Advances in Astronautics Science and Technology最新文献

The growth of micro-/nano-satellites requires miniaturized sun sensors which could be applied in the Attitude Determination and Control System easily, conveniently and cheaply. In this work, the error compensation methods of a low-cost Analogue Sun Sensor, COSSA, have been innovatively proposed, which mainly includes two error compensation mathematical models and related testing and calibration methods. From theory and engineering perspectives, Error Source Propagation Model and Linear Surface Fitting Model have been built, respectively; then zero-point calibration method and surface fitting calibration method have been illustrated to compensate the measurement error. After testing and calibration experiment, the accuracy of COSSA prototype is better than (0.25^circ ) (1(sigma )), which is 2 (sim ) 4 times higher in accuracy compared with most analogue sun sensors. Therefore, the feasibility and effectiveness of error compensation methods could be well-proved.

Integrating the artificial intelligence into space missions is attracting increasing attention from scholars. This paper concerns on the optimal guidance problem of orbital pursuit-evasion games, and an optimization method based on the deep neural network (DNN) is proposed to improve the efficiency of solution. First, the problem is formulated by a zero-sum differential game model, which transforms the original problem to a TPBVP. Second, we propose an optimization method using a DNN to generate individual guesses for further optimization through a gradient-based local optimization algorithm. Finally, numerical simulation results show that, after training the DNN with samples generated through the traditional method, the proposed optimization method statistically improves the efficiency over the traditional optimization by roughly two orders of magnitude without losing quality, and it is feasible in different cases.

The present study numerically investigates the shock-wave/boundary-layer interactions (SWBLIs) inside a scramjet intake at Mach 4.03. A 2D-planar and an axisymmetric intake are investigated using commercial code ANSYS-Fluent. The density gradient for intakes is computed to investigate and compare the shock cell structure and the separation bubble size. Besides, the velocity and pressure distributions are analyzed for planar and axisymmetric intakes. It is observed from the wall pressure data that the shock strength in the case of axisymmetric intake is lesser than the planar intake. Also, the interaction region in the axisymmetric intake is shifted further downstream with a progressive decrease in shock angle. The recirculation zone or the separation bubble size is minimal for the axisymmetric intake than for planar intake, resulting in higher effective mass flow into the combustion chamber. It can be observed that although the cowl surface experiences the maximum wall static pressure, the recirculation zone formed over the cowl surface is comparatively smaller than that of the ramp surface. The normalized total pressures at the isolator exit indicate that the axisymmetric intake is more efficient in conserving the flow energy than the planar intake. The temperature rise over the ramp surface is higher for planar intake; however, the temperature fluctuations over the ramp surface are more for axisymmetric intake.

At present, terrestrial food sources are used to provision astronauts for engaged in space missions confined to low Earth orbit. However, in the future, long-duration space exploration is planned for the Moon, and, beyond that, to Mars. Food for such extended missions needs a shelf-life of up to 5 years, a sustained nutritional and product quality. Space radiation can impact on such food, but little is known of what impact this could have on these materials. In this study, we evaluated the impact of radiation dosage and accelerated storage on infant milk powder (a formulated product consisting of proteins, fat, lactose, vitamins, and minerals), to evaluate its potential as an indicator for (chemical) space food stability. The milk powder was irradiated at different dosages (0, 2, 10, and 50 kGy) and underwent different storage conditions (20 or 50 °C for 0, 14, 28, 56, and 77 days), with subsequent color measurement and chemical analysis. It was found that γ irradiation had an impact on the milk powder’s color. It was speculated that this change was related to the Maillard reaction. Some changes were also found with the chemical composition, particularly, vitamins A and C, unexpectedly due to their susceptibility to radiation. Notable differences were not observed though for other components (vitamins, fatty acids, and amino acids). We conclude that infant milk powder shows great promise as an indicator of the impact of γ radiation, and accelerated storage, for (chemical) space food stability.

