Throttling of large-thrust liquid rocket engines, which can improve mission adaptability of a carrier rocket, reduce risk and facilitate rocket recovery, is a key technology for current and future space development. This paper summarizes the state of the art and trends of throttling technology for large-thrust liquid rocket engines at home and abroad. According to the working principles of propulsion for rocket engines, throttling the propellant flow rate is a major way of adjusting thrust, and regulation devices along with adjustable injectors are primary measures of throttling propellant flow rates. This paper clarifies the working principles of typical regulation devices and adjustable injectors, introduces the regulation schemes of typical large-thrust engines such as YF-100, RD-170, and SSME, and summarizes the main characteristics of current throttleable large-thrust engines. Finally, critical technologies and development trends of throttling are discussed, including combustion stability and reliable cooling of thrust chambers at low thrust levels, turbopump stability, and stable regulation and precise control in a wide range of operating conditions.

Queqiao relay communications satellite was developed to provide relay communications services for the lander and the rover on the far side of the moon. From entering into its halo mission orbit around the Earth-moon libration point 2 on June 14, 2018, it has operated on orbit more than fifteen months. It worked very well and provided reliable, continuous relay communications services for the lander and the rover to accomplish the goals of Chang’e 4 lunar far side soft landing and patrol exploration mission. The on-orbit operation status of Queqiao relay communications satellite is summarized in this paper.

As the closest celestial body to the Earth, the moon is a hot spot for international space science research at present. Countries around the world have conducted lunar exploration time after time, among which, China’s Lunar Exploration Program has achieved 6 consecutive successful lunar missions. China has made a series of significant achievements in deep space exploration, and its cooperation with international partners is increasingly strengthened. 
In order to gather global space power and scientists’ wisdom, the International lunar Research Station (ILRS) is proposed by China and will be jointly constructed by many countries, which will be equipped with the support capabilities of energy supply, central control, communications and navigation, space-Earth round-trip transportation, lunar surface scientific research, and ground support. All international partners are encouraged to jointly develop and build the ILRS, and to jointly initiate the establishment of the International Lunar Research Station Cooperation Organization (ILRSCO) to achieve the long-term effective, operation and management of the station. The vast universe sparks the exploration dream of humankind, so let’s set sail together.

The divergence angle of laser beam used in space laser communication is usually no more than 100 μrad. Using laser beam with small divergence angle to achieve acquisition and tracking for space laser link has al-ways been a difficult problem. In addition, the random nature of the atmosphere will affect the satellite-ground laser link, which increases the difficulty of the acquisition and stable tracking for the laser link. Thus, taking into account the above challenges for satellite-ground laser communication, an acquisition and tracking scheme of using both beacon beam and signal beam was designed for the Laser Communication Terminal (LCT) of Shijian 20 satellite. In-orbit test results indicated that under the condition of moderate atmospheric turbulence (atmospheric coherence length r0≈3cm), the process of acquisition and tracking for the satellite-ground laser link can be completed within 1s after the initial pointing between the LCT and Optical Ground Station (OGS) is performed, and the tracking error was less than 1 μrad (3σ). In addition, the laser link can be re-established quickly once being interrupted by unsteady atmospheric turbulence, and can be maintained for a long time under moderate twurbulence conditions, which lays a foundation for future application of satellite-ground laser communication.

According to the different types and characteristics of satellite fault, a kind of fault diagnosis method is proposed, which integrates multivariate threshold, model-based and fault tree-based method. In order to optimize the fault diagnosis method, it takes the advantages and remedy of a defect with other methods. This can diagnose many kinds of satellite fault occurring in the on-orbit phase rapidly and accurately. Besides, it can analyze the damage degree of the failure and establish the measures to eliminate the failure.

