Satellite Services Research Articles

The Effect of Work Stress, Work Conflict and Work Ability and Their Impact on Employee Performance Through Motivation as an Intervening Variable

The purpose of this research is to be able to analyze the results of the effect of stress at work, work conflict and an increase in work performance through work motivation. The population used in this study were all employees of PT. Bank Rakyat Indonesia Tbk, Satellite Services Operation Department used as a sample. The analytical method will use an analytical tool in the form of a Structural Equation Model (SEM) program through AMOS software. The results of the research work stress, conflict at work and the ability to work will have a significant influence on work motivation. However, work stress, work conflict and ability to work will affect work performance, while motivation will not have a significant effect on performance. Motivation is useful for mediating work stress and work conflict on performance and motivation is not able to mediate work ability on performance.

Resonance-Averaged Solar Torque Dynamics for Tumbling Satellites

Observations indicate that the spin states of retired and otherwise defunct satellites are diverse and can change significantly over time. Understanding defunct satellite spin state evolution is important for solar radiation pressure modeling, active debris removal, satellite servicing, and space situational awareness. Research has shown that many defunct satellites in geosynchronous earth orbit (GEO) are primarily driven by solar radiation torques via the Yarkovsky–O’Keefe–Radzievskii–Paddack (YORP) effect. Recent exploration of YORP-driven nonprincipal axis tumbling has uncovered rich dynamic behavior, including tumbling cycles, spin–orbit coupling, and tumbling period resonances. Radar and optical observations of the defunct Geostationary Operational Environmental Satellite (GOES) 8 strongly suggest that it has been captured in a tumbling resonance at least once since 2018. Motivated by these findings, we develop a numerical resonance-averaged dynamic model to understand YORP-driven resonance capture, building on our earlier nonresonant averaging framework. This resonance-averaged model illuminates resonance capture mechanisms. Also, by averaging over the satellite’s rotation, this model is roughly 20 times faster to propagate than the full (Euler) dynamics. Overall, this allows for rapid, broad exploration to determine resonance capture durations, spin states changes, and the influence of initial spin rate and resonance order on resonance strength. This resonance-averaged model can be easily applied to other environmental perturbations.

Space Detumbling Robot Arm Deployment Path Planning Based on Bi-FMT* Algorithm.

In order to avoid damage to service satellites and targets during space missions and improve safety and reliability, it is necessary to study how to eliminate or reduce the rotation of targets. This paper focused on a space detumbling robot and studied the space detumbling robot dynamics and robot arm deployment path planning. Firstly, a certain space detumbling robot with a ‘platform + manipulator + end effector’ configuration is proposed. By considering the end effector as a translational joint, the entire space detumbling robot is equivalent to a link system containing six rotating joints and three translational joints, and the detailed derivation process of the kinematic and dynamic model is presented. Then, ADAMS and MATLAB were used to simulate the model, and the MATLAB results were compared with the ADAMS results to verify the correctness of the model. After that, the robot arm deployment problem was analyzed in detail from the aspects of problem description, constraint analysis and algorithm implementation. An algorithm of robot arm deployment path planning based on the Bi-FMT* algorithm is proposed, and the effectiveness of the algorithm is verified by simulation.

Recent research and development activities on space robotics and AI

Deep space exploration missions have received a lot of attention in the world, such as the moon, Mars, asteroids for scientific observation and human activities. Recently, not only space agencies but also industries or universities have earnestly studied and developed lunar or planetary robots for lunar or planetary exploration. International cooperative missions are also under discussion including human lunar exploration. Space robotics including Al is a key technology for planetary exploration as well as orbital service. Future space programs require space AI and robotics technology to construct, repair and maintain satellites and space structures in orbit. This paper introduces recent space missions and surveys hot topics on new research activities and developed technology for the near future missions.

