Space Debris In Low Earth Orbit Research Articles

Estimation of the required energy for a channel of high-precision phase direction finding of low-earth orbit space debris based on large scale antenna array

To solve the problem of radar observations of small-sized space debris of natural and artificial origin, a multi-antenna distributed structure based on adaptive antenna arrays is proposed. A method for estimating noise errors of the phase method of low-Earth orbit space debris bearing for a channel of high-precision phase direction finding based on elements of a multi-antenna field is presented. The results obtained characterize the potential accuracy of the system. Based on the specified dispersion of phase fluctuations, the required signal-to-noise ratio at the input of the device is determined according to the proposed method.

TEST OPTICAL OBSERVATIONS OF THE COSMOS 1408 FRAGMENTS

The non-functioning spacecraft COSMOS 1408 (NSSDCA/COSPAR ID: 1982-092A) was destroyed as a result of tests involving Russian anti-satellite weapons on 15 November 2021. This led to the creation of a significant debris cloud that poses a threat to other objects in low Earth orbit (LEO), particularly those in close orbits. More than 1500 of these fragments reached trackable sizes. Such events require rapid and immediate monitoring through all available ground tracking means, including radar and optical observation. The following study presents the results of optical observations of the selected fragments of COSMOS 1408 in Ukraine. These observations were carried out by the telescope OES30 from the National Space Facilities Control and Test Center of the State Space Agency of Ukraine and the Fast Robotic Telescope (FRT) of the Research Institute "Mykolaiv Astronomical Observatory" in February 2022. The observations demonstrated that Ukrainian optical sensors are capable of tracking LEO space debris objects with radar cross-sections (RCS) less than 0.1 square meters when relatively accurate ephemeris data is available. The astrometric reduction has been performed for the acquired frames with fragments of the satellite, which revealed that orbital parameters of a significant part of the targeting objects were close to the orbital parameters of the original satellite before the event. Furthermore, the results of processing the available observations indicated that the range of apogee heights significantly exceeds the range of perigee heights. These findings align with conclusions drawn by previous researchers. In the future, it will be essential to assess the capabilities of sensors for observing the aftermath of object destruction in LEO, especially during the initial hours and days following such events when precise debris orbit data may be lacking.

Improved Initial Orbit Determination Based on the Gooding Method of Low Earth Orbit Space Debris Using Space-Based Observations

Initial orbit determination (IOD), as a basis for initial orbit association and accurate orbit determination (OD), has a crucial role in the process of obtaining space debris orbit information. Among the traditional methods, the Gooding method has better convergence and stability. In this study, the Gooding method is enhanced to solve the issues discovered. A novel initial orbit determination (IOD) method is developed using the proposed improvement measures of the single-parameter initial value determination (SIVD) method, the fitted-curve noise suppression method, the restricted corrective value solution method, the removal of trivial solutions, etc. The experimental results verify the effectiveness of the improved method. The success rate of the initial orbit determination reached 99%, and the accuracy of the solved orbit parameters was significantly improved, especially the semi-major axis (SMA) error of less than 50 km, accounting for 88% of the total. It can be seen that the method meets the demand of space-based space debris cataloging for initial orbit association and can serve in the field of space situational awareness, which has important practical significance and application potential.

Ground-based laser momentum transfer concept for debris collision avoidance

Satellite laser ranging (SLR) is a well-established technology within the scientific community used since the early 1960s to precisely measure distances. The technology evolved in support of the geodetic research striving for high accuracy measurements which nowadays are achieved by means of high repetition, low energy pulse lasers used in combination with satellites equipped with retroreflectors. The achieved accuracy allowed not only for quality improvement of orbit determination products but also remote estimation of the attitude of the observed target.The SLR technique constitutes a highly accurate, relatively cheap alternative to radars for the tracking of orbiting targets. In the last decade, the successful tracking of resident space objects, not equipped with retroreflectors, made SLR a fundamental and appealing technique also in the space debris domain.In this study, we will introduce a possible step forward - thanks to the availability of commercial high power (> 10 kW) continuous wave (CW) lasers - which consists in the setup of a network of ground stations able to efficiently contribute to space debris collision avoidance manoeuvres in the low Earth orbit (LEO).This paper will summarize the achievements of a conceptual study on ground-based laser momentum transfer to LEO space debris performed by a consortium under the guidance of the German Aerospace Centre (DLR) funded by the European Space Agency (ESA) in the frame of the ESA Space Safety Programme.The study was carried out approaching the problem from an astrodynamics, physical, technological and legal point of view. The required tracking precision and the fundamental physics of the laser momentum transfer (LMT) were studied to evaluate the achievable thrust on LEO debris objects with commercially available components. An astrodynamics analysis was carried out to assess the efficiency of the imposed thrust and the consequences on the probability of collision in LEO. In the paper we will report the outcomes of the study which allowed us to define: the requirements of a laser tracking and momentum transfer (LTMT) station, the minimum size of an LTMT network for LEO collision avoidance operation, the current technological challenges, and gaps to be filled before its implementation.

