Article

The Kessler Syndrome: Implications to Future Space operations

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Abstract

The term "Kessler Syndrome" is an orbital debris term that has become popular outside the professional orbital debris community without ever having a strict definition. The intended definition grew out of a 1978 JGR paper predicting that fragments from random collisions between catalogued objects in low Earth orbit would become an important source of small debris beginning in about the year 2000, and that afterwards, "...the debris flux will increase exponentially with time, even though a zero net input may be maintained". The purpose of this paper is to clarify the intended definition of the term, to put the implications into perspective after 30 years of research by the international scientific community, and to discuss what this research may mean to future space operations. The conclusion is reached that while popular use of the term may have exaggerated and distorted the conclusions of the 1978 paper, the result of all research to date confirms that we are now entering a time when the orbital debris environment will increasingly be controlled by random collisions. Without adequate collision avoidance capabilities, control of the future environment requires that we fully implement current mitigation guidelines by not leaving future payloads and rocket bodies in orbit after their useful life. In addition, we will likely be required to return some objects already in orbit.

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... The problem is greatly worsened by possible debris collision events that produce clouds of smaller objects that are typically very difficult to track, thus increasing the likelihood of future collisions with a cascading effect. This issue was first raised by Kessler and Cour-Palais [12], and subsequent analyses have confirmed the danger to space operations posed by debris [13,14], with particular attention to the cascading effect due to collision events [15,16,17]. ...
... These geometrical parameters are typically estimated during the preliminary design of a mission and for orbiting objects are available on ESA's DISCOSweb database [49]. DISCOSweb also reports for most spacecraft the value of the average cross-sectional area, which is usually close to the values given by the empirical relationship (17). However, the advantage of using Eq. ...
... The latter date is therefore considered as the initial epoch of the deorbiting phase. The satellite's attitude was actively controlled by hydrazine thrusters, so after decommissioning it is assumed that it undergoes a tumbling motion, and the average cross-sectional area A is estimated through Eq. (17). The mass m is made to coincide with the spacecraft dry mass, assuming that the propellant for attitude control has been completely exhausted during its operational life. ...
... A possible cascading effect due to the creation of new uncontrolled debris with each collision was also hypothesized, and this scenario is now known as the "Kessler syndrome". Subsequent and more in-depth analyses confirmed that this problem needs to be addressed appropriately [12][13][14]. The first strategy to be adopted is debris mitigation, which means to avoid creating new debris by properly disposing of satellites that are no longer operational. ...
... Solar radiation pressure is usually negligible within LEO orbital range, but because of the significant area-to-mass ratio A/m of a spacecraft equipped with drag sail, its effect is considered in this work. The acceleration generated by the solar radiation pressure a SRP is estimated with a modified ideal force model, which assumes a flat drag sail and takes into account a nonperfect reflection [63], yielding (14) where P ⊕ 4.5632 × 10 −6 Pa is the solar radiation pressure at the Sun-spacecraft distance, which is assumed constant, andŝ is the Sun-spacecraft unit vector. In addition, c r is the reflection coefficient of the drag sail, which is assumed to be small because drag sails, unlike solar sails, are not designed to take advantage of solar radiation pressure as a source of thrust. ...
... The characteristics of the satellite used in the test case scenarios are summarized in Table 1. The dynamics of a three-axis stabilized drag sail is obtained by integrating Equation (3) and evaluating the perturbative accelerations through Equations (7), (8), (13) and (14). However, in this case, it is assumed that the drag sail constantly exposes its entire surface to the flow of atmospheric particles by means of a perfectly functioning three-axis stabilization system or a suitable passively stabilizing drag sail design [44,[46][47][48]. ...
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The growing amount of space debris in geocentricorbit poses a significant threat to the future of space operations. To mitigate this problem, current international guidelines state that a satellite should be able to deorbit or insert into a graveyard orbit within 25 years from the end of its operational life. In this context, drag-enhancing devices such as drag sails are currently an active field of research and development because of their ability to make a spacecraft decay from low Earth orbit without the need for any on-board propellant. Drag sails, conceptually similar to solar sails, are thin membranes deployed by a spacecraft at the end of its operational life to increase the area-to-mass ratio and, consequently, atmospheric drag. To be effectively exploited, a drag sail should maximize the surface area exposed to atmospheric particle flow. However, this would require a fully functional three-axis stabilization system, which may either be unavailable or non-functional on an orbiting satellite after years of space operations. To simplify the deorbiting phase, in this paper we propose to use a spin-deployed and spin-stabilized drag sail, which represents a reasonable compromise between simplicity of implementation and deorbiting performance in terms of total decay time. In fact, a spinning drag sail could take advantage of centrifugal force to unfold and of gyroscopic stiffness to maintain an inertially fixed axis of rotation. Numerical simulations accounting for the main perturbation effects quantify the effectiveness of the proposed device compared with an optimal configuration (i.e., a three-axis stabilized drag sail) and a tumbling drag sail.
... As space debris mitigation is still being implemented too slowly, there is a rising probability of collisions in Low Earth Orbits (LEOs), as shown by predictions done in ESA's annual space environment report [1]. The report shows that even if we stop launching new objects into space, space debris will still grow due to collisions between objects already in orbit (i.e., the Kessler syndrome [2]). According to ESA models, LEOs likely have over one million objects larger than 1 cm capable of causing catastrophic damage. ...
