Добірка наукової літератури з теми "Assemblage en Orbite"

One of the most common direct methods for constructing [Formula: see text]-designs and large sets of [Formula: see text]-designs is assembling orbits obtained from the action of a permutation group [Formula: see text] on the set of all [Formula: see text]-subsets of a [Formula: see text]-set. It is well known that when G is a [Formula: see text]-homogeneous group, then each orbit is a [Formula: see text]-design. Therefore the problem is that how one could assemble these orbits to make [Formula: see text]-designs with the same index to construct a large set of [Formula: see text]-designs. The case where the orbit sizes are limited up to two values is already investigated. Here, we present a generalization of this method to assemble the set of orbits when the orbit sizes are limited up to three values. Meanwhile, as an example of this method, we construct the large sets [Formula: see text] for [Formula: see text] two of them are new.

Abstract Gliese 86 is a nearby K dwarf hosting a giant planet on a ≈16 day orbit and an outer white dwarf companion on a ≈century-long orbit. In this study we combine radial velocity data (including new measurements spanning more than a decade) with high angular resolution imaging and absolute astrometry from Hipparcos and Gaia to measure the current orbits and masses of both companions. We then simulate the evolution of the Gl 86 system to constrain its primordial orbit when both stars were on the main sequence; the closest approach between the two stars was then about 9 au. Such a close separation limited the size of the protoplanetary disk of Gl 86 A and dynamically hindered the formation of the giant planet around it. Our measurements of Gl 86 B and Gl 86 Ab’s orbits reveal Gl 86 as a system in which giant planet formation took place in a disk truncated at ≈2 au. Such a disk would be just big enough to harbor the dust mass and total mass needed to assemble Gl 86 Ab’s core and envelope, assuming a high disk accretion rate and a low viscosity. Inefficient accretion of the disk onto Gl 86 Ab, however, would require a disk massive enough to approach the Toomre stability limit at its outer truncation radius. The orbital architecture of the Gl 86 system shows that giant planets can form even in severely truncated disks and provides an important benchmark for planet formation theory.

AbstractThe Galileo spacecraft has found Jupiter’s inner regular moon Amalthea to be a porous assemblage of rock and ice. This and other factors point to Amalthea having first condensed in a solar orbit.

Small satellites are becoming more popular because they are cost-effective, easy to assemble, and use commercially available parts. However, traditional ground stations that communicate with small satellites require a lot of hardware and are expensive to build. This makes it challenging to get the most out of small satellites' information. Software Defined Radios (SDRs) have been developed to reduce the cost of these ground stations by doing many of the tasks in software. Many universities and organizations are developing SDR ground stations to communicate with satellites in different orbits. Communication with satellites is critical to their development and operation. This paper proposes a ground station that uses SDR technology to communicate with one or more small satellites in Low Earth Orbit (LEO). The station is cost-effective, portable, and easily scaled, allowing it to acquire data from satellites.

One goal of ethnoarchaeology is to strengthen archaeological inferences about the past. A fifteenth-century hunter-gatherer, open site in Utah is used to examine ethnoarchaeological contributions toward determining the use of space, duration of occupation, assemblage composition, and site function. Comparisons between macrorefuse and microrefuse patterning suggest that (1) the distribution of macrorefuse can help identify locations of ephemeral structures and household activity areas; (2) the distribution of microrefuse in this intermittently occupied open site is useful for assessing assemblage composition; (3) determining the characteristics of macro- and microrefuse improves hypotheses about duration of occupation; and (4) interpretation of plant remains can be improved by considering site-formation processes. The study points to the need for a closer linkage between ethnoarchaeology and the archaeology of the past.

Key morphological traits reveal changes in functional morphospace occupation of reef fish assemblages over time. We used measurements of key functional attributes (i.e., lower jaw length and orbit diameter) of 208 fossil fish species from five geological periods to create bivariate plots of functional morphological traits through time. These plots were used to examine possible function and ecological characteristics of fossil reef fish assemblages throughout the Mesozoic and Cenozoic. A previously unknown trend of increasing orbit diameter over time became apparent. The Teleostei are the principal drivers of this change. The Eocene appears to mark a dramatic increase in two previously rare feeding modes in fishes: nocturnal feeding and high-precision benthic feeding. Interestingly, members of the Pycnodontiformes had relatively large eyes since the Triassic and appear to be the ecological precursors of their later teleost counterparts and may have been among the earliest nocturnal feeding fishes. Our results highlight potential changes in the roles of fishes on coral reefs through time.

ABSTRACT We study the formation of over 6000 compact groups (CGs) of galaxies identified in mock redshift-space galaxy catalogues built from semi-analytical models of galaxy formation (SAMs) run on the Millennium Simulations. We select CGs of four members in our mock SDSS galaxy catalogues and, for each CG, we trace back in time the real-space positions of the most massive progenitors of their four galaxies. By analysing the evolution of the distance of the galaxy members to the centre of mass of the group, we identify four channels of CG formation. The classification of these assembly channels is performed with an automatic recipe inferred from a preliminary visual inspection and based on the orbit of the galaxy with the fewest number of orbits. Most CGs show late assembly, with the last galaxy arriving on its first or second passage, while only 10–20 per cent form by the gradual contraction of their orbits by dynamical friction, and only a few per cent forming early with little subsequent contraction. However, a SAM from a higher resolution simulation leads to earlier assembly. Assembly histories of CGs also depend on cosmological parameters. At similar resolution, CGs assemble later in SAMs built on parent cosmological simulations of high density parameter. Several observed properties of mock CGs correlate with their assembly history: early-assembling CGs are smaller, with shorter crossing times, and greater magnitude gaps between their brightest two members, and their brightest galaxies have smaller spatial offsets and are more passive.

Redescription of the holotype specimen of Cephalerpeton ventriarmatum Moodie, 1912, from the Middle Pennsylvanian (Moscovian) Francis Creek Shale of Mazon Creek, Illinois, confirms that it is a basal eureptile with close postcranial similarities to other protorothyridids, such as Anthracodromeus and Paleothyris . The skull is long and lightly built, with large orbits and a dorsoventrally short mandible similar to most basal eureptiles. Two specimens referred previously to Cephalerpeton cf. C . ventriarmatum from the approximately coeval Linton, Ohio, locality differ significantly from the holotype in cranial and mandibular proportions and tooth morphology. This material and an additional Linton specimen compare favourably to ‘short-faced’ parareptiles, such as Colobomycter and Acleistorhinus , and justify recognition of an acleistorhinid parareptile in the Linton assemblage. The new binomen is thus the oldest known parareptile.