Performance of a U-Net-based neural network for predictive adaptive optics.

We apply a U-Net-based convolutional neural network (NN) architecture to the problem of predictive adaptive optics (AO) for tracking and imaging fast-moving targets, such as satellites in low Earth orbit (LEO). We show that the fine-tuned NN is able to achieve an approximately 50% reduction in mean-squared wavefront error over non-predictive approaches while predicting up to eight frames into the future. These results were obtained when the NN, trained mostly on simulated data, tested its performance on 1 kHz Shack-Hartmann wavefront sensor data collected in open-loop at the Advanced Electro-Optical System facility at Haleakala Observatory while the telescope tracked a naturally illuminated piece of LEO space debris. We report, to our knowledge, the first successful test of a NN for the predictive AO application using on-sky data, as well as the first time such a network has been developed for the more stressing space tracking application.

Electromagnetic-launch-based method for cost-efficient space debris removal

Abstract The increase in space debris orbiting Earth is a critical problem for future space missions. Space debris removal has thus become an area of interest, and significant research progress is being made in this field. However, the exorbitant cost of space debris removal missions is a major concern for commercial space companies. We therefore propose the debris removal using electromagnetic launcher (DREL) system, a ground-based electromagnetic launch system (railgun), for space debris removal missions. The DREL system has three components: a ground-based electromagnetic launcher (GEML), suborbital vehicle (SOV), and mass of micrometer-scale dust (MSD) particles. The average cost of removing a piece of low-earth orbit space debris using DREL was found to be approximately USD 160,000. The DREL method is thus shown to be economical; the total cost to remove more than 2,000 pieces of debris in a cluster was only approximately USD 400 million, compared to the millions of dollars required to remove just one or two pieces of debris using a conventional space debris removal mission. By using DREL, the cost of entering space is negligible, thereby enabling countries to remove their space debris in an affordable manner.

Universal Rocket Space Engine and solving the problem of space debris

The total mass of only large fragments of space debris in low-earth orbits(LEO) exceeds 7,500 tons. The well-known concepts of solving the problem of space debris are considered. An approach to space debris as a valuable resource is formulated. It is proposed to use space debris as a propellant for the Universal Rocket Space Engine (URSE). The engine should consist of a thermal rocket engine in conjunction with accelerator – railgun, for example. The steam generated during the evaporation of space debris speeds accelerates to 10 – 50 km/s in this scheme. Power supply of the engine is planned to be implemented by solar energy or a nuclear power plant. When particles of debris passing through a high-temperature evaporator, it turns into steam. Then the steam passes into the nozzle, where the railgun is located. After railgun, the accelerating plasma expires in space. There are three methods to obtain high-temperature vapor in the evaporator: solar furnace (direct heating), electric arc heating or ion sputtering technology. The project is proposed to be divided into several stages, each characterized by the use of various technical solutions. URSE will allow using not only space debris, but also materials of small celestial bodies as fuel for space flights within the solar system. This will make it possible to radically change the schemes of space flight, since restrictions on the mass of fuel using the URSE are removed. For example, during flying from Mars to Earth, the material of the Martian satellites of Phobos and Deimos can be used as a propellant.

