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![Trails from Starlink satellites passing through the field of view of a telescope during an observation, shortly after launch [34].](publication/362378005/figure/fig2/AS:11431281222539670@1707303155551/Trails-from-Starlink-satellites-passing-through-the-field-of-view-of-a-telescope-during.jpg)
Trails from Starlink satellites passing through the field of view of a telescope during an observation, shortly after launch [34].
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![Number of cataloged space objects by NORAD [2].](publication/362378005/figure/fig1/AS:11431281222539667@1707303155303/Number-of-cataloged-space-objects-by-NORAD-2_Q320.jpg)
![The Tracking and Imaging Radar (TIRA) [64].](publication/362378005/figure/fig5/AS:11431281222613706@1707303156577/The-Tracking-and-Imaging-Radar-TIRA-64_Q320.jpg){kind=tracking}
The rapid development of Low Earth Orbit (LEO) mega constellations has significantly contributed to several aspects of human scientific progress, such as communication, navigation, and remote sensing. However, unrestrained deployment of constellations has also strained orbital resources and increased spacecraft congestion in LEO, which seriously af...
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Citations
... Compared with single complex spacecraft, constellation has the advantages of high coverage capability, uniform revisit period, and continuous visible time [1]. The rapid development of Low Earth Orbit (LEO) mega constellations has greatly contributed to several aspects of human scientific progress [2]. At present, satellite constellation has been applied in communication, reconnaissance, navigation, and other space missions [3], such as GPS, Glonass, Beidou, Starlink, etc. Mega constellation will inevitably become an important means of Earth observation and a key point in the development of future satellite technology [4]. ...
The configuration optimization design of Low Earth Orbit observation mega constellation in complex space environment is a nonlinear problem that is difficult to solve analytically. In this paper, a constellation design method is proposed, considering satellite imaging width, formation flying of subgroup satellites, and global uniform coverage by payloads. Firstly, a configuration of satellites with the same subsatellite trajectory is proposed, and its orbital analytical expression under J2 perturbation is provided. Then, the relative motion feature points are extracted near the orbit of each satellite, and a group of uniform natural accompanying satellites are set to corresponding points. Afterwards, the orbit parameters of satellite and its companions are set as initial values, and the precise orbits under the High Precision Orbit Propagator model are solved in the neighborhood by using the Nondominated Sort Particle Swarm Optimization algorithm. Finally, the correctness of the configuration design method is verified by numerical simulation.
... Digital Object Identifier X Densely populated urban areas are prone to penetration losses due to blockages that can cause severe power degradation, especially for high-frequency networks, whose performance can be limited by such blockages. Many LEO constellations, including OneWeb and IridiumNext, operate in the Ku and Ka frequency bands which can achieve higher throughput, wider bandwidth, smaller antenna size, and narrower beams [2]. Nevertheless, penetration losses persist, resulting in high levels of performance fluctuation, causing a disruption of key system characteristics such as user association and mobility. ...
... Moving forward, our ambitions include scaling up the deployment of the 5S payload across an array of satellites, with a special focus on LEO Mega constellations [54]. The ultimate objective is to forge a robust, real-time or near realtime, large-area Internet of Things (IoT) ecosystem. ...
The Satellite-based Internet of Things (S-IoT) system offers a promising solution for accessing IoT devices in areas where terrestrial networks are inaccessible. These devices have significant roles in various scenarios, including aeronautic and maritime surveillance, data collection from sensors, and distress signals from sinking ships. However, covering numerous IoT targets with a minimal number of satellites poses a challenge. This paper proposes a solution known as the 5S payload designed for S-IoT. The 5S payload integrates five subsystems into a single unit, comprising the following components: (1) Automatic Identification System (AIS) for ship surveillance, (2) Very High-Frequency Data Exchange System (VDES) enabling two-way communication for ships, (3) Automatic Dependent Surveillance-Broadcast (ADS-B) system for aircraft surveillance, (4) Data Collection System (DCS) for user-defined sensors, and (5) Emergency Search and Rescue (ESR) system. The design of the 5S payload adheres to the CubeSat standard and occupies a compact 1.5U size, enabling rapid manufacturing and deployment. The feasibility of the 5S payload was demonstrated on the TianTuo-5 satellite launched on August 23, 2020. Additionally, this paper presents in-orbit experimental results spanning three years to further illustrate the effectiveness of the 5S payload.
