Space Surveillance And Tracking Research Articles

An innovative sCMOS based autonomous astronomical camera dedicated to universal use for SST and other fields of optical astronomy

Creotech Instruments is advancing a game-changing sCMOS camera series. The Final Prototype Model of an astronomical camera for Space Surveillance and Tracking (SST) is in the test campaign phase. Designed for SST, NEO, and debris detection, its adaptable platform suits quantum tech and biological microscopy. Edge computing sets it apart, leveraging FPGA-based SoC for real-time processing and Linux-based pre-processing. Operating autonomously, it supports on-camera ML algorithms, revolutionizing astronomy. Data pre-processing, like frame stacking, reduces data load. This paper introduces the camera's concept, architecture, and prototype test results, emphasizing specific use cases and future product line development.

An orbit determination software suite for Space Surveillance and Tracking applications

AbstractThe growth of both operational satellites and orbital debris is creating the requirement for more robust Space Surveillance and Tracking (SST)-related applications. These systems necessarily must leverage ground-based sensors (optical and radar) to realise higher performance solutions. In this context, the European Union Space Surveillance and Tracking (EUSST) consortium groups European national agencies and institutions, and is in charge of carrying out the following services: conjunction analysis, fragmentation analysis and re-entry prediction, and the Italian Air Force is in charge of the latter two. In this framework, the Italian SST Operational Centre (ISOC) has recently upgraded its system to the ISOC Suite, an integrated platform providing multiple functions and services in the SST domain. This paper presents the orbit determination functions provided by the novel ISOC Suite. First, a statistical index is computed to assess the measurements correlation to a catalogued object. If it is successful, the object predicted orbit is refined through measurements according either to batch or sequential filters; otherwise these are used to refine a first estimate of the target orbital state computed according to dedicated methodologies. After the presentation of the prototypal software architecture, the ISOC Suite performance are assessed and discussed both in terms of synthetic and real data.

Enhancing the radar system simulator tool suite to allow the simulation of sensor networks

The number of human-made objects orbiting the Earth is growing steadily. This trend is further accelerating during recent years due to increasing commercialization in the field of satellite operations and an increasing launch rate. Concerning the area of space surveillance and tracking (SST), this leads to higher demands with respect to object observation capabilities. In order to ensure the safe usability of the different Earth orbits for all spacecraft operators, it is of great importance to continuously observe and catalog as many of the human-made objects as possible. This is especially true for inactive and uncontrollable objects, i.e. space debris. Only by maintaining accurate catalogs of the space debris environment, involuntary collisions can be avoided and risks of losing a spacecraft kept low. While the number of space debris objects can only be expected to further increase, it is not trivial to increase the number of observation sites, such as telescopes and radars, or their capabilities to counter this. One way to increase the observation capabilities without constructing new observation sites is to search for possibilities to improve the efficiency with which the existing sensors observe objects.With the goal to study and analyze single sensors, sensor networks, and how they can be used in the most efficient way, a sensor network simulator tool suite has been developed at the Institute of Space Systems of the Technical University of Braunschweig. Originally, the tool suite was developed as a radar system simulator concentrating on the different radar system configurations, such as reflector antennas or phased arrays that are used in a mono- or bistatic mode. Additionally, the corresponding radar performance model is able to simulate a tracking as well as a scanning mode. Building upon this tool suite, it is now extended to include an optical performance model and the possibility to simulate not only ground-based but also space-based sensors. Within this work, the preliminary results obtained with the newly implemented optical performance model are shown.Using the enhanced version of this sensor network simulator tool suite, thorough analyses can now be made using the radar and optical performance models. Sensor networks consisting of radars and telescopes being both ground- or space-based can be studied in different configurations. Thereby, different aspects, such as observation strategies, sensor tasking, or choosing the right location and sensor to reach a certain goal can be investigated.

Barriers and Gateways to Cleaning Up Earth Orbit: The Legal, Economic, and Political Dimensions of Debris Remediation

The preponderance of human-made debris in Earth orbit has long been recognized as a significant threat to continued safe operations in space. National space agencies and private space companies are paying considerable attention to the technical questions surrounding the active removal of debris (ADR). Nonetheless there are still significant legal, economic, and geopolitical questions that need to be addressed before any meaningful and sustained industry around the removal of debris can be established. This discussion will focus on identifying the legal issues of responsibility, jurisdiction and liability and proposing possible solutions within the current nexus of international agreements. Yet these must be considered alongside the economic roadblocks to funding ADR; the challenges for states looking to collaborate in current geopolitical circumstances; and the often overlooked ‘data deficit’ in respect of the space surveillance and tracking (SST) capabilities needed to enable the safe removal of debris. It is contended that any system for managing ADR, Debris Mitigation and general protection of the space environment should not emerge in isolation. A coherent system of managing and coordinating the orbital environment needs to be developed. This article will argue that it is for individual nations to show political leadership and an economic commitment to properly manage the delicate extraterrestrial environment. Failure to do so will represent a missed opportunity and leave a troubling legacy for future generations. Active Debris Removal, Astropolitics, Space Law, Dual use technology, Space Environment

