S p Gong

Beihang University (BUAA) | BUAA · school of astronautics

This paper presents an efficient indirect optimization method for the time- and fuel-optimal low-thrust many-revolution transfers with averaged dynamics. Compared with the previous indirect method, the proposed method involves a new set of variables and several near-optimal control laws to formulate the two-point boundary value problem based on thr...

Real-time guidance is critical for the vertical recovery of rockets. However, traditional sequential convex optimization algorithms suffer from shortcomings in terms of their poor real-time performance. This work focuses on applying the deep learning-based closed-loop guidance algorithm and error propagation analysis for powered landing, thereby si...

This paper proposed a new attitude determination method for low-orbit spacecraft. The attitude prediction accuracy is greatly improved by adding the unmodeled environmental torque to the dynamic equation. Specifically, the environmental torque extraction algorithm based on extended Kalman filter and series extended state observer is introduced, and...

The terminal guidance problem considering nonlinearity, optimality, and impact angle constraints is investigated. Firstly, the conditions for optimal guidance in the longitudinal plane are derived based on the Pontryagin's maximum principle, and then the to-be-solved two-point boundary value problem is equivalent to a backward integration problem....

Space vehicles’ real-time trajectory optimization is the key to future automatic guidance. Still, the current sequential convex programming (SCP) method suffers from a low convergence rate and poor real-time performance when dealing with complex obstacle avoidance constraints (OACs). Given the above challenges, this work combines homotopy and neura...

Traditional planetocentric low-thrust solutions mainly focus on orbital rephasing or transfer maneuvers, while the rendezvous maneuver is more challenging to obtain and cannot be approximated by existing solutions in some mission scenarios. In this paper, approximate solutions to the time-optimal rendezvous problem between two close circular orbits...

In the levitation and landing phases of unmanned aerial vehicles, the complicated interactions between drones and environment are difficult to be modeled, and the fast-changing motion status also makes the precise control challenging. In this paper, the dynamics of drones are first modeled and simplified. Then, an adaptive controller and deep neura...

This paper investigates the problem of magnetic sail-based spacecraft formation control around the artificial equilibrium points (AEPs), which can eliminate the requirement of the propellant. The thrusts are achieved by utilizing the interaction between the solar wind and the artificial magnetosphere generated by superconducting current coil onboar...

Internal torques generated from shape reconfiguration can be helpful in Micro-Satellite attitude control. The configuration-attitude-coupled non-holonomic dynamics of a multi-body spacecraft is investigated. A shape-based motion trajectory in the form of water drop curve is proposed to synchronously reach target attitude and target shape configurat...

This paper studies the feasibility of using the magneto plasma sail (MPS) as an exotic propellantless propulsion system for spacecraft formation reconfiguration around a heliocentric elliptic displaced orbit (HEDO). We assume that each spacecraft is equipped with superconducting current-carrying coil and predict the obtained thrust obtained due to...

The research on highly inclined mean motion resonances (MMRs), even retrograde resonances, has drawn more attention in recent years. However, the dynamics of polar resonance with inclination i≈90∘ have received much less attention. This paper systematically studies the dynamics of polar resonance and their effects on the Kozai–Lidov mechanism in th...

With the deepening of planetary exploration, rapid decision making and descent trajectory planning capabilities are needed to cope with uncertain environmental disturbances and possible faults during planetary landings. In this article, a novel decoupling method is adopted, and the analytical three-dimensional constraint equations are derived and s...

The real-time guidance algorithm is the key technology of the powered landing. Given the lack of real-time performance of the convex optimization algorithm with free final time, a lossless convex optimization (LCvx) algorithm based on the deep neural network (DNN) predictor is proposed. Firstly, the DNN predictor is built to map the optimal final t...

Traveling to outer space has long fascinated humanity, but the astronomical distances restrain us within our solar system. Laser-driven spacecraft is a promising candidate for interstellar explorations. The idea is to accelerate a sail to relativistic speeds using a laser beam aimed at the sail. Stable beam-riding is a passive mechanism that requir...

The difficulty of obtaining accurate dynamical models of hypersonic flight has been generally recognized, and modeling inaccuracy can severely deteriorate the performance of the flight control systems. To address this issue, an adaptive control approach using two neural networks (NNs) is proposed with the aim of achieving precise and robust control...