Juventae Chasma is a long depression associated with Valles Marineris and this study discusses the spectral observation made after analysing the Mars Reconnaissance Orbiter (MRO) Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) Full Resolution targeted (FRT) Images in the wavelength region of 1000–2600 nm. Observations reveal the presence of hydrous sulphates, pyroxenes (mafic minerals) and silica rich minerals, more likely opaline silica or glass. Hydrous mineral identified shows the absorption bands, which are more consistent with gypsum. Absorption bands at 2300–2350 nm, and 2500–2550 nm, which are characteristics of carbonates, have been also identified in the region. Presence of this mineral assemblage, confirmed by the observed spectral signatures ranging from volcanic to sedimentary origin, implies a relatively geologically active area, and a significant region in terms of aqueous activity.

The construction of large structures is one of the main development trends of the space exploration in the future, such as large space stations, large space solar power stations, and large space telescopes. It is one of important development tendency, which aims to make full use of space robots to assemble space structures autonomously in the aerospace industry. Considering that on-orbit assembly is an effective method to solve the problem of construction of large-scale spatial structures, it is necessary to motivate and facilitate the research of space robotics technologies for on-orbit assembly. Therefore, in this paper, the development status of space robot technology and the relevant space robot on-orbit assembly technology in recent decades are summarized. First, based on the space robot motion planning and assembly sequence planning, the development of space robot planning algorithms is introduced. For space robot assembly task, the space robot assembly method is summarized. From the control point of view, how to solve the vibration suppression and compliant assembly of on-orbit assembly is reviewed, which provides a reference for the autonomous intelligent assembly of space robots for large-scale structures in space. In order to simulate the space assembly scene on the ground, this paper introduces the development of ground verification experiments and provides ideas for the effective verification of space on-orbit assembly technology. In summary, though some of these problems have been satisfactorily solved in the past research, further research is still necessary in the future. Finally, it looks forward to the future research direction of space machine on-orbit assembly.

La complexité des missions spatiales a augmenté de façon exponentielle, avec des exigences croissantes en matière de performance, de précision et de robustesse. Cette évolution est due à la fois aux progrès technologiques et à la nécessité de satisfaire de nouveaux défis, tels que les satellites en rotation (spinnés), l'assemblage en orbite et le service en orbite. Ces missions nécessitent l'intégration de systèmes mécaniques complexes, notamment des réservoirs de carburant liquide et ballotant, des systèmes de pointage précis et des structures flexibles qui présentent généralement des modes à basse fréquence, proches en fréquence et peu amortis. À mesure que les engins spatiaux deviennent plus modulaires avec plusieurs composants interconnectés tels que les antennes et les charges utiles, il est essentiel de modéliser et de contrôler avec précision ces systèmes multicorps complexes. Les interactions entre les structures flexibles et les systèmes de contrôle peuvent avoir un impact significatif sur les tâches critiques telles que le contrôle de l'attitude et la précision du pointage. Il est donc essentiel de prendre en compte les dynamiques couplées et les perturbations externes pour garantir le succès de la mission.Afin de résoudre ces problèmes, cette thèse présente une approche unifiée de la modélisation et du contrôle des systèmes multicorps flexibles dans les missions spatiales. Elle utilise des modèles de représentation fractionnaire linéaire (LFR) pour capturer efficacement la dynamique complexe et les incertitudes inhérentes à ces scénarios. La recherche commence par la dérivation d'un modèle LFR pour une poutre extsc{Euler}- extsc{Bernoulli} flexible et en rotation, prenant en compte les forces centrifuges et leur dépendance par rapport à la vitesse angulaire. Ce modèle à six degrés de liberté (DOFs) intègre les dynamiques de flexion, de traction et de torsion et est conçu pour être compatible avec l'approche des ports à deux entrées et deux sorties (TITOP), permettant de modéliser des systèmes multicorps complexes. Ce manuscrit présente également un modèle multicorps pour un scénario de mission de vaisseau spatial en rotation, suivi de la conception d'un système de contrôle.La thèse étend l'application des modèles LFR à une mission de service en orbite, en se concentrant sur le contrôle robuste de la dynamique d'attitude malgré les incertitudes et les paramètres variables du système. Une nouvelle approche de modélisation pour le mécanisme d'amarrage est introduite pour prendre en compte les propriétés dynamiques de rigidité et d'amortissement de la chaîne cinématique en boucle fermée formée par le véhicule chasseur et le véhicule cible. Un système de contrôle par rétroaction assurant une stabilité et des performances robustes pendant toutes les phases de la mission est proposé et validé par une analyse structurée des valeurs singulières.A partir de ces éléments, la thèse développe finalement une méthodologie complète pour la modélisation d'une mission d'assemblage en orbite impliquant un robot à bras multiples construisant une grande structure flexible. Ce travail aborde également la dynamique de couplage entre le robot et la structure évolutive tout en considérant les changements significatifs d'inertie et de flexibilité au cours du processus d'assemblage. Un algorithme d'optimisation de planification de tâches est finalement proposé pour assurer des opérations robotiques stables et efficaces, mettant en évidence l'efficacité de l'approche de modélisation basée sur la représentation LFR
Space missions have grown exponentially in complexity, with increasing demands for performance, precision and robustness. This evolution is driven by both technological advancements and the need for spacecraft to support diverse mission objectives, such as spinning spacecraft, on-orbit assembly and on-orbit servicing. These missions require the integration of large and complex designs, including dynamic fuel tanks, precise pointing systems and flexible structures that typically exhibit low-frequency, closely spaced and poorly damped modes. As spacecraft become more modular with multiple interconnected components like antennas and payloads, accurately modeling and controlling these complex multibody systems is crucial. The interactions between flexible structures and control systems can significantly impact mission-critical tasks such as attitude control and pointing accuracy, making it essential to address the coupled dynamics and external disturbances to ensure successful mission outcomes.In order to tackle these problems, this thesis presents a unified approach to the modeling and control of flexible multibody systems in space missions. It utilizes linear fractional representation (LFR) models to effectively capture the complex dynamics and uncertainties inherent in these scenarios. The research begins with the derivation of an LFR model for a flexible and spinning extsc{Euler}- extsc{Bernoulli} beam, fully accounting for centrifugal forces and their dependence on the angular velocity. This six degrees of freedom model integrates bending, traction and torsion dynamics and is designed to be compatible with the Two-Input-Two-Output Ports (TITOP) approach, enabling the modeling of complex multibody systems. This manuscript also introduces a multibody model for a spinning spacecraft mission scenario, followed by the design of a control system.The thesis further extends the application of LFR models to an on-orbit servicing mission, focusing on the robust control of attitude dynamics despite uncertainties and varying system parameters. A novel modeling approach for a docking mechanism is introduced, capturing the dynamic stiffness and damping properties of the closed-loop kinematic chain formed by the chaser and target spacecraft. The design of a feedback control system ensuring robust stability and performance across all mission phases is proposed, validated through structured singular value analysis.Building on this foundation, the thesis finally develops a comprehensive methodology for modeling an on-orbit assembly mission involving a multi-arm robot constructing a large flexible structure. This work also addresses the coupling dynamics between the robot and the evolving structure while considering significant changes in inertia and flexibility during the assembly process. A path optimization algorithm is ultimately proposed to ensure stable and efficient robotic operations, highlighting the effectiveness of the LFR-based modeling approach

