Astrodynamics最新文献

Optimal, many-revolution spacecraft trajectories are challenging to solve. A connection is made for a class of models between optimal direct and indirect solutions. For transfers that minimize thrust-acceleration-squared, primer vector theory maps direct, many-impulsive-maneuver trajectories to the indirect, continuous-thrust-acceleration equivalent. The mapping algorithm is independent of how the direct solution is obtained and requires only a solver for a boundary value problem and its partial derivatives. A Lambert solver is used for the two-body problem in this work. The mapping is simple because the impulsive maneuvers and co-states share the same linear space around an optimal trajectory. For numerical results, the direct coast-impulse solutions are demonstrated to converge to the indirect continuous solutions as the number of impulses and segments increases. The two-body design space is explored with a set of three many-revolution, many-segment examples changing semimajor axis, eccentricity, and inclination. The first two examples involve a small change to either semimajor axis or eccentricity, and the third example is a transfer to geosynchronous orbit. Using a single processor, the optimization runtime is seconds to minutes for revolution counts of 10 to 100, and on the order of one hour for examples with up to 500 revolutions. Any of these thrust-acceleration-squared solutions are good candidates to start a homotopy to a higher-fidelity minimization problem with practical constraints.

Cubic rovers that traverse by hopping systems are promising in low-gravity environments. Although several analyses of the control methods and mobility of the cubic rover are available, investigations of its attitude-adjusting behavior are still limited. This study derives the dynamic equations of the two attitude-adjusting modes of the cubic rover, referred to as walking and twisting. The relationships between the speed threshold and rotation angle of the cubic rover were investigated in both rigid and regolith environments using a self-designed low-gravity testbed. Comparative studies were conducted by considering the experimental and simulated outputs. The results of this study can be interesting for roving mission planning when exploring planetary moons and small celestial bodies.

Orbits that are frozen in an averaged model, including the effect of a disturbing body laying on the equatorial plane of the primary body and the influence of the oblateness of the primary body, have been applied to probes orbiting the Moon. In this scenario, the main disturbing body is represented by the Earth, which is characterized by a certain obliquity with respect to the equatorial plane of the Moon. As a consequence of this, and of the perturbing effects that are not included in the averaged model, such solutions are not perfectly frozen. However, the orbit eccentricity, inclination, and argument of pericenter present limited variations and can be set to guarantee the fulfillment of requirements useful for lunar telecommunication missions and navigation services. Taking advantage of this, a practical case of a Moon-based mission was investigated to propose useful solutions for potential near-future applications.

Large-scale space membrane antennas have significant potential in satellite communication, space-based early warning, and Earth observation. Because of their large size and high flexibility, the dynamic analysis and control of membrane antenna are challenging. To maintain the working performance of the antenna, the pointing and surface accuracies must be strictly maintained. Therefore, the accurate dynamic modeling and effective active control of large-scale space membrane antennas have great theoretical significance and practical value, and have attracted considerable interest in recent years. This paper reviews the dynamics and active control of large-scale space membrane antennas. First, the development and status of large-scale space membrane antennas are summarized. Subsequently, the key problems in the dynamics and active control of large membrane antennas, including the dynamics of wrinkled membranes, large-amplitude nonlinear vibration, nonlinear model reduction, rigid-flexible-thermal coupling dynamic modeling, on-orbit modal parameter identification, active vibration control, and wave-based vibration control, are discussed in detail. Finally, the research outlook and future trends are presented.

A novel high-order target phase approach (TPhA) for the station-keeping of periodic orbits is proposed in this work. The key elements of the TPhA method, the phase-angle Poincare map and high-order maneuver map, are constructed using differential algebra (DA) techniques to determine station-keeping epochs and calculate correction maneuvers. A stochastic optimization framework tailored for the TPhA-based station-keeping process is leveraged to search for fuel-optimal and error-robust TPhA parameters. Quasi-satellite orbits (QSOs) around Phobos are investigated to demonstrate the efficacy of TPhA in mutli-fidelity dynamical models. Monte Carlo simulations demonstrated that the baseline QSO of JAXA’s Martian Moons eXploration (MMX) mission could be maintained with a monthly maneuver budget of approximately 1 m/s.