Control of a service satellite during its mission on space debris removal from orbits with high inclination by implementation of an ion beam method

The largest population of space debris is observed in the low-Earth-orbit region with altitudes of 600–1000 km and inclinations of 80–100°. As follows from the predictive calculations, space debris removal from this region exactly is of the first priority. For this reason, our article discusses the problems of controlling the motion of service spacecraft – space debris object cluster when the space debris object is removed from a low orbit with high inclination. In the conceptual design of the spacecraft presented hereinafter, the electric propulsion system contains two electric propulsion thrusters of stationary plasma thruster type, each of which is mounted with the possibility of independent rotation respect to two mutually perpendicular directions. An ion beam injector forms an ion beam with 65 mN of thrust. Spacecraft motion control, including the thrust vector control, is provided by coordinated rotation of thrusters. For such concept, a strategy and an algorithm for controlling the motion of the spacecraft center of mass are proposed, which are based on the control of the spacecraft lateral and longitudinal motion that is understood as the control of the relative distance between the spacecraft and the space debris object. The strategy of spacecraft lateral motion control assumes that due to the thrusters' rotation the spacecraft should be displaced in such a way that the vector of the relative range between the spacecraft and the space debris object coincides with the direction of the transversal of the orbital coordinate system. For the practical implementation of the control, an algorithm has been developed for controlling the thrusters' rotation to create the required values of the spacecraft acceleration projections. The mathematical model includes the equations of motion of the spacecraft center of mass taking into account the aerodynamic deceleration. The solar panels' orientation to the Sun is provided by the spacecraft roll rotation relative to its longitudinal axis and turning the solar panels relative to their axis of rotation. The change in the ion beam momentum transfer is considered using a simple simulation model. Mathematical modeling was performed for the following parameters of the initial orbit: altitude: 800 km; eccentricity: 0.0005; and inclination: 900. For the proposed control algorithm, a range of possible thrust of a single thruster was 51–60 mN. The simulation results show that the proposed control can be used to remove space debris object from low orbits with high inclination, taking into account the roll spacecraft rotation to keep the solar panels’ orientation to the Sun.

A Satellite Incipient Fault Detection Method Based on Decomposed Kullback-Leibler Divergence.

Detection of faults at the incipient stage is critical to improving the availability and continuity of satellite services. The application of a local optimum projection vector and the Kullback–Leibler (KL) divergence can improve the detection rate of incipient faults. However, this suffers from the problem of high time complexity. We propose decomposing the KL divergence in the original optimization model and applying the property of the generalized Rayleigh quotient to reduce time complexity. Additionally, we establish two distribution models for subfunctions and to detect the slight anomalous behavior of the mean and covariance. The effectiveness of the proposed method was verified through a numerical simulation case and a real satellite fault case. The results demonstrate the advantages of low computational complexity and high sensitivity to incipient faults.

Assessment of Capability Level and IT Governance Improvement Base on COBIT 5 and ITIL V3 2011 Framework: A Case Study PT. XYZ

Menjaga kinerja layanan merupakan tanggung jawab organisasi yang bergerak di bidang pelayanan. Sebagai organisasi penyedia layanan jaringan telekomunikasi baik jaringan setelit maupun terestrial, penurunan kinerja layanan adalah salah satu indikasi terjadinya masalah dalam pengelolaan TI di organisasi. Untuk mengetahui sejauh mana tingkat pengelolaan TI di organisasi diperlukan pengukuran tingkat kapabilitas. COBIT 5 dengan kombinasi kerangka kerja ITIL V3 2011 adalah kerangka kerja yang digunakan untuk mengukur tingkat kapabilitas proses-proses TI. Metodologi dalam penelitian ini dimulai dari mengidentifikasi permasalahan di organisasi, menentukan service lifecycle ITIL V3 2011 yang berkaitan, dan memetakan proses-proses pada service lifecycle ITIL V3 2011 tersebut dengan proses-proses pada COBIT 5. Dari hasil pemetaan ini diperoleh proses-proses COBIT 5 yang kemudian diseleksi kembali berdasarkan relevansi dengan permasalahan organisasi. Pengukuran proses-proses COBIT yang relevan dilakukan menggunakan metode PAM (Process Assessment Model) yang mengacu pada standar ISO/IEC 15504. Dengan menetapkan target tingkat kapabilitas, dapat dilakukan gap analysis, prioritisasi perbaikan proses, menetapkan KPI (Key Performace Indicator), dan memberikan rekomendasi aktivitas setiap proses TI. Dari hasil pengukuran terhadap 12 proses TI diperoleh hasil bahwa tingkat kapabilitas proses TI berada pada level 1 (performed) sebanyak 8 proses dan level 2 (managed) sebanyak 4 proses. Untuk memperbaiki tingkat kapabilitas proses- proses TI tersebut, COBIT 5 telah memberikan panduan dan rekomendasi aktivitas untuk setiap proses TI.