In this article, a successive convexification algorithm is presented for real-time ascent trajectory replanning of a multistage launch vehicle experiencing nonfatal dynamic faults, including the faults of thrust, mass flow, and states. This problem presents a challenge for onboard real-time guidance applications due to its nonconvex constraints, su...

Satellite-on-a-printed circuit board (PCBSat) is a kind of femto-satellite that integrates all the electronic devices onto a PCB. Constrained by the energy/volume capacity, traditional attitude actuators no longer suit the PCBSat. In the paper, employing the flexible PCB material and micro-steppers, a new design that enables the PCBSat to fold and...

Active attitude control of solar sails is required to control the direction of the force generated by Solar Radiation Pressure (SRP). It is desirable to control the attitude through propellant-free means. This paper proposes a new method for attitude control of solar sails: A boom consisting of “smart” structural material can be deformed by the pie...

In the history of solar sail research, numerous methods have been proposed to control the spacecraft attitude. Different in detailed operations, almost all of them rely on solar radiation pressure torques generated by manipulating the offset between the center of mass and the center of pressure. In this paper, a solar sail attitude control method t...

Traditionally, numerical trajectory integration for shooting equation calculation and iterations for shooting with randomly guessed initial solutions deteriorate the real-time performance of indirect methods for on-board applications. In this study, the indirect method is improved to achieve real-time trajectory optimization of fuel-optimal powered...

Solar sails with the capability of generating a tangential radiation pressure at the sun-pointing attitude, such as refractive sails can provide more efficient methods for attitude and orbital control of sailcraft. This paper presents the concept of gradient-index sail as an advanced class of refractive sail, which operates by guiding the solar rad...

Actively controlling the attitude of the solar sail is necessary to adjust the solar radiation pressure force for trajectory transfer and orbit control. The special configuration of the solar sail makes it very important to develop a unique attitude control strategy that differs from traditional methods. An attitude control method, based on shape v...

This paper focuses on the feasibility criterion of fuel-optimal powered landing problems. Due to the uncertainties during landing on the surface of the planet, the initial states of the powered descent and landing phase may be placed in an infeasible region. Clarifying the feasibility criterion of the fuel-optimal problem is critical to ensure the...

Precise soft rocket recovery landings require precise guidance, navigation, and control. A convex optimization guidance algorithm was developed for soft vertical rocket recovery landings and tested in a closed-loop simulation system. A lossless convex model was combined with successive convex iterations to transform the rocket recovery stage guidan...

Many asteroids move in the belt between the orbits of Mars and Jupiter under the gravitational attraction of the Sun and planets in the Solar system. If one of these asteroids does not leave the belt during a period, it is considered to be temporarily stable on that time-scale. This paper aims to study the time-scales on which asteroids could stay...

Mean motion resonances (MMRs) are widespread in our Solar System. Moreover, resonant dynamics has always been an essential topic in planetary research. Recently, the research about exoplanets and the potential Planet Nine with large eccentricity has given rise to our interests in the secular dynamics inside MMRs in the elliptic model. In this paper...

With the discovery of more and more retrograde minor bodies, retrograde orbits’ production mechanism has attracted much attention. However, almost all of the current research on the flip mechanism is based on the hierarchical approximation. In this paper, we study the flip mechanism of Jupiter-crossing orbits in a non-hierarchical Sun-Jupiter tripl...

This paper introduces a new type of diffractive solar sail composed of liquid crystal optical phased arrays, which control the thrust through electric modulation. The main feature of the proposed liquid crystal diffractive sail is its capability of generating a continuously variable and actively controllable tangential radiation pressure at the sun...

The real-time and fuel-optimal powered descent guidance is one of the critical technologies for planetary landing. This work focuses on the powered descent guidance algorithm based on pseudospectral convex optimization and aims to increase the accuracy and adaptability of the algorithm. The entire powered descent process is divided into phases acco...

In this paper, we investigate the dynamics of the exterior retrograde \(1/n\) resonances within the framework of the planar circular restricted three-body problem (PCRTBP), taking the \(1/{-2}\) and \(1/{-3}\) resonances as examples. We prove that there is no asymmetric libration in retrograde \(1/n\) resonances using analytical, numerical integrat...