In recent years, with the development of the world space industry, more and more new spacecraft have been launched to low-Earth orbit. The amount of space debris in space has been increasing year by year, with a net increase in total debris in outer space. It has become a serious environmental problem bringing potentially enormous harm to human activities. The traditional space debris mitigation international mechanism cannot change the status quo of the continuous growth of total space debris, which will have a serious impact on future development and operation in space. Although many countries are actively exploring and researching effective and feasible solutions for space debris, they have not yet developed an international legal mechanism specifically covering the issue of “proactive removal of space debris” to clearly define the responsibilities and obligations for the active removal of space debris. To further implement such a plan, it is necessary for the international community to clarify the international legal responsibility for the active removal of space debris. Therefore, this paper will start with the relevant legal provisions of space debris, analyze the current situation of space debris and the issue and status quo of the active removal of space debris, and further clarify the responsibility and obligation of space debris active removal for each country to actively remove space debris.

At present, the moon and Mars are the main focus of deep space exploration, scientific pursuits are the initial goal, and extensive cooperation leads to a greater prospect. China has made many scientific achievements and built considerable infrastructure through its lunar and Mars exploration activities. In the future, China will continue to carry out deep space exploration activities with scientific goals as the driving force, develop the International Lunar Research Station, explore the sun, inner planets and asteroids, discover exoplanets and build an asteroid defence system. 
In order to support future deep space exploration missions, China will construct an integrated communication, navigation and remote sensing constellation and develop heavy-lift launch vehicles. China offers a wide range of opportunities for cooperation, upholds the central role of Committee on the Peaceful Uses of Outer Space (UNCOPUOS), and welcomes all countries in the world to participate in deep space exploration activities.

Liquid propellant rocket engines for a launch vehicle are an essential aerospace technology, representing the advanced level of hi-tech in a country. In recent years, China’s aerospace industry has made remarkable achievements, and liquid rocket engine technology has also been effectively developed. In this article, the development processes of China’s liquid rocket engines are discussed. Then, the performance features of China’s new generation liquid rocket engines as well as the flight tests of the new-generation launch vehicles are introduced. Finally, the development direction and the most recent progress of the next generation large-thrust liquid rocket engine is presented.

 Recent advances in Artificial Intelligence (AI) have indicated that inspirations from the brain can effectively improve the level of intelligence for AI computational models, even if just local and partial inspirations. Nevertheless, realizing and exceeding intelligence at a human level still needs a deeper investigation and inspirations from the brain. The goal of brain-inspired intelligence is to achieve human intelligence inspired from brain neural mechanism and cognitive behavior mechanism. To this end, in this paper we introduce the relationship between AI and neuroscience, the current status of brain-inspired intelligence, the future work in intelligent control systems, and its profound influence in other fields.

The LM-6A new generation solid-liquid strap-on launch vehicle has the structural dynamic characteristics of lower frequencies, denser modes and coupling modes in longitudinal, bending and torsion modal space. During the development phase of LM-6A, modal tests of partial stacks and the full vehicle were designed to obtain the structural dynamic properties. The structural dynamic models using the finite element method (FEM) have been verified and calibrated based on the modal test data. This paper describes the pre-test predictions and test execution, and details the comparison between the pre-test predictions and the test data. The successful maiden flight of LM-6A further confirmed the effectiveness of structural dynamic modeling and modal test for LM-6A.

The far side of the moon is a unique place for some scientific investigations. Chang’e 4 is a Chinese lunar far side landing exploration mission. Relay communication satellite, named as Queqiao, is an important and innovative part of Chang’e 4 mission. It can provide relay communication to the lander and the rover operating on the lunar far side to maintain their contacts with Earth. It was launched by LM-4C launch vehicle at the Xichang Satellite Launch Center on May 21, 2018. After five precise orbit controls and a journey of more than 20 days, Queqiao inserted into final halo mission orbit around Earth-moon libration point 2, located about 65,000 km beyond the moon. It is the world’s first communication satellite operating in that orbit. Up to now, Queqiao worked very well and provided reliable, continuous communication relay service for the lander and the rover to ensure the mission success of Chang’e 4 exploration mission. Via Queqiao, the lander and the rover were controlled to work by ground stations and obtained a great amount of scientific data. The mission overview, operation orbit selection, relay communication system design and flight profile were introduced in this article.

