards (PCBs) and the utilization of a transition based on an extended SMA connector. The extended SMA connector provides two separate paths for the transmission of the RF signals. Hence, the proposed structure eliminates the need for intricate and bulky bandpass filters, allowing seamless integration with other planar devices and components within Ku-band satellite subsystems. In fact, the proposed architecture channelizes the divided output electromagnetic signals into two separate frequency spectrums. With the presented technique, two frequency ranges are envisaged, covering Ku-band applications at 13-15.8 GHz and 16.6-18.2 GHz. With the proposed structure, an insertion loss as low as 1.5 dB was achieved. A prototype of the proposed power-divider diplexing device was fabricated and measured. It exhibits a good performance in terms of return loss, isolation, and insertion losses.

NanoSMAD – A First Order System Configuration Design Tool for Nano and Micro Satellites

The emergence of nano and micro satellites, which weigh less than 100 kg, is causing a significant transformation in the space industry. The existing Space Mission Analysis and Design (SMAD) tools, which are primarily designed for larger satellites, often become irrelevant for these smaller satellites in terms of spacecraft mass, power, pointing requirement, total mission duration, fault tolerance, and design cost. To address this, we have developed a web based nanoSMAD tool specifically for designers of nano and micro satellites. This tool utilizes a comprehensive database of approximately 140 nano and micro satellites along with their internal subsystem specifications. By using the nanoSMAD tool, designers can efficiently develop nano and micro satellite systems by entering their requirements, which then generates high-level system design and requirement specifications. This process enables the tool to provide a basic satellite configuration design and generates a Master Equipment List (MEL) of subsystems. To further customize the design, users can provide more specific parameter inputs or select components from a drop-down menu, resulting in an iterative custom design approach. The satellite database used by the nanoSMAD tool is regularly updated through online surveys, including web scraping, to gather information on the latest non-space-grade off-the-shelf nano and micro satellite subsystems. This ensures that the tool stays up-to-date with the newest advancements in the field. Additionally, the nanoSMAD tool offers a unique feature of verifying the electrical interface compatibility of subsystems, which is an innovative aspect of the tool. Novice small satellite communities will greatly benefit from the nanoSMAD tool as it seamlessly generates an initial nano and micro satellite system design, providing a first-order understanding of the satellite’s configuration and requirements.

Basic Principles and Mechanical Considerations of Satellites: A Short Review

AbstractSatellites are used for navigation, communication, oceanography, astronomy, etc.. Satellites come in a diversity of sizes and forms. Depending on the satellite’s mission, different subsystems are used. These subsystems are installed inside a housing to protect them from the space environment. This housing, which is also known as the satellite primary structure or mechanical structure, is made of durable materials that can endure severe conditions during launch and in the orbit. The optimisation of satellite mass is crucial right now since satellites are losing mass every day to reduce the cost of manufacturing and launching. This review first introduces an overview of the satellite classifications and subsystems. Then, the different types of mechanical load analysis the satellite subjects itself to are demonstrated. The advanced approaches for promoting the performance of the mechanical structures of satellites are explored, with a spotlight on the effect of the optimisation parameters of isogrid and honeycomb sandwich structures on the mechanical performance of the satellite primary structure. The assembly, integration and testing (AIT) of the small satellite are briefly presented. Finally, the important potential designs to improve the mechanical performance of the satellite primary structure and the challenges of further research are summarised.

Anomaly Detection for Agile Satellite Attitude Control System Using Hybrid Deep-Learning Technique

Agile low-Earth-orbit (LEO) observation satellites need a robust attitude control and determination system. It is a critical satellite subsystem, which stabilizes the satellite to different desired orientations during its mission using different actuators. The detection of satellite misorientation is a highly challenging problem because it requires continuous monitoring of data from hundreds of satellite sensors to guarantee healthy operability. In this paper, the authors propose a data-driven deep-learning framework for detecting satellite misorientation by analyzing attitude control subsystem telemetry data. The proposed approach combines a hybrid predictive deep-learning model that consists of long short-term memory and convolutional neural networks in two parallel paths to predict telemetry data and a robust isolation forest classifier for anomaly detection purposes that can classify output residuals as normal or anomalous. The hybrid model was optimized by the particle swarm optimization algorithm to ensure faster fitness function convergence with optimal model hyperparameters. The suggested data-driven model was validated using real telemetry datasets, including real anomalous case studies. The experimental results proved the suggested approach’s superiority for identifying satellite misorientation as well as helping satellite operators monitor the system’s health and deduce the causes of anomalies to aid in decision-making.