We consider the coplanar planetary four-body problem, where three planets orbit a large star without the cross of their orbits. The system is stable if there is no exchange or cross of orbits. Starting from the Sundman inequality, the equation of the kinematical boundaries is derived. We discuss a reasonable situation, where two planets with known...

reflectivity control devices. The overactuated design that is proposed for the solar sail resulted in a mixed-integercontinuous and nonlinear optimization for control allocation. Trying to solve this complex problem by common numerical and analytical approaches, either the desired torque has been found at the expense of a long and noneligible lengt...

We investigate the Pursuit-Evasion Differential Game (PE Game) for satellites with continuous thrust from the viewpoint of reachable domain (RD). A concept of hyperreachable domain(HRD) is introduced to help analyze the problem, and a sufficient condition for capture in a PE game is proposed based on the players' HRD. Meanwhile, to practically use...

Environmental degradation has already reached space not because of the nature but through human space programs. Low earth orbit is suffering from increasing number of debris. In fact, there is a vast range of causes capable of imposing failure to the control systems of the spacecrafts other than collision, degradation and lack of fuel. Therefore, i...

The \(c^{2}E\) condition, for determining the Hill stability of a coplanar four-body system, is analyzed for the particular situation where the mass of a body is much greater than the other three. In this case, the criterion can be expressed in a closed form, which makes it easier to judge the stability of a system or predict the stable regions des...

We find an interesting fact that fictitious retrograde co-orbitals of Saturn, or small bodies inside the retrograde 1:1 resonance with Saturn, are highly unstable in our numerical simulations. It is shown that, in the presence of Jupiter, the retrograde co-orbitals will get ejected from Saturn’s co-orbital space within a time-scale of 10 Myr. This...

Aims. Asteroids in mean motion resonances (MMRs) with planets are common in the solar system. In recent years, increasingly more retrograde asteroids are discovered, several of which are identified to be in resonances with planets. We here systematically present the retrograde resonant configurations where all the asteroids are trapped with any of...

This paper presents a novel methodology for solving the time-optimal trajectory optimization problem for interplanetary solar-sail missions using successive convex programming. Based on the non-convex problem, different convexification technologies, such as change of variables, successive linearization, trust regions and virtual control, are discus...

Solar sails with the capability of generating a tangential radiation pressure at the sun-pointing attitude, such as refractive sails can provide more efficient methods for attitude and orbital control of sailcraft. This paper presents the concept of gradient-index sail as an advanced class of refractive sail, which operates by guiding the solar rad...

In the preliminary trajectory design of the multi-target rendezvous problem, a model that can quickly estimate the cost of the orbital transfer is essential. The estimation of the transfer time using solar sail between two arbitrary orbits is difficult and usually necessary to solve an optimal control problem. Inspired by the successful application...

Planetary research on the Near-Earth objects (NEOs) has always been a relevant and meaningful topic. Investigating the dynamical behaviour and physical properties of NEOs is significant for understanding the evolution and origin of the solar system. On the other hand, the study of some of these NEOs is crucial for Earth inhabitants because they exp...

In this work a method for generating a long-range optical pulling force is presented which is realized by utilizing a vortex beam and a device designed based on transformation optics through conformal mapping. The device works by transforming an input perfect vortex beam into an almost paraxial plane wave, and generates a pulling force by maximizin...

This paper reviews solar sail trajectory design and dynamics, attitude control, and structural dynamics. Within the area of orbital dynamics, methods relevant to transfer trajectory design and non-Keplerian orbit generation are discussed. Within the area of attitude control, different control strategies, including utilisation of solar radiation pre...

Transformation optics based on conformal mapping (CM) technique provides a practical approach to designing arbitrary-shaped all-dielectric devices. However, CM may result in large impractical refractive indices unachievable by current fabrication techniques. Furthermore, due to the low design flexibility of CM, the index-matching conditions at the...

We find an interesting fact that fictitious retrograde co-orbital bodies of Saturn, which we call Retrojans throughout this work, are highly unstable in our numerical simulations. It is shown that in the presence of Jupiter, these Retrojans will get ejected from Saturn's co-orbital space within a timescale of 1 Myr. This scenario reminds us of the...