Electromagnetic Interaction Between a Slowly Rotating Conducting Shell and Magnetic Dipoles: A Theoretical and Numerical Study

The non-contact electromagnetic detumbling technologies for space debris and defunct satellites attract a lot of interest from many researchers, in which service satellites use one or two electromagnetic devices onboard to generate a controllable torque to reduce the rotation of the target so that the robotic arm can capture the target without hazardous collisions. However, there are many challenges in modeling the interactions between electromagnetic devices and the target. In this study, the electromagnetic devices and the target are simplified as magnetic dipoles and a slowly rotating conducting shell with typical shape, respectively. The interactions of one and two magnetic dipoles with a slowly rotating conducting spherical shell are derived. Then, the interaction between a slowly rotating conducting non-spherical geometry (a cube or a cylinder) and two magnetic dipoles is calculated numerically. The numerical results show that non-spherical geometries can be regarded as spherical shells in terms of calculating the electromagnetic interactions when the magnetic dipoles are far away from the geometries.

Non-cooperative target clustering algorithm based on clonal selection

Orderly observation of non-cooperative targets for subsequent identification and control is one of the important prerequisites and key technologies of space on orbit service. Restricted by the limited number of ground observation equipment, the visible time window of each non-cooperative target, and the different types of targets, it is increasingly difficult to observe the transit non-cooperative targets and plan the observation tasks. In this paper, the fuzzy clustering algorithm based on clonal selection is used to cluster the non-cooperative targets which are about to cross the border according to their own characteristics, physical characteristics, geometric characteristics, orbital characteristics and other different attributes. Considering the urgency of the task, the importance and priority of each non-cooperative target relative to the observation task are formed, it can provide effective input for the subsequent task planning of non-cooperative target observation, reduce the problem complexity of orderly observation of non-cooperative target, and improve the efficiency of problem solving.

Decentralized Anonymous Authentication With Fair Billing for Space-Ground Integrated Networks

The space-ground integrated network (SGIN) has attracted growing attention due to its advantages of high-capacity, low-latency and global coverage. To guarantee the security requirements of SGIN, anonymous authentication is an essential approach to addressing severe threats such as unauthorized access and impersonation attack, while payment is another common method in service-oriented applications in order to encourage companies to participate and also prevent insider attackers from enjoying services without paying. Existing anonymous authentication protocols for SGIN either require users to involve in heavy computation especially in dynamic scenarios, or do not consider cross-domain authentication. In this paper, we first introduce the concept of cross-company satellite services, and then address the cross-domain authentication and billing issues in SGIN, i.e., we propose a decentralized anonymous authentication scheme supporting fast handover and also achieve fairness for the billing procedures. To reduce the authentication delays, the authentication process is delegated from ground to satellites, such that users can arbitrarily switch the satellite networks belonging to different companies. Specifically, users can be anonymously authenticated by showing the knowledge of a secret bound with a randomized verifiable credential and connect to different satellite networks through a fast handover authentication protocol building on a blockchain. Even all companies collude, they cannot forge a valid identity credential and access records for a user. In addition, we provide a fair billing mechanism that can prevent malicious users and greedy satellite companies from manipulating the network accessing fees based on a well-designed smart contract. Finally, we demonstrate that the proposed scheme is secure and efficient through security analysis and performance evaluation.

