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In order to help control the spread of space debris and junk, deorbit sail devices have been used for deorbiting techniques; however, this approach is still considered risky due to potential failure or malfunction as it need to be exposed to the harsh space environment for a prolonged period of time, particularly in low-Earth orbit. China has made new strides forward in managing space junk, as it has successfully unfolded a 25-square-meter deorbit sail developed by the Shanghai Academy of Spacecraft Technology in-orbit for the payload capsule of a recently launched rocket. Accordingly in this paper, a full life-cycle modelling based on Monte Carlo method is developed to reveal the damage behavior of the 25-square-meter deorbit sail surface under the combined effects of atomic oxygen erosion and deorbit sail defects. The simulation results show that as the atomic oxygen fluence increases and the material defect width widens, the interaction effect of the two factors becomes more and more pronounced, which decisively influences the erosion rate of the sail surface. Morphological characterization of aluminized film PET material, activated silanisation modified material and plasma-polymerization coating material before and after atomic oxygen erosion combined defects is carried out and the atomic oxygen erosion of the deorbit sail surfaces is quantitatively assessed. The assessment results show that compared to the PET material and activation silanisation surface modification material, the plasma polymeric coated material showed much better flexibility, folding resistance and irradiation resistance to prevent geological fold and to shield from the atomic oxygen erosion in space. The atomic oxygen erosion combined defects assessment method studied in this paper provides valuable reference data for the subsequent serialisation of deorbit sail products and other typical lightweight film materials for space applications. • Introduction of Monte Carlo method for material surface damage simulation analysis. • Compare the performance of off-orbit sail surface materials under different protection treatments. • Standardize the process of space flexible film material performance evaluation system. [ABSTRACT FROM AUTHOR]

In contrast to the rising technological applications of China's satellite systems, their applications and impacts in modern Chinese Society, particularly in the legal and administrative forums, have largely escaped under the radar. Specifically, the use of satellite outputs can now be found within a number of administrative and legal activities within China - including policy and rule-making, administrative investigations, and the production of court evidence. At the same time however, outdated legal practices, ambiguous status, and lack of guidance has prevented China's legal system from fully capitalizing on the advantages of satellite technologies. Therefore, to fill these legislative gaps, this review provides a comprehensive overview on the applications of satellite technologies within China's legal system, and provide important insights as to their current developments, legal framework, and legal issues. Additionally, having identified the aforementioned issues, this paper offers policy recommendations for the purposes of legislation. • Satellite applications in China's policy and rule-making processes. • Investigatory applications of satellite technologies within China's administrative organs. • Emerging evidentiary applications of satellite technologies in Chinese court systems. [ABSTRACT FROM AUTHOR]

With commercial participants now undertaking an ever-expanding role within the development and supply-chains of China's space industry post Document No. 60, the resulting legal challenges relating to this emerging industry status-quo has garnered much academic discussion. Specifically, while China's space industry has grown at a rapid pace within the past few decades, China's legislative framework has remained largely silent over matters relating to space. Instead, China continues to remain as the only major space-faring nation without a national space law and regime. This substantive legislative gap over China's space related activities has negatively impacted the industry's current deregulation process. While it has been the academic community's primary solution to address the industry's current substantive legislative gap through coordinated rulemaking activities, this paper aims to advance the current academic discussion by taking an alternative approach and arguing that the fundamental legislative challenge and solution to China's emerging commercial space industry, is not substantive, but rather procedural by nature. Importantly, by reconceptualizing the industry's substantive gap from one that is determined by the number of missing legal instruments, to one determined by the rate of legislative activity i.e., the pace of law-making activities vis-à-vis commercial expansion, this paper argues that only through the implementation of legal procedural rulemaking mechanisms will China's space law regime be able to sufficiently address the current substantive legislative gap at a pace matching commercial expansion. • The deregulation of China's space industry. • Regulatory structure and legal challenges of China's space industry. • A procedural argument to resolve China's substantive space law gap. [ABSTRACT FROM AUTHOR]

