Read Books Online and Download eBooks, EPub, PDF, Mobi, Kindle, Text Full Free.
Small Satellite Attitude And Orbital Control For Precise Pointing Missions
Download Small Satellite Attitude And Orbital Control For Precise Pointing Missions full books in PDF, epub, and Kindle. Read online Small Satellite Attitude And Orbital Control For Precise Pointing Missions ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
Book Synopsis Small Satellite Attitude and Orbital Control for Precise Pointing Missions by : Julián Sintes García
Download or read book Small Satellite Attitude and Orbital Control for Precise Pointing Missions written by Julián Sintes García and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Since spacecraft are subject to strict requirements in terms of angular position and actuation limits, advanced control algorithms are usually designed to combine robustness properties and limited control effort, including external disturbances and parametric uncertainties. The main objective of this research is the design of a control system for both orbit and attitude dynamics of a small spacecraft and carry out several simulations to evaluate the effectiveness of the used algorithms.
Book Synopsis Spacecraft Attitude Determination and Control by : J.R. Wertz
Download or read book Spacecraft Attitude Determination and Control written by J.R. Wertz and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 877 pages. Available in PDF, EPUB and Kindle. Book excerpt: Roger D. Werking Head, Attitude Determination and Control Section National Aeronautics and Space Administration/ Goddard Space Flight Center Extensiye work has been done for many years in the areas of attitude determination, attitude prediction, and attitude control. During this time, it has been difficult to obtain reference material that provided a comprehensive overview of attitude support activities. This lack of reference material has made it difficult for those not intimately involved in attitude functions to become acquainted with the ideas and activities which are essential to understanding the various aspects of spacecraft attitude support. As a result, I felt the need for a document which could be used by a variety of persons to obtain an understanding of the work which has been done in support of spacecraft attitude objectives. It is believed that this book, prepared by the Computer Sciences Corporation under the able direction of Dr. James Wertz, provides this type of reference. This book can serve as a reference for individuals involved in mission planning, attitude determination, and attitude dynamics; an introductory textbook for stu dents and professionals starting in this field; an information source for experimen ters or others involved in spacecraft-related work who need information on spacecraft orientation and how it is determined, but who have neither the time nor the resources to pursue the varied literature on this subject; and a tool for encouraging those who could expand this discipline to do so, because much remains to be done to satisfy future needs.
Book Synopsis Attitude and Orbit Control of Small Satellites for Autonomous Terrestrial Target Tracking by : Najmus Ibrahim
Download or read book Attitude and Orbit Control of Small Satellites for Autonomous Terrestrial Target Tracking written by Najmus Ibrahim and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Fundamentals of Spacecraft Attitude Determination and Control by : F. Landis Markley
Download or read book Fundamentals of Spacecraft Attitude Determination and Control written by F. Landis Markley and published by Springer. This book was released on 2014-05-31 with total page 486 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book explores topics that are central to the field of spacecraft attitude determination and control. The authors provide rigorous theoretical derivations of significant algorithms accompanied by a generous amount of qualitative discussions of the subject matter. The book documents the development of the important concepts and methods in a manner accessible to practicing engineers, graduate-level engineering students and applied mathematicians. It includes detailed examples from actual mission designs to help ease the transition from theory to practice and also provides prototype algorithms that are readily available on the author’s website. Subject matter includes both theoretical derivations and practical implementation of spacecraft attitude determination and control systems. It provides detailed derivations for attitude kinematics and dynamics and provides detailed description of the most widely used attitude parameterization, the quaternion. This title also provides a thorough treatise of attitude dynamics including Jacobian elliptical functions. It is the first known book to provide detailed derivations and explanations of state attitude determination and gives readers real-world examples from actual working spacecraft missions. The subject matter is chosen to fill the void of existing textbooks and treatises, especially in state and dynamics attitude determination. MATLAB code of all examples will be provided through an external website.