... Assuming that the two spacecraft orbits are coplanar and remain so for the entire duration of the motion, our control objective is to drive the leader position to a constant setpoint = [0, , 0] ⊤ with ∈ ℝ (i.e., the desired separation) and ̇= . Notice that, for the coplanarity of the orbits, the z-component of is always null; therefore, defining the reduced state * = [ , ] ⊤ , (1) can be rewritten as ̈ * =̂̇ * +̂ * +̂Δ (2) with ̂∈ ℝ 2×2 , ̂∈ ℝ 2×2 , and ̂∈ ℝ 2 defined as ...
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Over the past few years, Norway has shown keen interest in investing in space activities. As part of this endeavor, a launch site for small satellites has been established in Andøya Spaceport to enable commercial launch services. Consequently, this presents an exciting opportunity for small satellite projects in Norway. UiT the Arctic University of Norway in Narvik is working on the UNICube mission: a new CubeSat project designed by students to characterize mm-sized space debris in orbit. This ambitious mission will be one of the first launched from Norwegian soil, with an expected launch in 2026 from Andøya Spaceport. The UNICube initiative is financed by UiT and has the objective of "bringing Northern Norway to the stars" by developing, testing, and deploying a 2U CubeSat to orbit. The project serves a dual purpose of facilitating scientific research and promoting education. It also paves the way for future UiT students to construct their own CubeSat. By adhering to the established CubeSat standard from the California Polytechnic State University (Cal Poly), the project can minimize development time and costs, and increase the likelihood of success. UNICube will carry a space debris radar designed ad hoc to characterize space debris particles smaller than 3 mm, representing a size range of objects currently not detectable with ground-based radars. The planned radar will be a millimeter wavelength frequency-modulated continuous-wave (FMCW) radar based on a single-chip design with a phased array transceiver. This mission is highly innovative because it will provide in situ measurements and a better understanding of a rapidly growing problem. Indeed, space debris endanger space operations, as even small debris fragments can cause severe damage due to the high velocities involved (e.g., penetrating a space suit). A further novelty is that UNICube will test new AOCS algorithms for CubeSat control. The data and lessons learned from the UNICube mission will be leveraged in QBDebris, a mission funded by the Research Council of Norway and fully developed at UiT. QBDebris seeks to enhance the characterization of space debris through a two-CubeSats formation flight carrying the same space debris radar to be tested in the UNICube project. In this paper, we will introduce the UNICube mission, starting from its objectives and including the preliminary design of the main subsystems. In addition, we will discuss the primary challenges of such a mission and the expected outcomes.
... T increasing amount of space debris is a serious threat to operational satellites orbiting the Earth. According to the phenomenon known as the Kessler syndrome [1], debris will increase exponentially through cascaded collisions, even if all future launches are halted. The problem is becoming even more serious as the development of mega constellations such as Star-Link and OneWeb will result in more crowded near-Earth environment [2]. ...
... where the state variable 1 (one-dimensional scalar) of Problem 1 is defined as the th rendezvous epoch: 1 It is crucial to emphasize here that the globally optimal solution of Problem 0 is identical to that of Problem 1 , assuming the cost function approximates the minimum fuel consumption during the body-to-body transfer without error. This is because the globally optimal solution of Problem 0 necessarily signifies the minimum fuel consumption for each transfer between targets. ...
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This paper investigates the global optimization of multispacecraft successive rendezvous trajectories, which is divided here into three subproblems: target assignment, sequence optimization, and rendezvous time optimization. A method consisting of two novel algorithms is proposed to solve these subproblems. First, a multitree search framework is developed to assign multiple targets to each spacecraft and simultaneously optimize the rendezvous sequence for every single spacecraft. Specifically, a novel algorithm of local search combined with beam search is proposed. Second, this paper converts the rendezvous time optimization problem into a multistage decision problem. Based on a critical rendezvous-epoch-dependent characteristic found in this subproblem, the number of state variables is thereby reduced. A novel dual dynamic programming algorithm is proposed and combined with dynamic programming to solve for the globally optimal rendezvous epochs efficiently. Global optimality is guaranteed by Bellman’s principle of optimality, which is the first time in such a problem to our knowledge. The proposed method achieves state-of-the-art performance in several typical fuel-optimal scenarios of active debris removal. This open-sourced method is non-database-dependent and contains only one design stage, which is expected to be adopted in other successive rendezvous missions.
... Simultaneously, it is essential to stabilize the attitude of the base spacecraft that carries the robot. Once the spacecraft-target combination is safely captured and stabilized, on-orbit service can proceed, or the debris can be relocated to a graveyard orbit or deorbited for re-entry into Earth atmosphere within 25 years [4]. Given the high-risk nature of these operations, where the robot must physically contact with the target, it is imperative that the capture system and associated control algorithms are rigorously tested and validated on Earth before deployment in space [5]. ...