In the space surrounding the earth there are two major regions where orbital debris causes concern. They are the Low Earth Orbits (LEO) up to about 2000 km, and Geosynchronous Orbits (GEO) at an altitude of around 36000 km. The impact of the debris accumulations are in principle the same in the two regions; nevertheless they require different approaches and solutions, due to the fact that the perturbations in the orbital decay due to atmospheric drag effects predominates in LEO, gravitational forces including earth’s oblateness and luni solar effects dominating in GEO are different in these two regions. In LEO it is generally known that the debris population dominates even the natural meteoroid population for object sizes 1 mm and larger. This thesis focuses the study mainly in the LEO region. Since the first satellite breakup in 1961 up to 01 January 2003 more than 180 spacecraft and rocket bodies have been known to fragment in orbit. The resulting debris fragments constitute nearly 40% of the 9000 or more of the presently tracked and catalogued objects by USSPACECOM. The catalogued fragment count does not include the much more numerous fragments, which are too small to be detected from ground. Hence in order to describe the trackable orbital debris environment, it is important to develop mathematical models to simulate the trackable fragments and later expand it to untrackable objects. Apart from the need to better characterize the orbital debris environment down to sub millimeter particles, there is also a pressing necessity of simulation tools able to model in a realistic way the long term evolution of space debris, to highlight areas, which require further investigations, and to study the actual mitigation effects of space policy measures. The present thesis has provided newer perspectives for five major issues in space debris modeling studies. The issues are (i) breakup modeling, (ii) environment modeling, (iii) evolution of the debris environment, (iv) collision probability analysis and (v) reentry prediction. The Chapter 1 briefly describes an overview of space debris environment and the issues associated with the growing space debris populations. A literature survey of important earlier work carried out regarding the above mentioned five issues are provided in the Chapter 2. The new contributions of the thesis commence from Chapter 3. The Chapter 3 proposes a new breakup model to simulate the creation of debris objects by explosion in LEO named “A Semi Stochastic Environment Modeling for Breakup in LEO” (ASSEMBLE). This model is based on a study of the characteristics of the fragments from on orbit breakups as provided in the TLE sets for the INDIAN PSLV-TES mission spent upper stage breakup. It turned out that based on the physical mechanisms in the breakup process the apogee, perigee heights (limited by the breakup altitude) closely fit suitable Laplace distributions and the eccentricity follows a lognormal distribution. The location parameters of these depend on the orbit of the parent body at the time of breakup and their scale parameters on the intensity of explosion. The distribution of the ballistic coefficient in the catalogue was also found to follow a lognormal distribution. These observations were used to arrive at the proper physical, aerodynamic, and orbital characteristics of the fragments. Subsequently it has been applied as an inverse problem to simulate and further validate it based on some more typical well known historical on orbit fragmentation events. All the simulated results compare quite well with the observations both at the time of breakup and at a later epoch. This model is called semi stochastic in nature since the size and mass characteristics have to be obtained from empirical relations and is capable of simulating the complete scenario of the breakup. A new stochastic environment model of the debris scenario in LEO that is simple and impressionistic in nature named SIMPLE is proposed in Chapter 4. Firstly among the orbital debris, the distribution of the orbital elements namely altitude, perigee height, eccentricity and the ballistic coefficient values for TLE sets of data in each of the years were analyzed to arrive at their characteristic probability distributions. It is observed that the altitude distribution for the number of fragments exhibits peaks and it turned out that such a feature can be best modeled with a tertiary mixture of Laplace distributions with eight parameters. It was noticed that no statistically significant variations could be observed for the parameters across the years. Hence it is concluded that the probability density function of the altitude distribution of the debris objects has some kind of equilibrium and it follows a three component mixture of Laplace distributions. For the eccentricity ‘e’ and the ballistic parameter ‘B’ values the present analysis showed that they could be acceptably quite well fitted by Lognormal distributions with two parameters. In the case of eccentricity also the describing parameter values do not vary much across the years. But for the parameters of the B distribution there is some trend across the years which perhaps may be attributed to causes such as decay effect, miniaturization of space systems and even the uncertainty in the measurement data of B. However in the absence of definitive cause that can be attributed for the variation across the years, it turns out to be best to have the most recent value as the model value. Lastly the same kind of analysis has also been carried out with respect to the various inclination bands. Here the orbital parameters are analyzed with respect to the inclination bands as is done in ORDEM (Kessler et al 1997, Liou et al 2001) for near circular orbits in LEO. The five inclination bands considered here are 0-36 deg (in ORDEM they consider 19-36 deg, and did not consider 0-19 deg), 36-61 deg, 61-73 deg, 73-91 deg and 91- 180 deg, and corresponding to each band, the altitude, eccentricity and B values were modeled. It is found that the third band shows the models with single Laplace distribution for altitude and Lognormal for eccentricity and B fit quite well. The altitude of other bands is modeled using tertiary mixture of Laplace distributions, with the ‘e’ and ‘B’ following once again a Lognormal distribution. The number of parameter values in SIMPLE is, in general, just 8 for each description of altitude or perigee distributions whereas in ORDEM96 it is more. The present SIMPLE model captures closely all the peak densities without losing the accuracy at other altitudes. The Chapter 5 treats the evolution of the debris objects generated by on orbit breakup. A novel innovative approach based on the propagation of an equivalent fragment in a three dimensional bin of semi major axis, eccentricity, and the ballistic coefficient (a, e, B) together with a constant gain Kalman filter technique is described in this chapter. This new approach propagates the number density in a bin of ‘a’ and ‘e’ rapidly and accurately without propagating each and every of the space debris objects in the above bin. It is able to assimilate the information from other breakups as well with the passage of time. Further this approach expands the scenario to provide suitable equivalent ballistic coefficient values for the conglomeration of the fragments in the various bins. The heart of the technique is to use a constant Kalman gain filter, which is optimal to track the dynamically evolving fragment scenario and further expand the scenario to provide time varying equivalent ballistic coefficients for the various bins. In the next chapter 6 a new approach for the collision probability assessment utilizing the closed form solution of Wiesel (1989) by the way of a three dimensional look up table, which takes only air drag effect and an exponential model of the atmosphere, is presented. This approach can serve as a reference collision probability assessment tool for LEO debris cloud environment. This approach takes into account the dynamical behavior of the debris objects propagation and the model utilizes a simple propagation for quick assessment of collision probability. This chapter also brings out a comparison of presently available collision probability assessment algorithms based on their complexities, application areas and sample space on which they operate. Further the quantitative assessment of the collision probability estimates between different presently available methods is carried out and the obtained collision probabilities are match qualitatively. The Chapter 7 utilizes once again the efficient and robust constant Kalman gain filter approach that is able to handle the many uncertain, variable, and complex features existing in the scenario to predict the reentry time of the risk objects. The constant gain obtained by using only a simple orbit propagator by considering drag alone is capable of handling the other modeling errors in a real life situation. A detailed validation of the approach was carried out based on a few recently reentered objects and comparison of the results with the predictions of other agencies during IADC reentry campaigns are also presented. The final Chapter 8 provides the conclusions based on the present work carried together with suggestions for future efforts needed in the study of space debris. Also the application of the techniques evolved in the present work to other areas such as atmospheric data assimilation and forecasting have also been suggested.
Vikram Sarabhai Space Centre,Trivandrum