At 00:25 Beijing time on January 20, China launched the Tiantong 1-03 satellite onboard a LM-3B carrier rocket from the Xichang Satellite Launch Center. The satellite entered its preset orbit, marking the success of China’s first launch mission in 2021. 
The Tiantong 1 satellites were developed by the China Academy of Space Technology, of which the Tiantong 1-01 and 1-02 satellites were launched by LM3B in 2016 and 2020 respectively. The Tiantong 1-03 satellite will be networked with the previous two satellites, realizing China’s autonomous and controllable satellite mobile communications system that can cover the Asia-Pacific region.
The LM-3B carrier rocket was developed by the China Academy of Launch Vehicle Technology.
This was the 358th launch of the LM series launch vehicle and the 117th launch of the LM-3 family.
CASC plans to conduct more than 40 launch missions in 2021.

Mega-constellations of satellites are making a complex network in Low-Earth Orbit (LEO), which presents new legal and technical challenges. The widespread operation of mega-constellations necessitates a special technical and legal regulatory framework that is constantly evolving based on emerging technologies. Although it has not yet been completely established since it is fully dependent on the development of Space Traffic Management (STM), including the rules on space debris mitigation and collision avoidance systems, cyber security issues, environmental concerns, rules of registration, Radio Frequency Interferences (RFI), Space Surveillance & Tracking (SST), etc.
This paper addresses the legal issues of coordinating LEO mega-constellation operations within the framework of STM. The LEO mega-constellations creating the space environment congested necessitates the establishment of STM rules and standards to safeguard the safety, security, and sustainability of outer space activities. To do so, States and the private sector will have to develop effective, safe, and workable mechanisms that will allow space activities in the field of the deployment and operation of satellite constellations while ensuring the sustainability of all space activities on a long-term basis. Moreover, it needs the cooperation of related national and international organizations and other entities, including the United Nations Committee on the Peaceful Uses of Outer Space (UNCOPUOS), its Subcommittees, and Internation Telecommunication Union (ITU), to solve the legal and technical challenges of satellite constellations, especially mega-constellations, through the amendment of the current international legal regime, the implementation of a new international treaty, or the creation of soft law documents.

The slow progress and lack of fundamental breakthroughs in legislative practices are an important subject for China’s space legislation. Oriented by the idea to formulate China’s space law as soon as possible, it is necessary to solve five key issues. In the national policy, it is needful not only to implement China’s space policy and promote the development of the space industry in depth, but also to advance the deep integration of military and civil application in space field. In terms of legal orientation, three features should be reflected upon, including the functional integration of public and private laws, the balance of regulation by substantive and procedural laws, and the effective coordination of domestic and international laws. To this end, both top-level design and implementation should be paid close attention to in order to achieve significant progress in China’s space legislation.

Tiangong space station is a space station independently designed and developed by China. In order to build and operate the space station, it was necessary to make breakthroughs in many fields and master several key technologies, which were characterized over a long technological span and underwent difficult verifications. Therefore, in addition to ground verification, on-orbit flight tests of key technologies for the assembly, construction and operation of the space station were planned to be conducted used by the core module, taking into account the differences in the gravity environment between space and the Earth, in order to lay a foundation for the subsequent comprehensive assembly, construction and long-term on-orbit operation of the space station. In this paper, the mission characteristics of the space station are briefly introduced, along with the key technologies for the assembly and construction of the space station, and then the on-orbit verification tests are comprehensively introduced.

As a new support platform of information technology for social development, virtual reality technology 
(VRT) has been widely used in many fields. Here, the concept and important features of VRT are summarized first. 
Then, the analysis requirement for VRT in design, display, operation and maintenance training, and state monitoring for aerospace products is elaborated. This is followed with a review of foreign and domestic policy planning of VRT, and their application in aerospace. Last, future development of VRT is discussed.

Based on current research, the development trend of reusable liquid rocket engines was analyzed. Key technologies and research focuses of the reusable liquid rocket engine have been analyzed and summarized, and then suggestions on the development of future key technologies are proposed.