Book Synopsis Satellite Technology and Its Applications by : P. R. K. Chetty
Download or read book Satellite Technology and Its Applications written by P. R. K. Chetty and published by Notion Press. This book was released on 2023-12-27 with total page 766 pages. Available in PDF, EPUB and Kindle. Book excerpt: An authoritative reference on the latest Satellite Technology, including applications, history, evolution, design, descriptions, formulas, calculations and much more. Satellites play a vital role in today’s world and as satellite costs decrease, potential applications grow. Whether you’re a satellite systems engineer, designer, or manager, you need a good, all-purpose reference to this important technology. Now, with Satellite Technology and Its Applications – 3rd Edition, author provides broadened updated coverage of today’s satellite systems, including system data, design formulas and examples, and many other aspects of current spacecraft subsystems. Intended to save you time and effort in your research, this book offers a single source of information related to the design and analysis of satellite systems and their applications. Author’s extensive experience in the U.S., European and Indian space programs gives a wide perspective on this increasingly international scientific endeavor. Satellite design engineers, systems engineers, and managers will find this book to be completely up-to-date, comprehensive and accurate. Regardless of your field of concentration, you’ll discover this comprehensive guide to satellite technology is the most current general reference available.
Book Synopsis An Attitude Determination and Control System for Small Satellites by : Margaret Hoi Ting Tam
Download or read book An Attitude Determination and Control System for Small Satellites written by Margaret Hoi Ting Tam and published by . This book was released on 2015 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: A flexible, robust attitude determination and control (ADC) system is presented for small satellite platforms. Using commercial-off-the-shelf sensors, reaction wheels, and magnetorquers which fit within the 3U CubeSat form factor, the system delivers arc-minute pointing precision. The ADC system includes a multiplicative extended Kalman filter for attitude determination and a slew rate controller that acquires a view of the Sun for navigation purposes. A pointing system is developed that includes a choice of two pointing controllers -- a proportional derivative controller and a nonlinear sliding mode controller. This system can reorient the spacecraft to satisfy a variety of mission objectives, but it does not enforce attitude constraints. A constrained attitude guidance system that can enforce an arbitrary set of attitude constraints is then proposed as an improvement upon the unconstrained pointing system. The momentum stored by the reaction wheels is managed using magnetorquers to prevent wheel saturation. The system was thoroughly tested in realistic software- and hardware-in-the-loop simulations that included environmental disturbances, parameter uncertainty, actuator dynamics, and sensor bias and noise.
Book Synopsis The Role of Small Satellites in NASA and NOAA Earth Observation Programs by : National Research Council
Download or read book The Role of Small Satellites in NASA and NOAA Earth Observation Programs written by National Research Council and published by National Academies Press. This book was released on 2000-05-12 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: Remote observations of Earth from space serve an extraordinarily broad range of purposes, resulting in extraordinary demands on those at the National Aeronautics and Space Administration (NASA), the National Oceanic and Atmospheric Administration (NOAA), and elsewhere who must decide how to execute them. In research, Earth observations promise large volumes of data to a variety of disciplines with differing needs for measurement type, simultaneity, continuity, and long-term instrument stability. Operational needs, such as weather forecasting, add a distinct set of requirements for continual and highly reliable monitoring of global conditions. The Role of Small Satellites in NASA and NOAA Earth Observation Programs confronts these diverse requirements and assesses how they might be met by small satellites. In the past, the preferred architecture for most NASA and NOAA missions was a single large spacecraft platform containing a sophisticated suite of instruments. But the recognition in other areas of space research that cost-effectiveness, flexibility, and robustness may be enhanced by using small spacecraft has raised questions about this philosophy of Earth observation. For example, NASA has already abandoned its original plan for a follow-on series of major platforms in its Earth Observing System. This study finds that small spacecraft can play an important role in Earth observation programs, providing to this field some of the expected benefits that are normally associated with such programs, such as rapid development and lower individual mission cost. It also identifies some of the programmatic and technical challenges associated with a mission composed of small spacecraft, as well as reasons why more traditional, larger platforms might still be preferred. The reasonable conclusion is that a systems-level examination is required to determine the optimum architecture for a given scientific and/or operational objective. The implied new challenge is for NASA and NOAA to find intra- and interagency planning mechanisms that can achieve the most appropriate and cost-effective balance among their various requirements.