Effects of deorbit evolution on space-based pulse laser irradiating centimeter-scale space debris in LEO

The aim of this work is to address the dynamic response rules of deorbit evolution for removing centimeter-scale dangerous space debris near the international space station (ISS) by space-based single laser station. According to the theory of orbital dynamics and laser irradiation technology, the deorbit model of space-based laser irradiating the centimeter-scale debris in low earth orbit (LEO) was established. The deorbit process of driving the centimeter-scale debris was simulated by analyzing the orbit and laser parameters in coplanar/non-coplanar conditions, and the distribution rules of irradiation distance with action time were also obtained. Furthermore, the dynamic characteristics of deorbit evolution were investigated by calculating the flight paths and orbital elements after the dangerous debris is irradiated, and the interaction mechanism between space-based nanosecond pulse laser and the dangerous debris was detailedly discussed by estimating collision risk between the dangerous debris and the ISS. The simulation results indicated that the collision risk between the dangerous debris and the ISS was successfully eliminated based on the designed removal scheme and given clearance windows. Therefore, it is highly important for exploring excellent clear method to master removal rules of centimeter-scale dangerous space debris in LEO by the space-based nanosecond pulse laser.

Space debris observation performance research of CSTAR at Kunlun Station in Antarctica

Increasing space debris has seriously threatened the safety of spacecraft of various countries. The polar regions are the most densely distributed regions of Low-Earth orbit (LEO) space debris, and are ideal sites for observing LEO space debris. Through the real observation data and detection capabilities simulation, the advantages of China's Kunlun Station in Antarctica in observing LEO space debris are analyzed. Firstly, the real observation data of Chinese Small Telescope Array (CSTAR) are analyzed and compared with the space objects cataloging database (mean www.space-track.org), which confirms the high performance and superiority of Kunlun Station in LEO space debris observation. Secondly, the space debris observation performance of CSTAR is simulated and compared with its historical observation data in the same period, to confirm the reliability of the simulation model. Finally, based on the real observation data and simulation results, some hypothesis simulations and prospects for future space debris observation facilities at Kunlun Station are made. The simulation results can provide support for future observations at Kunlun Station in Antarctica.

Discrete evolution model based on mean spatial density for space debris environment

Concerning the increasing space debris and its collision threat on operational satellites, a simple and less computation consuming model is built to implement the long-term evolution and prediction of the Low-Earth orbit space debris environment. Space debris is divided into groups according to the orbital height and the area-mass ratio. For each group, the distribution state is described by the mean spatial density, and the dynamics of the evolution process under the effect of mutual collision and the perturbation of atmosphere drag is modeled by a partial differential equation (PDE). A two-dimensional analytical solution is obtained when the collision-associated terms of those PDEs are excluded. Moreover, the analytical results are shown compatible with the results of a numerical simulation code, which means that the mechanical model in the evolution model is reliable. In a hypothetical scenario, i.e. without future launch activities, the collisional “chain reaction” of the space debris environment will be reached, as shown by the numerically obtained solution of the general evolution model.

Satellite Laser Ranging System at Geochang Station

Korea Astronomy and Space Science Institute (KASI) has been developing the space optical and laser tracking (SOLT) system for space geodesy, space situational awareness, and Korean space missions. The SOLT system comprises satellite laser ranging (SLR), adaptive optics (AO), and debris laser tracking (DLT) systems, which share numerous subsystems, such as an optical telescope and tracking mount. It is designed to be capable of laser ranging up to geosynchronous Earth orbit satellites with a laser retro-reflector array, space objects imaging brighter than magnitude 10, and laser tracking low Earth orbit space debris of uncooperative targets. For the realization of multiple functions in a novel configuration, the SOLT system employs a switching mirror that is installed inside the telescope pedestal and feeds the beam path to each system. The SLR and AO systems have already been established at the Geochang station, whereas the DLT system is currently under development and the AO system is being prepared for testing. In this study, the design and development of the SOLT system are addressed and the SLR data quality is evaluated compared to the International Laser Ranging Service (ILRS) tracking stations in terms of single-shot ranging precision. The analysis results indicate that the SLR system has a good ranging performance, to a few millimeters precision. Therefore, it is expected that the SLR system will not only play an important role as a member of the ILRS tracking network, but also contribute to future Korean space missions.