Vikram Sarabhai Space Centre,Trivandrum
In the space surrounding the earth there are two major regions where orbital debris causes concern. They are the Low Earth Orbits (LEO) up to about 2000 km, and Geosynchronous Orbits (GEO) at an altitude of around 36000 km. The impact of the debris accumulations are in principle the same in the two regions; nevertheless they require different approaches and solutions, due to the fact that the perturbations in the orbital decay due to atmospheric drag effects predominates in LEO, gravitational forces including earth’s oblateness and luni solar effects dominating in GEO are different in these two regions. In LEO it is generally known that the debris population dominates even the natural meteoroid population for object sizes 1 mm and larger. This thesis focuses the study mainly in the LEO region. Since the first satellite breakup in 1961 up to 01 January 2003 more than 180 spacecraft and rocket bodies have been known to fragment in orbit. The resulting debris fragments constitute nearly 40% of the 9000 or more of the presently tracked and catalogued objects by USSPACECOM. The catalogued fragment count does not include the much more numerous fragments, which are too small to be detected from ground. Hence in order to describe the trackable orbital debris environment, it is important to develop mathematical models to simulate the trackable fragments and later expand it to untrackable objects. Apart from the need to better characterize the orbital debris environment down to sub millimeter particles, there is also a pressing necessity of simulation tools able to model in a realistic way the long term evolution of space debris, to highlight areas, which require further investigations, and to study the actual mitigation effects of space policy measures. The present thesis has provided newer perspectives for five major issues in space debris modeling studies. The issues are (i) breakup modeling, (ii) environment modeling, (iii) evolution of the debris environment, (iv) collision probability analysis and (v) reentry prediction. The Chapter 1 briefly describes an overview of space debris environment and the issues associated with the growing space debris populations. A literature survey of important earlier work carried out regarding the above mentioned five issues are provided in the Chapter 2. The new contributions of the thesis commence from Chapter 3. The Chapter 3 proposes a new breakup model to simulate the creation of debris objects by explosion in LEO named “A Semi Stochastic Environment Modeling for Breakup in LEO” (ASSEMBLE). This model is based on a study of the characteristics of the fragments from on orbit breakups as provided in the TLE sets for the INDIAN PSLV-TES mission spent upper stage breakup. It turned out that based on the physical mechanisms in the breakup process the apogee, perigee heights (limited by the breakup altitude) closely fit suitable Laplace distributions and the eccentricity follows a lognormal distribution. The location parameters of these depend on the orbit of the parent body at the time of breakup and their scale parameters on the intensity of explosion. The distribution of the ballistic coefficient in the catalogue was also found to follow a lognormal distribution. These observations were used to arrive at the proper physical, aerodynamic, and orbital characteristics of the fragments. Subsequently it has been applied as an inverse problem to simulate and further validate it based on some more typical well known historical on orbit fragmentation events. All the simulated results compare quite well with the observations both at the time of breakup and at a later epoch. This model is called semi stochastic in nature since the size and mass characteristics have to be obtained from empirical relations and is capable of simulating the complete scenario of the breakup. A new stochastic environment model of the debris scenario in LEO that is simple and impressionistic in nature named SIMPLE is proposed in Chapter 4. Firstly among the orbital debris, the distribution of the orbital elements namely altitude, perigee height, eccentricity and the ballistic coefficient values for TLE sets of data in each of the years were analyzed to arrive at their characteristic probability distributions. It is observed that the altitude distribution for the number of fragments exhibits peaks and it turned out that such a feature can be best modeled with a tertiary mixture of Laplace distributions with eight parameters. It was noticed that no statistically significant variations could be observed for the parameters across the years. Hence it is concluded that the probability density function of the altitude distribution of the debris objects has some kind of equilibrium and it follows a three component mixture of Laplace distributions. For the eccentricity ‘e’ and the ballistic parameter ‘B’ values the present analysis showed that they could be acceptably quite well fitted by Lognormal distributions with two parameters. In the case of eccentricity also the describing parameter values do not vary much across the years. But for the parameters of the B distribution there is some trend across the years which perhaps may be attributed to causes such as decay effect, miniaturization of space systems and even the uncertainty in the measurement data of B. However in the absence of definitive cause that can be attributed for the variation across the years, it turns out to be best to have the most recent value as the model value. Lastly the same kind of analysis has also been carried out with respect to the various inclination bands. Here the orbital parameters are analyzed with respect to the inclination bands as is done in ORDEM (Kessler et al 1997, Liou et al 2001) for near circular orbits in LEO. The five inclination bands considered here are 0-36 deg (in ORDEM they consider 19-36 deg, and did not consider 0-19 deg), 36-61 deg, 61-73 deg, 73-91 deg and 91- 180 deg, and corresponding to each band, the altitude, eccentricity and B values were modeled. It is found that the third band shows the models with single Laplace distribution for altitude and Lognormal for eccentricity and B fit quite well. The altitude of other bands is modeled using tertiary mixture of Laplace distributions, with the ‘e’ and ‘B’ following once again a Lognormal distribution. The number of parameter values in SIMPLE is, in general, just 8 for each description of altitude or perigee distributions whereas in ORDEM96 it is more. The present SIMPLE model captures closely all the peak densities without losing the accuracy at other altitudes. The Chapter 5 treats the evolution of the debris objects generated by on orbit breakup. A novel innovative approach based on the propagation of an equivalent fragment in a three dimensional bin of semi major axis, eccentricity, and the ballistic coefficient (a, e, B) together with a constant gain Kalman filter technique is described in this chapter. This new approach propagates the number density in a bin of ‘a’ and ‘e’ rapidly and accurately without propagating each and every of the space debris objects in the above bin. It is able to assimilate the information from other breakups as well with the passage of time. Further this approach expands the scenario to provide suitable equivalent ballistic coefficient values for the conglomeration of the fragments in the various bins. The heart of the technique is to use a constant Kalman gain filter, which is optimal to track the dynamically evolving fragment scenario and further expand the scenario to provide time varying equivalent ballistic coefficients for the various bins. In the next chapter 6 a new approach for the collision probability assessment utilizing the closed form solution of Wiesel (1989) by the way of a three dimensional look up table, which takes only air drag effect and an exponential model of the atmosphere, is presented. This approach can serve as a reference collision probability assessment tool for LEO debris cloud environment. This approach takes into account the dynamical behavior of the debris objects propagation and the model utilizes a simple propagation for quick assessment of collision probability. This chapter also brings out a comparison of presently available collision probability assessment algorithms based on their complexities, application areas and sample space on which they operate. Further the quantitative assessment of the collision probability estimates between different presently available methods is carried out and the obtained collision probabilities are match qualitatively. The Chapter 7 utilizes once again the efficient and robust constant Kalman gain filter approach that is able to handle the many uncertain, variable, and complex features existing in the scenario to predict the reentry time of the risk objects. The constant gain obtained by using only a simple orbit propagator by considering drag alone is capable of handling the other modeling errors in a real life situation. A detailed validation of the approach was carried out based on a few recently reentered objects and comparison of the results with the predictions of other agencies during IADC reentry campaigns are also presented. The final Chapter 8 provides the conclusions based on the present work carried together with suggestions for future efforts needed in the study of space debris. Also the application of the techniques evolved in the present work to other areas such as atmospheric data assimilation and forecasting have also been suggested.

