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Keywords = Starlink satellites

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23 pages, 5644 KiB  
Article
Exploring the Performance of Transparent 5G NTN Architectures Based on Operational Mega-Constellations
by Oscar Baselga, Anna Calveras and Joan Adrià Ruiz-de-Azua
Network 2025, 5(3), 25; https://doi.org/10.3390/network5030025 - 18 Jul 2025
Viewed by 315
Abstract
The evolution of 3GPP non-terrestrial networks (NTNs) is enabling new avenues for broadband connectivity via satellite, especially within the scope of 5G. The parallel rise in satellite mega-constellations has further fueled efforts toward ubiquitous global Internet access. This convergence has fostered collaboration between [...] Read more.
The evolution of 3GPP non-terrestrial networks (NTNs) is enabling new avenues for broadband connectivity via satellite, especially within the scope of 5G. The parallel rise in satellite mega-constellations has further fueled efforts toward ubiquitous global Internet access. This convergence has fostered collaboration between mobile network operators and satellite providers, allowing the former to leverage mature space infrastructure and the latter to integrate with terrestrial mobile standards. However, integrating these technologies presents significant architectural challenges. This study investigates 5G NTN architectures using satellite mega-constellations, focusing on transparent architectures where Starlink is employed to relay the backhaul, midhaul, and new radio (NR) links. The performance of these architectures is assessed through a testbed utilizing OpenAirInterface (OAI) and Open5GS, which collects key user-experience metrics such as round-trip time (RTT) and jitter when pinging the User Plane Function (UPF) in the 5G core (5GC). Results show that backhaul and midhaul relays maintain delays of 50–60 ms, while NR relays incur delays exceeding one second due to traffic overload introduced by the RFSimulator tool, which is indispensable to transmit the NR signal over Starlink. These findings suggest that while transparent architectures provide valuable insights and utility, regenerative architectures are essential for addressing current time issues and fully realizing the capabilities of space-based broadband services. Full article
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26 pages, 4569 KiB  
Article
Orbit Determination for Continuously Maneuvering Starlink Satellites Based on an Unscented Batch Filtering Method
by Anqi Lang and Yu Jiang
Sensors 2025, 25(13), 4079; https://doi.org/10.3390/s25134079 - 30 Jun 2025
Viewed by 451
Abstract
Orbit determination for non-cooperative low Earth orbit (LEO) objects undergoing continuous low-thrust maneuvers remains a significant challenge, particularly for large satellite constellations like Starlink. This paper presents a method that integrates the unscented transformation into a batch filtering framework with an optimized rho-minimum [...] Read more.
Orbit determination for non-cooperative low Earth orbit (LEO) objects undergoing continuous low-thrust maneuvers remains a significant challenge, particularly for large satellite constellations like Starlink. This paper presents a method that integrates the unscented transformation into a batch filtering framework with an optimized rho-minimum sigma points sampling strategy. The proposed approach uses a reduced dynamics model that considers Earth’s non-spherical gravity and models the combined effects of low-thrust and atmospheric drag as an equivalent along-track acceleration. Numerical simulations under different measurement noise levels, initial state uncertainties, and across multiple satellites confirm the method’s reliable convergence and favorable accuracy, even in the absence of prior knowledge of the along-track acceleration. The method consistently converges within 10 iterations and achieves 24 h position predictions with root mean square errors of less than 3 km under realistic noise conditions. Additional validation using a higher-fidelity model that explicitly accounts for atmospheric drag demonstrates improved accuracy and robustness. The proposed method can provide accurate orbit knowledge for space situational awareness associated with continuously maneuvering Starlink satellites. Full article
(This article belongs to the Section Remote Sensors)
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29 pages, 2193 KiB  
Article
Evaluation of TOPSIS Algorithm for Multi-Criteria Handover in LEO Satellite Networks: A Sensitivity Analysis
by Pascal Buhinyori Ngango, Marie-Line Lufua Binda, Michel Matalatala Tamasala, Pierre Sedi Nzakuna, Vincenzo Paciello and Angelo Kuti Lusala
Network 2025, 5(2), 15; https://doi.org/10.3390/network5020015 - 2 May 2025
Viewed by 972
Abstract
The Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) is widely recognized as an effective multi-criteria decision-making algorithm for handover management in terrestrial cellular networks, especially in scenarios involving dynamic and multi-faceted criteria. While TOPSIS is widely adopted in terrestrial cellular [...] Read more.
The Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) is widely recognized as an effective multi-criteria decision-making algorithm for handover management in terrestrial cellular networks, especially in scenarios involving dynamic and multi-faceted criteria. While TOPSIS is widely adopted in terrestrial cellular networks for handover management, its application in satellite networks, particularly in Low Earth Orbit (LEO) constellations, remains limited and underexplored. In this work, the performance of three TOPSIS algorithms is evaluated for handover management in LEO satellite networks, where efficient handover management is crucial due to rapid changes in satellite positions and network conditions. Sensitivity analysis is conducted on Standard Deviation TOPSIS (SD-TOPSIS), Entropy-TOPSIS, and Importance-TOPSIS in the context of LEO satellite networks, assessing their responsiveness to small variations in key performance metrics such as upload speed, download speed, ping, and packet loss. This study uses real-world data from “Starlink-on-the-road-Dataset”. Results show that SD-TOPSIS effectively optimizes handover management in dynamic LEO satellite networks thanks to its lower standard deviation scores and reduced score variation rate, thus demonstrating superior stability and lower sensitivity to small variations in performance metrics values compared to both Entropy-TOPSIS and Importance-TOPSIS. This ensures more consistent decision-making, avoidance of unnecessary handovers, and enhanced robustness in rapidly-changing network conditions, making it particularly suitable for real-time services that require stable, low-latency, and reliable connectivity. Full article
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19 pages, 4898 KiB  
Article
Near-Real-Time Global Thermospheric Density Variations Unveiled by Starlink Ephemeris
by Zhuoliang Ou, Jiahao Zhong, Yongqiang Hao, Ruoxi Li, Xin Wan, Kang Wang, Jiawen Chen, Hao Han, Xingyan Song, Wenyu Du and Yanyan Tang
Remote Sens. 2025, 17(9), 1549; https://doi.org/10.3390/rs17091549 - 27 Apr 2025
Viewed by 673
Abstract
Previous efforts to retrieve thermospheric density using satellite payloads have been limited to a small number of satellites equipped with GNSS (Global Navigation Satellite System) receivers and accelerometers. These satellites are confined to a few orbital planes, and analysis can only be conducted [...] Read more.
Previous efforts to retrieve thermospheric density using satellite payloads have been limited to a small number of satellites equipped with GNSS (Global Navigation Satellite System) receivers and accelerometers. These satellites are confined to a few orbital planes, and analysis can only be conducted after the data are processed and updated, resulting in sparse and delayed thermospheric density datasets. In recent years, the Starlink constellation, developed and deployed by SpaceX, has emerged as the world’s largest low Earth orbit (LEO) satellite constellation, with over 6000 satellites in operations as of October 2024. Through the strategic use of multiple orbital shells featuring various inclinations and altitudes, Starlink ensures continuous near-global coverage. Due to extensive coverage and frequent maneuvers, SpaceX has publicly released predicted ephemeris data for all Starlink satellites since May 2021, with updates approximately every 8 h. With the ephemeris data of Starlink satellites, we first apply a maneuver detection algorithm based on mean orbital elements to analyze their maneuvering behavior. The results indicate that Starlink satellites exhibit more frequent maneuvers during thermospheric disturbances. Then, we calculate the mechanical energy loss caused by non-conservative forces (primarily atmospheric drag) through precise dynamical models. The results demonstrate that, despite certain limitations in Starlink ephemeris data, the calculated mechanical energy loss still effectively captures thermospheric density variations during both quiet and disturbed geomagnetic periods. This finding is supported by comparisons with Swarm-B data, revealing that SpaceX incorporates the latest space environment conditions into its orbit extrapolation models during each ephemeris update. With a maximum lag of only 8 h, this approach enables near-real-time monitoring of thermospheric density variations using Starlink ephemeris. Full article
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16 pages, 630 KiB  
Article
A Study on Performance Improvement of Maritime Wireless Communication Using Dynamic Power Control with Tethered Balloons
by Tao Fang, Jun-han Wang, Jaesang Cha, Incheol Jeong and Chang-Jun Ahn
Electronics 2025, 14(7), 1277; https://doi.org/10.3390/electronics14071277 - 24 Mar 2025
Cited by 2 | Viewed by 457
Abstract
In recent years, the demand for maritime wireless communication has been increasing, particularly in areas such as ship operations management, marine resource utilization, and safety assurance. However, due to the difficulty of deploying base stations(BSs), maritime communication still faces challenges in terms of [...] Read more.