In this study, taking China’s Smart Dragon 3 solid launch vehicle, which made its first successful offshore launch on December 9, 2022, as an example, we focus on the technical characteristics and key technologies of various solid motors used for the launch vehicle. The current technological development status is introduced, and the key technologies needed for large solid motors are summarized. For comparison, we also list and analyze the technical characteristics of world-class P80 and P120C solid motors used in ESA’s Vega series of launch vehicles. On this basis, the development trends of large solid motors based on the requirements for launch vehicles is proposed, providing a reference for the development of large solid motor technology for future launch vehicles in China.

The United States was the first country in the world to develop a satellite navigation system, with rich experience in system management, R&D, operation, and satellite applications industry. It started the construction of the Global Positioning System (GPS) in 1973 and deployed the first satellite in 1978. It has successfully developed and deployed three series of GPS satellites with a total of seven models. The United States is now focusing on the research and development of cutting edge navigation technologies and constellation modernization, replacing old ones with new GPS III series of satellites and actively exploring and verifying the frontier navigation technologies represented through the Navigation Technology Satellite 3 (NTS-3). It is now upgrading the original ground-based operation and control system, actively developing and deploying the GPS Next Generation Operational Control System (GPS OCX), and upgrading the military user equipment supporting Military Code (M-Code). The U.S. attaches importance to multiple measures to improve the service performance of the GPS system and enhance the resilience of the system to provide positioning, navigation, and timing capabilities. In this context, the progress of the construction of GPS and the related technological innovations are separated out and analyzed, which will help the Global Navigation Satellite System (GNSS) solutions summarizing their experience and learning from each other’s development to better serve social progress and economic development.

China’s Chang’e 3 (CE-3) and Chang’e 4 (CE-3) missions made historic progress by sending rovers equipped with scientific instruments to the new sites on the nearside and farside of the moon, respectively. The same lunar penetrating radar (LPR) that uses pulses of electromagnetic energy to reveal the underground structure and properties of the lunar soil “regolith” covering most of the lunar surface was carried by the rovers. It provided for the first time the opportunity for in situ LPR measurements of the subsurface substrate in two geologically different places on the moon. 
At present, the Yutu rover of CE-3 mission traveled along a path of total length of about 114 m while the Yutu 2 rover of CE-4 has traversed over 1000 m and keeps going. This paper summarizes the fruitful results so far obtained by LPRs, including the physical properties and layered structure of the lunar regolith and shallow crust beneath the two landing sites. The regolith layer thickness at the CE-3 site is thinner than that at the CE-4 site due to its relatively young age. The penetration depth below CE-4 site is about 2.85 times (in terms of the forward and return path delay) deeper than CE-3 as indicated by their different loss tangent values (0.0039 ± 0.0002 vs. 0.013), which is probably due to the differences in abundance of ilmenite and rocks in the regolith. Other physical parameters including dielectric permittivity vs. depth profile, bulk density and electrical conductivity have been estimated using various methods. Thanks to the low signal loss, CE-4 LPR is able to present clear cross section views of two buried craters and the paleo-surface (ancient surface) of the landing site. The multiple stratums observed by the low frequency channel of LPRs indicate several episodes of lava eruptions occurred in the late stage of the formation of the nearside Imbrium Basin and the farside Von Kármán crater despite the asymmetric volcanisms distributed on two sides. 
The discoveries revealed by LPRs advance our knowledges on the formation process and roperties of lunar regolith, thickness of ejecta deposits caused by lunar impact events, the evolution of the nearside and farside volcanisms, etc. They also demonstrate the feasibility of applying ground penetrating radar for non-terrestrial explorations such as China’s first Martian mission, Tianwen 1 mission. 

In recent years, with the rapid growth in demand for commercial launches, space institutions like NASA have been succeeded in the commercialization of aerospace services. According to the latest development trends on international commercial aerospace services and the current development status of domestic commercial aerospace services, suggestions on the development of China’s commercial aerospace services based on policies, development modes and technical innovation are given.