Book Synopsis Spacecraft Momentum Control Systems by : Frederick A. Leve
Download or read book Spacecraft Momentum Control Systems written by Frederick A. Leve and published by Springer. This book was released on 2015-10-17 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this book is to serve both as a practical technical reference and a resource for gaining a fuller understanding of the state of the art of spacecraft momentum control systems, specifically looking at control moment gyroscopes (CMGs). As a result, the subject matter includes theory, technology, and systems engineering. The authors combine material on system-level architecture of spacecraft that feature momentum-control systems with material about the momentum-control hardware and software. This also encompasses material on the theoretical and algorithmic approaches to the control of space vehicles with CMGs. In essence, CMGs are the attitude-control actuators that make contemporary highly agile spacecraft possible. The rise of commercial Earth imaging, the advances in privately built spacecraft (including small satellites), and the growing popularity of the subject matter in academic circles over the past decade argues that now is the time for an in-depth treatment of the topic. CMGs are augmented by reaction wheels and related algorithms for steering all such actuators, which together comprise the field of spacecraft momentum control systems. The material is presented at a level suitable for practicing engineers and those with an undergraduate degree in mechanical, electrical, and/or aerospace engineering.
Book Synopsis Contributions to on-board navigation on 1U CubeSats by : Weiß, Sascha
Download or read book Contributions to on-board navigation on 1U CubeSats written by Weiß, Sascha and published by Universitätsverlag der TU Berlin. This book was released on 2022-04-07 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis investigates the use of GNSS receivers on 1U CubeSats, using the example of BEESAT-4 and BEESAT-9. The integration of such a device on satellites enables highly precise time synchronization, position acquisition and orbit determination and prediction The application fields that depend on an accurate attitude control and orbit determination system and can also be processed by CubeSats are highlighted. Therefore the state of the art of GNSS receivers is described, which are suitable for the use on satellites and could be integrated into 1U CubeSats. Further on it is investigated which subsystems of a small satellite are particularly affected and what the special challenges are to realize a precise positioning with a GNSS receiver. In addition, some developments are presented that have significantly increased the performance of 1U CubeSats in recent years. The system concept of BEESAT satellites is introduced and the evolution of the payload board including the use of the latest sensor technologies for attitude control is described. It is shown how the verification of the satellite's subsystems was performed on the ground, with the focus on testing and simulating the attitude control and the GNSS receiver. The necessary integration steps, the calibration and environmental test campaign are discussed. Both satellites were successfully operated and the results of the on-orbit experiments are presented. It is shown how a three-axis stabilized attitude control was first verified on BEESAT-4 and then a GNSS receiver was successfully operated on BEESAT-9 for more than one year. In addition, the inter-satellite link between BEESAT-4 and BIROS will be analyzed, since it is essential for the relative navigation of satellites. The acquired navigation data was sent to the ground and the identification of BEESAT-9 was carried out using this data. A qualitative analysis of the orbital elements (TLE) of BEESAT-9 was performed systematically due to a daily operation of the GNSS receiver. Furthermore, it was investigated how a small GNSS antenna affects the received signal strength from GNSS satellites and whether this antenna or its amplifier degrades over time. Additionally, an orbit determination and propagation based on the navigation data could be performed and the results are evaluated. The analyzed questions allow a statement about the continuous use of GNSS receivers on 1U CubeSats and if it is necessary to achieve the mission objectives. Diese Arbeit untersucht den Einsatz von GNSS-Empfängern auf 1U CubeSats am Beispiel von BEESAT-4 und BEESAT-9. Das Integrieren einer solchen Komponente auf Satelliten ermöglicht eine hochgenaue Zeitsynchronisation, Positions- und Orbitbestimmung sowie deren Vorhersage Es werden die Anwendungsfelder beleuchtet, die auf ein akkurates Lageregelungs- und Orbitbestimmungssystem angewiesen sind und außerdem auch von CubeSats bearbeitet werden können. Dazu wird der Stand der Technik von GNSS-Empfängern beschrieben, die für