Preprint
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This paper presents the development of a hardware-in-the-loop ground testbed featuring active gravity compensation via software-in-the-loop integration, specially designed to support research in autonomous robotic removal of space debris. The testbed is designed to replicate six degrees of freedom (6DOF) motion maneuvering to accurately simulate the dynamic behaviors of free-floating robotic manipulators and free-tumbling space debris under microgravity conditions. The testbed incorporates two industrial 6DOF robotic manipulators, a 3-finger robotic gripper, and a suite of sensors, including cameras, force/torque sensors, and tactile tensors. Such a setup provides a robust platform for testing and validating technologies related to autonomous tracking, capture, and post-capture stabilization within the context of active space debris removal missions. Preliminary experimental results have demonstrated advancements in motion control, computer vision, and sensor fusion. This facility is positioned to become an essential resource for the development and validation of robotic manipulators in space, offering substantial improvements in the effectiveness and reliability of autonomous capture operations in space missions.
... In future work, more accurate time-varying profiles could be easily included in the model. Moreover, similarly to the PMD approach, also the removals are considered applied only above the limiting radius in Fig. 2. According to Kessler's theory proposed in [23] and as demonstrated by recent investigations, on-orbit collisions are the major contribution to debris proliferation, a phenomenon that is growing and self-sustaining. In the model collisions are included adopting the approach in [12]. ...
Conference Paper
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The population of objects in space faced an unforeseeable growth in the last decades. Therefore, it is now imperative to reiterate the debris mitigation guidelines and reconsider the approach to the debris proliferation problem. Different counteractions are available to deal with the situation. However, how to efficiently combine and apply these methods for sustainable use of the space environment is still an open question. To respond to this need, the GREEN SPECIES project, funded by a consolidator grant of the European Research Council, will develop a controlled model of the space debris population to define optimal mitigation policies. In its current version, the system exploits a statistical model in which debris and intact objects move in a one-dimensional domain in orbital radius and binned in spherical shells. The evolution of the environment is modelled in terms of the objects' density dynamics. The system includes the effect of atmospheric drag, sources as launches and in-orbit fragmentations, and artificial sink mechanisms such as post mission disposals and active debris removals. The resulting set of ordinary differential equations is integrated with a state-dependent linear feedback controller to tune different inputs and reach a predefined target. The novel approach exploits the benefits of control techniques to investigate the effectiveness of diversified rules in space and time to mitigate the debris proliferation and its risk to missions in low Earth orbit.
... With space travel becoming a common occurrence, debris will increase, including operational and fragmented debris, which is, of course, a danger to other users. As it accumulates, the probability of inter-debris collisions will greatly increase, increasing the likelihood of the Kessler syndrome [76] as inter-debris collisions will be uncontrollable once they start, encasing the Earth in an impenetrable cloud of broken debris and making space travel all but impossible [77,78]. ...
Article
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In the 21st century, mega-constellations and interconnected satellite constellations deployed at various orbital altitudes, such as LEO, MEO, and GEO, with low Earth orbits (LEOs) being the most commonly used, have emerged as a trend, aiming to enhance the productivity and reduce the costs in space service delivery. The UNOOSA has noted the uncertainty in the exact number of satellites but conducted simulations based on a substantial sample, projecting a significant increase from the 2075 satellites recorded in orbit in 2018. This surge in the launch of mega-constellations poses profound challenges to existing international space laws, originally formulated with limited consideration for private space actors, who are increasingly engaging in space activities, particularly with the cost-effective utilization of mega-constellations. This study critically analyzes the compatibility of mega-constellations with the current international space laws by examining the applicability of mega-constellations concerning equitable access and the non-appropriation principle, addressing their potential occupation of substantial orbital spaces during activities, and analyzing whether the acquisition of orbital slot licenses violates these two principles. Following an in-depth analysis, this study proposes recommendations to amend the existing laws, aiming to resolve ambiguities and address emerging challenges. Recognizing the time-consuming process of amending international space laws, this study suggests practical recommendations for supplementary rules of the road, prompting reflection on the potential obsolescence of the current international space laws in the face of evolving space activities.
... According to the European Space Agency (ESA), there are over 34,000 objects larger than 10 cm, 900,000 objects from 1 cm to 10 cm, and around 128 million objects from 1 mm to 1 cm in orbit around Earth [1]. These objects travel at velocities high enough to inflict catastrophic damage on or completely destroy an operational spacecraft upon impact, which in turn can generate further debris, perpetuating the cycle described by the Kessler Syndrome which can result in ceasing space operations in the future [2]. Indeed, suspending all space missions would not halt the increase in space debris, as the potential for collisions among existing Resident Space Objects (RSO) remains. ...
Conference Paper
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In recent decades, the population of space debris has increased exponentially, impacting the sustainable development of near-Earth space operations. At present, several commercial space actors are considering deployment of small to medium-sized satellites, with an estimated count exceeding 20,000 by 2035. The prevailing statistics of the space domain pose a significant challenge for satellite operators, underscoring the necessity for sophisticated real-time orbit determination methodologies in the context of Space Domain Awareness (SDA). Typically, ground-based sensors are used for tracking and surveillance of Resident Space Objects (RSO). However, Space-Based Space Surveillance (SBSS) emerges as a promising approach to enhance existing capabilities by offering superior detectability, accuracy and independence from atmospheric conditions. Exploiting multiple optical sensors is imperative for precise RSO tracking, as a single sensor proves insufficient to accomplish the task due to limited Field of View (FOV) and observation time constraints. A Distributed Satellite System (DSS) architecture is discussed for a SBSS mission equipped with Electro-Optical (EO) sensors as piggy-backed payload and inter-satellite communication links to interact, communicate and cooperate with each other to accomplish optimized RSO surveillance tasks. More specifically, this paper proposes an SBSS tracking method that integrates angle data derived from image sequences captured by multiple EO sensors, through an Extended Kalman Filter (EKF). The performance of this method is evaluated across various simulated tracking scenarios. Fusing the data from multiple optical sensors is beneficial as the data from one camera view complements the data from the other camera view to obtain enhanced target measurement information resulting in accurate RSO state estimates. Results show the efficacy of the proposed tracking technique and highlight the opportunities for augmentation of conventional ground-based sensor networks with SBSS paving a path for future research in this field.
