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The massive mega constellation of satellites will have a significant impact on global space safety. With Starlink as an example, this paper is aimed at assessing the risk of in-orbit collision, analyzing the probability of collision in orbit in its natural operating state, and forecasting the probability of secondary collision between the collision...
Citations
... Satellite infrastructure is crucial in various fields [2][3][4][5][6], such as communications, transportation, and weather forecasting, and has become indispensable in our daily lives. Ensuring the safety of space assets is of paramount importance [7][8][9], as space collisions pose a significant threat. This highlights the necessity for spacecraft that can autonomously detect surrounding objects, a capability crucial to reducing collision risks and enhancing Space Situational Awareness (SSA), which is key to maintaining the safety and sustainability of space operations. ...
Recent advancements in space exploration technology have significantly increased the number of diverse satellites in orbit. This surge in space-related information has posed considerable challenges in developing space target surveillance and situational awareness systems. However, existing detection algorithms face obstacles such as complex space backgrounds, varying illumination conditions, and diverse target sizes. To address these challenges, we propose an innovative end-to-end Attention-Guided Encoder DETR (AgeDETR) model, since artificial intelligence technology has progressed swiftly in recent years. Specifically, AgeDETR integrates Efficient Multi-Scale Attention (EMA) Enhanced FasterNet block (EF-Block) within a ResNet18 (EF-ResNet18) backbone. This integration enhances feature extraction and computational efficiency, providing a robust foundation for accurately identifying space targets. Additionally, we introduce the Attention-Guided Feature Enhancement (AGFE) module, which leverages self-attention and channel attention mechanisms to effectively extract and reinforce salient target features. Furthermore, the Attention-Guided Feature Fusion (AGFF) module optimizes multi-scale feature integration and produces highly expressive feature representations, which significantly improves recognition accuracy. The proposed AgeDETR framework achieves outstanding performance metrics, i.e., 97.9% in mAP0.5 and 85.2% in mAP0.5:0.95, on the SPARK2022 dataset, outperforming existing detectors and demonstrating superior performance in space target detection.
... The critical range of attitude angle can be utilized to monitor attitude motion and to avoid quick tumbling caused by excessive attitude angle. With the gradual increase in the number of satellites launched by nations and commercial companies, the amount of debris has significantly increased in recent years [1,2]. For the safety of spacecraft in orbit and the development of future space activities, it is necessary to remove the debris and slow down the growth of debris [3][4][5][6][7]. ...
The libration motion of conductive tether in the electrodynamic tether system has been demonstrated to be inherently unstable. However, the relationship between the instability of libration motion and the tether current, orbital inclination and attitude of libration motion has not been thoroughly investigated. The novelty of this paper lies in the determination of the critical ranges of attitude and ε that lead to rapid tumbling of libration motion, and the study of how the instability of libration motion varies with attitude and ε, where ε accounts for the effects of tether current and orbital inclination. Some numerical simulations were conducted to demonstrate that, as attitude and ε increase, the instability of libration motion gradually becomes more pronounced, especially when the attitude angle or ε exceeds the respective critical range, in which case the libration will become unstable even with implementation of control strategy. The critical range of tether current, which leads to rapid tumbling of the libration motion, can be determined based on the range of ε, and this range of current can serve as a basis for designing the current regulation range, thereby preventing rapid tumbling that may result from improperly designed or regulated current values. The critical range of attitude angle can be utilized to monitor attitude motion and to avoid quick tumbling caused by excessive attitude angle.
... Five years later, with the launch of the "Starlink" satellite constellation, the probability of an orbital collision increased. According to estimates (Haicheng et al., 2022), the probability of collision of space debris with the "Starlink-61" satellite, which belongs to the "Starlink" satellite constellation, has the following values: 2020 -0.001, 2021 -0.005, 2022 -0.009, 2023 -0.017 and in 2024 is 0.014. To calculate the probability of a collision, it was assumed that the mass of the space debris fragment is more than 0.1 kilograms and the size exceeds 1 centimeter. ...
... To calculate the probability of a collision, it was assumed that the mass of the space debris fragment is more than 0.1 kilograms and the size exceeds 1 centimeter. The indicated collision probabilities exceed the red warning threshold of 10 −4 (Haicheng et al., 2022). Thus, NASA divided the probability threshold of evasive maneuvers into a yellow threshold with a value of 10 −5 and a red threshold with a value of 10 −4 . ...