... The LEO segment especially would be crowded in coming years with mega constellations like Star Link and One Web already orbiting and plans of other mega constellations like Kuiper by Amazon and Telesat planning to deploy thousands of satellites in LEO. 1 As the number of LEO space objects is growing dramatically, the safety and fault-free operation of in-orbit spacecraft is receiving increased attention. 2 The safety of the satellite is largely dependent on the operational state of the satellite and therefore monitoring and ensuring the correct health of the satellites is becoming a challenge when it comes to large constellations. 3 Mission operations related to determining the health of satellites are being achieved using Quantitative and Qualitative models traditionally. ...
Autonomy is becoming a prime requirement for satellite mission control operations. Data‐driven methods like Machine Learning models are playing a key role in bringing in autonomy. Health keeping data from satellite telemetry is a key ingredient in these data‐driven methods. In real‐world satellite operations, the health‐keeping telemetry data gradually drifts due to adverse space weather effects and wear and tear of electronic and mechanical components. The key question that arises is how to detect and quantify the data drift which is generally a gradual phenomenon. This paper discusses a novel statistical method for detecting data drift occurring in satellite telemetry. For the purpose of experimental work in this paper, an actual telemetry data set of the BUS CURRENT sensor which is part of the Electrical Power System of a Low Earth Orbit Satellite was considered. Data drift detection test was carried out using this sensor data using the developed novel statistical method and with Kolmogorov Smirnov test which is a probabilistic method. Both results are analysed and compared. Thereafter novel statical method was used to check its efficacy using a synthetic data set with induced drift.
... As a resurgence in the space industry, the declining cost of producing and launching nanosatellites has stimulated exponential growth in low Earth orbit (LEO) constellations over the past two decades [1,2]. The volume of space-native raw data increases exponentially with constellation size, and due to the bandwidth constraints of the satellite-ground link, timely downloads of all the updated data are not achievable [3]. ...
Large-scale low Earth orbit (LEO) remote satellite constellations have become a brand new, massive source of space data. Federated learning (FL) is considered a promising distributed machine learning technology that can communicate optimally using these data. However, when applying FL in satellite networks, it is necessary to consider the unique challenges brought by satellite networks, which include satellite communication, computational ability, and the interaction relationship between clients and servers. This study focuses on the siting of parameter servers (PSs), whether terrestrial or extraterrestrial, and explores the challenges of implementing a satellite federated learning (SFL) algorithm equipped with client selection (CS). We proposed an index called “client affinity” to measure the contribution of the client to the global model, and a CS algorithm was designed in this way. A series of experiments have indicated the advantage of our SFL paradigm—that satellites function as the PS—and the availability of our CS algorithm. Our method can halve the convergence time of both FedSat and FedSpace, and improve the precision of the models by up to 80%.
... These challenges highlight the need for alternative solutions and technologies to enhance the performance and robustness of GNSS in challenging environments. However, the use of Low Earth Orbit (LEO) constellations for PNT has attracted more and more interest due to the thousands of satellites launched or planned to be launched by private companies such as Starlink, OneWeb and Kuiper for applications such as the global internet, IoTs, telecommunications, etc. [5]. ...
The use of Low Earth Orbit (LEO) mega-constellations for Positioning, Navigation, and Timing (PNT) services has attracted a great deal of interest, as they could complement the Global Navigation Satellite System (GNSS) in specific conditions/environments. Despite the fact that it is recognized that the use of mega-constellations for positioning services could provide better performance in urban canyons, no work has provided an analysis of such performance improvement. This paper provides a statistical analysis of the performance in terms of availability and Geometric Dilution of Precision (GDOP) of the positioning service of some current mega-constellations in deep urban canyon environments and compares the performance with the one achieved by GNSS systems. A new geometric model for typical urban canyons is developed. The developed model has been used for the analysis of the availability and GDOP of the positioning service in two representative urban canyon areas, namely the city of London and the Manhattan district of New York City. The geometric parameters used in the simulations are derived by statistically processing publicly available data on the height and length of the buildings and the width of the streets in the considered urban areas.
... Finnish ICEYE [17] and American Capella [18] make use of very compact and lightweight design for both the bus and the payload. Further data can be found in [19,20]. ...
Observation frequency is analyzed over four areas of the Mediterranean basis where poaching, illegal fishing, and illegal trafficking of goods and people are active. To this end, a geometrical observation and dynamical model is utilized which accounts for multiple satellites and multiple orbital planes and is applied to SIASGE and Sentinel-1 missions. Statistics show that a few hours are needed in the mean to reobserve the same area.
... In recent years, increasing space exploration and development of mega-constellations have increased the space debris [1][2] formed by the collisions of dysfunctional or end-of-mission satellites [3]; this poses a serious threat to the security and stability of the space environment. The International Space Station (ISS) performed at least 3 maneuvers in 2020 to prevent potential collisions with space debris [4]. ...