Meteorological satellite stakeholder relationship network based on social network analysis

The meteorological satellite service range is extensive, and science and technology and related industries have become beneficiaries of it. The complex meteorological satellite stakeholder relationship warrants quantitative evaluation. This study investigates the meteorological satellite stakeholder relationship network to provide a new research perspective for meteorological satellites in the field of management. For literature analysis, 16 meteorological satellite stakeholders are identified through keyword screening, classified, and coded. A meteorological satellite stakeholder relationship network model is then constructed through social network analysis (SNA). Ego, local, and overall networks are analyzed from three perspectives to measure the network principle and to form a relationship network coordination degree evaluation system. The improved analytic hierarchy process (AHP)-fuzzy comprehensive evaluation method is then used to determine index weights and evaluate the relationship network coordination process design comprehensively. In empirical analysis, data for the meteorological satellite Fengyun-4 are obtained through questionnaire survey and literature analysis. Ucinet6 is used to generate relationship networks and analyze various stakeholder roles and status, stakeholder relationship network coordination degree, and evaluation results. The results demonstrate that the competent meteorological satellite department, the meteorological administration, the National Meteorological Centre, and the government are in the center of the Fengyun-4 stakeholder relationship network, with coordination degree in an "average" state. Thus, establishing a stakeholder coordination mechanism may strengthen connection and promote the development of meteorological undertakings.

Robotic Manipulation and Capture in Space: A Survey.

Space exploration and exploitation depend on the development of on-orbit robotic capabilities for tasks such as servicing of satellites, removing of orbital debris, or construction and maintenance of orbital assets. Manipulation and capture of objects on-orbit are key enablers for these capabilities. This survey addresses fundamental aspects of manipulation and capture, such as the dynamics of space manipulator systems (SMS), i.e., satellites equipped with manipulators, the contact dynamics between manipulator grippers/payloads and targets, and the methods for identifying properties of SMSs and their targets. Also, it presents recent work of sensing pose and system states, of motion planning for capturing a target, and of feedback control methods for SMS during motion or interaction tasks. Finally, the paper reviews major ground testing testbeds for capture operations, and several notable missions and technologies developed for capture of targets on-orbit.

Unsupervised anomaly detection for underwater gliders using generative adversarial networks

An effective anomaly detection system is critical for marine autonomous systems operating in complex and dynamic marine environments to reduce operational costs and achieve concurrent large-scale fleet deployments. However, developing an automated fault detection system remains challenging for several reasons including limited data transmission via satellite services. Currently, most anomaly detection for marine autonomous systems, such as underwater gliders, rely on intensive analysis by pilots. This study proposes an unsupervised anomaly detection system using bidirectional generative adversarial networks guided by assistive hints for marine autonomous systems with time series data collected by multiple sensors. In this study, the anomaly detection system for a fleet of underwater gliders is trained on two healthy deployment datasets and tested on other nine deployment datasets collected by a selection of vehicles operating in a range of locations and environmental conditions. The system is successfully applied to detect anomalies in the nine test deployments, which include several different types of anomalies as well as healthy behaviour. Also, a sensitivity study of the data decimation settings suggests the proposed system is robust for Near Real-Time anomaly detection for underwater gliders.

A fuel savings and benefit analysis of reducing separation standards in the oceanic airspace managed by the New York Air Route Traffic Control Center

New or improved satellite-based technologies are being introduced to improve the surveillance and communication capabilities in remote airspace. We study the benefits of reducing the separation standards among flights in the oceanic airspace managed by the New York Air Route Traffic Control Center (New York Oceanic) based on these technologies. We develop a model that simulates the activities of aircraft, pilots, and air traffic controllers (ATC) at the microscopic level to study the benefits of doing so in 2020 and 2025. With pessimistic assumptions on the reduced separation standards, the system-wide fuel savings within New York Oceanic are about (in million gallons) 2.25 in 2020 and 3.21 in 2025. After excluding additional variable cost, the monetary value of the fuel savings is about (in million 2018 US dollars) 3.65 and 6.38, respectively. The fuel benefits are more significant for aircraft with light or medium maximum takeoff weight. Some determinants of the workload of ATC and pilots can reduce by about 10% to 20%. With optimistic assumptions on the reduced standards, the corresponding statistics are about 2 to 3 times as high. This study can be used, for example, by air traffic control agencies to conduct benefit-cost analyses of adopting new/improved technologies, by airlines to develop strategies to make the best use of satellite services, and by satellite service providers to design service charging schemes and conduct market analysis.