den Einsatz auf Satelliten geeignet sind und von ihren Eigenschaften auch auf 1U CubeSats integriert werden könnten. Weitergehend wird untersucht, welche Subsysteme eines Kleinstsatelliten besonders betroffen sind und was die speziellen Herausforderungen sind, um eine präzise Positionsbestimmung mithilfe eines GNSS-Empfängers zu realisieren. Dazu werden auch einige Entwicklungen vorgestellt, die in den letzten Jahren die Leistungsfähigkeit von 1U CubeSats signifikant erhöht haben. Das Systemkonzept der BEESAT Satelliten wird eingeführt und die Evolution der Nutzlastplatine inklusive der Verwendung der jeweils neuesten Sensortechnologien für die Lageregelung beschrieben. Es wird gezeigt wie die Verifikation der Subsysteme des Satelliten am Boden erfolgte, wobei der Fokus auf dem Testen und Simulieren der Lageregelung und dem GNSS-Empfänger liegt. Dazu werden die notwendigen Integrationsschritte, die Kalibrations- und die Umwelttestkampagne diskutiert. Beide Satelliten wurden erfolgreich betrieben und die Ergebnisse der on-orbit Experimente werden vorgestellt. Es wird gezeigt wie zunächst eine dreiachsenstabilisierte Lageregelung auf BEESAT-4 verifiziert und anschließend auf BEESAT-9 über mehr als ein Jahr ein GNSS-Empfänger erfolgreich betrieben wurde. Zusätzlich wird der Intersatelliten Link zwischen BEESAT-4 und BIROS analysiert, da dieser für die Relativnavigation von Satelliten essentiell ist. Die akquirierten Navigationsdaten wurden zum Boden gesendet und die Identifizierung von BEESAT-9 erfolgte mithilfe dieser Daten. Eine qualitative Analyse der Orbitelemente (TLE) von BEESAT-9 konnte systematisch durchgeführt werden durch einen täglichen Einsatz des GNSS-Empfängers. Weiterhin wurde erforscht wie sich eine kleine GNSS-Antenne auf die empfangenen Signalstärken der GNSS Satelliten auswirkt und ob diese Antenne oder ihr Verstärker mit der Zeit degradieren. Zusätzlich konnte eine Orbitbestimmung und -propagation auf Basis der Navigationsdaten durchgeführt und die Ergebnisse ausgewertet werden. Die analysierten Fragestellungen erlauben eine Aussage über den durchgängigen Einsatz von GNSS-Empfängern auf 1U CubeSats und ob dieser notwendig ist um die Missionsziele zu erreichen.
Book Synopsis ACS Without an Attitude by : Harold L. Hallock
Download or read book ACS Without an Attitude written by Harold L. Hallock and published by Springer. This book was released on 2017-05-03 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book de-emphasizes the formal mathematical description of spacecraft on-board attitude and orbit applications in favor of a more qualitative, concept-oriented presentation of these topics. The information presented in this book was originally given as a set of lectures in 1999 and 2000 instigated by a NASA Flight Software Branch Chief at Goddard Space Flight Center. The Branch Chief later suggested this book. It provides an approachable insight into the area and is not intended as an essential reference work. ACS Without an Attitude is intended for programmers and testers new to the field who are seeking a commonsense understanding of the subject matter they are coding and testing in the hope that they will reduce their risk of introducing or missing the key software bug that causes an abrupt termination in their spacecraft’s mission. In addition, the book will provide managers and others working with spacecraft with a basic understanding of this subject.
Book Synopsis Handbook of Small Satellites by : Joseph N. Pelton
Download or read book Handbook of Small Satellites written by Joseph N. Pelton and published by Springer. This book was released on 2020-09-13 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the past decade, the field of small satellites has expanded the space industry in a powerful way. Hundreds, indeed thousands, of these innovative and highly cost-efficient satellites are now being launched from Earth to establish low-cost space systems. These smallsats are engaged in experiments and prototype testing, communications services, data relay, internet access, remote sensing, defense and security related services, and more. Some of these systems are quite small and are simple student experiments, while others in commercial constellations are employing state-of-the-art technologies to deliver fast and accurate services. This handbook provides a comprehensive overview of this exciting new field. It covers the technology, applications and services, design and manufacture, launch arrangements, ground systems, and economic and regulatory arrangements surrounding small satellites. The diversity of approach in recent years has allowed for rapid innovation and economic breakthroughs to proceed at a pace that seems only to be speeding up. In this reference work, readers will find information pertaining to all aspects of the small satellite industry, written by a host of international experts in the field.