... By using DSS architectures we can begin to further address the pressing environmental and commercial sustainability problems within the space domain, one of which is the uncertainty around the everincreasing number of Resident Space Objects (RSO) within the onorbit environment. This condition is perpetuating the irrefutably hazardous probability of collision between RSO's, with increasing concerns of initiating a irreversible, cascading debris generating process widely recognised as Kessler syndrome [8,9]. Historically the state vector of large orbiting objects (>10 cm) can be estimated and predicted with reasonable confidence, based upon data accrued by the SSA Space Surveillance and Tracking (SST) segment and other non-government owned ground-based sensors. ...
Article
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System autonomy plays a critical role in the success of next generation Distributed Satellite Systems (DSS) mission architectures, enabling the inference of external and internal environment conditions to support system adaptation in unexpected and unfamiliar situations. Artificial Intelligence (AI) based techniques show promise in achieving this desired self-adaptive capability by offering sophisticated on-board real time analytics, supporting an evolution towards Trusted Autonomous Satellite Operations (TASO). In parallel, TASO requires an evolution of the control and coordination of increasingly autonomous large scale DSS, achieved in the design and operation of intelligent Mission Planning Systems (MPS). In this paper, we focus on intelligent mission planning functionality problem utilising a distributed ant colony optimisation approach to achieve local task allocation and platform coordination. The approach is implemented in the context of a Space-Based Space Surveillance (SBSS) mission architecture that considers self-adaptive capabilities, global coordination and supervisory control aspects. The effectiveness of the approach is shown, demonstrating that the proposed solution based on metaheuristics enables opens the way for an efficient and pervasive SBSS capability.
... Naturally, a collision between two space objects is a rare event and has seldom been observed (at least officially). However, the rise in RSO population may induce a phenomenon known as Kessler syndrome [24]. First proposed by Donald Kessler, a JPL scientist in 1978, it describes the cascading chain of events in which the increasing number of objects leads to a higher likelihood of collision and the subsequent fragmentation of the involved objects. ...
Thesis
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Spacecraft tracking by use of various types of sequential filters in GEO, including particle filters, cubature Kalman filters and ensemble Kalman filters.
... Space debris consists of varying sizes of space objects, starting from decommissioned satellites and discarded rocket engines to paint chips and small remnants from collisions among space objects. These uncontrolled space objects cause a severe threat since even the small ones can initiate a chain collision among space debris, known as the Kessler syndrome [2]. To guarantee the safety of ongoing and future space missions, NASA and other space agencies around the world are planning to initiate space object removal projects using space robotics (e.g., in-orbit service, manufacturing, and assembly-ISAM [3]), which require direct interactions between a controllable spacecraft, also known as a chaser, and a non-cooperative space object (e.g., decommissioned satellites). ...
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In this paper, we propose a Bayesian Optimization (BO)-based strategy using the Gaussian Process (GP) for feature detection of a known but non-cooperative space object by a chaser with a monocular camera and a single-beam LIDAR in a close-proximity operation. Specifically, the objective of the proposed Space Object Chaser-Resident Assessment Feature Tracking (SOCRAFT) algorithm is to determine the camera directional angles so that the maximum number of features within the camera range is detected while the chaser moves in a predefined orbit around the target. For the chaser-object spatial incentive, rewards are assigned to the chaser states from a combined model with two components: feature detection score and sinusoidal reward. To calculate the sinusoidal reward, estimated feature locations are required, which are predicted by Gaussian Process models. Another Gaussian Process model provides the reward distribution, which is then used by the Bayesian Optimization to determine the camera directional angles. Simulations are conducted in both 2D and 3D domains. The results demonstrate that SOCRAFT can generally detect the maximum number of features within the limited camera range and field of view.
... Moreover, unauthorized access to a satellite poses a significant risk not just to its owners, but to the broader space environment as well. As a representative example, an attacker taking control of a satellite and activating its thrusters could lead to the Kessler Syndrome [8]. Kessler Syndrome is a scenario where debris from one satellite collision spreads and hits other satellites, creating more debris in a domino effect. ...
Preprint
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The recent rise of CubeSat has revolutionized global space explorations, as it offers cost-effective solutions for low-orbit space applications (including climate monitoring, weather measurements, communications, and earth observation). A salient feature of CubeSat is that applications currently on-boarded can either be updated or entirely replaced by new applications via software updates, which allows reusing in-orbit hardware, reduces space debris, and saves cost as well as time. Securing software updates employing traditional methods (e.g., encryption) remains impractical mainly due to the low-resource capabilities of CubeSat. Therefore, the security of software updates for CubeSats remains a critical issue. In this paper, we propose CubeSat Update Mechanism (CSUM), a lightweight scheme to provide integrity, authentication, and data freshness guarantees for software update broadcasts to CubeSats using a hash chain. We empirically evaluate our proof of concept implementation to demonstrate the feasibility and effectiveness of our approach. CSUM can validate 50,000 consecutive updates successfully in less than a second. We also perform a comparative analysis of different cryptographic primitives. Our empirical evaluations show that the hash-based approach is at least 61×\times faster than the conventional mechanisms, even in resource-constrained environments. Finally, we discuss the limitations, challenges, and potential future research directions for CubeSat software update procedures.
