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The purpose of this paper is to present the obtained analytic solutions of maximal and minimal inter-satellite distances for flying-around satellite formation.

The relative motion equation is used to express the inter-satellite distance as the function of the orbital elements of two participating satellites for the flying-around satellite formation. Then by taking the derivative of the distance function with respect to the true anomaly, some possible extreme value points are obtained. According to the detailed analysis, the maximal and minimal distance solutions are found. By a reverse process, the expected initial differential orbital elements that generate the required extreme inter-satellite distances are also obtained.

The maximal and minimal distances of the flying-around formation can be analytically written as the functions of three initial orbital elements differences, i.e. the differential orbital inclination, the differential eccentricity and the differential right ascension. For the given maximal and minimal distances, there are lots of solutions of the initial differential orbital elements, which can produce the expected relative motions.

The solutions of the maximal and minimal inter-satellite distances are only accurate for the circular or near circular reference orbit. For the elliptic reference orbit, there is a need to develop new methods to find the analytic solutions.

The results here can be applied to design the factual flying-around formation with dimension requirements in mission analysis stage.

By using the solutions presented in this paper, the engineers can design the expected flying-around formation with required maximal and minimal inter-satellite distances in a very easy way.

The purpose of this paper is to propose an intuitive and effective cluster flight orbit design method for fractionated spacecraft.

Based on the concept of fractionated spacecraft, orbit design requirements for cluster flight in the case of fractionated spacecraft are proposed, and categorized into three requirements: stabilization requirement, passive safety requirement, and the maximum inter‐satellite distance requirement. These design requirements are then reformulated in terms of relative eccentricity and inclination vectors (E/I vectors) using a relative motion model based on relative orbital elements (ROEs). By using ROEs theory, the cluster flight orbit design issue is modelled as the distribution of relative E/I vectors for each member satellite in the cluster, and solved by combining three different heuristic search methods and one nonlinear programming (NLP) method.

The simulation results show that the NLP method is valid and efficient in solving the cluster flight orbit design problem and that for some cluster flight scenarios, the heuristic search methods can be adopted to give feasible solutions without the NLP method.

The cluster flight scenario in this paper is limited because the cluster should be in the near‐circular low earth orbit (LEO), and the relative distance between the member satellites should be small enough to satisfy the relative motion linearization assumption.

The cluster flight orbit design method proposed in this paper can be applied by fractionated spacecraft mission designers to propose potential cluster flight orbit solutions.

In this paper, the relative E/I vectors method is adopted to propose an intuitive and effective cluster flight orbit design method for fractionated spacecraft.

This paper aims to improve the performance of the autonomous optical navigation using relativistic perturbation of starlight, which is a promising technique for future space missions. Through measuring the change in inter-star angle due to the stellar aberration and the gravitational deflection of light with space-based optical instruments, the position and velocity vectors of the spacecraft can be estimated iteratively.

To enhance the navigation performance, an integrated optical navigation (ION) method based on the fusion of both the inter-star angle and the inter-satellite line-of-sight measurements is presented. A Q-learning extended Kalman filter (QLEKF) is designed to optimize the state estimate.

Simulations illustrate that the integrated optical navigation outperforms the existing method using only inter-star angle measurement. Moreover, the QLEKF is superior to the traditional extended Kalman filter in navigation accuracy.

A novel ION method is presented, and an effective QLEKF algorithm is designed for information fusion.

The purpose of this paper is to provide a feasible method to solve the zenith pass problem that can occur when the inter‐satellite linkage antenna of the user satellite is tracing TDRS. The antenna uses the elevation‐over‐azimuth architecture.

The movement laws of the inter‐satellite linkage can be obtained based on the orbit predictions of the user satellite and TDRS. According to the movement laws, the zenith pass moments and blindness zones are found. The trajectory preprocessor is provided to design a command trajectory for driving the axis of the tilting mechanism.

In the worst situation, the blindness zone can appear once every half day. Three special orbit altitude values are obtained. When the user satellite picks one of them as its orbit altitude, the blindness zone may be avoided forever. The zenith pass tracing strategies based on the mechanical tilting method have been designed.

This method obtains the stable tracking during the zenith pass course by changing the hardware structure of the antenna. It is too expensive and can influence the pointing precision of the antenna.

The research can help the engineers analyze and solve the zenith pass problem of the antenna.

This paper studies the zenith pass problem that can occur when the inter‐satellite linkage antenna of the user satellite is tracing TDRS and provides a solving method.

This paper aims to present an innovative system able to establish an inter-satellite communication crosslink and to determine the mutual physical positioning for CubeSats belonging to a swarm.

Through a system involving a smart antenna array managed by a beamforming control strategy, every CubeSat of the swarm can measure the direction of arrival (DOA) and the distance (range) to estimate the physical position of the received signal. Moreover, during the transmission phase, the smart antenna shapes the beam to establish a reliable and directive communication link with the other spacecraft and/or with the ground station. Furthermore, the authors introduce a deployable structure fully developed at Politecnico di Torino that is able to increase the external surface of CubeSats: this surface allows to gain the interspace between elements of the smart antenna.

As a consequence, the communication crosslink, the directivity and the detection performance of the DOA system in terms of directivity and accuracy are improved.

Moreover, the deployable structure offers a greater usable surface, so a larger number of solar panels can be used. This guarantees up to 25 W of average power supply for the on-board systems and for transmission on a one-unit (1U) CubeSat (10 × 10 × 10 cm).

This paper describes the physical implementation of the antenna array system on a 1U CubeSat by using the deployable structure developed. Depending on actuators and ability that every CubeSat disposes, various interaction levels between elements can be achieved, thus making the CubeSat constellation an efficient and valid solution for space missions.