Electrodynamic tether (EDT) is a key prospective technique for space-debris removal without the use of propellant. However, there are 2 main shortcomings of the classical EDT system. One is that the conductive tether with a single wire should exceed several kilometers to produce the expected force, which increases the risk of collision and damage. The other is the heavy current or high voltage caused by the overlong tether, which may even melt itself. Therefore, a novel electrodynamic multi-tether (EMT) system has been proposed here to overcome the above disadvantages of the classical EDT system. The EMT system has multi tethers connecting the 2 end bodies, which has more complex dynamic behaviors than the EDT system. In order to promote the application of the EMT system, this paper will pay attention to the dynamic modeling and analysis of the EMT system, to reveal the primary dynamic characteristics. Firstly, the dynamic equation of the novel EMT system was established. Secondly, the linear assumption and vibration theory were utilized to illustrate its primary dynamic characteristic. Finally, the expressions of the vibration period and critical current of tether were given and numerical simulations were conducted to verify these analyses. The results showed that the tether libration equation can be simplified when the size of main satellite is much smaller than that of tether. Besides, the tether will go tumbling immediately when the practical current exceeds the critical current.
... In the past few years, on-orbit servicing compromising refueling, repairs, and upgrades has acquired significant attention because it would enhance the operational life and capability of space systems [1][2][3][4][5][6][7][8]. Long et al. [9] summarized five broad categories of benefits of servicing: (1) reduce risk of mission failure, (2) reduce mission cost, (3) increase mission performance, (4) improve mission flexibility, and (5) enable new missions. ...
This paper studies the multiple geosynchronous spacecraft refueling problem (MGSRP) with multiple servicing spacecraft (Ssc) and fuel depots (FDs). In the mission scenario, multiple Ssc and FDs are parked in the geosynchronous Earth orbit (GEO) initially. Ssc start from FDs and maneuver to visit and refuel multiple GEO targets with known demands. These capacitated Ssc are expected to rendezvous with fuel-deficient GEO targets and FDs for the purpose of delivering the fuel stored in FDs to GEO targets. The objective is to find a set of Pareto-optimal solutions with minimum fuel cost and mission duration. The MGSRP is a much more complex variant of multidepot vehicle routing problems mixing discrete and continuous variables. A two-nested optimization model is built. We propose a new multiobjective hybrid particle swarm optimization to solve the outer-loop problem, and the design variables are the refueling sequence, task assignment, time distribution, and locations of FDs. In the inner-loop problem, branch and bound method is used to find the optimal decision variable for a given outer-loop solution. Finally, numerical simulations are presented to illustrate the effectiveness and validity of the proposed approach.
... According to NASA, the number of cataloged objects larger than 10 cm in space is over 26,000 as of May 2023 [1]; more than half of these are fragments. In addition, because of the deployment of mega constellations, including Starlink, OneWeb, and Kuiper, the number of space objects in low Earth orbit (LEO) will further grow [2,3,4]. Such a large number of space objects would not only increase the collision probability with wellworking satellites but will also cause a waste of orbit resources by occupying valuable orbit slots [5]. ...
... Recently, several mega-constellations have been proposed, including Starlink, OneWeb, Telesat, and Kuiper. Among them, the constellations with the highest number of planned satellites are Starlink and OneWeb [2,3,4]. Their large scale makes them representative of constellation programs; therefore, they were selected to make constellation launch predictions in the context of their firstphase deployment plans and launch progress in recent years. ...
Increasingly frequent launch activities, as well as the development of mega constellations, would cause a drastic increase in the number of space objects, which will then alter the evolution of outer space. To reveal this long-term change, an accurate space-environment model is required. There are two main approaches to building this model, one of which is to track the state of space objects individually, which will use significant computing resources; the other is to take macroscopic variables, such as spatial density, as the state variable to depict a group of space debris, which requires less computational effort. In this study, a space debris environment evolution model with spatial density as the state variable is established, which considers the nonzero eccentricity of the debris orbit and utilizes the NASA breakup model to ensure accuracy. In addition, the Gaussian mixture model (GMM) is applied to take the uncertainty of launch activities into account. The long-term impacts of mega constellations and their post-mission disposal (PMD) on the debris environment are discussed based on the evolution model. It was found that constellations with high orbit altitude, such as OneWeb, will lead to an exponential increase in space objects in low Earth orbit (LEO). In addition, deorbit time is the main factor affecting the PMD efficiency, followed by deorbit strategies.