In recent years, the demand for maritime wireless communication has been increasing, particularly in areas such as ship operations management, marine resource utilization, and safety assurance. However, due to the difficulty of deploying base stations(BSs), maritime communication still faces challenges in terms of limited coverage and unreliable communication quality. As the number of users on ships and offshore platforms increases, along with the growing demand for mobile communication at sea, conventional terrestrial base stations struggle to provide stable connectivity. Therefore, existing maritime communication primarily relies on satellite communication and long-range Wi-Fi. However, these solutions still have limitations in terms of cost, stability, and communication efficiency. Satellite communication solutions, such as Starlink and Iridium, provide global coverage and high reliability, making them essential for deep-sea and offshore communication. However, these systems have high operational costs and limited bandwidth per user, making them impractical for cost-sensitive nearshore communication. Additionally, geostationary satellites suffer from high latency, while low Earth orbit (LEO) satellite networks require specialized and expensive terminals, increasing hardware costs and limiting compatibility with existing maritime communication systems. On the other hand, 5G-based maritime communication offers high data rates and low latency, but its infrastructure deployment is demanding, requiring offshore base stations, relay networks, and high-frequency mmWave (millimeter-wave) technology. The high costs of deployment and maintenance restrict the feasibility of 5G networks for large-scale nearshore environments. Furthermore, in dynamic maritime environments, maintaining stable backhaul connections presents a significant challenge. To address these issues, this paper proposes a low-cost nearshore wireless communication solution utilizing tethered balloons as coastal base stations. Unlike satellite communication, which relies on expensive global infrastructure, or 5G networks, which require extensive offshore base station deployment, the proposed method provides a more economical and flexible nearshore communication alternative. The tethered balloon is physically connected to the coast, ensuring stable power supply and data backhaul while providing wide-area coverage to support communication for ships and offshore platforms. Compared to short-range communication solutions, this method reduces operational costs while significantly improving communication efficiency, making it suitable for scenarios where global satellite coverage is unnecessary and 5G infrastructure is impractical. Additionally, conventional uniform power allocation or channel-gain-based amplification methods often fail to meet the communication demands of dynamic maritime environments. This paper introduces a nonlinear dynamic power allocation method based on channel gain information to maximize downlink communication efficiency. Simulation results demonstrate that, compared to conventional methods, the proposed approach significantly improves downlink communication performance, verifying its feasibility in achieving efficient and stable communication in nearshore environments. Full article
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14 pages, 3837 KiB  
Article
Solar Irradiance Mitigation in LEO Optical Inter-Satellite Links via Inter-Shell Based Path Optimization
by Jae Seong Hwang, Ji-Yung Lee and Hyunchae Chun
Appl. Sci. 2025, 15(6), 3364; https://doi.org/10.3390/app15063364 - 19 Mar 2025
Viewed by 719
Abstract
Solar irradiance is a critical factor influencing the reliability of optical inter-satellite links (O-ISLs). Despite its significance, limited research has focused on addressing this challenge. This work investigates the impact of solar irradiation on the optimal path configuration. A multi-directional field-of-view (FoV) model [...] Read more.
