Advances in Astronautics Science and Technology最新文献

In this paper, the spectral characteristics, performance of spaceborne radiation source, in orbit infrared radiometric calibration method and radiance data generation process of the Medium Resolution Spectral Imager (MERSI) of FY-3C satellite are introduced. The land surface temperature of typical areas is inversed using the radiometric calibration data. The nonlinear radiometric calibration method for the long wavelength infrared channel with wide spectrum is discussed, the cold space and on-board radiometer count values are obtained independently in each scanning cycle of the instrument, and the infrared channel in orbit calibration calculation is carried out. According to the infrared radiation calibration results, the single channel method is used to retrieve the land surface temperature. The calibration and inversion results provide an important basis for FY-3C/MERSI in orbit performance evaluation.

Ground tests of spacial mechanical products have the characteristics of few test subsamples and expensive test cost, which often appear the cases of zero-failure samples. The classic reliability evaluation methods cannot adapt to the reliability assessment needs of small subsamples and zero-failure samples for high-reliability, long-life spacial complex mechanical products. The characteristics of failure rate functions of typical mechanical products such as mechanical structure, motors, bearings, gears, valves, and so on have been analyzed. Then the reliability evaluation methods of spacial complex mechanical system have been deduced, which has been combined the prior data of Bayesian method. Bayesian posterior distribution function of exponential distribution has been established by the method, which makes use of uniform distribution as a prior distribution, and combines with the convex characteristics of exponential distribution’s failure rate. Bayesian posterior distribution function of exponential distribution has been utilized in products, such as motors, valves, etc., which have characteristics of presenting exponential distribution. The evaluation range of accumulative failure-rate has been reduced by making use of accumulative failure-rate and predicted failure rate of exponential distribution And the weighted least-squares method has been used in parametric fitting based on accumulative failure-rate Then high-precision estimated failure rate of exponential distribution has been obtained. In this paper, the calculation example of compressor filled with spacial propellant has verified the feasibility of the calculation method. The problems of the reliability tests’ few subsamples and evaluating efficiency for expensive, complex spacial mechanical products have been solved effectively by the above proposed method.

With the focus on docking and separation technology for on-orbit servicing, a novel docking mechanism designed for a modular satellite offers a highly effective approach for on-orbit satellite servicing and assembly. This paper introduces its principle and composition, the results of two kinds of tolerance mechanism and its simulation are given, and the conclusion that the two-valve tolerance mechanism is more suitable for allogeneic connection separation device is obtained. Finally, the prototype verification of the two-valve tolerance mechanism is introduced, and the conclusion to meet the requirements of the index is drawn.

With Kane dynamics theory, the multi-body dynamic models of deployable struts are established with considering the clearance root-joint and the deployable style and deployable process of the struts are studied. The dynamic performance of struts’ deployment is analyzed, such as geometric position, velocity, and acceleration, seeking the inherent regularity of each joint’s motion characteristics. The results show that root-joint’s clearance has almost no influence on the rotation angle and angular velocity of base strut, but to some extent effect on the angular acceleration of base strut. Amplitude of angular acceleration appears significant fluctuations in 0–2 s and stabilizes gradually, indicating the pin in the bush is in the state of constant contact and separation. The dynamic model of deployable struts considering root-joint’s clearance represents more realistically the dynamic characteristics of this system. The different hinges suffer different contact forces, and its impact how effects on the mechanism movement is different. Therefore, Analysis of the dynamic performance and design of deployable struts need to consider the impact of hinge clearance, which gain the motion characteristics of important parts during deploying process, providing guidance for future design of mechanisms and driving forces.

The Large Envelope Advanced Parachute System (LEAPS) is developed as a means of recovering the flight data to prove that a student-built sounding rocket, Stratos IV, has reached space. Several design modifications are outlined in this work. The drogue parachute is deployed using a hot gas deployment system to save mass and volume and to increase reliability. The main parachute has been changed to a Disk-Gap-Band parachute as it is better testable in the Open Jet Facility, a subsonic wind tunnel of Delft University of Technology. A heat shield is included to protect the parachute system during atmospheric re-entry. The key benefit of this work is creating a reliable and supersonic parachute recovery system for the safe recovery of flight data located in the sounding rocket's nose cone.

In this paper, a kind of micro–nanosatellite electromagnetic docking device is designed and a configuration of electromagnet with iron-core is proposed. Compared with the coreless coil, the electromagnetic force within the docking range can be significantly increased. To resolve the problem of limited capacity of electromagnet attitude correction, a type of taper hole–taper rod matching mechanism is designed to limit non-docking axial motion for docking in electromechanical coordination. Through the ground experiment, the function of electromagnetic docking device is verified.

To accurately determine the loads and energy absorption capability, which plays a vital role in the design and optimization process of a new landing gear system for a lunar lander, a new approach of landing impact dynamic analysis using nonlinear finite element method is developed. Abaqus/Explicit is selected to simulate the soft-landing event for its excellent nonlinear, transient dynamics capabilities. The aluminum honeycomb shock absorber model is established by plastic crushable foam material model and the lunar soil is built by Drucker–Prager/Cap material model. Finally, the load at connector between structure and landing gear and acceleration response of structure and dissipated energy by the shock absorber and lunar soil are presented.

Large cracks may occur in the pressured module under the impacts of micro-meteors and space debris during orbit, which may cause rapid instable extension of cracks under the internal pressure load. To reduce the risk, the design criterion of crack stop is put forward, and the mechanism of fracture extension, simulation analysis and test verification method are studied. At the same time, the critical crack length and the influence of different parameters on it are obtained by the analysis and test of a typical integrally stiffened structure. It is proved that the structure design of the integrally stiffened structure for a spacecraft has a good crack stop performance.

The orbital replacement unit and its core technology are the technical basis for the future spacecraft to achieve acceptable on-orbit service and support expansion and upgrading. It can realize on-orbit replacement, replenishment of consumables and other operations, effectively extend the service life of the target spacecraft and maintain the continuity of the mission. In this paper, the mechanical structure of the three-jaw docking interface has been taken as the object and designed the docking interface of the orbital replacement unit which is not mainly dependent on the mechanical arm insertion. The dynamic performance of the docking process was simulated as well. The research work can provide a reference for the design and application of the orbital replacement unit.

The dynamic characteristics of a large deployable support arm with uncertain parameters are studied. Due to the processing, manufacturing and other reasons, uncertainty is common in the actual structure, especially for the main bearing structure of high-precision imaging, the uncertainty becomes an important influence that cannot be ignored. In this paper, the modified perturbation method is used to study the change in the structural dynamic characteristics when the elastic modulus of the support arm has a small parameter variation, and the Monte Carlo simulation is used to verify the comparison. The natural vibration characteristics of the support arm structure are measured from the perspective of the statistical characteristics of probability.