A novel approach is proposed to fast estimate the gravitational field of the irregular asteroid by the DNN, and its application in the study of asteroid landing problem is investigated in this work. The traditional method of describing the gravitational field of irregular asteroids has obvious shortcomings in computational efficiency. For a fast es...

In this work a method for generating a long-range optical pulling force is presented which is realized by utilizing a vortex beam and a device designed based on transformation optics through conformal mapping. The device works by transforming an input perfect vortex beam into an almost non-paraxial plane wave, and generates a pulling force by maxim...

This paper presents a novel methodology for solving the time-optimal trajectory optimization problem for interplanetary solar-sail missions using successive convex programming. Based on the non-convex problem, different convexification technologies, such as change of variables, successive linearization, trust regions and virtual control, are discus...

In this work a method for generating a long-range optical pulling force is presented which is realized by utilizing a vortex beam and a device designed based on transformation optics through conformal mapping. The device works by transforming an input perfect vortex beam into an almost non-paraxial plane wave, and generates a pulling force by maxim...

An interplanetary trajectory optimization of the multi-asteroid rendezvous is investigated for a solar sail-based spacecraft. The optimal control problem is formulated using the calculus of variations and Pontryagin's maximum principle and the first order necessary condition for optimality of the problem is derived. To achieve the optimal solution,...

As the discoveries of more minor bodies in retrograde resonances with giant planets, such as 2015 BZ509 and 2006 RJ2, our curiosity about the Kozai-Lidov dynamics inside the retrograde resonance has been sparked. In this study, we focus on the 3D retrograde resonance problem and investigate how the resonant dynamics of a minor body impacts on its o...

Launching solar sails to low Earth orbit can provide cheap and frequent opportunities for test missions, orbit raising from low Earth orbit, or deorbiting space debris. This Paper considers the problem of attitude dynamics and control of a flexible solar sail under solar radiation pressure, aerodynamic forces, and gravity gradient torque. A geometr...

Aims . The asteroid 2015 BZ509 is the first asteroid confirmed to be in retrograde co-orbit resonance (or 1/−1 resonance) with the giant planets in the solar system. While Saturn is the only giant planet whose trojans have not yet been discovered, we identify some small bodies among centaurs and damocloids that are potentially in 1/−1 resonance wit...

We consider an elliptic restricted four-body system including three primaries and a massless particle. The orbits of the primaries are elliptic, and the massless particle moves under the mutual gravitational attraction. From the dynamic equations, a quasi-integral is obtained, which is similar to the Jacobi integral in the circular restricted three...

Aims. 2015 BZ509 is the first asteroid confirmed to be in retrograde co-orbit resonance (or 1/-1 resonance) with the giant planets in the solar system. While Saturn is the only giant planet whose Trojans are not discovered until now, we identify some small bodies among Centaurs and Damocloids that are potentially in 1/-1 resonance with Saturn in th...

Asteroids in mean motion resonances with giant planets are common in the solar system, but it was not until recently that several asteroids in retrograde mean motion resonances with Jupiter and Saturn were discovered. A retrograde co-orbital asteroid of Jupiter, 2015 BZ509 is confirmed to be in a long-term stable retrograde 1:1 mean motion resonanc...

Asteroids in mean motion resonances with giant planets are common in the solar system, but it was not until recently that several asteroids in retrograde mean motion resonances with Jupiter and Saturn were discovered. A retrograde co-orbital asteroid of Jupiter, 2015 BZ509 is confirmed to be in a long-term stable retrograde 1:1 mean motion resonanc...

We consider a coplanar four-body system including a binary subsystem. The Hill stability is studied using the zero velocity surface of the four-body problem. The value of c²E determines the topology of zero-velocity surfaces and hence regions of possible motions that bifurcates at the collinear equilibrium points. The Hill stability of the system i...

We apply a numerical searching method to investigate three-dimensional periodic orbits of charged dust particles in planetary magnetospheres. A classic generalized Stormer model of magnetic planets along with the parameters of Saturn is employed. More periodic orbits are found, besides the already known circular periodic orbits in or parallel to th...