Solar irradiance is a critical factor influencing the reliability of optical inter-satellite links (O-ISLs). Despite its significance, limited research has focused on addressing this challenge. This work investigates the impact of solar irradiation on the optimal path configuration. A multi-directional field-of-view (FoV) model is used to practically accommodate the solar irradiance imposed on each optical transceiver module in a single satellite. The effectiveness of the optimal path configurations is evaluated through detour mitigation strategies, comparing inter-plane and inter-shell link alternatives in intercontinental scenarios within the northern hemisphere. In the scenarios, it is found that there is a tradeoff between the FoV and the level of the signal-to-noise ratio (SNR) required to overcome the effects of solar irradiance. Also, seasonal alterations in the sun’s incident direction significantly influence the link availability, with unusable link rates nearly doubling in summer compared to spring because of orbital inclinations tending to be aligned more closely with the solar direction toward Earth. The proposed inter-shell-based path optimization reduces the total link distance by up to 2500 km compared to those of the inter-plane configurations, demonstrating superior performance in mitigating impairment due to solar irradiance. Full article
(This article belongs to the Section Aerospace Science and Engineering)
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22 pages, 2490 KiB  
Article
Quantifying the Environmental Impacts of Manufacturing Low Earth Orbit (LEO) Satellite Constellations
by Sritharan Thirumalai Kumaran, Chekfoung Tan and Michael Emes
Sustainability 2024, 16(21), 9431; https://doi.org/10.3390/su16219431 - 30 Oct 2024
Cited by 1 | Viewed by 2480
Abstract
The growing amount of space debris in the low Earth orbit poses a danger to manned as well as uncrewed missions. Additionally, the new business model of providing internet from space is emerging among new space players, making low Earth orbit more crowded. [...] Read more.
The growing amount of space debris in the low Earth orbit poses a danger to manned as well as uncrewed missions. Additionally, the new business model of providing internet from space is emerging among new space players, making low Earth orbit more crowded. These factors have encouraged the space community to focus on sustainability in space. Satellite manufacturers typically have the capability to perform complete life cycle analysis (LCA) on their own products based on the manufacturing data. However, there is a lack of a method for non-manufacturers such as environmentalists and the general public to predict the carbon footprint of satellite manufacturing using a subsystem-level mass budget. Hence, this paper presents a method to quantify environmental pollution caused by the production of satellite constellations. Starlink is taken as a case study in this paper, and mass budget is predicted based on space systems engineering budget estimation techniques, the parametric method, and Federal Communication Commission orbital data. With the budget table used as an input, space-specific life cycle assessment is performed based on European Space Agency’s life cycle inventory database. Finally, the single score for Starlink constellation version 1 was found to be 76 kilo points. This signifies the annual environmental load. These results could be helpful in obtaining an overview of the environmental effects of the production phase of satellite constellations. Further, the results could act as a foundation for further research on implementing more circular approach practices on Earth as well as in space. Full article
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35 pages, 1750 KiB  
Article
The Past, Present, and Future of the Internet: A Statistical, Technical, and Functional Comparison of Wired/Wireless Fixed/Mobile Internet
by Shahriar Shirvani Moghaddam
Electronics 2024, 13(10), 1986; https://doi.org/10.3390/electronics13101986 - 19 May 2024
Cited by 6 | Viewed by 6263
Abstract
This paper examines the quantitative and qualitative situation of the current fixed and mobile Internet and its expected future. It provides a detailed insight into the past, present, and future of the Internet along with the development of technology and the problems that [...] Read more.
This paper examines the quantitative and qualitative situation of the current fixed and mobile Internet and its expected future. It provides a detailed insight into the past, present, and future of the Internet along with the development of technology and the problems that have arisen in accessing and using broadband Internet. First, the number of users and penetration rate of the Internet, the various types of services in different countries, the ranking of countries in terms of the mean and median download and upload Internet data speeds, Internet data volume, and number and location of data centers in the world are presented. The second task introduces and details twelve performance evaluation metrics for broadband Internet access. Third, different wired and wireless Internet technologies are introduced and compared based on data rate, coverage, type of infrastructure, and their advantages and disadvantages. Based on the technical and functional criteria, in the fourth work, two popular wired and wireless Internet platforms, one based on optical fiber and the other based on the 5G cellular network, are compared in the world in general and Australia in particular. Moreover, this paper has a look at Starlink as the latest satellite Internet candidate, especially for rural and remote areas. The fifth task outlines the latest technologies and emerging broadband Internet-based services and applications in the spotlight. Sixthly, it focuses on three problems in the future Internet in the world, namely the digital divide due to the different qualities of available Internet and new Internet-based services and applications of emerging technologies, the impact of the Internet on social interactions, and hacking and insecurity on the Internet. Finally, some solutions to these problems are proposed. Full article
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17 pages, 4734 KiB  
Article
BRDF-Based Photometric Modeling of LEO Constellation Satellite from Massive Observations
by Yao Lu
Universe 2024, 10(5), 215; https://doi.org/10.3390/universe10050215 - 14 May 2024
Cited by 1 | Viewed by 1366
Abstract
Modeling the brightness of satellites in large Low-Earth Orbit (LEO) constellations can not only assist the astronomical community in assessing the impact of reflected light from satellites, optimizing observing schedules and guiding data processing, but also motivate satellite operators to improve their satellite [...] Read more.