... The space domain scenario is envisioned to aggravate as various commercial entities like Space-X and One Web plan to deploy mega constellations comprising hundreds to thousands of space assets. The current trend implies a chain of collision events typically referred to as Kessler syndrome which can lead to space operations ceasing in the future [4]. Space debris poses a formidable threat to space infrastructure and operations due to the large uncertainty of their population, trajectories, mass, size, etc. ...
Conference Paper
Resident Space Objects (RSO) include satellites, spacecrafts, and other equipment remaining in Earth's orbit for an extended period following activities such as space launches, orbital missions and collisions, thereby posing a formidable threat to space infrastructure and operations due to the large uncertainty of their population, trajectories, mass, size, etc. It is therefore necessary not only to track the total number of objects in space, but also to continuously estimate the trajectory of these objects and probability of accidental collisions with other objects. At present, RSO are tracked and catalogued using ground-based observations, but Space-Based Space Surveillance (SBSS) represents a valid complementary alternative due to its ability to offer enhanced performances in terms of sensor resolution, tracking accuracy, and weather independence. Accurate and continuous orbit determination of RSO is essential for establishing a unique scheme for an accurate prediction of the RSO dynamics for applications like Point-To-Point Suborbital Transport (PPST) that are envisioned to be commercialized in future. This article proposes an innovative trajectory estimation algorithm through Data Fusion from multiple Electro-Optical (EO) sensors performing Space-Based Space Surveillance (SBSS). A verification case study is performed on a constellation of Distributed Satellite Systems (DSS) that aim to carry out a piggy-backed mission by performing SBSS and Earth observation operations simultaneously.
... With an ever growing number of satellites in orbit, the risk of collision between a satellite and space debris, e.g., rocket bodies, defunct satellites or pieces from a previous collision, is steadily rising. Such a collision would not only cause the destruction of a functional satellite but also dramatically increase the number of space debris [2], thereby further increasing the risk of such a collision [3]. As a result, private companies and space agencies are working on Active Debris Removal (ADR) [4,5,6] missions that aim at de-orbiting space debris. ...
Preprint
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We address the estimation of the 6D pose of an unknown target spacecraft relative to a monocular camera, a key step towards the autonomous rendezvous and proximity operations required by future Active Debris Removal missions. We present a novel method that enables an "off-the-shelf" spacecraft pose estimator, which is supposed to known the target CAD model, to be applied on an unknown target. Our method relies on an in-the wild NeRF, i.e., a Neural Radiance Field that employs learnable appearance embeddings to represent varying illumination conditions found in natural scenes. We train the NeRF model using a sparse collection of images that depict the target, and in turn generate a large dataset that is diverse both in terms of viewpoint and illumination. This dataset is then used to train the pose estimation network. We validate our method on the Hardware-In-the-Loop images of SPEED+ that emulate lighting conditions close to those encountered on orbit. We demonstrate that our method successfully enables the training of an off-the-shelf spacecraft pose estimation network from a sparse set of images. Furthermore, we show that a network trained using our method performs similarly to a model trained on synthetic images generated using the CAD model of the target.
... As the space industry expands rapidly, the volume of space debris also increases, presenting considerable hazards to functioning satellites, ongoing space missions, and astronaut safety. A pressing issue arises from the risk of cascading collisions, commonly termed the Kessler Syndrome Kessler et al. (2010), where a single collision can generate substantial additional debris, triggering a domino effect of subsequent collisions. Various factors influence the deterioration and decay of space debris, such as solar activity, geomagnetic storms, weathering of the debris, atmospheric compositional changes, and collisions, with the solar cycle's impact emerging as a significant contributor Nwankwo (2018); Klinkrad (2006); Walterscheid (1989). ...
Preprint
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The rapid increase in the number of space debris represents a substantial threat to the sustained viability of space operations. Monitoring these debris is critical for space situational awareness. Therefore, it has become of immense importance to understand the impact of solar activity on the space debris orbit. This study examines the effect of solar cycles, specifically Solar Cycles 22, 23, and 24, on the orbital decay of space debris. Utilizing TLE data for 95 objects in LEO and MEO dating back to the 1960s, we examined the orbital decay rates of these objects across the three solar cycles. Our analysis reveals a significant correlation between orbital decay and various indices serving as proxies for solar and geomagnetic activity. Notably, Solar Cycle 22 exhibited the highest decay rates, while Solar Cycle 24 showed the lowest. Moreover, we observed a similar impact at altitudes exceeding 2000 km, albeit with a time lag of over 14 months compared to the shorter lag observed at LEO orbits during peak solar activity. These findings underscore the crucial relationship between solar activity and its enduring influence on space debris.
... The problem of an uncontrolled debris proliferation has been discussed since the '70s, when Kessler and Cour-Palais raised attention on the exponential generation of small particles in the next future [1]. Since then, the focus of the scientific community has been set on the definition of models to better understand the debris problem and to predict the evolution of the inert space population. ...