We investigate the dynamics of a pair of massive secondaries pushed towards mean-motion resonance by centripetal migration due to interactions with a planetesimal disc surrounding a common primary. An analytical model of planetary systems evolving towards orbital resonance is developed to the second order in eccentricities, allowing for an assessme...

The Hill stability of the nine known triple asteroid systems in the solar system has been investigated in a framework of the three body system. In this paper, the Sun and triple-asteroid system are treated as a four body system to analyze the influence of the Sun on the Hill stability of the triple subsystem. First, the relationship of the total en...

This paper studies the binary disruption problem and asteroid capture mechanism in a sun-planet-binary four-body system. Firstly, the binary disruption condition is studied and the result shows that the binary is always disrupted at the perigee of their orbit instantaneously. Secondly, an analytic expression to describe the energy exchange between...

We consider a coplanar four-body system including a binary subsystem. The Hill stability is studied using the zero velocity surface of the four-body problem. The value of c 2 E determines the topology of zero-velocity surfaces and hence regions of possible motions that bifurcates at the collinear equilibrium points. The Hill stability of the system...

The attitude passive stability design during inclination cranking is developed using a rigid solar sail model. The criterion shows that the solar sail can be stabilized by designing the structure parameters and the spin rate. An oscillation-attitude-orbit dynamical model by hybrid method is employed to quantify the flexibility effect on the passive...

We consider a four body system, where three bodies, constituting a subsystem, orbit around a larger body. This paper is devoted to study the Hill stability of the subsystem using a coplanar four-body problem. Starting from the equation of zero velocity surface for the general coplanar four body problem (Loks and Sergysels, 1985), we derive two crit...

In traditional error analysis for rendezvous remote guidance, both relative position and velocity between chaser spacecraft and target spacecraft are used to describe the error state. The Monte Carlo simulation in this paper shows that this method will amplify the error state, because both relative position and velocity are correlative. So the trad...

Solar sail spacecraft are proposed to accomplish body-fixed hovering missions over elongated asteroids. The body-fixed hovering flight is to maintain a fixed position relative to the surface of the spinning asteroid. A solar sail without fuel consumption can greatly expand the range of hovering locations in a variable lightness number for an extend...

The stability and topological structure of equilibrium points in the potential field of the asteroid 101955 Bennu have been investigated with a variable density and rotation period. A dimensionless quantity is introduced for the non-dimensionalization of the equations of motion, and this quantity can indicate the effect of both the rotation period...

As demonstrated in the Interplanetary Kite-craft Accelerated by Radiation Of the Sun (IKAROS), reflectivity control devices (RCDs) are switched on or off independently with each other, which has nevertheless been ignored by many previous researches. This paper emphasizes the discrete property of RCDs, and aims to obtain an appropriate switch law of...

The attitude and orbit motion of a spinning solar sail containing a huge membrane is discussed. Solar sail is a feasible option to attain high-inclination heliocentric orbit through an inclination cranking maneuver. This paper investigates the strategies of station keeping and slew maneuver during the inclination cranking in the presence of membran...

Due to the time-dependent Jacobi integral in the elliptic restricted three body problem, it is difficult to develop analytical criteria of Hill stability. In this paper, the Hill stability of the orbit around the one primary is concerned. Several analytical criteria are established based on the bifurcation of the extremum of the Jacobi integral. On...

Electrochromic devices have been used for the attitude control of a spinning solar sail in a deep space mission by modulating the reflectivity of the sail membrane. As a flexible spinning solar sail has no rigid structure to support its membrane, the distributed load due to solar radiation will lead to the deformation of the sail membrane, and the...

The dynamics of a fourth body in the sun-planet-satellite system is used to study the planetary capture and escape. An expression to describe the energy exchange between the satellite and the fourth body is derived when the fourth body is in the vicinity of the planet. The analytic result can be obtained when the fourth body is within the sphere of...

This paper focuses on the approach which enables us to capture an asteroid using the lunar flyby. Assume that the asteroid is able to enter the Earth-Moon system. The orbits of the asteroid before and after lunar flybys are investigated for different Jacobi constants in the restricted three body problem. The capture will happen when the post-flyby...