Modeling the brightness of satellites in large Low-Earth Orbit (LEO) constellations can not only assist the astronomical community in assessing the impact of reflected light from satellites, optimizing observing schedules and guiding data processing, but also motivate satellite operators to improve their satellite designs, thus facilitating cooperation and consensus among different stakeholders. This work presents a photometric model of the Starlink satellites based on the Bidirectional Reflectance Distribution Function (BRDF) using millions of photometric observations. To enhance model accuracy and computational efficiency, data filtering and reduction are employed, and chassis blocking on the solar array and the earthshine effect are taken into account. The assumptions of the model are also validated by showing that the satellite attitude is as expected, the solar array is nearly perpendicular to the chassis, and both the solar array pseudo-specular reflection and the chassis earthshine should be included in the model. The reflectance characteristics of the satellites and the apparent magnitude distributions over station are finally discussed based on the photometric predictions from the model. In addition to assessing the light pollution and guiding the development of response measures, accurate photometric models of satellites can also play an important role in areas such as space situational awareness. Full article
(This article belongs to the Section Solar and Stellar Physics)
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19 pages, 1304 KiB  
Article
Cooperative Caching and Resource Allocation in Integrated Satellite–Terrestrial Networks
by Xiangqiang Gao, Yingzhao Shao, Yuanle Wang, Hangyu Zhang and Yang Liu
Electronics 2024, 13(7), 1216; https://doi.org/10.3390/electronics13071216 - 26 Mar 2024
Cited by 2 | Viewed by 1766
Abstract
Due to the rapid development of low earth orbit satellite constellations, e.g., Starlink, OneWeb, etc., integrated satellite-terrestrial networks have been viewed as a promising paradigm to globally provide satellite internet services for users. However, when the contents from ground data centers are provided [...] Read more.
Due to the rapid development of low earth orbit satellite constellations, e.g., Starlink, OneWeb, etc., integrated satellite-terrestrial networks have been viewed as a promising paradigm to globally provide satellite internet services for users. However, when the contents from ground data centers are provided for users by satellite networks, there will be high capital expenditures in terms of communication delay and bandwidth usage. To this end, in this paper, a cooperative-caching and resource-allocation problem is investigated in integrated satellite–terrestrial networks. Popular contents, which are cached on satellites and ground data centers, can be accessed via inter-satellite and satellite–terrestrial networks in a cooperative way. The optimization problem is formulated to jointly minimize the deployment costs of storage resource usage and network bandwidth consumption. A cooperative caching and resource allocation (CCRA) algorithm based on a neighborhood search is proposed to address the problem. The simulation results demonstrate that the proposed CCRA algorithm outperforms Greedy and BFS in reducing the deployment costs. Full article
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16 pages, 4608 KiB  
Article
Exploring Interference Issues in the Case of n25 Band Implementation for 5G/LTE Direct-to-Device NTN Services
by Alexander Pastukh, Valery Tikhvinskiy and Evgeny Devyatkin
Sensors 2024, 24(4), 1297; https://doi.org/10.3390/s24041297 - 17 Feb 2024
Cited by 5 | Viewed by 3767
Abstract
This paper delves into an interference analysis, focusing on the forthcoming Starlink Generation 2 satellites, stated to operate within the 1990–1995 MHz frequency band. The aim is to assess the potential interference from this Starlink system to the satellite receivers of mobile satellite [...] Read more.