Design and Validation of a U-Net-Based Algorithm for Star Sensor Image Segmentation

The present work focuses on the investigation of an artificial intelligence (AI) algorithm for brightest objects segmentation in night sky images’ field of view (FOV). This task is mandatory for many applications that want to focus on the brightest objects in an optical sensor image with a particular shape: point-like or streak. The algorithm is developed as a dedicated application for star sensors both for attitude determination (AD) and onboard space surveillance and tracking (SST) tasks. Indeed, in the former, the brightest objects of most concern are stars, while in the latter they are resident space objects (RSOs). Focusing attention on these shapes, an AI-based segmentation approach can be investigated. This will be carried out by designing, developing and testing a convolutional neural network (CNN)-based algorithm. In particular, a U-Net will be used to tackle this problem. A dataset for the design process of the algorithm, network training and tests is created using both real and simulated images. In the end, comparison with traditional segmentation algorithms will be performed, and results will be presented and discussed together with the proposal of an electro-optical payload for a small satellite for an in-orbit validation (IOV) mission.

Tracklet-to-orbit association for maneuvering space objects using optimal control theory

The maintenance of a catalog of space objects is integral for Space Surveillance and Tracking (SST). In order to enable safe space operations, this catalog shall be complete, accurate and traceable. One of the challenges to keep custody of active satellites comes from their unknown maneuvers plan that adds significantly to the uncertainty on their precise dynamics. This fact can imply the failure of conventional measurement-to-orbit association methods leading at the best to an inconsistent traceability in the catalog (a physical object represented by two or more catalog objects) or, at worst, to the loss of the tracking of an object. This paper presents a method to tackle the measurement-to-orbit association in the presence of unknown maneuvers. It is based on optimal control theory coupled with the admissible region. In particular, the orbit-to-orbit association problem is solved with an energy-optimal indirect approach, which is then generalized to the measurement-to-orbit association problem using the admissible regions concept. Measurements are supposed to be a collection of time-close optical measurements or tracklet that can be represented by an attributable vector. A broad bench of simulated tests is presented in the case of a geostationary (GEO) maneuvering satellite, and the method is finally applied to a real case of a longitude-shift GEO satellite using the data provided by the TAROT telescope network.

Monitoring the final orbital decay and the re-entry of Tiangong-1 with the Italian SST ground sensor network

The uncontrolled re-entry of spacecraft and upper stages is quite common, occurring nearly every week. Among them, intact objects having a mass greater than five metric tons re-enter, on average, 1–2 times per year. Therefore, the re-entry of the first Chinese Space Station, Tiangong-1, was far from unusual, but attracted anyway a great worldwide attention and some concerns. For these reasons, the Italian component of the European SST (Space Surveillance and Tracking) consortium took this opportunity for carrying out a national exercise. According to Chinese official sources, the ground control of Tiangong-1 was lost in March 2016, precluding the planned de-orbiting in the South Pacific Ocean Unpopulated Area (SPOUA). Tiangong-1 consisted of a cylindrical section, 10:5 m in length and 3:4 m in (maximum) diameter, with two rectangular solar panels of 3 m × 7 m. The mass was estimated to be around 7500 kg.The Italian network of sensors activated for the campaign included mono-static and bi-static radars, optical telescopes, a laser ranging station and a network of all-sky cameras, originally deployed for the observation of fireballs and bolides. In addition to providing complementary information, concerning the orbit, the attitude and the photometry of Tiangong-1, this quite heterogeneous collection of national assets provided also the occasion for testing, in an operational environment, the Italian sensor tasking preparedness and the data acquisition, exchange and processing capabilities within the European SST consortium.In this respect, it is important to remember that in 2014 the European Commission, well aware of the topic criticality, took the commitment to implement a European network of sensors for surveillance and tracking of objects in Earth’s orbit by starting a dedicated SST support framework program. Italy, France, Germany, Spain and UK joined it and constituted, together with SatCent, the front desk for SST services, the EUSST Consortium. In this paper, a description of the Tiangong-1 monitoring activities and of the main observations results obtained by the Italian sensor network are reported. Attention is also devoted to the coordination aspects of several Italian entities (military, civil and research organizations) that worked together. Finally, a description of the re-entry prediction and alert procedure for the national civil protection authorities is presented.