The Paleogene experienced the most profound climatic shift of the past 65 million years of Earth history, Earth’s climate changing from a ‘greenhouse’ in the early Paleocene, to an ‘icehouse’ in the Oligocene. This transition resulted in significant re-organization of oceanic circulation, marine communities, and biogeochemical cycles. Particularly, climate changes occurred during the Eocene are forced (or thought to be forced) by variations of orbital parameters, especially by precession (21ky) and eccentricity (100ky), which can be detected by biotic proxies, like planktonic foraminifera, calcareous nannofossils and dinoflagellates (e.g., variation in their diversity, abundance and size), in hemipelagic and shallow waters. The high abundance of calcareous nannofossils in pelagic marine sediments, makes this group one of the most useful tools to perform biostratigraphic, paleoecologic and paleoclimatic studies. Calcareous nannofossils, showing high evolutionary rate, result to be a good biostratigraphic marker, particularly for Cenozoic, when they reach high diversification. In this PhD thesis, I investigate the relationships between orbital parameters and the variation of calcareous nannofossil abundances, expressed in eccentricity cycles of three different stratigraphic successions in the Basque-Cantabrian Basin (Spain): the Sopelana (early Ypresian), the Gorrondatxe (upper Ypresian) and the Oyambre sections (upper Lutetian). Most of the studies applying such an approach, are focused on the Neogene and Quaternary, and only few studies have been carried out in older Cretaceous and Jurassic records. Up to now, no detailed studies have been performed with the aim to investigate precession and eccentricity cycles and their forcing on calcareous nannofossil aassemblages during the Eocene. The three analyzed sections are constituted by rhythmic alternations of marls and limestones. A depositional-sedimentological model has been previously proposed for the three studied sections, on the base of geochemical proxies variation (CaCO3 content, Oxygen and Carbon isotopes). For the Oyambre and Gorrondatxe sections, a detailed biostratigraphy was already present, and the role of orbital forcing on sedimentation had been already highlighted by previous studies, while, for the Sopelana section there was a lack of this information. Concerning the Sopelana section (Chapter 2), before analysing the influence of precession and eccentricity forcing on calcareous nannofossil abundances, I provide a detailed nannofossil biostratigraphy, and, by means of spectral analysis on CaCO3 record, I highlight the role of the precession cycle in driving the deposition of marl-limestone couplets, and the effect of the eccentricity cycles on the sedimentation of bundles (each of which is composed by five marl- limestone couplets). The variation of calcareous nannofossil abundances induced by orbital forcing has been investigated in Chapter 3. The statistical analyses (implemented with Principal Component Analysis and Cluster methods), based on the variation of calcareous nannofossil abundances, carried out in the Sopelana, Oyambre and Gorrondatxe sections, confirm the previous sedimentological models, adding new information regarding the sedimentary environments during the Eocene in the Basque-Cantabrian Basin. The performed analyses indicate that the major calcareous nannofossil assemblages variations occur at the maximum eccentricity, in correspondence of which we observe a decrease in oligotrophic and stable environments taxa and an increase in eutrophic and low salinity taxa. These observations confirm that the maximum eccentricity corresponds to the maximum seasonality, leading to an increase in nutrients supply from continents and a higher water mixing (upwelling). A further work has been performed in the framework of the studies for the definition of the GSSP, considering that for the Paleogene two GSSPs are still pending (i.e., the base of Bartonian, middle Eocene, and the Priabonian, middle-upper Eocene). In our work, we focus on the definition of the Bartonian Stage. In Chapter 4, I report the results of a multidisciplinary study based on calcareous nannofossil, dinoflagellate, larger and smaller benthic foraminifera and magnetostratigraphy to assess potential correlations and placements for the Lutetian/Bartonian boundary. The Bartonian unit stratotype is located at the Barton coastal section (Hampshire Basin, UK). In this work, I study the parastratotype section, located 7 km away at Alum Bay, since it shows a better exposure. Basing on the obtained results, the Alum bay section is within the nannoplankton Zones CNE14 and CNE15. The Base of Rhombodinium draco, (dinoflagellate), an important and correlatable event in the Tethys domain, is recognized within the section, which also coincides with the acme of N. prestwichianus (formerly indicated as the base of the Bartonian Stage in the Barton area), both of which are correlated with nannoplankton Zone NP16, spanning the upper Lutetian and lower Bartonian. The palaeomagnetic correlation with calcareous nannofossil data allows to assign the normal Chron at the base of the section to C19n, considered an approximation for the base of the Bartonian Stage according to the Geological Time Scale. The remaining portion of the section correlates to C18n and C18r. All analyses, therefore, support that the section is lower Bartonian in age, with the palaeomagnetic data indicating that the first 5 m of the section also contains the Upper Lutetian.