Conference Paper
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Space utilisation faced unforeseeable changes in the last decades. However, the policy definition for debris mitigation has not matched the rapid growth of the inert population on orbit. The interdisciplinary framework proposed in the GREEN SPECIES project, funded by the European Research Council, aims at providing scientific support to the reactive definition of regulations and at systematic investigating debris mitigation strategies. In this respect, this paper focusses on the concurrent development of a propagator of the objects' dynamics with sources, sinks and mitigation measures and of a feedback controller acting on the population. The objects orbiting low-Earth space are modelled as a fluid with continuous properties. A deposition profile is modelled along with a term emulating post-mission disposal of objects. As a first approach, a feedback, proportional and linear control logic automatically selects the post-mission disposal compliance of the deposited objects, to limit the growth of the inert population on orbit. An example of the methodology is provided, and the results discussed in terms of validity of the approach.
... The increasing presence of space debris poses a significant and escalating threat to the safety of space activities [1]. These debris, which are mainly produced by explosions and collisions with fragments of old space missions, are the primary sources of spacecraft fragmentation, leading to the generation of additional space debris and contributing to an increasingly congested orbital environment [2,3]. This situation poses serious risks to the functionality and integrity of existing and future satellites [4]. ...
Article
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Spacecraft fragmentation due to collisions with space debris is a major concern for space agencies and commercial entities, since in the next years the production of collisional fragments is expected to become the major source of space debris. Experimental studies have shown that the fragmentation process is highly complex and influenced by various factors, such as the satellite design, the material properties, the velocity and angle of the debris impact, and the point of collision (e.g., central, glancing, on spacecraft appendages). This paper summarizes the current state of research in spacecraft fragmentation, including the methods and techniques used to simulate debris impacts, the characterization of fragment properties and the analysis of the resulting debris cloud. It provides an overview of the main experiments performed, underlining the most critical issues observed. Moreover, it presents a set of experiments performed at the University of Padova and proposes some future directions for this research.
... In return, these models require lower computational times than the tools that propagate each single object; therefore, they can be propagated for longer simulation times and extensively run within sensitivity analyses and optimization procedures. These models have already been adopted in literature: examples can be found in the works of Farinella and Cordelli [9]; Kessler et al. [10][11][12], who considered the primary sources and sinks present in LEO to study the growth of space debris and the stability of LEO; Talent, who described the evolution of the space environment using a simple source-sink model with one first-order ODE [13], and afterwards examined the Fengyun-1C ...
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The Low Earth Orbit (LEO) environment will likely experience an exponential growth of the Anthropogenic Space Object population, also due to the many proposed large constellations (proposed or partially already in orbit), which could negatively affect the sustainability of the space environment if no proper regulatory actions are introduced. This paper introduces a methodology to analyze high-capacity sustainable solutions of the LEO region from 200 to 900 km altitude. Sustainability is assessed through the stable equilibrium points of a source-sink model, called MOCAT-3. Capacity is estimated using an optimization procedure which aims to compute the optimal launch rate that maximizes the number of satellites in LEO, subject to a risk-rate constraint. Results show that the sustainable number of satellites increases with the risk rate constraint. Moreover, the resilience of the proposed solutions is tested against a more accurate time-varying atmospheric density model and perturbations of the initial equilibrium population. The compatibility of the proposed solutions with future traffic launches and a strategy to accommodate future traffic needs are presented. Limitations of the current work are discussed, chiefly the importance of validation of model coefficients and behavior before resulting capacity estimates are used to guide actual decision-making.
... Nowadays, it has become a major issue and, according to the so-called "Kessler Syndrome", it was theorized that the increase of the space debris density can lead to a selfsustaining chain reaction of collision. In this way, some orbits may become impractical for several years [5]. Objects bigger than some centimeters can be tracked from ground [6,7] and therefore it is possible to predict an impact and perform avoidance maneuvers against catastrophic fragmentations [8,9]. ...
Article
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AlbaSat is a 2-Unit CubeSat which is being developed by a student team at the University of Padova. The Alba project aims to design, build, test, launch, and operate the first student CubeSat of the University of Padova, featuring four different payloads. The first goal is to collect data regarding the debris environment in Low Earth Orbit, the second goal is the study of the satellite vibrations, the third one is about CubeSat attitude determination through laser ranging technology, and the fourth goal concerns satellite laser and quantum communication. The Alba CubeSat mission has been selected by the European Space Agency to join the Fly Your Satellite! Design Booster program in December 2022. This paper presents the feasibility study of the Alba CubeSat mission reproduced in the framework of the “Space Systems Laboratory” class of Master of Science in Aerospace Engineering at the University of Padova. In the beginning, a mission requirements definition was conducted. After that, the mission feasibility was considered, with preliminary requirements verification to assess the ability of the spacecraft to survive the space environment, including compliance with Debris Mitigation Guidelines, ground station visibility and minimum operative lifetime evaluation. The Alba mission sets a base for a better understanding of the space environment and its interaction with nanosatellites, and an improvement of the accuracy of debris models. Furthermore, this paper, describing the educational experience and the results achieved, will provide a useful example for future students’ studies on CubeSat mission design.