Effects of space-based nanosecond pulse laser driving centimeter-sized space debris in LEO

The aim of this article was to address the effects of dynamic response for space-based nanosecond pulse laser irradiating centimeter-sized space debris. A dynamic response model of nanosecond pulse laser irradiating aluminum alloy debris was established, and the variation characteristic of kinetic energy and space-time distributing rule of shock wave were simulated based on different pulse width laser. Further, a deorbit model of space-based pulse laser irradiating the debris was established in low earth orbit (LEO), and the corresponding distribution rule of impulse coupling coefficient with zenith angle was simulated based on different laser pulses width. As a result, the interaction rules of different parameters including perigee altitude, semi-major axis, eccentricity and laser irradiating direction with initial true anomaly were investigated after the debris deorbit. The results indicated that the effects of active deorbit by laser irradiating centimeter-sized debris was superior when the initial true anomaly was 60° to 180° based on the condition of this paper. Especially, when the action direction of laser irradiating debris was opposite to the moving direction of debris circumferential velocity, a wider irradiating area was gotten while the initial true anomaly was about 120° or 240°.

An optimal beam alignment method for large-scale distributed space surveillance radar system

Large-scale distributed space surveillance radar is a very important ground-based equipment to maintain a complete catalogue for Low Earth Orbit (LEO) space debris. However, due to the thousands of kilometers distance between each sites of the distributed radar system, how to optimally implement the Transmitting/Receiving (T/R) beams alignment in a great space using the narrow beam, which proposed a special and considerable technical challenge in the space surveillance area. According to the common coordinate transformation model and the radar beam space model, we presented a two dimensional projection algorithm for T/R beam using the direction angles, which could visually describe and assess the beam alignment performance. Subsequently, the optimal mathematical models for the orientation angle of the antenna array, the site location and the T/R beam coverage are constructed, and also the beam alignment parameters are precisely solved. At last, we conducted the optimal beam alignment experiments base on the site parameters of Air Force Space Surveillance System (AFSSS). The simulation results demonstrate the correctness and effectiveness of our novel method, which can significantly stimulate the construction for the LEO space debris surveillance equipment.

Estimation of ballistic coefficients of space debris using the ratios between different objects

This paper proposes a new method to estimate the ballistic coefficient (BC) of low earth orbit space debris. The data sources are the historical two-line elements (TLEs). Since the secular variation of semi-major axes is mainly caused by the drag perturbation for space objects with perigee altitude below 600km, the ballistic coefficients are estimated based on variation of the mean semi-major axes derived from the TLEs. However, the approximate parameters used in the calculation have error, especially when the upper atmosphere densities are difficult to obtain and always estimated by empirical model. The proportional errors of the approximate parameters are cancelled out in the form of ratios, greatly mitigating the effects of model error. This method has been also been validated for space objects with perigee altitude higher than 600km. The relative errors of estimated BC values from the new method are significantly smaller than those from the direct estimation methods used in numerical experiments. The estimated BC values are used for the prediction of the semi-major axes, and good performance is obtained. This process is also a feasible method for prediction over a long period of time without an orbital propagator model.

Bi-objective optimization of a multiple-target active debris removal mission

The increasing number of space debris in Low-Earth Orbit (LEO) raises the question of future Active Debris Removal (ADR) operations. Typical ADR scenarios rely on an Orbital Transfer Vehicle (OTV) using one of the two following disposal strategies: the first one consists in attaching a deorbiting kit, such as a solid rocket booster, to the debris after rendezvous; with the second one, the OTV captures the debris and moves it to a low-perigee disposal orbit. For multiple-target ADR scenarios, the design of such a mission is very complex, as it involves two optimization levels: one for the space debris sequence, and a second one for the “elementary” orbit transfer strategy from a released debris to the next one in the sequence. This problem can be seen as a Time-Dependant Traveling Salesman Problem (TDTSP) with two objective functions to minimize: the total mission duration and the total propellant consumption.In order to efficiently solve this problem, ONERA has designed, under CNES contract, TOPAS (Tool for Optimal Planning of ADR Sequence), a tool that implements a Branch & Bound method developed in previous work together with a dedicated algorithm for optimizing the “elementary” orbit transfer. A single run of this tool yields an estimation of the Pareto front of the problem, which exhibits the trade-off between mission duration and propellant consumption. We first detail our solution to cope with the combinatorial explosion of complex ADR scenarios with 10 debris. The key point of this approach is to define the orbit transfer strategy through a small set of parameters, allowing an acceptable compromise between the quality of the optimum solution and the calculation cost. Then we present optimization results obtained for various 10 debris removal scenarios involving a 15-ton OTV, using either the deorbiting kit or the disposal orbit strategy.We show that the advantage of one strategy upon the other depends on the propellant margin, the maximum duration allowed for the mission and the orbit inclination domain. For high inclination orbits near 98 deg, the disposal orbit strategy is more appropriate for short duration missions, while the deorbiting kit strategy ensures a better propellant margin. Conversely, for lower inclination orbits near 65 deg, the deorbiting kit strategy appears to be the only possible with a 10 debris set. We eventually explain the consistency of these results with regards to astrodynamics.

