In terms of cataloged debris produced, the anti-satellite test carried out by Russia, in November 2021, at an altitude of about 480 km, leading to the destruction of the old satellite Cosmos 1408, ...was the second worst to date and represented the third worst fragmentation in orbit. It generated more than 1/4 of the cataloged debris produced over 55 years by all such tests and almost twice as many as were produced by all previous Soviet tests. After placing this event in its historical context, this paper analyzes in detail how the evolution of the Cosmos 1408 debris cloud affected the environment below 600 km in the first seven months, focusing on the two operational space stations and the Starlink large constellation of satellites. During the first six months following the test, the Cosmos 1408 cloud of fragments nearly doubled the average flux of cataloged objects on the International Space Station and increased by about 3/4 that on China's Tiangong. In the same period, the Starlink large constellation saw an average increase in the flux of cataloged objects of about 20%. Some orbital planes, the “counter-rotating” ones with respect to the Cosmos 1408 debris cloud, were more affected than others, and the affected planes gradually changed over time, due to the differential precession of cloud and constellation nodes. However, being the Starlink constellation 70 km higher up, the flux of Cosmos 1408 cataloged debris steadily decreased over the period analyzed, due to the cloud orbital decay, reducing to just over a quarter of its extrapolated initial value after seven months.
•A review of ASAT tests as a source of orbital debris was presented.•The impact of the Cosmos 1408 destruction was put into context.•The cataloged debris flux increase on space stations was computed and discussed.•The debris flux increase and evolution on Starlink orbit planes was analyzed.•A moratorium on this type of ASAT tests was recommended, including low LEO.
Signal Structure of the Starlink Ku-Band Downlink Humphreys, Todd E.; Iannucci, Peter A.; Komodromos, Zacharias M. ...
IEEE transactions on aerospace and electronic systems,
10/2023
Journal Article
Recenzirano
Odprti dostop
We develop a technique for blind signal identification of the Starlink downlink signal in the 10.7 to 12.7 GHz band and present a detailed picture of the signal's structure. Importantly, the signal ...characterization offered herein includes the exact values of synchronization sequences embedded in the signal that can be exploited to produce pseudorange measurements. Such an understanding of the signal is essential to emerging efforts that seek to dual-purpose Starlink signals for positioning, navigation, and timing, despite their being designed solely for broadband Internet provision.
The Shortest Distance Path (SDP) problem is a critical routing issue in communication networks, particularly in satellite networks. Typically, SDP is solved by graph-based iterative algorithms, while ...an explicit or analytic approach is challenging. However, considering the orbit dynamics and topology regularity, this paper proposes, for the first time, an explicit analytic phase-based algorithm StepClimb to directly solve the SDP in low-Earth orbit (LEO) satellite networks. Based on the relationship between satellite phase and inter-satellite link distance, the SDP is modeled with the satellite phase, and SDP problem is converted into a total phase offset problem through theoretical derivations. Then StepClimb is derived in two cases, respectively. Monte-Carlo simulations verify StepClimb's accuracy, which has zero error in the mono-valley case and has less than 0.1% error in the bi-valley case. The algorithm performs better in larger-scale constellations and can save over 99.4% computational cost compared to Dijkstra algorithm. Further, the SDP pattern and features in Starlink constellation are analyzed. The model proves that most inter-plane hops in the SDP occur successively, and the simulations further indicate that these hops prefer satellites in the higher latitude regions.
On 4 February 2022, 38 Starlink satellites were destroyed by the geomagnetic storm, which brought significant financial, aerospace and public influences. In this letter, we reveal the space weather ...process during 3–4 February 2022 geomagnetic disturbances, from the Sun all the way to the satellite orbiting atmosphere. Initiated by an M1.0 class flare and the following coronal mass ejection (CME), a moderate geomagnetic storm was stimulated on 3rd February by the CME arrival at Earth. Subsequently, another moderate storm was triggered on 4th February by the passage of another CME. Model simulations driven by solar wind show that the first geomagnetic storm induced around 20% atmospheric density perturbations at 210 km altitude on 3rd February. The unexpected subsequent storm on 4th February led to a density enhancement of around 20%–30% at around 210 km. The resulting atmospheric drag can be even larger, since the regional density enhancement was over 60% and the satellite orbits were continuously decaying. This event brings forth the urgent requirements of better understanding and accurate prediction of the space weather as well as collaborations between industry and space weather community.
Plain Language Summary
The operating satellites in low‐Earth orbit give the rapid information transfer between the satellites and the Earth. At the same time, these satellites are continuously slowed down and affected by the dense atmosphere of the Earth, which is referred to as the atmospheric drag. This effect can be greater during space weather events such as geomagnetic storms. Over the past years, thousands of Starlink satellites have been deployed by the SpaceX company into low‐Earth orbit. However, on 4th February, 38 Starlink satellites were destroyed before they were lifted to a higher Earth orbit, which brought an economic loss estimated to be several tens of millions of dollars. Geomagnetic indices indicated two successive geomagnetic storms, which could warm the upper atmosphere and increase the atmospheric drag. In this work, we provide a comprehensive review on the process of space weather during this event from the Sun all the way to the terrestrial atmosphere. We have illustrated the solar eruption, solar wind propagation, and atmospheric density enhancement, using both observed data and model simulations. This study calls for more accurate modeling and better understanding of space weather as well as collaborations between industry and space weather community.
