The main contribution of this note is the scheme for despinning space debris using a modified yo-yo mechanism installed on the ADM module. The scheme can be used for space debris that rotates around the axis of symmetry with high angular velocity.
The modified yo-yo mechanism does not contribute to the space debris problem. Each mass of the mechanism consists of two separable dome-shaped shells filled with liquid. Instead of releasing the masses after despin, the liquid is released from the shell, for example,byseparationofthemassintoparts.Wireguidesforthereel are proposed, which follow the motion of the wires and prevent coming off the wires from the reel due to the attitude motion of the debris. A mathematical model of the spatial motion of the yo-yo mechanism is developed. The model is used to demonstrate the possibility of using the proposed scheme to despin space debris. The proposed scheme can be used to despin debris objects without using thrusterengines.Therotationofthedebrisaroundthetransverseaxes alsocanbeeliminatedwithoutusingthrusterstakingadvantageofthe tether connecting the tug with the ADM module. In this case, the design of the ADM module can be simplified.
One of the interesting applications of tethered satellite systems is the active debris removal problem. Although there have been several recent investigations, many aspects of this problem remain unexplored. One of them is the possibility of chaotic behaviour of the system, which includes a space tug, a tether, and space debris. Understanding the dynamical behaviour of such systems is essential for the success of any tether-assisted active debris removal mission. The chaotic motions of the system appear during the passive orbital motion of the system in an elliptical orbit or can be caused by the out-of-plane librations of the tether. On the active (post-burn) phase the chaotic motions of the system also possible in the presence of low-thrust applied to the space tug. We consider the chaotic motion of the system caused by the combined effects of the eccentricity of the orbit of the centre of mass, the thrust on the tug and the out-of-plane roll oscillations of the tether. Stable and unstable stationary solutions are presented for the in-plane motion of the system in a circular orbit, which depend on the value of the tug’s thrust. The unstable solutions give rise to the chaotic motion of the system in the presence of additional disturbances. Poincare sections and Lyapunov exponents are used to investigate the motion of the system for different initial conditions and parameters. It is shown that the chaotic motions of the system depend on the value of the tug’s thrust, so that using the tug with low thrust and starting the active phase of the active debris removal from unsuitable initial conditions (for the pitch and roll angles of the tether) can lead to chaotic motion of the system. The results obtained in the paper will be useful for selecting the system parameters of the space tug and the tether for a space debris removal system. Copyright © 2016 by the International Astronautical Federation (IAF). All rights reserved.
В статье представлен анализ динамики малого космического аппарата (МКА) с присоединёнными панелями солнечных батарей, обладающими в силу своей конструкции определённой степенью упругости. Сформирована математическая модель возмущённого движения космического аппарата на активном участке траектории, учитывающая упругость корпуса и наличие жидкого наполнения. При составлении модели, учитывая рассеяние энергии, получена конечномерная система уравнений возмущённого движения упругого МКА. Рассмотрены вопросы упругих колебаний конструкции, возникших после динамических операций, связанных с переориентацией МКА или с перестройкой отдельных его элементов, которые приводят к длительным переходным процессам в каналах управления. Проведены исследования на моделирующем комплексе по оценке влияния упругих колебаний конструкции МКА на точностные и динамические характеристики системы управления, такие как длительность переходного процесса и максимальная амплитуда колебаний измеренного значения угловой скорости МКА. Получены зависимости угловой скорости МКА от времени. Анализ полученных результатов показывает, что упругие колебания конструкции МКА существенно влияют на динамику аппарата в режимах закрутки. Отмечено, что наиболее критичными являются колебания в канале тангажа, где при номинальном положении панелей солнечных батарей наблюдаются колебания «из плоскости панели» и крутильные колебания относительно оси симметрии раскрытых створок панелей. Рассмотрено движение аппарата в процессе его отделения от аппарата-носителя с учётом воздействия малого аэродинамического момента.
The paper deals with the process of separating a CubeSat from a deployer. The equations of the motion of a CubeSat in the CubeSat deployerare developed. The influence of the parameters of the CubeSat and the parameters of the CubeSat deployer to the angular velocities of the CubeSat is investigated. The recommendations are made to reduce the angular velocity of the CubeSat.
Active debris removal using a space tug with a tether is one of the promising techniques to decrease the population of large non-functional satellites and orbital stages in near Earth orbits. Properties of debris should be taken into account in the development of the space tugs. In this paper we consider the motion of a debris objects with fuel residuals that can affect the safety of the debris transportation process. The equations of the attitude motion of the tug-debris system in a central gravitational field are derived. Stationary solutions of the equations are found. The system of linearized equations are introduced that can be used for short term analysis. The numerical simulation results are provided that show good accuracy of the linearized equations. Proposed equations can be used to analyze the attitude motion of the tug-debris system and to determine the conventional parameters for safe tethered transportation of space debris.