Intercomparison review of IPWV retrieved from INSAT-3DR sounder, GNSS and CAMS reanalysis data

Abstract. The spatiotemporal variations of integrated precipitable water vapor (IPWV) are very important in understanding the regional variability of water vapor. Traditional in situ measurements of IPWV in the Indian region are limited, and therefore the performance of satellite and Copernicus Atmosphere Meteorological Service (CAMS) retrievals with the Indian Global Navigation Satellite System (GNSS) as reference were analyzed. In this study the CAMS reanalysis data of 1 year (2018) and the Indian GNSS and INSAT-3DR sounder retrieval data for 1.5 years (January 2017 to June 2018) were utilized, and statistics were computed. It is noticed that seasonal correlation coefficient (CC) values between INSAT-3DR and Indian GNSS data mainly lie within the range of 0.50 to 0.98 for all the selected 19 stations except Thiruvananthapuram (0.1), Kanyakumari (0.31) and Karaikal (0.15) during the monsoon season and Panjim (0.2) during the post-monsoon season. The seasonal CC values between CAMS and GNSS IPWV range from 0.73 to .99 except for Jaipur (0.16) and Bhubaneswar (0.29) during the pre-monsoon season, Panjim (0.38) during the monsoon season, Nagpur (0.50) during the post-monsoon season, and Dibrugarh (0.49) Jaipur (0.58) and Bhubaneswar (0.16) during the winter season. The root mean square error (RMSE) values are higher under the wet conditions (pre-monsoon and monsoon season) than under dry conditions (post-monsoon and winter season), and we found differences in magnitude and sign of bias for INSAT-3DR and CAMS with respect to GNSS IPWV from station to station and season to season. This study will help to improve understanding and utilization of CAMS and INSAT-3DR data more effectively along with GNSS data over land, coastal and desert locations in terms of the seasonal flow of IPWV, which is an essential integrated variable in forecasting applications.

Dual‐band modified rectangular shaped dielectric resonator antenna with diversified polarization feature

AbstractIn this communication, the aperture coupled modified rectangular dielectric resonator antenna (rDRA) is designed and studied. The modified rectangular DRA is the same as Swastik shape. An asymmetrical microstrip line‐fed aperture stimulated a triple radiating mode pattern inside the ceramic material, that is, , respectively. Swastik‐shaped ceramic radiator provides two important advantages: (a) lower Q‐factor, which in turn improves the impedance bandwidth, and (b) the creation of degenerated orthogonal mode with 90° phase shifts, which provides CP waves in one of the operating bands. Experimental outcomes confirm that the proposed antenna is working in dual‐frequency bands, that is, 6.41–7.38 GHz and 10.2–12.8 GHz, respectively. It supports left‐handed CP waves from 11.51 to 11.89 GHz. The proposed antenna is widely employable for fixed service satellite (FSS) for defense applications.

Орбітальний сервіс — крок до подальшого освоєння навколоземного космосу

The purpose of the publication is to draw the attention of the Ukrainian scientific and technical community to the development of a new area of activity in outer space - orbital service. The content, technical and economic preconditions and competitive advantages of its development in Ukraine are outlined. Definitions of orbital services such as customer inspection, orbital (inter-orbital) transportation, refueling and resupply, upgrade, assembly, collision avoidance are given. The competence of Ukrainian enterprises in this direction has been analyzed. The expediency and possibility of developing the direction of orbital servicing for further exploration of near space, in particular, the developments of Ukrainian enterprises for the development and manufacture of systems for rendezvous and docking of spacecraft, have been substantiated. Scenarios of interaction between a space service vehicle and a client vehicle in near-earth orbit are described. The basic requirements for carrying out of Servicer and the Client autonomous proximity operations, as well as the operation of seizing the client machine are given. Proposals for the functionality of spacecraft for the provision of orbital space services are presented, it is proposed to consider the need to create specialized cargo modules and examples of their application in orbit are given. The tendencies of the approach to the creation of spacecraft structures adapted for in-orbit service are considered. The predicted volume of orbital service operations by type of service and with orbits is given. Provided information about the key players in a given market. The design of Servicer, which is being developed by Kurs NPK JSC, Yuzhnoye Design Bureau, for the provision of transport services, is presented. The specified features of its construction in general and the composition of the modules, as well as the possibility of further expanding the functionality of the Servicer.