Key Points
We reveal the space weather process during 3–4 February 2022 geomagnetic storms, from the Sun to the satellite orbiting atmosphere
Two coronal mass ejections led to the unexpected complex sequential storms and enhanced global atmospheric density over 20% at 210 km
This event calls for the urgent need of accurate space weather prediction and collaborations between industry and space weather community
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.
This quantitative study explores the impact of the Starlink project on the internet service provider market in Thailand. A convenience sampling technique was used to recruit 617 participants, who ...completed an online questionnaire. The study examined several independent variables, including demographic factors, such as gender, age, education, status and income, and user behaviour, such as devices used for internet access, time spent online and social media platforms used. Binary regression was used to analyse the data. The results showed that the Starlink project had a significant impact on the competitive structure of the internet service provider market in Thailand. This impact was influenced by factors such as age, education, income, internet duration, mobile internet use, Facebook and TikTok. The study recommends that businesses develop effective strategies to meet the needs and expectations of their customers. Organisations with internet access have the opportunity to collect data to develop new products, which can give them a competitive edge. It is important to maintain a competitive environment to prevent artificially low collection rates or exorbitant prices due to collusion or tacit pricing agreements.
•The quantitative study examines the effects of the Starlink project on the Internet service provider market in Thailand.•The introduction of Starlink, a satellite-based internet service, has influenced the dynamics and competition within the market.•Internet service providers should adapt their offerings and improve their services to remain competitive in the changing landscape influenced by the Starlink project.•This study highlights the significant impact of the Starlink project on Thailand's Internet service provider market and underscores the importance of adapting business strategies to meet customer demands.•This study emphasises the potential competitive advantage gained through data collection and the need to maintain a competitive environment in the market.
Satellite constellations are widely used for communication, navigation, and Earth observation purposes. They provide good ground coverages and serve better for these needs. Of all the configurations, ...the Walker constellation is extensively applied in many navigation satellite systems and some low Earth orbit communication constellations, since it can be easily designed and has good coverage. Despite of these advantages, the satellites in Walker constellation generally have different ground tracks. When multiple Walker constellations are to be coordinated, in terms that the orbital planes precess synchronously with the same satellite mean motion Ω1, the semi-major axes a of these Walker constellations would be significantly different even when the orbital inclinations differ by a small amount. The Space Exploration Corp (SpaceX) claimed a new constellation design in a patent for their multi-shell Starlink satellite constellation. Constellation shells with different inclinations have small altitude differences, which facilitates regulatory approval and deployment. Satellites in the same shell can also be easily designed to share the same ground track. Although they claimed these features in the patent, SpaceX shared little technical details regarding how to design these constellations. Here in this paper, we analyze the features of the Starlink constellation, and try to find a practical approach to design a Starlink-like constellation, as well as how to determine the rules for inter-satellite links within the constellation.
The number of satellites orbiting the Earth has significantly increased and large constellations based on thousands of satellites are currently being designed and operated. Among them the Starlink ...project, owned by SpaceX, is in advanced phase. The massive presence of orbiting objects could have a negative impact on astronomical research. In the case of observations with long exposure times and/or wide field of view (FoV), numerous bright tracklets, caused by the reflection of sunlight on a transiting satellite, may appear in the images. For this reason, the Sapienza Space Systems and Space Surveillance Laboratory (S5Lab), which has been involved in research on space debris and space surveillance for many years, started a new research project on the photometric characterization of some satellites of the Starlink project, using red, green and blue filters and comparing the results with observations performed without filters in order to analyze the features of the transit of Starlink satellites. The observations will stress the high complexity of the Starlink satellites reflection pattern, producing interesting results concerned with the used filters and the observation geometry.
SpaceX—Sailing Close to the Space Weather? Hapgood, Mike; Liu, Huixin; Lugaz, Noé
Space weather,
March 2022, 2022-03-00, 20220301, Letnik:
20, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The 3 February 2022 launch of 49 of SpaceX's Starlink satellites has provided a fascinating example of how even modest space weather can have significant practical and financial consequences. ...Enhanced atmospheric drag associated with a minor geomagnetic storm led to the loss of the majority of the 49 launched satellites. Although the 36th launch by SpaceX in the past 3 years, it was the first that experienced stormy space weather. We expect more stormy space weather as Solar Cycle 25 ramps up toward its peak expected in 2025. A subsequent Starlink launch on 21 February used a higher initial orbit at 300 km, reducing the payload from 49 to 46 satellites, and can be considered an agile response to the space weather losses experienced 2 weeks earlier. Lessons to be learned by the space industry and the space weather community are discussed, including a better dialog, nuanced understanding of space weather risks associated with modest events, but also an opportunity to investigate the space environment in relatively unexplored regions such as very low and high low Earth orbits.
Key Points
38 out of 49 Starlink satellites launched on 3 February 2022 were lost due to enhanced atmospheric drag linked to a minor geomagnetic storm
This shows how even modest space weather can have significant practical and financial consequences
We need better dialog between industry and the space weather community, leading to a more nuanced understanding of space weather risks
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