1,721,577 research outputs found
Dynamical System Description of the Solar Radiation Pressure and j2 Phase Space for End-Of-life Design and Frozen Orbit Design
Full text linkn this work we review the effect of solar radiation pressure on the eccentricity of circumterrestrial orbits, perturbed also by the oblateness of the Earth. We compute the equilibrium points of a reduced system of equations describing the time evolution of the eccentricity, the longitude of the ascending node and the argument of pericenter, and their linear stability. This analysis is the basis for understanding how the phase space is organized in terms of central and hyperbolic orbits. The role of the initial phase with respect to the Sun and of the magnitude of the inclination evolution is also examined. The results follow previous investigations performed by the authors, providing a more complete picture of the whole dynamics, that can be applied to design convenient end-of-life strategies for small satellites equipped with a solar sail or to determine quasi stable Sun-following orbits for satellites swarms
Long-Term Evolution of Orbits in Cislunar Space: Characterisation and Stability Analysis
Full text linkPhase space description of the dynamics due to the coupled effect of the planetary oblateness and the solar radiation pressure perturbations
Full text linkThe aim of this work is to provide an analytical model to characterize the equilibrium points and the phase space associated with the singly averaged dynamics caused by the planetary oblateness coupled with the solar radiation pressure perturbations. A two-dimensional differential system is derived by considering the classical theory, supported by the existence of an integral of motion comprising semi-major axis, eccentricity and inclination. Under the single resonance hypothesis, the analytical expressions for the equilibrium points in the eccentricity-resonant angle space are provided, together with the corresponding linear stability. The Hamiltonian formulation is also given. The model is applied considering, as example, the Earth as major oblate body, and a simple tool to visualize the structure of the phase space is presented. Finally, some considerations on the possible use and development of the proposed model are drawn
Trade-Off Study on Large Constellation Deorbiting using Low-Thrust and De-Orbiting Balloons
Full text linkTime Characterization of the Coupled Solar Radiation Pressure-Planetary Oblateness Dynamics
No full textDynamical taxonomy of the coupled solar radiation pressure and oblateness problem and analytical deorbiting configurations
Full text linkRecent works demonstrated that the dynamics caused by the planetary oblateness coupled with the solar radiation pressure can be described through a model based on singly averaged equations of motion. The coupled perturbations affect the evolution of the eccentricity, inclination and orientation of the orbit with respect to the Sun–Earth line. Resonant interactions lead to non-trivial orbital evolution that can be exploited in mission design. Moreover, the dynamics in the vicinity of each resonance can be analytically described by a resonant model that provides the location of the central and hyperbolic invariant manifolds which drive the phase space evolution. The classical tools of the dynamical systems theory can be applied to perform a preliminary mission analysis for practical applications. On this basis, in this work we provide a detailed derivation of the resonant dynamics, also in non-singular variables, and discuss its properties, by studying the main bifurcation phenomena associated with each resonance. Last, the analytical model will provide a simple analytical expression to obtain the area-to-mass ratio required for a satellite to deorbit from a given altitude in a feasible timescale
End-Of-Life Disposal Parametric Analysis in Cislunar Space: Earth-Moon L2 Escape No-Return Trajectories
Full text linkA new method for identifying dynamical transitions in rubble-pile asteroid scenarios
Full text linkContext. Evidence supports the idea that asteroids are rubble piles, that is, gravitational aggregates of loosely consolidated material. This makes their dynamics subject not only to the complex N-body gravitational interactions between its constituents, but also to the laws of granular mechanics, which is one of the main unsolved problems in physics.Aims. We aim to develop a new method to identify dynamical transitions and predict qualitative behavior in the granular N-body problem, in which the dynamics of individual bodies are driven both by mutual gravity, contact and collision interactions.Methods. The method has its foundation in the combination of two elements: a granular N-body simulation code that can resolve the dynamics of granular fragments to particle-scale precision, and a theoretical framework that can decode the nature of particle-scale dynamics and their transitions by means of ad hoc indicators.Results. We present here a proof-of-concept of the method, with application to the spinning rubble-pile asteroid problem. We investigate the density-spin parameter space and demonstrate that the approach can identify the breakup limit and reshape region for spinning rubble-pile aggregates.Conclusions. We provide the performance of several ad hoc indicators and discuss whether they are suitable for identifying and predicting the features of the dynamical problem
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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