Q-SAT, a small spherical satellite designed and developed by Tsinghua university, was successfully launched on Aug 6, 2020 at Jiuquan satellite launch center in China. The mission of Q-Sat is the joint measurement of long-wavelength Earth gravity field and upper atmosphere density, which is of great significance for improving spacecraft orbit prediction and promoting the development of satellite gravity measurement technology. The satellite is designed in spherical shape innovatively and deploys high dynamic dual-frequency GPS as the main payload. On-orbit data shows that the atmospheric density detection precision is in the order of 10−14kg/m3 and the gravity recovery precision achieves the level of 30 orders. All mission success criteria and objectives were achieved. This paper presents the design, space mission, key technologies, science capabilities and preliminary results of the satellite. • Q-SAT, a spherical satellite for the joint measurement of long-wavelength Earth gravity field and upper atmosphere density, was launched in 2020. • An electromagnetic separation system with point connection-release structure is designed for the Q-Sat. • As secondary payload a powerful GPU module is implemented to validate artificial intelligence computing capabilities in orbit. • Modifications for the Jacchia-Roberts atmospheric density model are proposed in the paper. [ABSTRACT FROM AUTHOR]

With the ability to detect low-frequency gravitational waves (GWs), space-borne detectors will play an important role in exploring the universe in the future. The TianQin project proposed in China participates in this challenge by aiming to detect millihertz GWs. The TianQin GW detector consists of three spacecraft forming a triangular constellation. Each spacecraft carries a pair of test masses (TM) which, inside shielding cages, are left to free fall along the local geodesic. In this way, a pair of TMs on two separate spacecraft can be each other aligned to become the gravitational references of the GW detector, made by an inter-satellite laser interferometer. Each free-falling TM is limited by parasitic forces to be appropriately bounded. The relevant acceleration bound has been fixed to 10−15 m/s2/ Hz within the TianQin measurement bandwidth (MBW) ranging from 0.1 mHz to 0.1 Hz. In turn, TM to cage fluctuations must be kept below 4nm/ Hz to limit the stiffness coupling with the spacecraft displacement caused by non-gravitational disturbances, such as solar radiations and the thruster noise. Suppression of such disturbances calls for a challenging drag-free control technology, since the center of mass (CoM) of a single spacecraft cannot track the separated CoMs of two TMs simultaneously, and consequently tracking must be limited to three degrees of freedom (DoF): two non-orthogonal sensitive axes (one for each TM) and the perpendicular direction to their plane. Control design and simulated tests of this paper will be restricted to the drag-free control along the sensitive axes. The remaining nine DoFs of the two TMs (position and attitude) are controlled by electrostatic suspensions, not to be treated here, but accounted for in the simulated trials. The design of the two-DoF drag-free control relies on a model-based control methodology, the Embedded Model Control (EMC), capable of predicting and suppressing unknown disturbances within the required bandwidth and of decoupling the TM dynamics along the non-orthogonal sensitive axes. The paper starts with the nonlinear model of the TM to cage dynamics, followed by the relevant EMC design, restricted to the sensitive axes. Numerical simulations are employed to validate closed-loop performance and robust stability. Simulated results show that the residual TM to cage fluctuations can be kept below 3nm/ Hz , which leaves a margin within the required spectral bound. The EMC methodology discussed in the paper can provide a reference for future developments and implementations. • Test mass dynamics can be decoupled by 'thruster coupling' or 'sensor coupling'. • Embedded Model Control predicts and compensates unknow disturbances. • Reference generator smooths test mass centering process. • Test mass to cage displacement has satisfied TianQin requirement. • Monte Carlo trails have validated the closed-loop robust stability. [ABSTRACT FROM AUTHOR]

In terms of cataloged debris produced, the anti-satellite test carried out by Russia, in November 2021, at an altitude of about 480 km, leading to the destruction of the old satellite Cosmos 1408, was the second worst to date and represented the third worst fragmentation in orbit. It generated more than 1/4 of the cataloged debris produced over 55 years by all such tests and almost twice as many as were produced by all previous Soviet tests. After placing this event in its historical context, this paper analyzes in detail how the evolution of the Cosmos 1408 debris cloud affected the environment below 600 km in the first seven months, focusing on the two operational space stations and the Starlink large constellation of satellites. During the first six months following the test, the Cosmos 1408 cloud of fragments nearly doubled the average flux of cataloged objects on the International Space Station and increased by about 3/4 that on China's Tiangong. In the same period, the Starlink large constellation saw an average increase in the flux of cataloged objects of about 20%. Some orbital planes, the "counter-rotating" ones with respect to the Cosmos 1408 debris cloud, were more affected than others, and the affected planes gradually changed over time, due to the differential precession of cloud and constellation nodes. However, being the Starlink constellation 70 km higher up, the flux of Cosmos 1408 cataloged debris steadily decreased over the period analyzed, due to the cloud orbital decay, reducing to just over a quarter of its extrapolated initial value after seven months. • A review of ASAT tests as a source of orbital debris was presented. • The impact of the Cosmos 1408 destruction was put into context. • The cataloged debris flux increase on space stations was computed and discussed. • The debris flux increase and evolution on Starlink orbit planes was analyzed. • A moratorium on this type of ASAT tests was recommended, including low LEO. [ABSTRACT FROM AUTHOR]

