Large aperture space telescope is a significant scientific instrument to achieve high resolution remote sensing and high sensitivity detection. The current approach to space telescope is designed to meet the volume and mass requirements associated with a single launch vehicle, one potential approach that addresses these current challenges and achieves that future is In-Space Assembly. First of all, the development status and technologies of In-Space Assembly Telescope (ISAT) are reviewed, and some typical projects are presented to show the future application. Then, the key technologies involved are analyzed from multiple aspects: large truss structure, robot technologies and lightweight segmented mirrors. On this basis, several potential technical difficulties and challenges in the future are given, which need to be further developed to promote the capability of space technology. Finally, the future development trends and technologies of ISAT are prospected, which may provide a reference for evolution of large aperture space telescope.
The existence of diffraction limits forces optical remote sensing to develop towards a super-large aperture, but it is limited by the production process, manufacturing cost and carrying capacity. Although block expandable optical imaging technology, thin film diffraction imaging, optical synthetic aperture imaging and other technologies have been developed, these technologies have high requirements on process level and control accuracy, and are difficult to implement. Based on the Arago spot, this paper proposes a new ultra-high-resolution imaging technology suitable for space-based optical remote sensing, replacing the traditional optical system with a visor disk to achieve the lowest-cost high-resolution observation. Simulation results show that the visor disk with a diameter of 100 meters is deployed at the Lagrangian point 450,000 kilometers away from the Earth, with a resolution of 2.5 meters, which can achieve high-resolution observations of Earth-Moon space.
The spatial information of high-resolution remote sensing images is more abundant, and the expression of ground object information in detail is clearer. Vegetation is a component of the environment and the most important component of terrestrial ecosystems. Therefore, vegetation information extraction from remote sensing images is particularly significant. This paper takes Shanghai Pudong New Area as the research area, adopts threshold classification method and membership function classification method to extract vegetation information, and introduces normalized vegetation index as feature to extract vegetation information from WorldView-3 satellite remote sensing image. The results show that the accuracy of vegetation information extraction based on membership function classification method is higher. The classification accuracy of typical vegetation area is higher than 90%, and the Kappa coefficient is higher than 0.86, which can significantly reduce the fragmentation caused by classification. At the same time, high-resolution remote sensing images show great potential for the extraction of vegetation information in urban areas.
The research showed the simulation of position error when assembling a reflective mirror of parabolic trough concentrator. The shape of a reflective mirror is like a parabolic cylinder model, relying on the back of the four-point mounted on a special setup, making it unable to move. Therefore, it is of great importance of the machining precision of special bracket. We need to analyze the influence of reflective mirror‘s intercept factor in order to guide the processing precision. It is assumed that each reflective mirror is rigid, we have calculated the intercept factor of reflector with mounting points’ random error of different standard deviation, comparing the simulating results with TRACEPRO. As a sequence, we can approve the feasibility of the algorithm, and give the effect of different random errors on the light-gathering efficiency. On the basis, we provide the machining accuracy of bracket. The simulation results show that when the mounting points’ standard deviation of position error is less than 0.5 mm, the intercept factor of receiver has reached upwards of 92% with 60 mm diameter for receiver, which can satisfy the design requirements.
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