The goal of the work is to investigate the mutual influence of the tether vibrations and the vibrations of flexible appendages during thrusting phase. A mathematical model of the space tug and the towed space debris with flexible appendages is developed. Parameters of the system are determined with assumptions that the system is moving in straight line, avoiding high amplitude vibrations of flexible appendages. The expression of the discriminant indicates that the vibrations of the tether and flexible appendages influence each other. A critical tether stiffness exists for the given space tug mass that should be avoided.
The motion of a free gyrostat consisting of a platform with a triaxial ellipsoid of inertia and a rotor with a slight asymmetry with respect to the axis of rotation is considered. Dimensionless equations of motion for a system with perturbations caused by the small asymmetries of the rotor are written in Andoyer-Deprit variables. These perturbations result in a chaotic layer in the separatrix vicinity. Heteroclinic and homoclinic trajectories are written in analytical form for gyrostats with different ratios of their moments of inertia. These trajectories are used to construct a modified Melnikov function, and to produce control that eliminates separatrix chaos. The Poincare sections and Melnikov function are constructed via numerical modeling that demonstrates the effectiveness of control.
Active exploration of the space leads to growth a near-Earth space pollution. The frequency of the registered collisions of space debris with functional satellites highly increased last ten years. As a rule a large space debris can be observed from the Earth and catalogued, then it is possible to avoid collision with the active spacecraft. However every large debris is a potential source of a numerous small debris particles. To reduce debris population in the near Earth space the large debris should be removed from working orbits. The active debris removal technique is considered that intend to use a tethered orbital transfer vehicle, or a space tug attached by a tether to the space debris. This paper focuses on the dynamics of the space debris with flexible appendages. Mathematical model of the system is derived using the Lagrange formalism. Several numerical examples are presented to illustrate the mutual influence of the oscillations of flexible appendages and the oscillations of a tether. It is shown that flexible appendages can have a significant influence on the attitude motion of the space debris and to the safety of the transportation process.
At present, thousands of space debris are located in Earth’s orbits. It has a different size ranging from a few millimeters to tens of meters. Tethered systems are promising technology to de-orbit the space debris. The tethers have been proposed for reduction of space debris either through momentum transfer or use of electrodynamic effects. Another possible way to remove the large space debris from the critical areas of near-Earth orbit is using a tethered space tug attached to the space debris. Large space debris can strongly affect the motion of the space tug and the tether during the transportation process, which can lead to the loss of control of the tethered system. The problem of removal a large space debris from the orbit to the Earth’s surface is studied. The space transportation system is composed of two bodies connected by the tether. The first body is a space debris (upper rocket stage or a large nonfunctional satellite) and the second body is a space tug. The spatial motion of the system is studied in the gravity field of the Earth under the action of the space tug thruster, aerodynamic drag and the gravitational torque. Osculating elements of the orbit are used to describe the motion of the center of mass of the system. Particular attention is given to investigate the spatial motion of the space debris relative to the tether and to the space tug. The influence of the initial conditions and the properties of the system on the motion of the system is studied.
A spatial motion of a large passive satellite (space debris) and a space tug connected by an elastic tether is considered. The motion of the system is excited by a thrust force acting on the space tug. Major attention is given to a derivation of the equations of the motion based on the Lagrange formalism. Correctness of the mathematical model is proved by the theorem on variation of angular momentum and by the numerical simulations. The influence of the initial conditions and the system parameters on the behavior of the passive satellite is studied. The possibility of critical modes of the system motion leading to entanglement of the tether is shown by means of the numerical simulations.
We study the motion of the free dual-spin gyrostat spacecraft that consists of the platform with a triaxial ellipsoid of inertia and the rotor with a small asymmetry with respect to the axis of rotation. The system with perturbations caused by a small asymmetry of the rotor and the time-varying moments of inertia of the rotor is considered. The dimensionless equations of the system are written in Serret-Andoyer canonical variables. The system
The motion of spacecraft as a rigid body connected to a space tow with a viscoelastic tether in the cen- tral gravitational field is discussed in the paper. The equations of spacecraft spatial motion and the orbital motion of the system’s center of mass in osculating elements are obtained on the basis of Lagrange formalism. The in- fluence of the system’s parameters and the initial conditions of motion on the motion of the spacecraft is ana- lyzed. The possibility of critical modes of motion leading to the entanglement of the tether is shown.
В работе рассмотрена задача оценки влияния эффекта температурных деформаций больших упругих элементов космической лаборатории на модуль микроускорений, возникающих в ее внутренней среде. Проведена оценка для панели солнечной батареи на основе ее конечноэлементной модели. Показана актуальность оценки влияния для космических аппаратов, на борту которых планируется проводить гравитационно-чувствительные технологические процессы.
Multibody systems with changing structure are considered. These systems have stages in their motion that distinct from each other by degree of freedom (DOF), joint connection structure and joint types. These mechanical systems are common in space application e.g. separation subsystems. Single coordinate set is used to formulate Newton