Abstract The Lithic Imagination from More to Milton explores how stones, rocks, and the broader mineral realm play a vital role in early modern England’s religious and cultural systems that in turn informs the period’s poetic and visual imagination. The twin buttresses of a human lifespan and the gyre-like turns of England’s long Reformation provide a broad dome under which to locate the many textual and visual archives this book studies. These texts and images participate in specifically English histories (literary, artistic, political, religious), although Continental influences are frequently in dialogue. The religious orbit tracks the rivalries firstly between Jewish and Christian culture, touches on Christianity’s tension with Islam, but most intently follows the antagonisms of Catholic and variants of Reformed or Protestant belief. The bibliography features canonical names such as Shakespeare, Spenser, Donne, Wroth, Herbert, Milton, and Pulter, but puts them in company with lesser-known religious polemicists, alchemists, anatomists, painters, mothers, and stonemasons. The visual archive attends to biblical illustration, tapestries, church furniture, and paintings, anatomical drawings, as well as statues to form a multimedia archive. Similarly, the lithic embraces a wide continuum of mineral forms from bodily encrustations like the kidney and bezoar stone, to salt, iron, limestone, marble, flint, and silicon. The assemblage of materials speaks to aspirational imperial fantasies, looming colonial conquests, syncretism, and supersession, as well as issues of gender and the race-making category of hue, alongside elitist ideologies of an elect, chosen people. All connect via the storied pathways of stone as densely material and a foundation for the abstract imaginary along the scala naturae. Across these human–stone encounters, stone fascinates and betrays and is equal parts damnation and salvation.

This paper is concerned with the mathematical description of orbits that do not have a constant central gravitating mass. Instead, the attracting mass is a diffuse condensate, a situation which classical orbital dynamics has never encountered before. The famous Coma Cluster of Galaxies is embedded in Dark Matter. Condensed Neutrino Objects (CNO), which are stable assemblages of neutrinos and anti-neutrinos, are candidates for the Dark Matter. A CNO solution has been attained previously for the Coma Cluster, which allows mathematical modeling of galaxy orbital mechanics within Dark Matter, first reported here. For non-zero eccentricity galaxy orbits, each point along the trajectory sees a different gravitating central mass, akin to satellite orbits inside Earth. Mathematically, the galaxy orbits are non-Keplerian, spirographs.

The corpse is a social entity that disrupts distinctions between persons and things, subjects and objects, agency and passivity. Assemblages made up of living, dead, animate, and inanimate entities collaborate to allow their members to be carried along a trajectory toward a shared, mutually beneficial goal—motivating action, restoring political stability, burying the corpse, moving living and dead bodies through space. Juan de Silva, Philip II of Spain’s diplomat in Portugal, injured and aware of his own reduced powers to disseminate information, grasps the lingering subjectivity Sebastian’s cadaver retains its status as a repository of epistemological power. He succeeds in bringing himself within the gravitational pull of its orbit long enough to be carried along the trajectory of its translation from North Africa to a Portuguese mausoleum. This powerless living narrator forges a symbiotic alliance with the more animate and mobile royal corpse, joining its trajectory home. Silva’s efforts to associate with or substitute his own injured bodies with the dead one highlights the power of the corpse in early modern economies of knowledge.

Abstract Galaxies such as our Milky Way system have somehow succeeded in maintaining a youthful appearance for billions of years. The Sun takes about 100 million years to orbit the Milky Way, and we can think of a solar orbit as lasting a galactic year. Our galaxy is about 100 galactic years old. By any measure of the rate at which the gas clouds in the galaxy have collapsed, there should be little gas remaining. By all accounts it should be a decrepit assemblage of old and dying stars. Yet it is blossoming with the vitality of youth, as new stars are born. Indeed, our Milky Way is a fertile breeding site for stars.

This paper presents a brief synopsis of the Miocene Epoch, an important transitory chapter in the history of the Earth. It was during the Miocene that the major continents and oceans attained a “modern” configuration in terms of paleogeography and tectonics, oceanic ventilation and circulation, ocean chemistry, and faunal and floral assemblages. It also was during the Miocene that global climate fully transitioned into its current icehouse state, including marked growth of the Antarctic ice sheet and initiation of the Arctic ice cap. Long-term global cooling was controlled by a number of factors including tectonics, the large-scale changes in the distribution of flora, particularly the expansion of grasslands, and by fluctuating orbital parameters of the Earth. This global cooling trend was briefly interrupted by a short period of warming in the middle Miocene. Miocene sea-level changes consisted of a number of glacio-eustatic third-order (1–5 million year [m.y.] duration) cycles superposed upon three longer-term, second-order (5–20 m.y. duration) supercycles. Development of large-scale tropical carbonate systems in the Miocene was relegated to three main geographic regions: the circum-Caribbean, Mediterranean, and Indo-Pacific. In addition, a pronounced cool-water platform system developed along the southern margin of Australia. Miocene reefal buildups were dominated by tropical to subtropical framework assemblages consisting primarily of large scleractinian corals, encrusting red algae, and rhodoliths (free-living coralline red algae) that grew on platform margins and interiors or on isolated atolls. Miocene carbonates were deposited in a variety of oceanic and structural settings and constitute important petroleum reservoirs, particularly in Southeast Asia. Deep-water terrigenous clastic sediments of Miocene age are also important petroleum reservoirs in some regions. In addition, the Miocene interval contains numerous prolific petroleum source rocks, most composed of Type III (gas-prone) kerogen.

Abstract Seventeenth-century concerted music for voices and instruments survives in two main forms. On the Continent, church music and secular vocal music were commonly published in sets of part-books, while theatre works were copied in score and were sometimes published in that form. In England, by contrast, the music publishing industry was relatively undeveloped until the 1 690s, so sizeable works for voices and instruments rarely got into print. Nearly all Restoration odes, symphony anthems, masques, and operas survive only in manuscript score. These two formats--scores and sets of part-books-are so familiar to us that we tend to forget that they rarely convey all the information we need to recreate the composers’ intentions. Neither format normally tells us exactly how many performers to assemble or how many to allocate to each part, and scores frequently obscure the precise role of instruments by conflating vocal and instrumental bass parts or by leaving out supporting instrumental parts altogether in choral sections. Similarly, we must be wary of assuming that printed sets of parts were actually used for performance and are reliable guides to the size and disposition of the performing forces. Their main function would have been to transmit repertory to musicians outside the orbit of the composer, and they often need to be supplemented by duplicate parts, printed or manuscript, before they can be used. Indeed, I suspect that many purchasers thought them too precious to be used in performance, and treated them as repositories from which manuscript parts were copied.