As human aeronautic and aerospace technology continues to prosper and the aerial flight space domain further expands, traditional fixed-shape air vehicles have been confronted with difficulties in satisfying complex missions in cross-domain scenarios. Owing to their flexible and deformable appearance, morphing air vehicles are expected to realize cross-domain intelligent flight, thus emerging as the most subversive strategic development trend and research focus in aeronautic and aerospace fields. This paper primarily reviews the research background and challenges of flexible and deformable cross-domain intelligent flight, proposing a corresponding research framework and mode as well as exploring the scientific issues and state-of-the-art solutions, where key research progress is introduced. The explorations covered in this paper also provide ideas and directions for the study of deformable cross-domain intelligent flight, which has critical scientific significance in promoting the study itself.

Upper stage is an indispensable vehicle in the space transportation system. For its role in multi-satellite transportation area in China, the development of the Yuanzheng 3 upper stage was approved. The article introduces in detail the Yuanzheng 3 upper stage development requirements, task definition and systems as well as main features and performance including payload capacity and insertion accuracy for typical orbits, interfaces with satellites. The article also presents the development cycle of Yuanzheng 3 upper stage, which is divided into 3 stages including concept demonstration stage, prototype stage and flight proof stage. The Yuanzheng 3 upper stage, which will make its maiden flight in 2018, is capable of restarting more than 20 times, and operating for more than 48 hours. It is equivalent to mainstream upper stages in the world in terms of performance, such as restart times, in-orbit operation time, independent digital control system, and adaptable behavior for various tasks. Technologies tackled and accumulated in the development of the Yuanzheng 3 upper stage will lay a solid foundation for the development of future space transportation vehicles.

Common-track constellation is a special kind of constellation, all ground tracks of satellites are in one track. With recursive orbit or quasi-recursive orbit, the ground track of the constellation is a closed loop with a repeating track. In particular, if the constellation is in one orbit plane, the constellation can meet the requirement for a multi-satellite launch mission and fast satellite-satellite link establishment. The characteristics and coverage properties of a common-track constellation in one orbit plane are studied in this paper. The simulation results show that a common-track constellation in one orbit plane can provide favorable coverage to a target station in the polar areas.

In this paper, the properties of different low-density heat-resistant coating prescriptions were compared, and a heat-resistant coating with a density of 0.65 g/cm3, a tensile strength of 2.04 MPa, and a thermal conductivity of 0.126 W/(m·K) was obtained. The thermal performance of the coating was characterized by an oxygen-acetylene ablation test, a hot radiation test using a quartz lamp and in an arc-heated wind tunnel test. The results indicated that the low-density heat-resistant coating prescription has advantages of high temperature resistance, erosion resistance, ablative resistance and excellent heat resistance, which can satisfy the heat resistance requirements of new-generation launch vehicle fairings.
The successful application of this heat-resistant coating technology resolved the problems of low efficiency and poor adhesive performance of the traditional hand-pasted cork process, and realized the rapid spray application of the thermal protection layer, effectively improved the manufacturing efficiency and production quality of the heat-resistant layer of new-generation launch vehicle fairings.

In an era of unprecedented scientific advancements and ambitious space exploration goals, international collaboration has become a key driver of progress. China’s kind and peaceful invitation to engage in collaborative ventures within the International Lunar Research Station (ILRS) and deep space exploration project presents a significant opportunity to respond with constructive contributions in engineering and scientific domains. This article aims to illuminate the potential advantages of becoming a partner in the ILRS and deep space exploration project, showcasing a selection of captivating missions that await exploration. By embracing this generous and peace-promoting offer extended by China, the global scientific community can foster meaningful partnerships and achieve groundbreaking advancements in lunar and deep space exploration. China’s resolute dedication to international cooperation in lunar and deep space exploration has resulted in immeasurable contributions, propelling our understanding of the universe and pushing the limits of human knowledge. Through a shared vision, these collective endeavors have brought us closer to unraveling the enigmas of the cosmos and expanding the frontiers of our comprehension. By conducting a series of scientific experiments, Türkiye will actively contribute in the domains of science and technology. Building upon the knowledge and expertise acquired through its own lunar mission, Türkiye has been diligently conducting a comprehensive analysis of the prospective realms of contribution delineated within the ILRS and deep space missions conducted thus far.