This paper delves into an interference analysis, focusing on the forthcoming Starlink Generation 2 satellites, stated to operate within the 1990–1995 MHz frequency band. The aim is to assess the potential interference from this Starlink system to the satellite receivers of mobile satellite systems (MSSs), which are set to function within the 1980–2010 MHz range, and satellite receivers of the NTN systems, which are planned to operate in the n256 bands, defined by the 3GPP specifications. Through simulation-based evaluations, both single-entry and aggregate interference levels from Starlink to MSSs and NTN systems are comprehensively explored. To estimate the interference impact, several protection criteria were used. The study is in line with the Recommendations of International Telecommunication Union (ITU-R) and common approaches that are used when performing compatibility studies between satellite systems. The findings of this study demonstrate the feasibility of utilizing the n25 band for NTN direct-to-device services. Full article
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20 pages, 575 KiB  
Article
Signal Occlusion-Resistant Satellite Selection for Global Navigation Applications Using Large-Scale LEO Constellations
by Junqi Guo, Yang Wang and Chenyang Sun
Remote Sens. 2023, 15(20), 4978; https://doi.org/10.3390/rs15204978 - 16 Oct 2023
Cited by 3 | Viewed by 1635
Abstract
With the continuous construction of large-scale Low Earth Orbit (LEO) constellations, their potential for Global Navigation Satellite System (GNSS) applications has been emphasized. This study aims to derive an optimal positioning configuration formula based on the ratio of high-elevation and low-elevation satellites, which [...] Read more.
With the continuous construction of large-scale Low Earth Orbit (LEO) constellations, their potential for Global Navigation Satellite System (GNSS) applications has been emphasized. This study aims to derive an optimal positioning configuration formula based on the ratio of high-elevation and low-elevation satellites, which can improve the positioning accuracy and overcome the accuracy loss due to signal occlusion. A genetic algorithm is used to solve the optimal positioning configuration problem for large-scale satellite selection. Through a simulation using Starlink satellites currently in orbit, it is verified that the traditional recursive algorithm cannot be applied to satellite selection for large-scale constellations. The proposed formula has a similar accuracy to the Quasi-Optimal algorithm when there is no signal occlusion and the satellites are uniformly selected. However, the accuracy of the latter deteriorates significantly under signal occlusion. Our algorithm can effectively overcome this problem. Moreover, we discuss the effect of different types of obstructions on the accuracy loss. We find that the Quasi-Optimal algorithm is more sensitive to a single large-angle obstruction than multiple small-angle obstructions. Our proposed formula can reduce the localization accuracy degradation caused by signal occlusions in both scenarios. Full article
(This article belongs to the Special Issue GNSS Advanced Positioning Algorithms and Innovative Applications)
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15 pages, 545 KiB  
Article
Space Weather Effects on Satellites
by Rositsa Miteva, Susan W. Samwel and Stela Tkatchova
Astronomy 2023, 2(3), 165-179; https://doi.org/10.3390/astronomy2030012 - 22 Aug 2023
Cited by 12 | Viewed by 9134
Abstract
The study presents a concise overview on the main effects on satellites due to space weather drivers compared to the well-known interplanetary, magnetospheric and ground-based consequences. The solar-activity-driven influences include specific physics-based effects on the spacecraft surface and on-board electronics due to electromagnetic [...] Read more.
The study presents a concise overview on the main effects on satellites due to space weather drivers compared to the well-known interplanetary, magnetospheric and ground-based consequences. The solar-activity-driven influences include specific physics-based effects on the spacecraft surface and on-board electronics due to electromagnetic emission and energetic particles as well as complex effects due to geomagnetic storms which may endanger the mission performance and spacecraft longevity. We select as test examples the Starlink satellites in the period 2019–2022 and present the temporal correspondence between their launches and the space weather phenomena. Based on comparative analysis, we discuss whether the occurrence vs. the intensity of solar and interplanetary drivers of space weather can be considered as a cause for orbital stability problems and satellite loss. The results suggest that a sequence of geomagnetic disturbances together with multiple weak space weather events could lead to severe levels of atmospheric drag ending in a service or satellite loss. Full article
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13 pages, 5834 KiB  
Article
Ionospheric Weather at Two Starlink Launches during Two-Phase Geomagnetic Storms
by Tamara Gulyaeva, Manuel Hernández-Pajares and Iwona Stanislawska
Sensors 2023, 23(15), 7005; https://doi.org/10.3390/s23157005 - 7 Aug 2023
Cited by 4 | Viewed by 2927
Abstract
The launch of a series of Starlink internet satellites on 3 February 2022 (S-36), and 7 July 2022 (S-49), coincided with the development of two-phase geomagnetic storms. The first launch S-36 took place in the middle of the moderate two-phase space weather storm, [...] Read more.