This paper proposes new quasi-periodic orbits around Earth–Moon collinear libration points using solar sails. By including the time-varying sail orientation in the linearized equations of motion for the circular restricted three-body problem (CR3BP), four types of quasi-periodic orbits (two types around L1 and two types around L2) were formulated. Among them, one type of orbit around L2 realizes a considerably small geometry variation while ensuring visibility from the Earth if (and only if) the sail acceleration due to solar radiation pressure is approximately of a certain magnitude, which is much smaller than that assumed in several previous studies. This means that only small solar sails can remain in the vicinity of L2 for a long time without propellant consumption. The orbits designed in the linearized CR3BP can be translated into nonlinear CR3BP and high-fidelity ephemeris models without losing geometrical characteristics. In this study, new quasi-periodic orbits are formulated, and their characteristics are discussed. Furthermore, their extendibility to higher-fidelity dynamic models was verified using numerical examples.

The current methods for designing periodic orbits in the elliptic restricted three-body problem (ERTBP) have the disadvantages of targeting limited orbits and ergodic searches and considering only symmetric orbits. A universal method for designing periodic orbits is proposed in this paper. First, the homotopy classes of orbits are structured based on their topological structures. Second, a dynamic model based on homotopy classes, ranging from the circular restricted three-body problem (CRTBP) to the ERTBP, can be built using the homotopy method. Third, a multi- and a single-period orbit were selected based on the resonance ratios. Finally, the corresponding orbit in the ERTBP was computed by modifying the initial condition of the orbit in the CRTBP. This method, without an ergodic search, can extend to any orbit, including an asymmetric orbit in the CRTBP, to the ERTBP model, and the two orbits are of the same homotopy class. Examples of the Earth–Moon ERTBP are presented to verify the efficiency of this method.

This paper answers how multiple satellites are seen from the ground. This question is inspired by space-advertising, a public exhibition in the night sky using a dot matrix of satellites that are bright enough to be seen by the naked eye. Thus, it is important for space advertisement that the specific dot matrix is seen. Moreover, the stability of the dot matrix during a visible span is very valuable. To stabilize the dot matrix, this study formulates an apparent position of a dot from a representative dot seen from the ground. The formulation, linear functions of a set of relative orbital elements, reveals the appearance of the dot matrix. The proposed relative variable in the formulation drives the instability of the dot matrix, thereby revealing an initial stable configuration of deputies from a chief. The arbitrary dot matrix designed using the configuration is stable even at low elevations without orbital control during the visible span.

The primary technique used for air traffic surveillance is radar. However, nowadays, its role in surveillance is gradually being replaced by the recently adopted Automatic Dependent Surveillance-Broadcast (ADS-B). ADS-B offers a higher accuracy, lower power consumption, and longer range than radar, thus providing more safety to aircraft. The coverage of terrestrial radar and ADS-B is confined to continental parts of the globe, leaving oceans and poles uncovered by real-time surveillance measures. This study presents an optimized Low-Earth Orbit (LEO)-based ADS-B constellation for global air traffic surveillance over intercontinental trans-oceanic flight routes. The optimization algorithm is based on performance evaluation parameters, i.e., coverage time, satellite availability, and orbit stability (precession and perigee rotation), and communication analysis. The results indicate that the constellation provides ample coverage in the simulated global oceanic regions. The constellation is a feasible and cost-effective solution for global air supervision, which can supplement terrestrial ADS-B and radar systems.

This study proposes a parametric formation control method for the cooperative observation of the China Space Station (CSS) using multiple nanosatellites. First, a simplified geometrical model of the CSS is constructed using fundamental solids, such as the capsule body and cuboid. Second, the spacecraft formation configuration for the observation mission is characterized by a three-dimensional (3D) Lissajous curve using related design parameters under the full-coverage observation requirements of specific parts, such as the CSS connecting section and collision avoidance constraints. Third, a double-layer control law is designed for each nanosatellite, in which the upper layer is a distributed observer for recognizing the target formation configuration parameters, and the lower layer is a trajectory-tracking controller to make the nanosatellite converge to its temporary target position calculated from the upper layer’s outputs. The closed-loop control stability is proven under the condition that the communication network topology of the nanosatellite cluster contains a directed spanning tree. Finally, the control method is verified by numerical simulation, where the CSS connecting section is selected as the observation target, and ten small nanosatellites are assumed to perform the cooperative observation mission. The simulation results demonstrate that the double-layer control law is robust to single-point communication failures and suitable for the accompanying missions of large space objects with multiple nanosatellites.