Advances in Astronautics Science and Technology最新文献

Manned lunar exploration missions require thousands of tons of launch vehicles to deliver astronauts and a small number of payloads to the lunar surface. To improve the system performance of manned lunar exploration missions, an analysis is conducted at the system level, including the design concepts, design methods, model optimization, and data correction. The proposed technologies include probability-based systems design, integrated design of spacecraft and launch vehicle, optimization design based on digital models, and system performance improvement based on measured data correction. Based on the practice of the systems design of manned lunar exploration missions, the application effects of these technologies are summarized, and the direction for future research is pointed out. These technologies play an important role in improving the system performance of manned lunar exploration and maximizing the efficiency.

The purpose of this study is to report the numerical investigation on the aerodynamic performance of tangent ogive wedge of varying fineness ratio from 2 to 4 when fully submerged in an incoming supersonic airflow having a velocity of Mach 2.5 and at zero degrees angle of attack. Numerical simulations have been carried out for flow over tangent ogive wedge using ANSYS CFD. A computation domain was created with appropriate geometrical constraints and was meshed into elements of optimum size. The supersonic airflow was simulated to observe and analyze the effects of change in fineness ratio of tangent ogive wedge on various aerodynamic parameters of interest under given boundary conditions and flow physics. It was observed that tangent ogive wedge with increasing fineness ratio experienced decreasing pressure drag force. The nature of shock generated for various tangent ogive wedge has been compared to understand airflow/shock interactions. The presented study revealed the dependency of different aerodynamic parameters on the fineness ratio of tangent ogive wedge, which may be efficiently utilized in missiles, rockets, and bullet design. The reported findings would contribute towards optimizing tangent ogive wedge shapes for supersonic missiles, rockets, and bullets, delivering optimum aerodynamic performance under given operating conditions.

To prolong the service life of satellites, space crawling robots are used for in-orbit services such as inspection and repair. However, the complex structure of the satellite surface requires path planning. Most current path planning algorithms are only applicable to the planar and 3D unconstrained case, and cannot be applied to CubeSat surface with abrupt changes in normal vectors. In this paper, we design a cube unfolding method to reduce the cube surface path planning problem to a planar path planning problem. This is accomplished by obtaining obstacle point cloud data through laser radar and converting the point cloud data into a grid map using the Gmapping algorithm. And considering the limitation of arithmetic power for operations on satellites, this paper uses PSO to solve this planar path planning problem. The experimental results show that the method can be applied to the surface of the CubeSat.

In view of ESA’s horizon goal of establishing a human presence on the Moon by 2040, the Earth’s moon is increasingly coming into the focus of research and industry. Lunar exploration can benefit from systems developed for low-Earth orbit, as the environmental conditions are overlapping. The development of the CubeSat industry in recent decades has led to a revolution in access to near-Earth space. The goal of Neurospace and its partners is to explore the similarities of both environments for a direct application of existing CubeSat technologies for lunar exploration. Using an open standard and a tiered approach for the development of lunar rovers will allow future missions to focus more on the actual use case rather than the individual development, qualification, and certification of required components. This paper introduces the HiveR rover and provides a classification of the future importance of robotic systems for lunar exploration. It also discusses, in review of past lunar missions, how such rovers differ from previous lunar rovers, and how important they can be in supporting increasingly complex missions. The similarities and differences between the low-Earth orbit and the lunar surface are outlined. Based on this, the new challenges in adapting existing CubeSat technologies for robotics on the lunar surface will be discussed and initial solutions presented. As examples of potential payloads, various experiments are presented, such as a robot arm that was developed to fit in a 1 U volume. It can be used for docking operations between individual systems or various tool handling operations.

Cyclically asymmetrically distributed charges introduced to explain a cause of gravity produce significant directed forces for useful safe energy generation, as harnessed by the Electric Kinetic Pulse generator, an experiment to illustrate cyclically asymmetrically distributed charges. This is established by analysing solutions to the equations of motion and energy of 4 charges in the Electric Kinetic Pulse generator, as they alternately move close to and from electric field singularities using repulsion in each of the 4 cylinders; with extensions to several charges. The system is shown to be robust against transverse vibrations. The theoretical validity of the generator and the principles underlying cyclically asymmetrical charge distributions is established. The theoretical verification proposes an iterative process for solving first order differential equations which requires continuity but no separation of variables. Ample useful nuclear energy independent of heat phenomena or the atmosphere can be generated with no harmful radiation or radioactive waste.

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.