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Fraction of ZTF images with at least one Starlink satellite trail. Black dots (blue squares) mark images taken when the solar elevation was greater than −18° (−30°). Currently, nearly 20% of images taken during twilight are affected.
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There is a growing concern about an impact of low-Earth-orbit (LEO) satellite constellations on ground-based astronomical observations, in particular, on wide-field surveys in the optical and infrared. The Zwicky Transient Facility (ZTF), thanks to the large field of view of its camera, provides an ideal setup to study the effects of LEO megaconste...
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... 64% of the detected trails were imaged during twilight (solar elevation greater than -18°) and about 70% (45%) were at elevation lower than 40° (30°). Figure 2 presents the fraction of ZTF images (taken when the solar elevation was greater than −18° and −30°) with at least one Starlink satellite trail. In late 2020, about 6% of images taken during twilight were affected, and this fraction went up to ≈18% in 2021 August. ...
Citations
... Yet in the near future, companies such as OneWeb and Telesat plan to establish smaller constellations. Tech giants like Amazon and Samsung have also announced intentions to deploy their own constellations, consisting of 3236 and 4600 broadband satellites, respectively [162]. ...
This research aims to contribute to the development of the Eco-LeanSat concept by focusing on a sustainable approach to satellite manufacturing and the repurposing of remaining satellite capabilities after failure. Despite satellites no longer being suitable for their original purposes, these remaining capabilities can find new applications. The study begins by identifying relevant innovative eco-design applications. Subsequently, it examines sustainability within the satellite lifecycle supply chain, categorizing it into four methods: (1) active debris removal, (2) transport logistics, (3) mission extension, and (4) repair and construction. Aligned with emerging trends in space activities, the study also considers future developments to maximize satellites’ potential to provide new services. Additionally, the research includes a description of a potential lean manufacturing process that encompasses logistic chains to support the development of a more sustainable space economy. Finally, the study concludes with a technological survey tracing the evolution of the development of the SmallSat and CubeSat platforms that identifies relevant innovative designs for a sustainable space environment.
... In addition, a larger input size can effectively prevent streak truncation and enable the better distinction of artificial satellites, which are typically longer than streaks. Recently, more satellites, such as SpaceX Starlink Satellites, have been deployed, and the number of affected images have increased [12,13]. Due to satellite similarity in morphology to NEAs, satellites confuse the model's recognition ability. ...
Detecting near-Earth asteroids (NEAs) is crucial for research in solar system and planetary science. In recent year, deep-learning methods have almost dominated the task. Since NEAs represent only one-thousandth of the pixels in images, we proposed an ICC-BiFormer model that includes an image compression and contrast enhancement block and a BiFormer model to capture local features in input images, which is different from previous models based on Convolutional Neural Network (CNN). Furthermore, we utilize a larger input size of the model, which corresponds to the side length of the input image matrix, and design a cropping algorithm to prevent NEAs from being truncated and better divide NEAs and satellites. We apply our ICC-BiFormer model into a dataset of approximately 20,000 streak and 40,000 non-streak images to train a binary classification model. The ICC-BiFormer achieves 99.88% accuracy, which is superior to existing models. Focusing on local features has been proven effective in detecting NEAs.
... 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\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\varepsilon$$\end{document} that lead to rapid tumbling of libration motion, and the study of how the instability of libration motion varies with attitude and ε\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\varepsilon$$\end{document}, where ε\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\varepsilon$$\end{document} accounts for the effects of tether current and orbital inclination. Some numerical simulations were conducted to demonstrate that, as attitude and ε\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\varepsilon$$\end{document} increase, the instability of libration motion gradually becomes more pronounced, especially when the attitude angle or ε\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\varepsilon$$\end{document} 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\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\varepsilon$$\end{document}, 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.
... For instance, having tens of thousands of satellites in orbit could generate additional space debris and heighten the risk of collisions between orbiting objects. This could also potentially impact astronomical observations, both in terms of reflected light from satellites on optical and near-infrared (NIR) observations [4][5][6][7][8] and in terms of broadcast signals from satellites on radio observations [9,10]. The astronomical community has recognized the issue of light pollution, especially since the launch of the first Starlink satellites into orbit. ...
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.
... The recent acceleration in the number of artificial satellites, especially those in large constellation formations like StarLink, has begun to compromise astronomical research via frequent light trails across images (e.g. Mroz et al. 2022). It has been increasingly visible to naked-eye observers, as well. ...
“The Harmony of Heaven and Earth” The 19th Annual Sophia Centre Conference, in Partnership with the Harmony Institute, University of Wales Trinity Saint David, Lampeter, 25th–26th June, 2022.
... 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]. ...
... (1) and (2), all the acceleration, velocity and control input in Eqs. (1)and(2)are set to zero, then Eqs.(1) and(2)can be rewritten as follows: ...
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.
... Members of the astronomy community have published articles reporting the brightness of communications constellation satellites (Horiuchi et al. 2020;Mallama 2020Mallama , 2021Tyson et al. 2020;Tregloan-Reed et al. 2021;Boley et al. 2022;Halferty et al. 2022;Mróz et al. 2022). These reports provided valuable information to the community asking how bright these satellites are. ...