Along with the development and achievements of cosmonautics, another type of object in near-Earth space appeared -- space debris. It poses a threat to satellites and future missions. According to the size, fragments of space debris are classified into four categories: 10 centimeters and more, from 1 to 10 centimeters, from 0.3 to 1 centimeter and less than 0.3 centimeters. Space debris is spread over all Earth orbits and has selected areas of orbits with a greater concentration. This is explained by the events of intentional and unintentional destruction of satellites in the past. As a result of a series of such events, as well as the launch of a certain class of satellites into Earth orbit for almost 60 years, the probability of space debris colliding with a satellite has increased 7 times in the area of LEO orbits. Collision probability estimates were 10-9 in 1966, and in 2024 the estimate increased to 10-2. So, in 2013, these estimates were 0.0005, and in 2020 it is already 0.001. The increase in the probability of a collision in 2020 and in the years from 2020 to 2024 is associated with the launch of the "Starlink" constellation of satellites. There are already several cases of the close passage of the "Starlink" satellite constellation with active satellites and the need to perform maneuvers to avoid collisions. Thus, not only has the number of maneuvers to avoid space debris increased, but also the need to avoid collisions with other satellites. At the same time, measures adopted to reduce and remove space debris are already being applied. In order to predict the future space debris environment more effectively and remove the most dangerous objects, a number of models of the evolution of the space debris environment have been created. They make it possible to simulate various scenarios of an increase in the number of objects in near-Earth space and to consider the possibilities and degree of necessity of their removal. Along with the fact that space debris poses a threat to the future development of cosmonautics and modern achievements of the 21st century, these objects are of interest for modeling their movement in near-Earth space. However, if the state of the space debris problem is not qualitatively changed in the coming years, there is a threat in the next 50 years to lose the achievements of the space sphere over the past almost 60 years.
... Consequently, certain orbital bands around the Earth may become both unusable and unsafe for transitioning to higher orbits. Moreover, various risk assessment models [2][3][4][5] have evaluated the collision threats posed by large satellite constellations. Strategies are being developed for the reconfiguration of satellite clusters to avoid such scenarios [6]. ...
... The projected outcome of a satellite collision within these orbits suggests it would generate a minimum of 4092 debris pieces, posing a significant danger to other spacecraft. Furthermore, the model anticipates a probability of a second collision between the short-term debris cloud and a Starlink satellite within the same orbit, occurring within 30 minutes [3]. This secondary collision represents a heightened threat to space safety, necessitating further research into strategies for avoidance and control. ...
Predicting the ionospheric aerodynamic forces acting on a satellite in low Earth orbit (LEO) is critical both in terms of avoiding collisions with other satellites in this area as well as deorbiting the spacecraft according to the international guidelines. The LEO is an ensemble of charged and neutral ions and it has been shown that the momentum exchange between these particles and a charged body has a significant impact on the drag forces acting on the body, and in-turn on its motion. Given the substantial variations in densities and relative composition of charged species with altitude and latitude, the resultant drag force on the satellite spans a wide range. This paper presents a comprehensive study of drag forces resulting from the interaction of plasma in LEO and a floating object. The simulations are performed using pdFOAM, an electrostatic particle-in-cell code. We show that the different ion percentages play a critical role in the value of the drag coefficient. Moreover, cases with lower density and high percentage of H+, have the largest value of drag coefficient. The drag coefficient increases significantly with increasing altitude, i.e. for lower ion density.
... This section delves into the prospective ramifications of Kessler's Syndrome, envisioning a scenario where satellite communication is entirely compromised over the span of two to three decades, and explores its profound implications on humans. The authors highlight the increasing risk of collisions between active space vehicles and space debris, an effect attributed to the increase in the affordability of satellite launches and the commercialization of the space industry Tao et al. (2022). Understanding the gravity of such a prospect is vital for informed decision-making and robust contingency planning. ...