Author :National Academies of Sciences, Engineering, and Medicine Publisher :National Academies Press ISBN 13 :030944263X Total Pages :131 pages Book Rating :4.3/5 (94 download)
Book Synopsis Achieving Science with CubeSats by : National Academies of Sciences, Engineering, and Medicine
Download or read book Achieving Science with CubeSats written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2016-11-06 with total page 131 pages. Available in PDF, EPUB and Kindle. Book excerpt: Space-based observations have transformed our understanding of Earth, its environment, the solar system and the universe at large. During past decades, driven by increasingly advanced science questions, space observatories have become more sophisticated and more complex, with costs often growing to billions of dollars. Although these kinds of ever-more-sophisticated missions will continue into the future, small satellites, ranging in mass between 500 kg to 0.1 kg, are gaining momentum as an additional means to address targeted science questions in a rapid, and possibly more affordable, manner. Within the category of small satellites, CubeSats have emerged as a space-platform defined in terms of (10 cm x 10 cm x 10 cm)- sized cubic units of approximately 1.3 kg each called "U's." Historically, CubeSats were developed as training projects to expose students to the challenges of real-world engineering practices and system design. Yet, their use has rapidly spread within academia, industry, and government agencies both nationally and internationally. In particular, CubeSats have caught the attention of parts of the U.S. space science community, which sees this platform, despite its inherent constraints, as a way to affordably access space and perform unique measurements of scientific value. The first science results from such CubeSats have only recently become available; however, questions remain regarding the scientific potential and technological promise of CubeSats in the future. Achieving Science with CubeSats reviews the current state of the scientific potential and technological promise of CubeSats. This report focuses on the platform's promise to obtain high- priority science data, as defined in recent decadal surveys in astronomy and astrophysics, Earth science and applications from space, planetary science, and solar and space physics (heliophysics); the science priorities identified in the 2014 NASA Science Plan; and the potential for CubeSats to advance biology and microgravity research. It provides a list of sample science goals for CubeSats, many of which address targeted science, often in coordination with other spacecraft, or use "sacrificial," or high-risk, orbits that lead to the demise of the satellite after critical data have been collected. Other goals relate to the use of CubeSats as constellations or swarms deploying tens to hundreds of CubeSats that function as one distributed array of measurements.
Book Synopsis High Performance Attitude Determination and Control for Nanosatellites Missions by : Bryan Johnston-Lemke
Download or read book High Performance Attitude Determination and Control for Nanosatellites Missions written by Bryan Johnston-Lemke and published by . This book was released on 2011 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: Small satellites are growing in popularity because they offer an effective option that enables missions otherwise too schedule or cost limited. However, many possible missions require improved platform capabilities without sacrificing the cost effective nature of small satellites before they become viable. Described is the development and validation of high performance attitude determination and control for nanosatellite missions. Considered are astronomy missions, requiring very fine pointing stability, and formation flying missions requiring rapid manoeuvring while maintaining antenna coverage towards secondary pointing targets. It will be shown that power and volume limited nanosatellites are capable of this level of attitude performance by leveraging the techniques normally reserved for larger spacecraft. Discussed are attitude state estimation techniques and control laws developed for the BRITE stellar photometry constellation and CanX-4 and CanX-5 formation flying mission, along with the challenges associated with implementing and validating these designs for real space missions.
Book Synopsis High-precision Pointing and Attitude Estimation and Control Algorithms for Hardware-constrained Spacecraft by : Christopher Masaru Pong
Download or read book High-precision Pointing and Attitude Estimation and Control Algorithms for Hardware-constrained Spacecraft written by Christopher Masaru Pong and published by . This book was released on 2014 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: The overarching objective of this thesis is to develop algorithms for high-precision pointing and attitude estimation and control on hardware-constrained spacecraft. This includes small spacecraft, where tight mass, volume, power, and cost constraints exist, as well as spacecraft where certain hardware has failed. As a case study, the attitude determination and control subsystem (ADCS) for ExoplanetSat will be designed. ExoplanetSat is a three-unit CubeSat (10 x 10 x 34 cm, ~ 4 kg) designed to detect exoplanets around bright Sun-like stars via the transit method. To achieve the photometric precision necessary to detect Earth-sized exoplanets, a pointing precision on the arcsecond level must be achieved. This is an unprecedented level of pointing precision on a spacecraft of this size that will be accomplished through a two-stage control system: reaction wheels for coarse attitude control and a