Broadband Futures Forum: Regional and Rural Broadband Access

On 24 March 2021, TelSoc hosted the sixth Broadband Futures Forum, held online, with a focus on regional and rural broadband access. Mr Gavin Williams from NBN Co, the developer of Australia’s National Broadband Network (NBN), spoke about developments in Fixed Wireless and Satellite services and described NBN Co’s commitment to ongoing enhancement of broadband access in regional and rural Australia. A question-and-answer session followed the presentation in which Mr Williams fielded a variety of questions on broadband access and technological developments.

Моделювання взаємодії космічних апаратів з іоносферною розрідженою плазмою

Principles of simulation of the physical-chemical and electromagnetic interaction of a spacecraft with the near-satellite environment and principles of probe diagnostics of rarefied plasma flows onboard a spacecraft are stated. Equivalence criteria are formulated for the interaction of a spacecraft with the near-satellite environment and hypersonic rarefied plasma flows on dedicated setups, in particular on the plasmaelectrodynamic setup of the Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine, which has the status of the National Patrimony of Ukraine. The features of spacecraft interaction with the near-satellite environment were studied along the following three lines: - degradation of the materials and performance characteristics of spacecraft components in a long-term orbital service: - magnetohydrodynamic interaction of a spacecraft with hypersonic rarefied plasma flows; - probe diagnostic of rarefied plasma flows onboard a spacecraft. Along the first line, a calculation-and-experiment procedure was developed to evaluate the power decrease of spacecraft silicon solar batteries under long-term (~ 10 years) exposure to the space factors and the near-satellite environment in circular orbits. Principles of accelerated life tests for the resistance of spacecraft polymer materials to long-term exposure to atomic oxygen flows and vacuum ultraviolet radiation were developed. Simultaneous exposure of polymers to atomic oxygen and vacuum ultraviolet radiation results in the synergic effect of mass loss by materials that contain a monomer of the (CH)n group. Along the second line, models were formulated for magnetohydrodynamic interaction in the magnetized spacecraft – ionospheric plasma system. It was shown that the interaction of a ?0,8 – 1.5 T magnetic field of a space debris object (in particular, a spent spacecraft) with the ionospheric plasma produces an electromagnetic drag force sufficient for removing it to a low orbit followed by its burn-up in the dense atmosphere. Along the third line, procedures were developed for ionospheric plasma probe diagnostics using onboard instrumentation that includes mutually orthogonal cylindrical electrical probes and a two-channel neutral-particle detector. It was shown that this instrumentation with the use of proprietary output signal interpretation algorithms and procedures allows one to locate sources of space-time disturbances in inospheric plasma parameters caused by natural and technogeneous catastrophic phenomena on the subsatellite track.

Featured services and performance of BDS-3

BeiDou Global Navigation Satellite System (BDS-3) not only performs the normal positioning, navigation and timing (PNT) functions, but also provides featured services, which are divided into geostationary orbit (GEO) and medium earth orbit (MEO) satellite-based featured services in this paper. The former refers to regional services consisting of the regional short message communication service (RSMCS), the radio determination satellite service (RDSS), the BDS satellite-based augmented service (BDSBAS) and the satellite-based precise point positioning service via B2b signal (B2b-PPP). The latter refers to global services consisting of the global short message communication service (GSMCS) and the MEO satellite-based search and rescue (MEOSAR) service. The focus of this paper is to describe these featured services and evaluate their performances. The results show that the inter-satellite link (ISL) contributes a lot to the accuracy improvement of orbit determination and time synchronization for the whole constellation. Compared with some other final products, the root mean squares (RMS) of the BDS-3 precise orbits and broadcast clock are 25.1 cm and 2.01 ns, respectively. The positioning accuracy of single frequency is better than 6 m, and that of the generalized RDSS is usually better than 12 m. For featured services, the success rates of RSMCS and GSMCS are better than 99.9% and 95.6%, respectively; the positioning accuracies of single and dual frequency BDSBAS are better than 3 and 2 m, respectively; the positioning accuracy of B2b-PPP is better than 0.6 m, and the convergence time is usually smaller than 30 min; the single station test shows that the success rate of MEOSAR is better than 99%. Due to the ISL realization in the BDS-3 constellation, the performance and capacities of the global featured services are improved significantly.