Kessler’s Syndrome is a global phenomenon characterized by the presence of tens of millions of debris pieces of various sizes that disrupt satellite operations. This article delves into the potential outcomes of a Kessler’s Syndrome occurrence and its implications on satellite operations. The potential threats posed by this scenario are discussed, including the implications of minimal to no satellite function on human impacts, including crashes and minimized or disrupted functions in essential utility services, as these sectors heavily rely on satellites. In addition, we discuss how the loss of satellite communications could gradually or rapidly affect global affairs. As humans are a dominant force on Earth, their endangerment would reverberate throughout the ecological system, potentially leading to the demise of other species. It is crucial for policymakers and relevant stakeholders to recognize these implications and work towards safeguarding satellite communication to mitigate potential negative outcomes for humanity’s wellbeing and progress. The recycling of space debris emerges as a promising and long-term sustainable solution to the mitigation of space debris. By repurposing decommissioned satellites and debris into useful materials to support other space missions, this recycling strategy presents a win-win scenario, promoting environmental sustainability and resource efficiency in space exploration.
... With the rapidly acceleration of satellite deployments by nations and commercial companies, the number of debris has increased significantly in recently years [1] [2]. For the safety of in orbit spacecrafts and the development of future space activities, it is necessary to remove these debris and slow down its growth [3]- [7]. ...
The libration motion of conductive tether in electrodynamic tether system had been demonstrated unstable inherently. This paper conducts a further dynamic analysis of the instability in electrodynamic tether system, specifically investigating the existence of periodic solution and equilibrium point, as well as exploring the condition for rapid instability in libration motion. The dumbbell model is employed to depict the in-plane and out-plane libration motion, and the parameter ε is introduced to incorporate the influences of tether current and inclination. The critical ranges of ε and out-plane angle that determine whether the libration motion will go tumbling quickly are derived analytically based on the existence condition of periodic solution and equilibrium point. The numerical simulations were conducted to demonstrate these analytical critical ranges, and the results show that the libration motion will become unstable quickly if the out-plane angle or ε exceeds the critical range even under control strategy. This critical range of ε and out-plane angle is a general conclusion applicable to any situation (within the limitation of the model considered in this study), which can be utilized in guiding the design of system parameters to avoid rapid instability of electrodynamic tether system.
... The next mission that is analyzed for hypothetical SSPT support is a Starlink satellite. Using data for the Starlink-61 satellite, the orbital parameters are as follows [37]: Based on the dimensions of the satellite, it is assumed that a rectenna can be fitted onto the satellite with a diameter of 3.5 meters. ...
Space-based solar power has emerged as a promising solution for meeting the increasing demand for energy from sustainable sources. This research shows the potential of this technology by exploring a proposed system architecture of solar power stations in orbit around the Earth. These stations would collect and convert sunlight into energy and transmit it back to the Earth. The focus of this study is on spacecraft-to-spacecraft power transfer and the necessary guidance, navigation, and control considerations and the astrodynamics challenges that need to be addressed for the successful deployment and maintenance of this technology in orbit. A model is developed to understand the viability of spacecraft-to-spacecraft power transfer through the simulation of different use cases. While the potential benefits of this technology are significant, the implementation of such a system involves numerous technical hurdles. These challenges must be addressed and overcome to make space-based solar power a viable option for meeting our energy needs in the future.
The extent of the impact of mega constellations on the low-orbiting geospace environment, which has not yet been assessed in more concrete quantitative terms, is an extremely important issue to consider as mega constellations are built. Satellite safety and lifetime can clearly represent the situation of space targets, and thus can reflect the impact of mega constellations on geospace security. Three target satellites with different characteristics were selected and the Accepted Collision Probability Level (ACPL) was calculated to obtain the impact of Starlink on satellite mission lifetime. Upon considering Starlink without early avoidance control, the lifetimes of the three target satellites were shortened by 56.21%, 99.09%, and 99.82%, respectively. After 10 revolutions of early avoidance control, two were shortened to 92.166% and 91.99%, while the lifetime of JILIN-01 was extended by 155.44%. After joining Starlink, the total risk became larger; even if the target satellite avoided control far more frequently than before joining Starlink, it will face a worse geospace environment. Adopting the most aggressive orbit avoidance control cannot avoid the deterioration of the geospace environment from the perspective of satellite lifetime, which is an irreversible and deteriorating process.