Bernal's quote is a bit wordy, but he was basically saying that life can be understood as a continuous chemical reaction, and I agree. Throughout this book I will be describing ideas about how life can begin on habitable planets, which are defined as planets with orbits not too close and not too far from a star so that the temperature permits liquid water to exist. The conditions in which life can begin must have sufficient complexity to permit primitive life to assemble from organic chemicals dispersed in a sterile environment which then begin to react and evolve into more complex structures. This chapter will describe the main parameters of geochemical and geophysical complexity, and then consider them in terms of scales from the nanoscopic to the macroscopic. Questions to be addressed: What scales must be considered to understand how life can begin? What are the properties of the scales? How do the scales relate to the origin of life? The physical dimensions related to the origin of life can be described in terms of four scales—global, local, microscopic, and nanoscopic— and these dimensions must be related to the chemical and physical properties of each scale. The global scale is easiest to understand because the parameters are averages of very broad variables. For instance, we can state that the global temperature today is 15° C and even follow changes in the temperature to accuracies of a tenth of a degree on a year to year basis. However, within the global scale are extreme variations between winter temperatures of - 60° C at the poles and summer temperatures of 50° C in Death Valley, California. Of course, even higher temperatures are associated with hydrothermal fields, up to boiling at 100° C, but sometimes nearer to 90° C because the fields are usually at higher elevations associated with volcanoes. Table 2.1 summarizes the main parameters of the global scale on Earth and Mars today and compares their values with those near the time that life began on the Earth 4 billion years ago.

This book describes a hypothetical process in which populations of protocells can spontaneously assemble and begin to grow and proliferate by energy- dependent polymerization. This might seem to be just an academic question pursued by a few dozen researchers as a matter of curiosity, but in the past three decades advances in engineering have reached a point where both NASA and the European Space Agency (ESA) routinely send spacecraft to other planetary objects in our solar system. A major question being pursued is whether life has emerged elsewhere than on Earth. The limited funds available to support such missions require decisions to be made about target priorities that are guided by judgment calls. These in turn depend on plausible scenarios related to the origin of life on habitable planetary surfaces. We know that other planetary bodies in our solar system have had or do have conditions that would permit microbial life to exist and perhaps even to begin. By a remarkable coincidence, the two most promising objects for extraterrestrial life happen to represent the two alternative scenarios described in this book: An origin of life in conditions of hydrothermal vents or an origin in hydrothermal fields. This final chapter will explore how these alternative views can guide our judgment about where to send future space missions designed as life-detection missions. Questions to be addressed: What is meant by habitability? Which planetary bodies are plausible sites for the origin of life? How do the hypotheses described in this book relate to those sites? There is healthy public interest in how life begins and whether it exists elsewhere in our solar system or on the myriad exoplanets now known to orbit other stars. This has fueled a series of films, television programs, and science fiction novels. Most of these feature extrapolations to intelligent life but a few, such as The Andromeda Strain, explore what might happen if a pathogenic organism from space began to spread to the human population. There is a serious and sustained scientific effort—SETI, or Search for Extraterrestrial Intelligence—devoted to finding an answer to this question.

Around the time the steady convection model was being developed, Akasofu (1964) was arranging ground-based magnetometer and all-sky camera observations of the complex time dependence of nightside auroral activity into the central phenomenological conception of tune-dependent magnetospheric physics—the auroral substorm. In this chapter, we assemble a description of a substorm from modern observations. We will see that observations of electric fields, auroral X rays, cosmic noise absorption, ionospheric density, and geomagnetic micropulsations have also been successfully ordered by the substorm paradigm. At the same time, it will become clear that each individual substorm has its own irreducible individuality, and that our summary description is really a list of effects that anyone thinking about substorms ought to consider. No real substorm will look exactly like the one described here. Spacecraft observations of auroral light, precipitation, currents, and fields from polar orbit have held out high promise for unified understanding of the development of the auroral substorm around the entire oval. Without truly global auroral observations, it would be difficult to establish decisive contact with observations of large-scale convection and the associated changes in magnetospheric configuration. Despite the high promise and the many other successes of spacecraft observations of the aurora, synthetic understanding of the time development of the auroral substorm at all local times, dayside and nightside, evening and dawn, has been slow in emerging, perhaps because a stringent combination of field of view, sensitivity, space and time resolution, and multispectral capability is required. One needs images of the whole oval with sufficient space resolution to identify important arc structures (50-100 km or better) in a temporal sequence that can articulate the evolution of activity on better than the 10-minute time scale on which polar cap convection develops. Only recently has it been possible to observe auroral activity at all local tunes around the auroral oval simultaneously and follow its time development from the beginning of the growth phase until well into the expansion phase. This amplification of the original paradigm is the subject of Sections 12.2 and 12.3.

Abstract We present a distributed control law to assemble a cluster of satellites into an equally-spaced, planar constellation in a desired circular orbit about a planet. We assume each satellite only uses local information, transmitted through communication links with neighboring satellites. The same control law is used to maintain relative angular positions in the presence of disturbance forces. The stability of the constellation in the desired orbit is proved using a compositional approach. We first show the existence and uniqueness of an equilibrium of the interconnected system. We then certify each satellite and communication link is equilibrium-independent passive with respective storage functions. By leveraging the skew symmetric coupling structure of the constellation and the equilibrium-independent passivity property of each subsystem, we show that the equilibrium of the interconnected system is stable with a Lyapunov function composed of the individual subsystem storage functions. We further prove that the angular velocity of each satellite converges to the desired value necessary to maintain circular, areostationary orbit. Finally, we present simulation results to demonstrate the efficacy of the proposed control law in acquisition and station-keeping of an equally-spaced satellite constellation in areostationary orbit despite the presence of unmodeled disturbance forces.

To study the intrinsic physics and improve computation efficiency of free–surface flow problems, in this study we propose a proper orthogonal decomposition (POD) technique that couples the velocity flow field and the level–set function field for free–surface flows. In this method, the snapshots data from numerical or experimental results are used to assemble a low–dimensional basis so that the flow characteristics can be retrieved with a priori knowledge of equal distribution of the total variance between velocity and level–set function data. Through numerical examples of a sloshing problem and a water entry problem, we show that the low–dimensional components obtained provide an efficient and accurate approximation of the flow field Moreover, we show that the velocity contour and orbits projected on the space of the reduced basis greatly facilitate understanding of the intrinsic dynamics of the flow systems.

Earth radiation budget instruments (RBI) are devices designed to study global climate change. These instruments use telescopes mounted on low earth orbit satellites to measure emitted and reflected solar radiation from the earth. Radiation is measured by virtue of temperature changes caused by absorbed radiation from the earth scans on the surface of a delicate gold-black detector. In this paper a thermal model of the detector in a typical radiation budget instrument is formulated. A numerical solution is developed using a complex model building procedure. The idea is to split complex physical processes into simpler, individual physical processes. The basic procedure is to solve for each individual physical process in a numerically stable and efficient manner, and then assemble these processes in a cascading sequence to form a complete numerical solution of a complex model. The major advantage is that complicated mathematical models can be solved as a sequence of much simpler and less computationally intensive processes. Parameter studies are performed on the numerical accuracy, conduction effects, initial conditions, boundary conditions due to contact with adjoining surfaces, radiation exchange with surfaces optically visible to the detector, and the volumetric heat source due to absorbed radiation from the earth scene. Extremely accurate temperature predictions are required due to the low signal to noise ratio. It is found that predictions are most sensitive to the amount and distribution of irradiation on the detector surface, which is computed independently using a Monte Carlo ray trace method.