piezo stage for fine pointing control. A linear analysis developed using stochastic linearization techniques is used to analyze the various contributions to pointing error, allowing software improvements to be made, which decrease pointing error by as much as 50%. Simulations show that a pointing precision of 2.3 arcsec (3[sigma]) can be achieved, which is two to four orders of magnitude beyond the current capability of other comparable spacecraft. In addition to performing high-precision pointing, the spacecraft must perform many other ADCS modes. These modes are complicated due to the lack of certain hardware, specifically gyros and coarse Sun sensors covering the entire sky. To deturrble the spacecraft after initial deployment, a novel control algorithm is proposed that will simultaneously detumuble the spacecraft while avoiding angular rate observability singularities, allowing the rate to be properly estimated with a magnetometer alone throughout the detumnbling process. This is done by regulating the amount of kinetic energy in the system relative to the decreasing momentum, which excites nutation in the spacecraft and maintains a full-rank nonlinear observability matrix. To search for the Sun, a guidance and control law is developed that efficiently searches the sky while navigating based on the body magnetic field direction alone and again avoiding observability singularities. During the slews between orbit day and night, the star camera is the main sensor. To dramatically reduce the image processing time, a method of tracking stars with small windows will be developed. To support this star camera mode, a new and efficient window generation technique is developed to find new stars to track as stars fall out of the field of view of the star camera during the slew. While these algorithms will be designed with ExoplanetSat in mind, they can easily be applied to other spacecraft with similar hardware. Finally, a three-degree-of-freedom air bearing testbed was developed to test some of these algorithms on flight-equivalent hardware in a representative environment. Testbed results show the ability to initialize the star camera and operate it in a fast windowed mode, use the reaction wheels to slew to a target attitude, and achieve 12 arcsec (3[sigma]) pointing with the reaction wheels and piezo stage. The simulation, modified to match the environment and parameters of the testbed, correctly predicted the testbed results within 10%, verifying the simulation and increasing confidence in the on-orbit simulation predictions. This successful hardware demonstration increases the technology readiness level (TRL) of this pointing control system to TRL 6.
Book Synopsis Small Satellite Missions for Earth Observation by : Rainer Sandau
Download or read book Small Satellite Missions for Earth Observation written by Rainer Sandau and published by Springer Science & Business Media. This book was released on 2010-01-23 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book was compiled from contributions given at the 7th IAA Symposium on Small Satellites for Earth Observation, May 4–8, 2009, Berlin (IAA – International Academy of Astronautics). From the 15 sessions for oral presentations and two poster sessions, 52 contributions were selected which are representative for the new developments and trends in the area of small satellites for Earth observation. They re ect the potentials of a diversity of missions and related technologies. This may be based on national projects or international co-operations, single satellites of constellations, pico-, nano-, micro- or mini-satellites, developed by companies, research institutions or agencies. The main focus is on new missions to monitor our Earth’s resources (Part I), and the environment in which our Earth is emb- ded (Part II). Part III deals with distributed space systems, a unique feature of small satellites and in most cases impractical to do with large satellites. Here we concentrate on constellations of satellites with focus on future missions relying on co-operating satellites. For all the new developments and projects we need well e- cated specialists coming from the universities. Many universities included already the development and implementation of small satellites in their curriculum. The u- versity satellites chapter (Part IV) shows the high quality which is already reached by some of the universities worldwide.
Book Synopsis Pointing System Performance Analysis for Optical Inter-satellite Communication on CubeSats by : Hyosang Yoon
Download or read book Pointing System Performance Analysis for Optical Inter-satellite Communication on CubeSats written by Hyosang Yoon and published by . This book was released on 2017 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt: Free-space optical communication using lasers (lasercom) is a leading contender for future space-based communication systems with potential advantages over radio frequency (RF) communication systems in size, weight, and power consumption (SWaP). Key benefits are due to the shorter wavelength: additional bandwidth and narrow beam width. The narrower beam supports higher energy density for a given aperture size, so that lasercom can transmit data at the same rate with smaller SWaP as well as improve link security since the beam footprint is smaller. Lasercom is an attractive option for improving inter-satellite links (ISL) for resource-constrained CubeSats, which have emerged as a standard form of a small satellite since 1999. However, lasercom requires much more accurate pointing because of its narrower beam width. Accurate pointing is not trivial for most CubeSat platforms due to their resource constraints. A