Explore the vast range of titles available.

The Space Advanced Technology demonstration satellite (SATech-01), a mission for low-cost space science and new technology experiments, organized by Chinese Academy of Sciences (CAS), was successfully launched into a Sun-synchronous orbit at an altitude of ∼500 km on July 27, 2022, from the Jiuquan Satellite Launch Centre. Serving as an experimental platform for space science exploration and the demonstration of advanced common technologies in orbit, SATech-01 is equipped with 16 experimental payloads, including the solar upper transition region imager (SUTRI), the lobster eye imager for astronomy (LEIA), the high energy burst searcher (HEBS), and a High Precision Magnetic Field Measurement System based on a CPT Magnetometer (CPT). It also incorporates an imager with freeform optics, an integrated thermal imaging sensor, and a multi-functional integrated imager, etc. This paper provides an overview of SATech-01, including a technical description of the satellite and its scientific payloads, along with their on-orbit performance.

Space debris is growing dramatically with the rapid pace of human exploration of space, which seriously threatens the safety of artificial spacecraft in orbit. Therefore, the active debris removal (ADR) is important. This review aims to review the ADR methods and to advance related research in the future. The current research and development status are clearly demonstrated by mapping knowledge domain and charts. In this paper, the latest research results are classified and summarized in detail from two aspects of space debris capture and removal. The scheme comparison and evaluation of all ADR methods are performed, and the applicable scopes of various methods are summarized. Each ADR method is scored using a cobweb evaluation model based on six indicators. Future development of ADR is discussed to promote further research interest.

Space robots play a significant role in on‐orbit servicing (OOS) missions, such as inspecting, capturing, refueling, and repairing satellites, assembling and maintaining large space infrastructure, and removing orbital debris. Over the past four decades, many space robot engineering applications and technology verifications for OOS have been accomplished. This article comprehensively reviews the advances by representative space robotic programs on space shuttles, outside/inside the International Space Station and the China Space Station, as well as on satellites, and the development trends of space robots are summarized. In addition, the primary key technologies and challenges are explored, including the following: 1) visual perception for noncooperative targets; 2) motion planning and control with a free‐floating base and flexibility; 3) multifunctional end‐effectors; 4) ground teleoperation with long time delays; and 5) high‐fidelity ground verification. Finally, the prospects for space robot future research are presented. This review highlights advances in representative space robotic programs on space shuttles, outside/inside the International Space Station and the China Space Station, and on satellites, and their development trends are summarized. The leading critical technologies and challenges in using space robots are investigated herein. Subsequently, it presents the prospects for future space robot research.

For the complex on-orbit service (OOS) mission planning problem, an improved hybrid variant particle swarm optimization (PSO) method was proposed to improve the fuel utilization efficiency of spacecraft. Firstly, considering the time and fuel constraints, a model for OOS mission planning under the scenario of multiple target spacecrafts is established. The Lambert orbit maneuver method is used and the problem is transformed into a large-scale hybrid nonlinear integer programming problem. Next, an improved hybrid variant PSO algorithm is designed to optimize the fuel performance cost, and its simple structure and lightweight operation facilitate autonomous planning, considering the limited computing power of the onboard computer. The hybrid algorithm is composed of discrete particle swarm optimization (DPSO) and PSO, so it has a strong ability to search for the optimal service sequence and orbit maneuver time simultaneously. Moreover, the adaptive and variant operators are used to improve the searching ability and avoid falling into local optimal solutions. Finally, simulation experiments show that the proposed method can quickly give optimal results, reducing fuel consumption effectively in the OOS mission and improving the OOS capability of the spacecraft.

This paper presents the development of the UPMSat-2 sun sensor, from the design to on-orbit operation. It also includes the testing of the instrument, one of the most important tasks that needs to be performed to operate a sensor with precision. The UPMSat-2 solar sensor has been designed, tested, and manufactured at the Universidad Politécnica de Madrid (UPM) using 3D printing and COTS (photodiodes). The work described in this paper was carried out by students and teachers of the Master in Space Systems (Máster Universitario en Sistemas Espaciales—MUSE). The solar sensor is composed of six photodiodes that are divided into two sets; each set is held and oriented on the satellite by its corresponding support printed in Delrin. The paper describes the choice of components, the electrical diagram, and the manufacture of the supports. The methodology followed to obtain the response curve of each photodiode is simple and inexpensive, as it requires a limited number of instruments and tools. The selected irradiance source was a set of red LEDs and halogen instead of an AM0 spectrum irradiance simulator. Some early results from the UPMSat-2 mission have been analyzed in the present paper. Data from magnetometers and the attitude control system have been used to validate the data obtained from the sun sensor. The results indicate a good performance of the sensors during flight, in accordance with the data from the ground tests.

