Astrodynamics最新文献

The limited space around the Earth is getting cluttered with leftover fragments from old missions, creating a real challenge. As more satellites are launched, even debris pieces as small as 5 mm must be tracked to avoid collisions. However, it is an arduous and challenging task in space. This paper presents a technical exploration of ground-based and in-orbit space debris tracking and orbit determination methods. It highlights the challenges faced during on-ground and in-orbit demonstrations, identifies current gaps, and proposes solutions following technological advancements, such as low-power pose estimation methods. Owing to the numerous atmospheric barriers to ground-based sensors, this study emphasizes the significance of spaceborne sensors for precise orbit determination, complemented by advanced data processing algorithms and collaborative efforts. The ultimate goal is to create a comprehensive catalog of resident space objects (RSO) around the Earth and promote space environment sustainability. By exploring different methods and finding innovative solutions, this study contributes to the protection of space for future exploration and the creation of a more transparent and precise map of orbital objects.

The tradeoff between accuracy and efficiency in gravitational field modeling for binary asteroid landing is one of the challenges in dynamical analyses. Four representative gravitational modeling methods are employed and compared in this study. These are the sphere–sphere model, ellipsoid–sphere model, inertia integral-polyhedron method, and finite element method. This study considers the differences between these four models, particularly their effects on the landing dynamics of a lander. A framework to simulate the coupled orbit–attitude motion of a lander in a binary system is first established. Numerical simulations are then performed on the natural landings on the second primary of the (66391) Moshup–Squannit system. The results show significant differences in the final landing dispersions, settling time, and sliding distance when applying the simplified models. On the basis of the modeling accuracy and computational efficiency, the finite element method should be chosen for future missions.

This study examines the impact of electric solar wind sail (E-sail) parameters on the attitude stability of E-sail’s central spacecraft by using a comprehensive rigid-flexible coupling dynamic model. In this model, the nodal position finite element method is used to model the elastic deformation of the tethers through interconnected two-node tensile elements. The attitude dynamics of the central spacecraft is described using a natural coordinate formulation. The rigid-flexible coupling between the central spacecraft and its flexible tethers is established using Lagrange multipliers. Our research reveals the significant influences of parameters such as tether numbers, tether’s electric potential, and solar wind velocity on attitude stability. Specifically, solar wind fluctuations and the distribution of electric potential on the main tethers considerably affect the attitude stability of the spacecraft. For consistent management, the angular velocities of the spacecraft must remain at target values. Moreover, the attitude stability of a spacecraft has a pronounced dependence on the geometrical configuration of the E-sail, with axisymmetric E-sails proving to be more stable.

The solar sail is one of the most promising space exploration systems due to its theoretically infinite specific impulse achieved through solar radiation pressure (SRP). Recently, researchers have proposed “transformable spacecraft” capable of actively reconfiguring their body configurations using actuatable joints. Transformable spacecraft, if used similarly to solar sails, are expected to significantly enhance orbit and attitude control capabilities owing to their high redundancy in control degrees of freedom. However, controlling them becomes challenging due to their large number of inputs, leading previous researchers to impose strong constraints to limit their potential control capabilities. This study focuses on novel attitude control techniques for transformable spacecraft under SRP. We developed two methods, namely, joint angle optimization to obtain arbitrary SRP force and torque, and momentum damping control driven by joint angle actuation. Our proposed methods are formulated in a general manner and can be applied to any transformable spacecraft comprising front faces that can predominantly receive the SRP on each body. The validity of our proposed method is confirmed through numerical simulations. Our study contributes to making most of the high control redundancy of transformable spacecraft without the need for expendable propellants, thus significantly enhancing the orbit and attitude control capabilities.

In real scenarios, the spacecraft deviates from the intended paths owing to uncertainties in dynamics, navigation, and command actuation. Accurately quantifying these uncertainties is crucial for assessing the observability, collision risks, and mission viability. This issue is further magnified for CubeSats because they have limited control authority and thus require accurate dispersion estimates to avoid rejecting viable trajectories or selecting unviable ones. Trajectory uncertainties arise from random variables (e.g., measurement errors and drag coefficients) and processes (e.g., solar radiation pressure and low-thrust acceleration). Although random variables generally present minimal computational complexity, handling stochastic processes can be challenging because of their noisy dynamics. Nonetheless, accurately modeling these processes is essential, as they significantly influence the uncertain propagation of space trajectories, and an inadequate representation can result in either underestimation or overestimation of the stochastic characteristics associated with a given trajectory. This study addresses the gap in characterizing process uncertainties, represented as Gauss–Markov processes in mission analysis, by presenting models, evaluating derived quantities, and providing results on the impact of spacecraft trajectories. This study emphasizes the importance of accurately modeling random processes to properly characterize stochastic spacecraft paths.

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.