PyBIRALES: A Radar Data Processing Backend for the Real-Time Detection of Space Debris

The growing population of artificial satellites in near-Earth orbit has made the monitoring of orbital debris objects ever more important. Orbital debris objects pose a threat to these satellites as their orbit cannot be changed in order to avoid a collision. In recent years, the European Space Agency (ESA)’s Space Surveillance and Tracking (SST) programme has been assisting national institutions in the upgrading of their space debris detection and monitoring capabilities. One of the latest such systems within this programme is the BIRALES space surveillance system based in Italy. The receiving antenna is a radio telescope that is made up of 32 receivers which are placed on eight parabolic cylindrical reflectors of the North–South arm of the Istituto Nazionale di Astrofisica (INAF)’s Northern Cross. This work introduces a new software backend which was developed for this novel space debris sensor. The system was designed to be a fast, highly configurable software backend for the radio telescope’s acquisition and processing system and whose monitoring and control can be realized by a simple front-end web-based application. The real-time detection of Resident Space Object (RSO) is an important prerequisite for such a system as it gives the operator an immediate feedback loop on any detections whilst keeping the storage requirements at a minimum given that there is no need to save the raw data. The detection of high-velocity objects is achieved by means of a specially developed data processing pipeline that uses the received raw antenna voltages to generate a number of beams, collectively known as a multipixel, that cover the Field of View (FoV) of the instrument. The trajectory of the detected objects is determined by considering the illumination sequence within this multipixel. The initial results on known objects represent the first steps in extending the growing network of European SST systems.

Outer space SARPs: A mechanism for implementation of space safety standards

The global space sector is undergoing a profound transformation and some trends currently observed (e.g. increased traffic, new actors, emerging concepts) are raising new safety and security concerns for space infrastructures. This situation has been widely acknowledged by governmental and commercial stakeholders, including European ones. Space surveillance and tracking (SST) capabilities are one of the tools to address these growing space security concerns.This paper proposes a thorough contextual analysis of the current state of play of the space surveillance and tracking domain in Europe. The analysis covers European and national frameworks as well as private initiatives and concludes with the identification of some key elements to take into consideration for the future of European SST capabilities.

European SST landscape: Current status and challenges on the way ahead

The global space sector is undergoing a profound transformation and some trends currently observed (e.g. increased traffic, new actors, emerging concepts) are raising new safety and security concerns for space infrastructures. This situation has been widely acknowledged by governmental and commercial stakeholders, including European ones. Space surveillance and tracking (SST) capabilities are one of the tools to address these growing space security concerns.This paper proposes a thorough contextual analysis of the current state of play of the space surveillance and tracking domain in Europe. The analysis covers European and national frameworks as well as private initiatives and concludes with the identification of some key elements to take into consideration for the future of European SST capabilities.

First laser measurements to space debris in Poland

The Borowiec Satellite Laser Ranging station (BORL 7811, Borowiec) being a part of the Space Research Centre of the Polish Academy of Sciences (SRC PAS) went through modernization in 2014–2015. One of the main tasks of the modernization was the installation of a high-energy laser module dedicated to space debris tracking. Surelite III by Continuum is a Nd:YAG pulse laser with 10 Hz repetition rate, a pulse width of 3–5 ns and a pulse energy of 450 mJ for green (532 nm). This new laser unit was integrated with the SLR system at Borowiec performing standard satellite tracking. In 2016 BORL 7811 participated actively to the observational campaigns related to the space debris targets from LEO region managed by the Space Debris Study Group (SDSG) of the International Laser Ranging Service (ILRS).Currently, Borowiec station regularly tracks 36 space debris from the LEO regime, including typical rocket bodies (Russian/Chinese) and cooperative targets like the inactive TOPEX/Poseidon, ENVISAT, OICETS and others. In this paper the first results of space debris laser measurements obtained by the Borowiec station in period August 2016 – January 2017 are presented. The results gained by the SRC PAS Borowiec station confirm the rotation of the defunct TOPEX/Poseidon satellite which spins with a period of approximately 10 s. The novelty of this work is the presentation of the sample results of the Chinese CZ-2C R/B target (NORAD catalogue number 31114) which is equipped (probably) with retroreflectors. Laser measurements to space debris is a very desirable topic for the next years, especially in the context of the Space Surveillance and Tracking (SST) activity. Some targets are very easy to track like defunct ENVISAT or TOPEX/Poseidon. On the other hand, there is a big population of different LEO targets with different orbital and physical parameters, which are challenging for laser ranging like small irregular debris and rocket boosters.