A fuel-optimal interplanetary trajectory design is investigated for a hybrid propulsion system based on solar sailing and solar electric propulsion. The optimal-control problem is formulated using the calculus of variations and Pontryagin's maximum principle. The solution to the corresponding two-point boundary problem is a bang–bang control for th...

The purpose of this paper is to systematically establish in arbitrary timespan a full set of instantaneous ground launch windows for certain accurate three-dimensional asymmetric free return circumlunar trajectories tailored to human lunar missions for China, and in general propose a novel methodology useful for determining ground launch windows fo...

The transfer orbits connecting equilibrium points of irregular-shaped asteroids are studied. A new method is proposed to generate the transfer orbits connecting any two equilibrium points near an arbitrary irregular asteroid. This new method has three steps, including the approximate searching, the first transfer orbit correction and the flight tim...

The use of the electrochromic device has been proposed for the attitude control of spacecraft for decades because its optical characteristics can be altered by electrical excitation. The technology was recently employed and verified successfully on Interplanetary Kite Craft Accelerated by Radiation of the Sun, the world's first interplanetary sailc...

A simple strategy for attitude maneuver of an axisymmetric spinning solar sail is proposed. To achieve a large-angle slew maneuver, the center of mass along the spin axis is adjusted, which means that utilization of the moving mass along the spin axis is possible. The time-optimal problem is formulated using the maximum principle; the solution is a...

The resonant orbits around elongated celestial bodies are investigated by using an unified approximate model, aiming at providing a basic understanding of the resonance effect in the vicinal orbital motion. The unified approximate model is a rotating mass dipole with four independent parameters. The essential of the 1:1 resonant orbits is first pre...

This paper presents a method for designing a lunar orbit insertion (LOI) targeting sequence from a two-segment lunar free-return trajectory. To reduce the fuel consumption for lunar orbit targeting, the algorithm modifies the LOI sequence and simultaneously optimizes the midcourse lunar-targeting maneuver (LTM) time. The circular restricted three-b...

In this paper, the Lorentz force in Jupiter’s magnetic field is used to design the transfer trajectory between Galileo moons’ Lagrange points. The equatorial orbits of charged spacecraft in three-body axis-aligned nontilted-dipole magnetic field model are analyzed and the results show that the libration point L1 and L2 become nearer or further away...

The periodic orbits of a solar sail in the elliptic restricted three-body problem are designed in this paper. The dynamical equation of a solar sail is derived in a non-uniformly rotating and pulsating coordinate frame, where out-of-plane artificial equilibria do not exist. Two families of displaced periodic orbits in the vicinity of the out-of-pla...

Solar sails are well-suited for long-term, multiple-asteroid missions. The dynamics of solar sails near an asteroid have not yet been studied in detail. In this paper, out-of-plane artificial equilibria in a Sun-asteroid rotating frame and hovering points in a body-fixed rotating frame are studied (using a solar sail equipped with reflection contro...

The concept of fast solar sail rendezvous missions to near Earth asteroids is presented by considering the hyperbolic launch excess velocity as a design parameter. After introducing an initial constraint on the hyperbolic excess velocity, a time optimal control framework is derived and solved by using an indirect method. The coplanar circular orbit...

To support China's lunar exploration mission requirements of high-latitude landing and anytime return, i.e., the capability of safely returning the crew exploration vehicle at any time from any lunar parking orbit, an analytical model for determining a transearth trajectory is presented. With a finite sphere of influence model, families of analytic...

The orbit of a spacecraft will be a non-Keplerian orbit if forces other than the two-body Newtonian gravitational force are exerted on the spacecraft. The solar sail orbits are always non-Keplerian orbits if the solar sail is not coasting. Three free variables of the solar sail are required to make the solar sail equilibrate at a three dimensional...

Fast intercept trajectories are proposed to impact dangerous Earth-crossing asteroids by using a solar sail spacecraft for mid to far-term missions. A heliocentric trajectory with single solar photonic assist is considered to transfer the sail kinetic impactor from Earth’s orbit to the collision point with the asteroid. Two options of such trajecto...

The advantage of solar sails in deep space exploration is that no fuel consumption is required. The heliocentric distance is one factor influencing the solar radiation pressure force exerted on solar sails. In addition, the solar radiation pressure force is also related to the solar sail orientation with respect to the sunlight direction. For an id...