The Steward Observatory LEO Satellite Photometric Survey is a comprehensive observational survey to characterize the apparent brightness of the Starlink and OneWeb low Earth orbit satellites and evaluate the potential impact on astronomy. We report the results of over 16,000 independent measurements of nearly 2800 individual satellites. In addition to photometry, we also measured the astrometric position of each satellite and evaluated the accuracy of predicting satellite position with the available two-line element sets. The apparent brightness of a satellite seen in the sky is not constant and depends on the Sun-satellite-observer geometry. To capture this, we designed the survey to create an all-geometries set of measurements to fully characterize the brightness of each population of satellites as seen in the sky. We visualize the data with sky-plots that show the correlation of apparent brightness with on-sky position and relative Sun-satellite-observer geometry. The sky-plots show where in the sky the satellites are brightest. In addition to visual magnitudes, we also present two new metrics: the expected photon flux and the effective albedo. The expected photon flux metric assesses the potential impact on astronomy sensors by predicting the flux for a satellite trail in an image from a theoretical 1 m class telescope and sensor. The effective albedo metric assesses where a satellite is more reflective than baseline, which ties to the physical structure of the satellite and indicates the potential for brightness-reducing design changes. We intend to use this methodology and resulting data to inform the astronomy community about satellite brightness. Observing programs use a variety of telescopes and instruments and look at different parts of the sky. With the expected photon flux metric and a complete all-sky characterization of satellite brightness, observers can evaluate the potential impacts to their projects and possibly avoid the worst effects.
... For instance, McDowell (2020) studied the LEO satellite population and the impacts of the SpaceX Starlink constellation. Mróz et al. (2022) explored the impacts of SpaceX Starlink satellites on the Zwicky Transient Facility (ZTF) survey observations. Few studies investigated the public perception of the Starlink Satellite project, especially in Thailand. ...
Starlink is a long-term project to address disparities in rural broadband Internet access that is led by SpaceX and Elon Musk. The project’s goal is to launch thousands of smallsat-class satellites into low Earth orbit (LEO) as part of a mega-constellation to provide continuous, high-speed Internet around the world. SpaceX believes that its technology can outperform the competition by using shallow orbits. When compared to traditional geosynchronous satellite Internet infrastructure, Starlink promises lower latency and higher-quality connections to its customers (Walker & Elliott, 2021). This study aims to investigate the public perception of the Starlink Satellite project in Thailand. A quantitative approach was used and an online questionnaire was conducted to collect data from a convenience sample of 1,258 participants in Thailand. Binary regression analysis was performed to analyse the data. The findings revealed that the public perception of the Starlink Satellite project in Thailand could be described by gender, age, computer, laptop, tablet, wearable device, Internet duration, mobile Internet, Instagram, TikTok and YouTube. Consequently, Starlink should devise an effective strategy to entice users to increase their awareness and use satellite Internet in countries where fibre Internet is more affordable and convenient.
... This is a problem that will be exacerbated for astronomical observatories and many science projects based on wide field instruments and requiring larger time exposures [1,3,5,6]. For instance, the Zwicky Transient Facility has already seen an increase in affected images from 0.5% in late 2019 to 18% in August 2021 [7]. The 3.5 degrees wide-field imager of the near-future Vera C. Rubin Observatory in Chile will contain at least one streak in the majority of exposures, further complicated by cascading electronics effects [8]. ...
The growing population of man-made objects with the build up of mega-constellations not only increases the potential danger to all space vehicles and in-space infrastructures (including space observatories), but above all poses a serious threat to astronomy and dark skies. Monitoring of this population requires precise satellite characterization, which is is a challenging task that involves analyzing observational data such as position, velocity, and light curves using optimization methods. In this study, we propose and analyze the application of two optimization procedures to determine the parameters associated with the dynamics of a satellite: one based on the Theory of Functional Connections (TFC) and another one based on the Nelder-Mead heuristic optimization algorithm. The TFC performs linear functional interpolation to embed the constraints of the problem into a functional. In this paper, we propose to use this functional to analytically embed the observational data of a satellite into its equations of dynamics. After that, any solution will always satisfy the observational data. The second procedure proposed in this research takes advantage of the Nealder-Mead algorithm, that does not require the gradient of the objective function, as alternative solution. The accuracy, efficiency, and dependency on the initial guess of each method is investigated, analyzed, and compared for several dynamical models. These methods can be used to obtain the physical parameters of a satellite from available observational data and for space debris characterization contributing to follow-up monitoring activities in space and astronomical observatories.
... Currently, profitable lunar sites correspond to 'common-pool resources' (Edwards & Steins 1998 ) in which 'no single nation has a generally recognized e xclusiv e jurisdiction' (Wijkman 1982 ). The impact of the SpaceX Starlink Satellites has been observed on the Zwicky Transient Facility Survey observations (Mr óz et al. 2022 ). Growing concerns o v er the impact on astronomical observations from low Earth orbit satellite constellations demonstrate the urgency to protect future research from similar experiences (Lawrence 2021 ). ...
The origin and evolution of structure in the Universe could be studied in the Dark Ages. The highly redshifted HI signal between 30 < z < 80 is the only observable signal from this era. Human radio interference and ionospheric effects limit Earth-based radio astronomy to frequencies >30 MHz. To observe the low-frequency window with research from compact steep spectrum sources, pulsars, and solar activity, a 200 km baseline lunar far-side radio interferometer has been much discussed. This paper conducts a preliminary site survey of potential far-side craters, which are few in number on the mountainous lunar far-side. Based on LRO LOLA data, 200 m resolution topographic maps of eight far-side sites were produced, and slope and roughness maps were derived from them. A figure of merit was created to determine the optimum site. Three sites are identified as promising. There is a need to protect these sites for astronomy.