The launch of a series of Starlink internet satellites on 3 February 2022 (S-36), and 7 July 2022 (S-49), coincided with the development of two-phase geomagnetic storms. The first launch S-36 took place in the middle of the moderate two-phase space weather storm, which induced significant technological consequences. After liftoff on 3 February at 18:13 UT, all Starlink satellites reached an initial altitude of 350 km in perigee and had to reach an altitude of ~550 km after the maneuver. However, 38 of 49 launched spacecrafts did not reach the planned altitude, left orbit due to increased drag and reentered the atmosphere on 8 February. A geomagnetic storm on 3–4 February 2022 has increased the density of the neutral atmosphere up to 50%, increasing drag of the satellites and dooming most of them. The second launch of S-49 at 13:11 UT on 7 July 2022 was successful at the peak of the two-phase geomagnetic storm. The global ionospheric maps of the total electron content (GIM-TEC) have been used to produce the ionospheric weather GIM-W index maps and Global Electron Content (GEC). We observed a GEC increment from 10 to 24% for the storm peak after the Starlink launch at both storms, accompanying the neutral density increase identified earlier. GIM-TEC maps are available with a lag (delay) of 1–2 days (real-time GIMs have a lag less than 15 min), so the GIMs forecast is required by the time of the launch. Comparisons of different GIMs forecast techniques are provided including the Center for Orbit Determination in Europe (CODE), Beijing (BADG and CASG) and IZMIRAN (JPRG) 1- and 2-day forecasts, and the Universitat Politecnica de Catalunya (UPC-ionSAT) forecast for 6, 12, 18, 24 and 48 h in advance. We present the results of the analysis of evolution of the ionospheric parameters during both events. The poor correspondence between observed and predicted GIM-TEC and GEC confirms an urgent need for the industry–science awareness of now-casting/forecasting/accessibility of GIM-TECs during the space weather events. Full article
(This article belongs to the Special Issue Advances in GNSS Positioning and GNSS Remote Sensing)
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17 pages, 5000 KiB  
Article
Research on Enhanced Orbit Prediction Techniques Utilizing Multiple Sets of Two-Line Element
by Junyu Chen and Chusen Lin
Aerospace 2023, 10(6), 532; https://doi.org/10.3390/aerospace10060532 - 3 Jun 2023
Cited by 8 | Viewed by 4137
Abstract
Acquiring accurate space object orbits is crucial for many applications such as satellite tracking, space debris detection, and collision avoidance. The widely used two-line element (TLE) method estimates the position and velocity of objects in space, but its accuracy can be limited by [...] Read more.
Acquiring accurate space object orbits is crucial for many applications such as satellite tracking, space debris detection, and collision avoidance. The widely used two-line element (TLE) method estimates the position and velocity of objects in space, but its accuracy can be limited by various factors. A combination of multiple TLEs and advanced modeling techniques such as batch least squares differential correction and high-precision numerical propagators can significantly improve TLE accuracy and reliability, ensuring better space object surveillance. Previous studies analyzed additional factors that may influence TLE accuracy and evaluated the accuracy of Starlink TLE using precise ephemeris data from SpaceX. The results indicate that utilizing multiple TLEs for precise orbit determination can significantly enhance the performance of orbit prediction methods, particularly when compared to SGP4. By leveraging 10-day Starlink TLEs, the accuracy of 5-day predictions can be improved by approximately twofold. Additionally, producing two pseudo-observations within an orbital period near the TLE epoch yields the greatest effect on prediction accuracy, with this distribution of pseudo-observations increasing accuracy by approximately 10% compared to a uniform distribution. Further research can explore more data fusion and machine learning approaches to optimize operations in space. Full article
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