typical 3U CubeSat is 34 cm x 10 cm x 10 cm with less than 5 kg mass and about 10 W of available orbit-average power. This thesis presents pointing and tracking technologies to support lasercom on CubeSats. It covers three critical issues: (1) attitude determination and control of CubeSats, (2) relative orbit determination, and (3) development of a miniaturized fine beam pointing module. New attitude determination and control algorithms are developed, simulated, and validated with hardware in the loop demonstrations; results indicate that lasercom at data rates competitive with or better than RF is feasible on CubeSats. For attitude determination and control (ADC), this thesis develops a new attitude estimation algorithm, which is called Attitude and Parameter estimation Kalman filter (APKF). Attitude determination (AD) is thought to be more challenging than attitude control (AC) for CubeSats because of the limited capabilities of sensors that are compatible with the small form factor and resource constraints of CubeSats. The largest difference between a CubeSat and a larger satellite is the gyroscopes that measure rotation rates. Since a CubeSat is normally not able to accommodate high quality gyroscopes, the APKF is used to improve estimation without relying on gyroscope measurements. The APKF estimates CubeSat attitude and body rates as well as other unknown parameters such as the moment of inertia (MOI), actuator alignment, and the residual dipole moments. For relative orbit determination, this thesis describes an estimation algorithm that fuses different types of orbital measurements using the Kalman filter. There are three measurements that can be used in the relative orbit estimation for low earth orbiting (LEO) lasercom crosslink CubeSats: Global Navigation Satellite System (GNSS) navigation solutions for an individual satellite (e.g. Satellite A or "SatA"), beacon beam measurements at SatA, and GNSS navigation solutions of the other satellite (SatB) transferred through ground station networks. The GNSS and beacon are measured at SatA, so these can be assumed to have negligible time delay, but the arrival time of the SatB navigation solutions will be an out-of-sequence measurement (OOSM) whose arrival time will be delayed due to the ground station relay. To fuse the sensor data with different measurement times, a new algorithm called the Augment Fixed- Lag Smoother (AFLS) is developed. To update the Kalman filter with an OOSM, the AFLS generates the estimates at the measurement time of the OOSM by interpolation. The AFLS is applied to a nonlinear system as the extended AFLS (EAFLS). The Satellite Tracking Kalman Filter (STKF) is developed using the EAFLS. The fine pointing system (FPS) is necessary because while the CubeSat attitude determination and control and the orbit determination developments cover the Cube- Sat's body pointing capability, due to the extremely narrow beam desired for high-rate laser communications, body pointing alone cannot satisfy the beam pointing requirements. The example case used in this thesis is a CubeSat design concept mission with an inter-satellite laser communication link. To reduce the pointing error, a FPS needs to be implemented as the final stage for beam pointing. This thesis demonstrates the feedback control loop of the FPS using a hardware-in-the-loop test. A key component of the FPS is the miniaturized micro-electro-mechanical systems (MEMS) fast steering mirror (FSM) which is the actuator used to point the laser beam. Using a commercial-off-the-shelf (COTS) MEMS FSM that is also planned for use on the flight module, the fine pointing control loop has been demonstrated with results that show that it is feasible to meet the pointing requirement for a 3U CubeSat mission whose goal is 20 Mbps link at 25 km to 1000 km crosslink range. By developing and demonstrating the critical technologies for both spacecraft body pointing and the fine beam pointing, this thesis has demonstrated the feasibility of a CubeSat lasercom crosslink at a data rate and form factor that can outperform RF, leading to a high-speed and secure ISL for CubeSats.
Book Synopsis Thermospheric Density and Wind Determination from Satellite Dynamics by : Eelco Doornbos
Download or read book Thermospheric Density and Wind Determination from Satellite Dynamics written by Eelco Doornbos and published by Springer Science & Business Media. This book was released on 2012-01-19 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Earth's atmosphere is often portrayed as a thin and finite blanket covering our planet, separate from the emptiness of outer space. In reality, the transition is gradual and a tiny fraction of the atmophere gases is still present at the altitude of low orbiting satellites. The very high velocities of these satellites ensure that their orbital motion can still be considerably affected by air density and wind. This influence can be measured using accelerometers and satellite tracking techniques. The opening chapters of this thesis provide an excellent introduction to the various disciplines that are involved in the interpretation of these observations: orbital mechanics, satellite aerodynamics and upper atmospheric physics. A subsequent chapter, at the heart of this work, covers advances in the algorithms used for processing satellite accelerometry and Two-Line Element (TLE) orbit data. The closing chapters provide an elaborate analysis of the resulting density and wind products, which are generating many opportunities for further research, to improve the modelling and understanding of the thermosphere system and its interactions with the lower atmosphere, the ionosphere-magnetosphere system and the Sun.