It is extremely important to accurately estimate reliability and lifetime of Bioregenerative Life Support System (BLSS) for its proper design, building and operation. However, this problem remains unsolved due to data deficiency of long-period prototype experiments. In this paper, the first ground-based experimental prototype of BLSS in China, Lunar Palace 1 (LP1), was selected as representative to estimate the reliability and lifetime of BLSS, because the number and time of each unit failure of LP1 was accurately recorded during the 370-day closed human experiment of LP1. Based on these time-series data, failure number probability distribution function of each unit and overall LP1 were formulated through parameter estimation and composite probability distribution function derived from units' series and parallel connection. Then, the influence of each unit failure on overall BLSS reliability and lifetime was determined correspondingly through sensitivity analysis and Monte Carlo simulations. Finally, the numerous pseudo-random numbers obeying the overall failure probability distribution function of LP1 were generated to estimate the reliability and lifetime of BLSS through maximum likelihood estimation and Monte Carlo simulations. The results demonstrate that the failure possibility of five units, water treatment unit, mineral element supply unit, LED light source unit, atmosphere management unit and temperature and humidity control unit have greater impact on reliability and lifetime of BLSS, and the mean lifetime of BLSS was 19112.37 days (about 52.4 years) with 95% confidence interval of [17367.11, 20672.68] days (about [47.58, 56.64] years) under normal operation and maintenance of BLSS. This research can lay a theoretical foundation for design, building and operation of BLSS with high reliability and long lifetime in the future. • Number and time of each unit failure in the 370-day closed human experiment of Lunar Palace 1 (LP1). • Failure number probability distribution function of each unit and overall LP1. • Sensitivity of LP1's reliability to each unit failure probability. • Generation of peculiar pseudo-random numbers by Monte Carlo simulations. • Mean lifetime of BLSS was 19112.37 days under normal operation and maintenance. [ABSTRACT FROM AUTHOR]

Abstract: Human space exploration is at a turning point which should find its outcome during the coming decade: Shuttle is being retired, ISS will be exploited up to 2020 minimum. Today the US exploration plans are sucked down into political battles, Europe and Japan are nearly nowhere, Russia''s plans are hazy, China''s ambitions are clear and implemented, and new actors such as India are raising their profile. In this uncertain environment, the question might be asked: who will be the leaders of human space exploration in 10–15 years from now? The assumption of the paper is that some key enabling factors are essential for a country to play a substantial role in human space exploration: [–] There should be some long term political stability or continuity [–] The domain should be high in the political agenda of the country''s decision makers [–] The global budget environment of the country should be positive [–] Space should not be too much competed by other budget “catchers” The paper will propose a tentative comparison of the main space faring countries plans, ambitions and likely positioning, for human space exploration. Starting from the today situation and recent past evolutions, we will try to establish future trends for these key factors, and through that to identify which countries might be the most dynamically engaged in human space exploration. [Copyright &y& Elsevier]

China has tremendous coal fields in its Northern regions. Not all of them are accessible for mining yet despite the fact, that China is the world''s largest coal producer (about 1 billion tons annually). Many coal seams are reaching the surface and show self-ignited fires of considerable extension. Furthermore, fires occur in mines or in the underground. 56 areas of large fires are known to the Chinese authorities and numerous small ones exist in addition.Due to the vast dimensions of some burning coal fields, extinguishing the fires requires a huge effort. Besides the economic losses caused by burning coal (more than 20 million tons p.a.); 3 to 5 times of this amount is heavily affected by the fire and is therefore of no economic use. The environmental impact regionally and globally must not be neglected. It has been estimated by Chinese scientists that the carbon dioxide produced by these uncontrolled fires contributes with approximately 3 % to the Chinese CO2 production.Spaceborne remote sensing offers important information such as digital elevation models(DEMs) as basic data for geologic formations and routes for access to burning areas, such as hot spot detection for fire assessment, such as land use classification and deposit estimation, such as estimation of environmentally harmful gases. Multitemporal measurements (e.g. differential SAR interferometry) offer a measure for ground subsidence and estimations of burned coal volumes. Furthermore, it is an efficient means for an early warning system of new fires.In the paper, examples of burning areas will be shown and some relevant computed DEMs. Furthermore, some land use data and some infrared data will be presented. The application of these data for other involved disciplines like modelling of the geologic vicinity surrounding the burning coal seams, analysis and modelling of the fire and its 3-dimensional propagation also based on ground and underground air (oxygen) supply (chimneys) will be mentioned.Based on these models, the best method for extinguishing the fire under observation may be derived as well as methods to prevent new self ignition by oxidation processes. But this will not be covered in the paper. [Copyright &y& Elsevier]