Electrochemical Engineering to Optimize the Next Generation of Space Power

The increasing democratization of space has sparked new research developments for on-orbit systems. As the technology flown becomes more sophisticated, their power needs increase as well, highlighting the battery as a critical component that ensures a consistent supply of electricity can be fed to the necessary satellite subsystems, independent of solar panel exposure (i.e. during eclipse conditions). However, despite the growth of the industry, space batteries are derived from technology engineered for terrestrial use, and thus are not optimized for all on-orbit challenges. It is the job of the electrochemist to develop batteries designed to meet the unique needs of the space environment. This talk will outline some of the key challenges facing the future of space power, including power requirements for in-space manufacturing, reduced capacity after an extended lifetime in space, and SWAP-C (size, weight, power and cost) considerations for smallsat constellations. Different pathways to optimize electrochemical engineering to meet these needs will be discussed, and recent efforts by the National Reconnaissance Office to support basic research and academic outreach will be highlighted.

Numerical study about thermal performance evaluation of PCM and PCM/fins composite-based thermal control module at microgravity conditions

Satellite subsystems are becoming smaller and have extra power density. There are only two types of heat transport in space: conduction and radiation, making thermal management more difficult. For the thermal regulation of satellite subsystems, thermal energy storage materials are appropriate. In the present study, small satellite subsystems were controlled using a phase change material (PCM)-based heat sink. The design of the aluminium heat sink was according to the outside dimensions of the subsystem in a small satellite. The PCM material used in the work was RT 35. Integrated fins of various shapes were used to overcome PCM's poor thermal conductivity. Three fin geometries were investigated: parallel fins, cross fins, and pin fins. Three shapes of pin fins were evaluated: square pin, circular pin, and triangular pin fins. The heat sink was exposed to a thermal cycle with 80 min cooling and 10 min heating processes. The results reveal that pin fins have better thermal performance than cross and parallel fins. For pin fins, the triangular pin fin provides the best thermal performance among all cases. Maximum temperatures reported for triangular pin fin were 41.5 °C with a 10.8 % reduction. The results indicated a considerable improvement in thermal performance by increasing the number of pin fins.

Boosting the thermal management performance of a PCM-based module using novel metallic pin fin geometries: Numerical study

Satellite avionics and electronic components are getting compact and have high power density. Thermal management systems are essential for their optimal operational performance and survival. Thermal management systems keep the electronic components within a safe temperature range. Phase change materials (PCMs) have high thermal capacity, so they are promising for thermal control applications. This work adopted a PCM-integrated thermal control device (TCD) to manage the small satellite subsystems under zero gravity conditions thermally. The TCD's outer dimensions were selected upon a typical small satellite subsystem. The PCM adopted was the organic PCM of RT 35. Pin fins with different geometries were adopted to boost the lower thermal conductivity of the PCM. Six-pin fins geometries were used. First, the conventional geometries were square, circular, and triangular. Second, the novel geometries were cross-shaped, I-shaped, and V-shaped fins. The fins were designed at two-volume fractions of 20% and 50%. The electronic subsystem was assumed to be "ON" for 10 min releasing 20 W of heat, and "OFF" for 80 min. The findings show a remarkable decrease in the TCD's base plate temperature by 5.7 ℃ as the fins' number changed from 15 to 80 for square fins. The results also show that the novel cross-shaped, I-shaped, and V-shaped pin fins could significantly enhance thermal performance. The cross-shaped, I-shaped, and V-shaped reported a decrease in the temperature by about 1.6%, 2.6%, and 6.6%, respectively, relative to the circular fin geometry. V-shaped fins could also increase the PCM melt fraction by 32.3%.