The Long March 11 launch vehicle (LM-11) is the only solid launch vehicle within China’s new-generation launch vehicle series, enabling a full spectrum of Chinese launch vehicles. Compared with other China’s LM series launch vehicles, it has the shortest launch preparation time. With the characteristics of appropriate launch capability, quick response, easy-to-use, flexible operation, universal interface and strong task adaptability, LM-11 can better meet the launch requirements for various small networking satellite, replacement and for emergency use. After four successful launches, LM-11 has become the main Chinese launch vehicle oriented to the international small satellite commercial launch market.

Satellite laser ranging (SLR) is an unambiguous measurement technique and generates high accuracy satellite orbit data. All satellites in the BeiDou navigation satellite system (BDS) carried laser retro-reflector arrays (LRAs), so they can be tracked by ground SLR stations in order to provide the accurate observation data. The Shanghai astronomical observatory (SHAO) designed the LRAs, and also developed the dedicated SLR systems using a 1 m-aperture telescope and a transportable cabin-based SLR system with a telescopes of 60 cm aperture. These enable BDS satellite ranging during daytime and nighttime with centimeter-level precision, allowing highly accurate estimations of satellite orbits. Moreover, some of the BDS satellites are also equipped with laser time transfer (LTT) payloads, which were developed by the SHAO and China Academy of Space Technology (CAST), providing a highly accurate time comparison between the satellites and ground clocks. This paper describes the dedicated SLR system and the design of the LRAs for BDS satellites, as well as global SLR measurements. The SLR tracking data is used for evaluating the orbit accuracy of BDS satellites and broadcast ephemeris, with an accuracy of less than 1 m. The LTT measurements to BDS satellites for a single shot have a precision of approximately 300 picoseconds, with a time stability of 20 picoseconds in 500 s.

The research status on the development of RBCC engines and corresponding aerospace vehicles around the world was overviewed, and the technical and application characteristics of RBCC technology were summarized. 
New development trends of combined cycle engines as well as space transportation were analyzed, and lastly, some suggestions on the development of RBCC and the relative aerospace vehicles were proposed.

High power Hall electric propulsion technology is a very competitive electric propulsion technology for future large space missions such as large GEO satellites, manned space programs, deep space explorations, cargo ships, space tugs. Based on the experience of more than 20 years in research and development of Hall electric propulsion, the Shanghai Institute of Space Propulsion (SISP) has developed 3 high power Hall thrusters, i.e., the 10 kW class HET-500, 20 kW class HET-1000, and 50 kW class HET-3000. This paper presents the development status of the high power ( ≥ 10 kW) Hall electric propulsion at SISP, including tests of 3 high power Hall thrusters in the power range from 10 kW to 50 kW, the qualification of a single string of a 10 kW Hall electric propulsion system, and the study of a cluster of two 1.35 kW HET-80 Hall thrusters to understand the technical issues related to multi-thruster high power electric propulsion systems.

This paper reviews the recoverable satellites China has developed over the past forty years. The main missions, technical specifications, scientific and technical experiments of these satellites, including the SJ-10 scientific experiment satellite launched on April 6, 2016 are introduced. Recommendations for future technical upgrades for recoverable satellites are also proposed in the paper.

 As one of the newly developing intelligent/smart materials, shape memory alloys (SMAs) have become an important material and have broad application prospects. With smart structures, the integration of SMAs as actuators and sensors in structural components, has drawn significant attention and interest in the aerospace field. In this paper, the research status of SMAs at home and abroad in recent years was reviewed, including the characteristics, classification, investigation progress and applications in the aerospace field. Finally, the development trend prospects for SMAs was also presented.