... The European Space Agency (ESA) estimates that there are approximately 39,000 pieces of debris orbiting Earth (ESA Space Debris Office, 2023), with much of this in LEO. In fact, the amount of debris could reach a critical limit resulting in Kessler Syndrome, where orbital collisions produce fragments that initiate a runaway feedback loop of continual debris collisions and fragmentation (Kessler et al., 2010;Kessler & Cour-Palais, 1978). Such a scenario could render many potential orbits unusable, or at least highly dangerous to navigate due to self-propagating collisions and dense debris congestion. ...
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Global services like navigation, communication, and Earth observation have increased dramatically in the 21st century due to advances in outer space industries. But as orbits become increasingly crowded with both satellites and inevitable space debris pollution, continued operations become endangered by the heightened risks of debris collisions in orbit. Kessler Syndrome is the term for when a critical threshold of orbiting debris triggers a runaway positive feedback loop of debris collisions, creating debris congestion that can render orbits unusable. As this potential tipping point becomes more widely recognized, there have been renewed calls for debris mitigation and removal. Here, we combine complex systems and social-ecological systems approaches to study how these efforts may affect space debris accumulation and the likelihood of reaching Kessler Syndrome. Specifically, we model how debris levels are affected by future launch rates, cleanup activities, and collisions between extant debris. We contextualize and interpret our dynamic model within a discussion of existing space debris governance and other social, economic, and geopolitical factors that may influence effective collective management of the orbital commons. In line with previous studies, our model finds that debris congestion may be reached in less than 200 years, though a holistic management strategy combining removal and mitigation actions can avoid such outcomes while continuing space activities. Moreover, although active debris removal may be particularly effective, the current lack of market and governance support may impede its implementation. Research into these critical dynamics and the multi-faceted variables that influence debris outcomes can support policymakers in curating impactful governance strategies and realistic transition pathways to sustaining debris-free orbits. Overall, our study is useful for communicating about space debris sustainability in policy and education settings by providing an exploration of policy portfolio options supported by a simple and clear social-ecological modeling approach.
... In this phase, and all others, safety is of primary concern [7]. Collisions can be devastating to orbital regimes as the debris created from one collision increases the likelihood of other collisions [8]. An example of a failed autonomous RPO occurred in 2005 when the DART satellite collided with the MUBLCOM satellite due to a miscalculated gain [9]. ...
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... Discarded rocket bodies and non-functional satellites dwell in space for many years. Due to collision, these objects are fragmented into even smaller parts, and the number of parts increases even further [72]. There are 34,000 objects larger than 10 cm, 900,000 larger than 1 cm, and 128 million larger than 1 mm floating in LEO orbit with a speed greater than 11 km/s. ...
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... This kind of generated debris cloud increases the likelihood of further collision, which could eventually lead to a long-feared Kessler syndrome phenomenon that could make space un-usable for the future. Nowadays [10], there is no doubt that the result of the so-called "Kessler Syndrome" is a significant source of future debris. The development of new operational procedures over the last 30 years has slowed the growth in orbital debris but these procedures have not been sufficient to prevent growth in the debris population from random collisions. ...
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Nearly a quarter century has passed since a new emphasis on space debris mitigation began, following two, nearly simultaneous seminal events: the publication of “Space Debris: An AIAA Position Paper” and the realization that numerous, intense Delta second stage fragmentations had been induced by residual propellants. Since that time the major space-faring nations of the world have adopted a wide range of debris mitigation practices which have arguably reduced the rate of growth of the debris population in Earth orbit. A study has been undertaken to quantify the likely historical effects of these debris mitigation measures on the current satellite population based upon vehicle-specific launch rates. The mitigation measures addressed in the study include those associated with mission-related debris, satellite breakups, and the disposal of satellites. Mitigation measures have been classified according to their near- and far-term consequences and to the degree of their implementation by the international aerospace community. The history of the application of space debris mitigation measures can be used in conjunction with long-term satellite evolutionary models to provide a more realistic expectation of the future environment.
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Unlike planets and satellites, smaller bodies in the solar system, like asteroids, comets, and meteoroids, are affected by nongravitational forces due to collisions, viscosity, and in some cases electromagnetic forces. The way such forces change the orbits of the bodies seems not to have been analyzed until recently. For example, it is generally believed that collisions between asteroids will make their orbits spread over an increasing volume of space and that collisions inside meteor streams will make their cross sections increase. At least under certain conditions the reverse is true, as shown by the papers of Baxter and Trulsen at this symposium. Furthermore, besides the usual picture of meteoroids being emitted by comets, we should also discuss the reverse process; viz, comet formation by bunching in a meteor stream.
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A new orbital debris evolutionary model is being developed by the NASA Orbital Debris Program Office at Johnson Space Center. LEGEND, a LEO-to-GEO Environment Debris model, is capable of reproducing the historical debris environment as well as performing future debris environment projection. The model covers the near Earth space between 200 and 40,000 km altitude and outputs debris distributions in one-dimensional (altitude), two-dimensional (altitude, latitude), and three-dimensional (altitude, latitude, longitude) formats. LEGEND is a three-year (2001–2003) project. The historical part of the model has been completed and the future projection part is being developed/tested. The model utilizes a recently updated historical satellite launch database, two efficient and accurate propagators, and a new NASA satellite breakup model. This paper summarizes the justifications for building a full-scale three-dimensional debris evolutionary model, the overall model structure, and several key components of the model. Preliminary model predictions of debris distributions in the Low Earth Orbit (LEO), Medium Earth Orbit (MEO), and Geosynchronous Earth Orbit (GEO) regions are presented.