This article presents the systematic design process for a low-cost 6U CubeSat platform, drawing on the experience of the highly motivated Pluto team. The team's success in a national academic CubeSat design competition led to the establishment of a space startup and the decision to develop a 6U platform. The primary motivation for writing this research is to increase access to space and space services by helping startups _especially in underdeveloped countries, design and build a CubeSat with the least cost and effort in the shortest possible time. In the design process, simplicity, reliability, and the possibility of reproduction at the lowest possible cost have been prioritized. Aligned with ECSS standards tailored for CubeSats, the design method parameters of the 6U platform are thoroughly examined. The article highlights the development of a state machine and the justification of design requirements through standard methods and tracking them using RTM and RVTM tables. Effective interface control while using COTS components is emphasized to reduce costs by approximately 50% while ensuring quality and meeting space environment requirements. The architecture of the Pluto platform, comprising entirely of commercial components, is showcased, providing insights into its system characteristics. This systematic design underscores the importance of modularity, affordability, and utilization of COTS components. By sharing their experiences, the Pluto team aims to support space industry startups and inspire innovative CubeSat projects.

International cooperation in commercial space is an effective way to optimise the space industry and maximise the interests of all parties. China’s commercial space industry started relatively late, and China is also actively seeking cooperation. However, some developed countries, including the United States, have strictly controlled the export of space-related goods, technology and services through Missile Technology Control Regime, the Wassenaar Arrangement and related domestic laws. In addition, China’s export control regulations related to the space industry are scattered and lack unified applicable rules, which is not conducive to potential commercial space internationalisation. China needs to establish a comprehensive, scientific and practical legal regime and policy support mechanism for the export control of space-related items. Meanwhile, China should participate more in the international multilateral export control system and break through the bottleneck of international cooperation in commercial space through transparency, mutual trust and reciprocity.

Currently, low-orbit mega-constellations have been fully utilized in military applications, but the standards for using them as military targets are still lacking, and international legal provisions are ambiguous. Existing theories are also unable to clearly define and distinguish the military applications of low-orbit mega-constellations. Whether low-orbit mega-constellations can be used as military targets should be considered from two aspects: whether they violate the principle of neutrality and whether they belong to weapon systems. Since the majority of the holders of mega-constellations are currently private space companies, which are not subjects of international law, the application of the principle of neutrality should be analyzed based on the impact of private company behavior on the neutrality of non-directly belligerent states. Regarding whether low-orbit mega-constellations belong to weapon systems, it should be observed from different application scenarios of mega-constellations and compared with the definition of weapon systems to ultimately define the boundary conditions for whether low-orbit mega-constellations belong to weapon systems in different scenarios.

Structural tests are to gain confidence in the analytical predictions that support spacecraft development, and ultimately to support the qualification and flight acceptance of the spacecraft system. Based on envelopes of real-time launch vehicle data or simulation results, the input level of the vibration test is calculated with a certain safety margin. This conventional approach to vibration test may lead to over-testing problems, which will severely harm the spacecraft at resonance frequencies. To elaborate on the appropriate force input, Multiple DOF dynamic interface forces during the lift-off must be measured. The force sensor, which should be placed between the spacecraft and launch vehicle, is apparently not a good strategy, because it changes the connecting stiffness and strength of the interface between spacecraft and launch vehicle. Accordingly, a novel identification method for dynamic interaction force, based on the strain status of the spacecraft adapter ring, is proposed in the current study. Some special observation locations are selected along the surface of the adapter ring, on which strain rosettes are pasted to measure the local normal and shear strain. During the lift-off, the telemetry strain signal will be gathered to estimate Multiple DOF forces by theoretical analysis combined with ground test results. It is a promising method for future application.

Projects concerning space are hugely valuable to our species. Two notable physical districts are (a) the various orbits local to earth and (b) areas that are more remotely located in the interplanetary and interstellar regions. However, the legacy of decades of human space observation, exploitation, and exploration has not always been positive. Environments have been impacted and key groups have been inconvenienced and even their safety threatened due to the ventures of some actors. If such activity continues, the damage caused to our societies, our local space, and even our outer space might become irretrievable. This paper calls for actors to work with their fellow earthlings to identify and address the negative consequences of space endeavours prior to their eventuation. By employing notions of long-view sustainability, we may visualise how our projects affect not only the environment, but also us, and the legacy that we leave for our future generations.