The Smart Dragon 3 launch vehicle is a commercial carrier rocket based on the experience with the existing solid-fuel rocket Long March 11 to meet the growing market demand in China for launching commercial satellites to low and medium orbits. The carrier rocket has the characteristics of integral rocket storage, usable for both sea- and land-based launches, rapid response and cost-effectiveness. It is a solid carrier rocket with the largest lift capacity and the largest fairing envelope successfully flown domestically. This paper introduces the main technical index and overall scheme of the rocket. It also introduces the main difficulties encountered in the development of the rocket focusing on the aspects of the thermal emission at sea, the “Big hood” configuration and low commercial cost, as well as the interfaces with satellites. It is expected to provide a better commercial launch service for users through technological and economic integration.

Following the successful maiden flight of the Long March 11 (LM-11) launch vehicle from the Jiuquan Satellite Launch Center in September 2015, the first sea-launched carrier rocket dedicated to provide a launch service for small satellites and their constellations, the Long March 11 Sea Launch (LM-11SL) has been under development by the China Academy of Launch Vehicle Technology (CALT) and the China Great Wall Industry Corporation (CGWIC). It is planned to commence launch service in 2018. Based on the LM-11, a land-launched four-staged solid launch vehicle which has entered the market and accomplished launch missions for several small satellites in the past 3 years, the newly adopted sea launch technology enables transport and launch of LM-11SL from maritime ships, providing flexible launch location selection.
After inheriting the mature launch vehicle technologies from previous members of the Long March launch vehicle family and adopting a new way of launching from the sea, the LM-11SL is capable of sending payloads into low Earth orbits with all altitudes and inclinations, from 200 km to 1000 km, from equatorial to sun synchronous, within a shortduration launch campaign. The LM-11SL provides a flexible, reliable and economical launch service for the global small satellite industry.

 With the development of satellite navigation technology, the user demands for the integrity of Global Navigation Satellite System (GNSS) have increased more and more. A ground-based monitoring system can hardly report an alarm message to GNSS users during the valid alarming period due to the satellite-Earth propagation delay. It is beneficial to monitor abnormal events and report the corresponding alarms from orbit. Adopting this approach, which is an important feature for future GNSS integrity monitoring, the time needed to provide an alarm is shorter and the system integrity capability is strengthened. The BeiDou Navigation Satellite System (BDS) new generation satellites have the capabilities of satellite autonomous integrity monitoring (SAIM). This paper presents the technical scheme of SAIM, and proposes the integrity monitoring method of both navigation signals and the clocks onboard. The proposed method was verified through the onboard test on the BDS satellites. In addition, we analyzed the integrity telemetry data from the new generation of BDS satellite, including signal delay, power, carrier phase measurement, correlation peak, consistency of pseudo-code and carrier phase, clock phase and frequency step. The analysis results indicated that the quality of the data on orbit met the requirements, and SAIM could monitor effectively any abnormal change of satellite clocks and navigation signal, generate rapidly an alarm message, and transmit it to the user. The alarm time was less than 6 s through the message, and 2 s through non-standard code (NSC). Finally, we present future opportunities for improving the SAIM technology of BDS.

In the recovery process of the reusable rocket with vertical take-off and landing, it has to go through the active control process, such as power drop, hover and vertical landing. The key technology lies in the development of high-precision vertical recovery control algorithm. Therefore, a vertical take-off and landing reusable launch vehicle prototype is developed to verify the rationality of the flight control algorithm of rocket vertical recovery.
The vertical take-off and landing reusable launch vehicle prototype is 0.45 m long, 0.45 m wide, 0.6 m high, and has 23 kg take-off weight with a maximum thrust of 400 N jet engine as the power plant, through four gas rudders to achieve the aircraft pitch and yaw and roll-on control. The prototype focuses on the verification of the guidance and control algorithm of the vertical recovery algorithm. Therefore, it is equipped with the vector control capability, avionics and measurement system similar to that of the vertical recovery rocket. The prototype can be used for verification of the flight control algorithm.