Abstract: The history of spaceflight would not have been possible without a single object, the rocket—one of the most complex engineering feats in human history. However, a closer examination of the earliest history of the basic rocket, a gunpowder-propelled device developed in China around 900 years ago, suggests that it originated as an accidental discovery rather than as a deliberately planned invention. This paper will examine the evidence in support of the idea of accidental discovery, including new observations on the earliest concepts of rocket motion, not only in China but also in the West. [Copyright &y& Elsevier]

Abstract: Russia is a strategic partner for Europe, in particular in its space endeavour. However, in the past decade the Russian partner has significantly changed. Strengthened by a better economic situation, Russia is now reasserting strong ambitions, and its leadership aims to reaffirm the country''s position on the international scene. As a result, Russia''s international partnerships in the space field have evolved and the country has recently intensified relationships with China and India. This development has the potential to strongly impact Europe, its space activities and the relations between all those actors. This paper investigates the relations between Russia, India and China, their possible evolution and the consequences for Europe. It evaluates the potential impact on Europe''s space activities and on its cooperation with the Russian partner. It concludes with recommended actions to be taken by European decision-makers in order to maximise opportunities and minimise risks in this changing environment. [Copyright &y& Elsevier]

Abstract: For the attitude stabilization of networked flexible spacecraft during large angle slew maneuver, a novel type of adaptive fuzzy sliding mode control (AFSMC) method for solving the dynamic model with network-induced delay, nonlinear and uncertain parameters is proposed in this paper. A novel and systematic sliding mode control (SMC) scheme, which integrates a time-advanced nonlinear predictor, is proposed to compensate for the network-induced delay and to overcome the negative effect of uncertainties. Then, an adaptive fuzzy system is used to approximate the strong coupling nonlinear dynamics between rigid hub and flexible appendages. Following that, the designed adaptive algorithms are developed in the sense of the Lyapunov stability theorem, so that system-tracking stability can be guaranteed. Finally, simulation results show that, with the application of the proposed method, not only high-precision attitude stabilization of flexible spacecraft is achieved, but also the elastic vibration of flexible spacecraft during maneuver is suppressed effectively, and the system is robust against system uncertainties, network-induced delays and any outer disturbances. [Copyright &y& Elsevier]

Abstract: At 9:00am October 15, 2003, Shenzhou 5, with China''s first astronaut Yang Liwei onboard, was launched into space on a LM-2F rocket from the Jiuquan Satellite Launch Center. After 21 hours and 23 minutes’ flight, the return module landed on the grasslands in central Inner Mongolia at 6:23am October 16. China''s first manned space flight achieved a complete success. This paper will briefly introduce the Shenzhou spaceship and its development. The further development of China manned aerospace technology is also mentioned. [Copyright &y& Elsevier]

Abstract: China plans to implement its first lunar exploration by 2007. The mission objectives are: obtaining the lunar surface three-dimensional stereo image; analyzing the distribution of the useful elements and estimating their abundance, surveying the thickness of lunar soil and evaluating resource of He-3, exploring the environment between the Moon and Earth. To achieve the above mission goals, five kinds of scientific instruments are chosen as the payloads of the lunar satellite. These include stereo camera and Sagnac-based interferometer spectrometer imager, laser altimeter, microwave radiometer, gamma and X-ray spectrometer system and space environment monitor system. In order to collect, process, store and transmit the scientific data of the payloads a special payload data management system (PDMS) is also included. In this paper, the goals of Chinese first lunar exploration and the payloads of the lunar satellite are described in detail. [Copyright &y& Elsevier]