低轨空间碎片弹道系数及应用

低轨空间碎片弹道系数及应用

低轨空间碎片弹道系数及应用

低轨空间碎片弹道系数及应用

A laser-optical system to re-enter or lower low Earth orbit space debris

Collisions among existing Low Earth Orbit (LEO) debris are now a main source of new debris, threatening future use of LEO space. Due to their greater number, small (1–10cm) debris are the main threat, while large (>10cm) objects are the main source of new debris. Flying up and interacting with each large object is inefficient due to the energy cost of orbit plane changes, and quite expensive per object removed. Strategically, it is imperative to remove both small and large debris. Laser-Orbital-Debris-Removal (LODR), is the only solution that can address both large and small debris. In this paper, we briefly review ground-based LODR, and discuss how a polar location can dramatically increase its effectiveness for the important class of sun-synchronous orbit (SSO) objects. With 20% clear weather, a laser-optical system at either pole could lower the 8-ton ENVISAT by 40km in about 8 weeks, reducing the hazard it represents by a factor of four. We also discuss the advantages and disadvantages of a space-based LODR system. We estimate cost per object removed for these systems. International cooperation is essential for designing, building and operating any such system.

An analytical theory for avoidance collision between space debris and operating satellites in LEO

This paper provides a Hamiltonian formulation of equations of motion of an artificial satellite or space debris moving in Low Earth orbit (LEO). This Hamiltonian is the base to develop an analytical theory of order three, which the theory has been formulated using canonical transformations using Hori-Lie method. The theory accounts for the influence of the Earth gravity field up to degree and order of geopotential harmonics (50×50), luni-solar perturbations, solar radiation pressure, atmospheric drag, albedo forces, and the post Newtonian effects arising from Schwarzschild solutions. In this theory, we pay particular attention to the resonance and very long period perturbations, which are modeled with the use of semi-secular terms. The fourth order Runge–Kutta numerical integrator is used to integrate the equations of motion in order to compare with the analytical theory. Including all possible perturbations, in particularly Aledo force and post Newtonian effect in addition to the adequate section of the integrator found to have an importance on the improving the accuracy of the current theory compared with the previous solution. The orbital theory is precise and enables the short term predictions on a few centimeters level. Finally, we show some results concerning the short term dynamics of a different satellite and space debris in LEO under the influence of the considered perturbations.

A novel signal processing approach for LEO space debris based on a fence-type space surveillance radar system

The increase in space debris can seriously threaten regular activities in the Low Earth Orbit (LEO) environment. Therefore, it is necessary to develop robust, efficient and reliable techniques to understand the potential motions of the LEO debris. In this paper, we propose a novel signal processing approach to detect and estimate the motions of LEO space debris that is based on a fence-type space surveillance radar system. Because of the sparse distribution of the orbiting debris through the fence in our observations, we formulate the signal detection and the motion parameter estimation as a sparse signal reconstruction problem with respect to an over-complete dictionary. Moreover, we propose a new scheme to reduce the size of the original over-complete dictionary without the loss of the important information. This new scheme is based on a careful analysis of the relations between the acceleration and the directions of arrival for the corresponding LEO space debris. Our simulation results show that the proposed approach can achieve extremely good performance in terms of the accuracy for detection and estimation. Furthermore, our simulation results demonstrate the robustness of the approach in scenarios with a low Signal-to-Noise Ratio (SNR) and the super-resolution properties. We hope our signal processing approach can stimulate further work on monitoring LEO space debris.