While many secondary schools offer courses or extracurricular activities that focus on satellite engineering, e.g. CanSats or the assembly of ground stations, these projects usually stay close to ground. With SpaceTeamSat1, the TU Wien Space Team wants to enhance this approach and tackle the challenge to perform various experiments in space, enabling students to participate in a space mission that actually orbits our planet. Therefore, our goal is to develop a 1U CubeSat platform, which allows students at secondary schools to access a set of different sensors connected to a Raspberry Pi. Consequently, students can write their own software experiments in Python and exploit the possibilities of sensors in space. In this context, participation happens at different stages: For one, students are getting in contact with Python, which also allows an easy step into software engineering paradigms. Moreover, our team will pose some challenges, such as re-doing an earlier satellite mission and giving impressions about how CubeSats can be used, e.g. to combat climate change. To complete these challenges, the CubeSat is equipped with various sensors such as temperature sensors, gyrometers, magnetometers, as well as two cameras. Moreover, the participating students also have the possibility to design their own experiments independently to leave room for creativity. Further enhancing this educational mission, participating students are also invited to work on hardware topics. This is mainly aimed at engineering schools, which are encouraged to assemble Raspberry Pi HATs which contain the actual mission sensors, as well as a SatNOGS ground station, which also enables students to get an insight on satellite communication. It needs to be considered that the educational mission follows a modular setup since the combination of all individual tasks is not realizable within a single school year. Thus, schools are also able to individually select appropriate tasks. In the past we were already collaborating with the European Space Education Resource Office as we are acting as launch provider of CanSats for ESERO’s Austrian CanSat competition. In this sense, STS1 shall be an extension to the space educational program in Austria. Based on that, we believe that the STS1 mission has a high potential to bring something that is currently out of reach for most people, outer space, closer to a demographic with a lot of talent and enthusiasm for engineering and potential future engineers

With the development of the next generation of Earth observation and science Space missions, there is an increasing trend towards highly performing payloads. This trend is leading to increased detector resolution and sensitivity, as well as longer integration time which directly drive pointing requirements to higher stability and lower line-of-sight (LOS) jitter [1]. Such instruments typically come with stringent pointing requirements and constraints on attitude and rate stability over an extended frequency range well beyond the attitude control system bandwidth, by entailing micro-vibration mitigation down to the arcsecond (arcsec) level or less [2]. Micro-vibrations are defined in [3] as low-level vibrations causing a distortion of the LOS during on-orbit operations of mobile or vibratory parts. However, in order to guarantee high pointing performance, it is necessary to entirely characterise the transmission path between the micro-vibration source and the payload. The earlier the model is available, the easier it is to meet the stringent pointing requirements, by designing appropriate control strategies. The main difficulties encountered in Space system characterisation are both the impossibility to correctly identify the system on ground due to the presence of gravity and the consideration of all possible system uncertainties. Several uncertainties are in fact determined by: manufacture imperfections of structures and mechanisms, evolution of the system during the mission (i.e. material exposition to Space environment, mass and inertia variation due to ejected ergol), misknowledge of sensors/actuator dynamics. Uncertainty quantification is the preliminary step to be accomplished before designing robust control laws which provide a certificate on the closed-loop system stability and performance. The increased need in pointing performance together with the use of lighter and flexible structures directly come with the need of a robust pointing performance budget from the very beginning of the mission design. An extensive understanding of the system physics and its uncertainties is then necessary in order to push control design to the limits of performance and constrains the choice of the set of sensors and actuators. An analytical methodology to model all flexible elements and mechanisms of a scientific satellite and its optical payload in a multi-body framework is presented. In particular the Two-Input Two-Output Ports approach is used to propose novel models for a reaction wheel assembly including its imbalances and two kinds of actuators to control the line-of-sight: an FSM and a set of PMAs. This approach allows the authors to assemble a complex industrial spacecraft where detailed finite element models can be easily included as well. All these feature are available in the Satellite Dynamics Toolbox Library (SDTlib) [4]. Since in this framework an uncertain Linear Parametric-Varying system can be directly derived by including all possible configurations and uncertainties of the plant, two novel robust active control strategies are proposed to mitigate the propagation of the microvibrations to the LOS error. A first one consists in synthesising an observer of the LOS error by blending the low-frequency measurements of the LOS directly provided by a CCD camera and the accelerations measured in correspondence of the most flexible optical elements (primary and secondary mirrors of a space telescope) together with the accelerations measured on a passive isolator placed at the base of the payload. An FSM then uses this information to mitigate the pointing error. In order to obtain even tighter micro-vibration attenuation, a second stage of active control was proposed as well. This strategy consists in measuring the accelerations of the payload isolator and actuating six PMAs attached to the same isolator. Thanks to this double-stage active control strategy, the propagation of the micro-vibrations induced by the RWs and SADMs is finely reduced on a very large frequency band. In particular, a reduction of the pointing error to 10 arcsec is guaranteed at low frequency approximatively 1 rad/s) with a progressive reduction of the jitter until 40 marcsec for higher frequencies where micro-vibration sources act. This application finally allows the authors to demonstrate the interest of the proposed modelling approach, that is able to finely capture the dynamics of a complex industrial benchmark by including all possible uncertainties in a unique LFT model. This modular framework, which permits to easily build and design a multi-body flexible structure, is in fact conceived in order to perfectly fit with the modern robust control theory. In this way the authors demonstrate how to push the control design to the limits of achievable performance, which is fundamental in the preliminary design phases of systems with very challenging pointing requirements. The present work synthesises the results obtained in an ESA Open Invitations to Tender initiative “Line of Sight Stabilization Techniques (LOSST)” performed together with Thales Alenia Space, Cannes, France (Contract NO. 1520095474 / 02) [5]. [1] C. Dennehy, O. S. Alvarez-Salazar, Spacecraft Micro-Vibration: A Survey of Problems, Experiences, Potential Solutions, and Some Lessons497 Learned, Technical Report NASA/TM-2018-220075, NASA, 2018. [2] A. J. Bronowicki, Vibration isolator for large space telescopes, Journal of Spacecraft and Rockets 43 (2006) 45–53. [3] A. Calvi, N. Roy, E. Secretariat, ECSS-E-HB-32-26A Spacecraft Mechanical Loads Analysis Handbook, Technical Report, ESA, 2013. [4] Alazard, Daniel, and Francesco Sanfedino. "Satellite dynamics toolbox for preliminary design phase." 43rd Annual AAS Guidance and Control Conference. Vol. 30. 2020. [5] Sanfedino, F., Thiébaud, G., Alazard, D., Guercio, N., & Deslaef, N. (2022). Advances in fine line-of-sight control for large space flexible structures. Aerospace Science and Technology, 130, 107961.