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Active debris removal (ADR) was suggested as a potential means to remediate the low Earth orbit (LEO) debris environment as early as the 1980s. The reasons ADR has not become practical are due to its technical difficulties and the high cost associated with the approach. However, as the LEO debris populations continue to increase, ADR may be the only option to preserve the near-Earth environment for future generations. An initial study was completed in 2007 to demonstrate that a simple ADR target selection criterion could be developed to reduce the future debris population growth. The present paper summarizes a comprehensive study based on more realistic simulation scenarios, including fragments generated from the 2007 Fengyun-1C event, mitigation measures, and other target selection options.The simulations were based on the NASA long-term orbital debris projection model, LEGEND. A scenario where, at the end of mission lifetimes, spacecraft and upper stages were moved to 25-year decay orbits, was adopted as the baseline environment for comparison. Different annual removal rates and different ADR target selection criteria were tested, and the resulting 200-year future environment projections were compared with the baseline scenario. Results of this parametric study indicate that (1) an effective removal strategy can be developed using a selection criterion based on the mass and collision probability of each object, and (2) the LEO environment can be stabilized in the next 200 years with an ADR removal rate of five objects per year.
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Several studies conducted during 1991–2001 demonstrated, with some assumed launch rates, the future unintended growth potential of the Earth satellite population, resulting from random, accidental collisions among resident space objects. In some low Earth orbit (LEO) altitude regimes where the number density of satellites is above a critical spatial density, the production rate of new breakup debris due to collisions would exceed the loss of objects due to orbital decay.A new study has been conducted in the Orbital Debris Program Office at the NASA Lyndon B. Johnson Space Center, using higher fidelity models to evaluate the current debris environment. The study assumed no satellites were launched after December 2005. A total of 150 Monte Carlo runs were carried out and analyzed. Each Monte Carlo run simulated the current debris environment and projected it 200 years into the future. The results indicate that the LEO debris environment has reached a point such that even if no further space launches were conducted, the Earth satellite population would remain relatively constant for only the next 50 years or so. Beyond that, the debris population would begin to increase noticeably, due to the production of collisional debris. Detailed analysis shows that this growth is primarily driven by high collision activities around 900–1000 km altitude – the region which has a very high concentration of debris at present.In reality, the satellite population growth in LEO will undoubtedly be worse than this study indicates, since spacecraft and their orbital stages will continue to be launched into space. Postmission disposal of vehicles (e.g., limiting postmission orbital lifetimes to less than 25 years) will help, but will be insufficient to constrain the Earth satellite population. To better preserve the near-Earth environment for future space activities, it might be necessary to remove existing large and massive objects from regions where high collision activities are expected.
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Equations are derived which relate orbital parameters to the probability of collision between orbiting objects. These equations follow from a new conceptual approach, and are in a form to be easily applied to a variety of orbital collision problems. The equations are used in this paper to calculate the collision lifetime of Jupiter's eight outer satelites. The average time between collisions for any of the four retrograde moons was calculated to be 270 billion years, while the corresponding time for the four posigrade moons was 0.9 billion years. This relatively short time for the posigrade moons is strongly suggestive of a past collision history. The consequences of these collisions and the possible relationship to the Pioneer 10 and 11 penetration data is discussed.
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The probability of satellite collisions increases with the number of satellites. In the present paper, possible time scales for the growth of a debris belt from collision fragments are determined, and possible consequences of continued unrestrained launch activities are examined. Use is made of techniques formerly developed for studying the evolution (growth) of the asteroid belt. A model describing the flux from the known earth-orbiting satellites is developed, and the results from this model are extrapolated in time to predict the collision frequency between satellites. Hypervelocity impact phenomena are then examined to predict the debris flux resulting from collisions. The results are applied to design requirements for three types of future space missions.
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A very fast method of calculating the collision frequency between two low-eccentricity orbiting bodies has been developed for evaluating the evolution of Earth orbiting objects, such as space debris. The result is very accurate and the required computer time is negligible. This method is now applied without modification to calculate the collision frequencies for moderately and highly eccentric orbits. In collisions between the Earth and Earth-crossing bodies deviations in results are noticed when compared with the results published by Opik, Shoemaker et al., and Steel and Baggaley. The cause for some large deviations comes mainly from different methods used by different research groups in calculating the collision probabilities between ojects in similar inclinations. The errors in the results because of the approximation applied to the moderately and highly eccentric orbits are rather small. Furthermore, considering the tremendous computer time saved and the similar order of magnitude results, the fast method will be of great value in calculating the evolution of millions of objects circulating around a massive central attractor.
Fragmentation Algorithms for Satellite Targets (FAST) Empirical Breakup Model, Version 2.0", Prepared for DOD/ DNA Orbital Debris Spacecraft Breakup Modeling Technology Transfer Program by Kaman Sciences Corporation
  • D S Mcknight
  • Robert Maher
  • Larry Nagl
D.S. McKnight, Robert Maher and Larry Nagl, "Fragmentation Algorithms for Satellite Targets (FAST) Empirical Breakup Model, Version 2.0", Prepared for DOD/ DNA Orbital Debris Spacecraft Breakup Modeling Technology Transfer Program by Kaman Sciences Corporation, September 1992.