On-orbit debris removal is an important and challenging problem in space engineering. A low-cost method for this problem is to use uncontrolled rendezvous with a sub-spacecraft released by a service spacecraft. The sub-spacecraft do not carry any control system and are designed to rendezvous with the target debris to remove it. This paper presents a comprehensive study on the mission planning. First, we analyze and dynamically model the uncontrolled rendezvous process for elliptical orbit targets, and study various aspects such as maneuver, sub-spacecraft release parameter solution, and rendezvous accuracy estimation. Then, we use NSGA-II, a multi-objective optimization genetic algorithm, to establish the mission planning model, focusing on the design of decision variables, constraints and fitness functions. Finally, we apply our proposed method to two specific cases of Molniya orbit, and verify the effectiveness of the planning model. We also conduct a deep analysis of the planning results, and summarize the commonalities and differences of various effective strategies.

This review paper presents a comprehensive evaluation and forward‐looking perspective on the underexplored topic of servicing target objects using spacecraft swarms. Such targets can be known or unknown, cooperative or uncooperative, and pose significant challenges in modern space operations due to their inherent complexity and unpredictability. Successfully servicing space objects is vital for active debris removal and broader on‐orbit servicing tasks such as satellite maintenance, repair, refueling, orbital assembly, and construction. Significant effort has been invested in the literature to explore the servicing of targets using a single spacecraft. Given its advantages and benefits, this paper expands the discussion to encompass a swarm approach to the problem. This review covers various single‐spacecraft approaches and presents a critical examination of the existing, although limited, body of work dedicated to servicing orbital objects using multiple spacecraft. The focus is also broadened to include some influential studies concerning the characterization, capture, and manipulation of physical objects by general multiagent systems, a subject with significant parallels to the core interest of this manuscript. Furthermore, this article also delves into the realm of simultaneous localization and mapping, highlighting its application within close‐proximity operations in space, especially when dealing with unknown uncooperative targets. Special attention is paid to the benefits that this field can receive from distributed multiagent architectures. Finally, an exploration of the promising field of swarm robotics is presented, with an emphasis on its potential to revolutionize the servicing of orbital target objects. Concurrently, a survey of general research directly engaging swarms in the orbital context is conducted. This review aims to bridge the knowledge gap and stimulate further research in the underexplored domain of servicing space targets with spacecraft swarms.

In a formation-flying mission where multiple spacecraft must cooperate and maintain a prescribed relative separation, the early detection of possible anomalies is a primary requirement. This is possible, for example, by employing an inspector spacecraft whose aim is to monitor the condition of the formation members with an on-orbit inspection. This paper analyzes a rest-to-rest multiple-impulse transfer that the inspector spacecraft must accomplish to visit all of the formation members. The problem is studied using the linearized Hill–Clohessy–Wiltshire equations and is solved in an optimal framework by minimizing the total velocity variation along the transfer trajectory. The solution algorithm implements a two-step procedure that combines differential evolution algorithms and Nelder–Mead simplex method-based routines. A case study is thoroughly investigated where a formation of six satellites covers a circular orbit of altitude 300km over Earth. The proposed algorithm could efficiently find a solution and with reduced computational times.

Ever since the space tether was first proposed by Tsiolkovsky, it has been extensively utilized in space missions, for attitude stabilization, momentum exchange, and space elevators. Developments in engineering technology and changes in the space environment have diversified the current applications for the space tether. New applications for the space tether include the Tethered Space Robot, Tethered Space Net, and Tethered Spacecraft Formation. These are quickly being adapted for in-orbit maintenance such as fueling service, orbit maneuvering, and active space debris capture/removal. The flexibility and elasticity of the space tether lead to complex issues with tethered space systems, including the mechanics design, dynamics modeling and analysis, and control scheme design. In this paper, we review several new applications for the space tether during service in orbit, and research the on structure, dynamics, and control of each application. This review is conducted to provide an overall summary of the space tether for On-Orbit Servicing, and further the conversation regarding possible research interests in the future.

Recently, the ring images or the shadow images of the centers of the galaxy M87 and the Milky way have been reported by Event Horizon Telescope Collaboration. It is believed that the ring images imply that the central objects form unstable light circular orbits. Some of wormholes with [Formula omitted] symmetry against a throat are wrongly excluded from the candidates at the centers of M87 and the Milky way due to the overlooking the unstable light circular orbits on the throat. A general asymptotically-flat, static, and spherical symmetrical wormhole without a thin shell has at least one unstable circular light orbit at the throat or elsewhere. If the wormhole has [Formula omitted] symmetry against the throat, it has the unstable circular light orbits on the throat or it has stable circular light orbits on the throat and unstable ones near the throat. We need to analyze the throat carefully to make sure we do not unfairly rule out the [Formula omitted]-symmetrical wormholes. In this study, we categorize the numbers of the circular light orbits of the [Formula omitted]-symmetrical wormhole and their stability from the derivatives of an effective potential at the throat and we investigate the circular light orbits around a Simpson-Visser black-bounce spacetime, a Damour-Solodukhin wormhole spacetime, a Reissner-Nordström black-hole-like wormhole spacetime or a charged Damour-Solodukhin wormhole spacetime as examples. We give complete treatments including degenerated circular light orbits made from more than one stable and unstable circular light orbits on and off the throat.