The purpose of this paper is to present a novel high-precision relative navigation method for tight formation-keeping based on thrust on-line identification.

Considering that thrust acceleration cannot be measured directly, an on-line identification method of thrust acceleration is explored via the estimated acceleration of major space perturbation and the inter-satellite relative states obtained from space-borne acceleration sensors; then, an effective identification model is designed to reconstruct thrust acceleration. Based on the identified thrust acceleration, relative orbit dynamics for tight formation-keeping is established. Further, using global positioning system (GPS) measurement information, a modified extended Kalman filter (EKF) is suggested to obtain the inter-satellite relative position and relative velocity.

Compared with the normal EKF and the adaptive robust EKF, the proposed modified EKF has better estimation accuracy in radial and along-track directions because of accurate compensation of thrust acceleration. Meanwhile, high-precision relative navigation results depend on high-precision acceleration sensors. Finally, simulation studies on a chief-deputy formation flying control system are performed to verify the effectiveness and superiority of the proposed relative navigation algorithm.

This paper provides a reference in solving the problem of high-precision relative navigation in tight formation-keeping application.

This paper proposes a novel on-line identification method for thrust acceleration and shows that thrust identification-based modified EKF is more efficient in relative navigation for tight formation-keeping.

This study aims to establish the laser links between satellites among large-scale distributed satellite systems; a combined attitude control strategy containing two stages is proposed in this paper.

These two stages are: one is the attitude initial pointing control to change the attitude of satellite pointing to the other satellite based on the position information of each satellite; the other one is the high precision attitude tracking control to scan the uncertainty cone because the initial pointing control accuracy is not enough to establish the laser link. At the initial pointing control stage, a method to determine the target attitude of each satellite is presented based on the position information of each satellite, and the fuzzy adaptive control algorithm is used to control the satellites to its calculated attitude. Then, at the high precision attitude tracking control stage, a strategy for laser link acquisition and scanning the uncertainty cone by the lasers of the spacecraft is proposed, and an angular velocity tracking scanning controller is designed while the convergence of the attitude tracking error is ensured through Lyapunov–Krasovskii theory.

Simulations are conducted to verify the effectiveness of the proposed control algorithm, and the laser link for a large-scale distributed satellite system with super long distance is achieved through a combined attitude control strategy.

A combined attitude control strategy is valid for a large-scale distributed satellite system with super long distance.

A combined attitude control strategy can be used to achieve laser link acquisition for a large-scale distributed satellite system like space gravitational wave detection.

A combined attitude control strategy can provide a way to solve the typical problem that pointing control accuracy is not enough to establish the laser link for a large-scale distributed satellite system.

Addresses the current state of the art of wireless technologies and infrastructures, projects where the field will be in the next decade, and discusses some of the challenges that must be met. Elaborates on the established major areas of commercial wireless access technology in the USA, ranked by deployment extent, which are: terrestrial mobile wireless access; terrestrial broadband wireless access; and mobile satellite service.

The purpose of this study is to develop new tandem configurations of erbium-doped fiber amplifier (EDFA) using all possible pump-signal-direction schemes in simulation to identify a system configuration with the best performance in the means of the highest gain with the lowest noise figure (NF) output.

The spatial evolution of the physical properties such as gain, NF, population density and amplified spontaneous emission along the total length of the double-stage single-pass EDFA and single-stage double-pass EDFA configurations under all possible pumping direction schemes was investigated. Giles and Desurvire method was used for the mathematical modeling of these configurations where the two level coupled system model equations was solved in MATLAB. In the simulation of the all proposed configurations, an input signal of −35 dBm at the wavelength of 1550 nm and a total of 14 mW pump power at the wavelength of 1480 nm was used for a consistent analysis.

The numerical value of the results obtained is specific to the input parameter values used in the simulations; however, configuration-wise, the EDFA systems found with the best performance are not parameter specific.

The results of this numerical work will help future experimental research of designing and developing ultra-efficient EDFA systems.

During the service period of communication satellite systems, their performance is often degraded due to the depletion mechanism. In this paper, the grey system theory is applied to the multi-state system effectiveness evaluation and the grey Lz-transformation ADC (availability, dependability and capability) effectiveness evaluation model is constructed to address the characteristics of the communication satellite system such as different constituent subsystems, numerous states and the inaccuracy and insufficiency of data.

The model is based on the ADC effectiveness evaluation method, combined with the Lz transformation and uses the definite weighted function of the three-parameter interval grey number as a bridge to incorporate the possibility of system performance being greater than the task demand into the effectiveness solution algorithm. At the same time, using MATLAB (Matrix laboratory) to solve each state probability, the same performance level in the Lz transform is combined. Then, the system effectiveness is obtained by Python.

The results show that the G-Lz-ADC model constructed in this paper can accurately evaluate the effectiveness of static/dynamic systems and certain/uncertain system and also has better applicability in evaluating the effectiveness of the multi-state complex system.

The G-Lz-ADC effectiveness evaluation model constructed in this paper can effectively reduce the complexity of traditional effectiveness evaluation models by combining the same performance levels in the Lz-transform and solving the effectiveness of the system with the help of computer programming, providing a new method for the effectiveness evaluation of the complex MSS. At the same time, the weaknesses of the system can be identified, providing a theoretical basis for improving the system’s effectiveness.

The possibility solution method based on the definite weighted function comparing the two three-parameter interval grey numbers is constructed, which compensates for the traditional calculation of the probability based on numerical values and subjective preferences of decision-makers. Meanwhile, the effectiveness evaluation model integrates the basic theories of three-parameter interval grey number and its definite weighted function, Grey−Markov, grey universal generating function (GUGF), grey multi-state system (GMSS), etc., which is an innovative method to solve the effectiveness of a multi-state instantaneous communication satellite system.