ATOMIC OXYGEN IN LOW EARTH ORBITS, A RETROSPECTIVE REVIEW STUDY

The article presents a retrospective review of atomic oxygen (AO) research in low Earth orbit (LEO).The space environment of LEO is a barrier to all satellites passing through it. Several of its constituent parts pose a great danger to satellite materials and subsystems. Such orbits are convenient for remote sensing and experimental satellites. In order to maintain the operational level of spacecraft, it is necessary to carry out thorough studies of the LEO environment and its components. AO, which is a hyperactive state of oxygen, is considered one of the most dangerous components of the LEO environment. It can react with many materials and thereby change the physical, optical and mechanical properties that affect the functionality of the satellite. To maintain the satellite in its orbit with a certain margin of reliability, it is necessary to reduce the aggressive influence on it of the environmental components of LEO. Predicting the impact of AO on materials that will be used in space ensures their correct selection. The work provides some recommendations for the creation of AO facilities for testing materials exposed to the aggressive influence of the space environment.

Stray Magnetic Field Measurement Method of Magnetic Hysteresis Curve of Open-Ended Sensor and Actuator Cores

In the design and development of measurement systems, such as magnetometric security systems or sophisticated devices such as satellites, it is necessary to consider the magnetic properties of all its parts and components, especially if it contains any magnetometric subsystem. The magnetic parameters of the materials are generally well described by the manufacturers in relation to their unprocessed raw state. However, their magnetic properties change as the subsequent machining or heat treatment is performed. These behavioral reactions of the material may lead to changes in its hysteresis during the magnetization cycles. This effect is necessary to consider, especially in the case of metallic ribbons, the magnetic characteristics of which are usually estimated by measurements performed on toroidal cores. Since the magnetic properties of a toroidal core differ from the magnetic properties of the preferably used open-ended samples, the corresponding measurement method needs to be used to determine its magnetic characteristics. Therefore, in the proposed article, the authors present a stray magnetic field-based method and measuring workstation intended to measure the magnetic hysteresis curves of the ferromagnetic open-ended samples used in the applications concerning the magnetometric systems and stabilization subsystems of small satellites. The physical background of the measurement method is described in detail, as well as the hardware and software used. The magnetic hysteresis curves of a small satellite electromagnetic actuator were measured as an example of an open-ended ferromagnetic component produced from amorphous ribbons, the permeability of which differs in comparison to manufacturer-stated permeability of raw amorphous material. The results are supplemented by measurements of the core characteristics of the used magnetometer probe, as well as by the characteristics of the semi-produced materials used for the production of both investigated cores. The primary advantage of the presented measurement method lies in the ability of design validation prior to the production of the final component and its assembly.

Reasoning-Based Scheduling Method for Agile Earth Observation Satellite with Multi-Subsystem Coupling

With the rapid development of agile Earth observation satellites (AEOSs), these satellites are able to conduct more high-quality observation missions. Nevertheless, while completing these missions takes up more data transmission and electrical energy resources, it also increases the coupling within each satellite subsystem. To address this problem, we propose a reasoning-based scheduling method for an AEOS under multiple subsystem constraints. First, we defined the AEOS mission scheduling model with multi-subsystem constraints. Second, we put forward a state variable prediction method that reflects the different coupling states of a satellite after analyzing the coupling relationships between various subsystems and identifying the primary limiting coupling states for each subsystem. Third, we established the reasoning rules corresponding to the planning strategies of different coupling states of the satellite by adding two planning strategies based on the planning strategies of existing planning methods. By comparing the proposed method to three heuristic scheduling methods and a meta-heuristic scheduling method, the results show that our method has better performance in terms of scheduling results and efficiency.

CanSat design and implementation for remote sensing applications

With the increasing potential of satellite technology, it becomes crucial to learn its principles and develop the basic satellite subsystems for the undergraduate level. Working on a real satellite is a challenging target and requires a solid technical background. In contrast, less complex models, such as CanSat, CubSat and HeptaSat, introduce basic ideas to the undergraduate studies level. This paper presents the CanSat design and implementation for remote sensing applications such as measuring the CO2 level in contaminated areas. The CanSat has the size of a soft drink can and simulates the subsystems of the satellite (e.g., payload, power, communication, onboard computer, and structural). Its mission was to be released from a certain altitude and send real-time data to the ground station during landing. The design process was elucidated at the subsystem level. It included the mission requirements and specifications, component selection, and software and hardware design. Arduino nano was utilised as an onboard computer. A printed Circuit Board (PCB) was designed using Diptrace© to connect the electronic components to Arduino Nano. Xbee was used as a communication module to send the collected data to the host computer. This data was visualised in real-time by LabView©.