SPOOK - A comprehensive Space Surveillance and Tracking analysis tool

Space Surveillance and Tracking (SST) is the ability to detect and predict the movement of space debris in orbit around the Earth. SPOOK (SPace Object Observations and Kalman filtering) is a versatile and highly configurable software tool developed by Airbus, for the detection, cataloguing and orbit prediction analysis of Earth orbiting objects. It provides an integrated framework for all the activities related with SST sensor architecture simulation. Throughout this paper, the functionalities of the tool are described and examples of different simulation scenarios are provided.

English

The recently unveiled EU Global Strategy for Foreign and Security Policy presents bold and ambitious plans in several increasingly important domains for Europe, including outer space. The EU has committed itself to securing an autonomous access to space, providing security for its space-based assets, and promoting the adoption of a voluntary code of conduct in space. With the evolving dynamics in astropolitics, space security has become an ever more important aspect of space activities. Clearly, the EU has a vested interest in space security, whereas space-enabled services form an important part of European economy and contribute to effective implementation of its energy policy, migration, border control as well as domestic and international crisis management. Since the EU is currently in the process of drafting a European Space Strategy, it should seize the opportunity to take stock of its existing space programs and lay out a promising way forward. Besides reinforcing the existing Copernicus and Galileo programs and further developing the Governmental Satellite Communications (GOVSATCOM) project, the EU should make a significant investment in space security, particularly through boosting its Space Surveillance and Tracking (SST) capabilities and actively working on the international fora to promote a responsible behavior in outer space that could be eventually transformed into a voluntary international code of conduct. Through a comprehensive space policy and by reinforcing its autonomy in outer space, the EU will not only strengthen its foreign and security policy, but also reconfirm its relevant role in global affairs.

Evaluation of minimum coverage size and orbital accuracy at different orbital regimes for one order of magnitude reduction of the catastrophic collision risk

One of the main objectives of Space Surveillance and Tracking (SST) systems is to support space collision avoidance activities. This collision avoidance capability aims to significantly reduce the catastrophic collision risk of space objects. In particular, for the case of the future European SST, the objective is translated into a risk reduction of one order of magnitude whilst keeping a low number of false alarm events. In order to translate this aim into system requirements, an evaluation of the current catastrophic collision risk for different orbital regimes is addressed. The reduction of such risk depends on the amount of catalogued objects (coverage) and the knowledge of the associated orbits in the catalogue (accuracy). This paper presents an analysis of the impact of those two aspects in the capability to reduce the catastrophic collision risk at some orbital regimes.A reliable collision avoidance support depends on the accuracy of the predicted miss-events. The assessment of possible conjunctions is normally done by computing the estimated miss-distances between objects (which is compared with a defined distance threshold) or by computing the associated collision risk (which is compared with the corresponding accepted collision probability level). This second method is normally recommended because it takes into account the reliability of the orbits and allows reducing false alarm events. The collision risk depends on the estimated miss-distance, the object sizes and the accuracy of the two orbits at the time of event. This accuracy depends on the error of the orbits at the orbit determination epoch and the error derived from the propagation from that epoch up to the time of event.The modified DRAMA ARES (Domínguez-González et al., 2012, 2013a,b; Gelhaus et al., 2014) provides information on the expected number of encounters for a given mission and year. It also provides information on the capacity to reduce the risk of collision by means of avoidance manoeuvres as a function of the accepted collision probability level and the cataloguing performance of the surveillance system (determined by the limiting coverage size-altitude function and the orbital data accuracy). The assessment of avoidance strategies takes into account statistical models of the space object environment, as provided by ESA’s MASTER-2009 model, and a mathematical framework for the collision risk estimation as used in satellite operations.In this papers, results are provided for some orbit types, covering different orbital regimes. The analysis is done for different cataloguing capacity levels (accuracy and coverage), concluding that 5cm are to be covered at LEO for diminishing the catastrophic collision risk by one order of magnitude. For MEO and GEO regime, coverage down to 40 and 100cm respectively allow similar reduction of risk.

Space Situational Awareness in Europe: The Fractures and the Federative Aspects of European Space Efforts

Space is a strategic sector, integral to virtually every facet of life in Europe, thus protection of this vital European space infrastructure is critical. No European organization, however, is able to provide a sufficiently independent assessment of the space environment. Efforts, therefore, are being pursued to develop an integrated Space Situational Awareness (SSA) capability in Europe. This article reviews the undertaking of SSA in Europe and the roles played by the European Union (EU) and the European Space Agency (ESA). It examines some of the obstacles ESA has faced in implementing its SSA efforts, challenges which range from budgetary limitations to the refusal of member states to share their military facilities, with the result being that ESA focuses on space weather and near-Earth objects rather than the more controversial and national security aspects of SSA, space surveillance and tracking (SST). The article also assesses the European Commission’s proposal for establishing a SST support program and coordinating European states’ SST assets while the national European governments—namely, their respective military authorities—retain control of SST sensor and processing functions.