In this paper, we concern multi-objective mission planning problem of a constellation of the next generation agile Earth-observing satellites. As usual, the goal of Earth-observing satellite mission planning is to maximize the sum weights of selected tasks. But for agile satellites, based on its stronger ability, single criterion is often a poor measure of planning results. For agile satellite, the starting times of the observations are free, different starting time to observe brings different image quality. Meanwhile, for a constellation of satellites, some of them are used frequently and the others are used scarcely may be bad way of usage. The good planning solution is to arrange the satellites reasonably to take images as many as possible with good quality and satisfy different users. We give four criteria to evaluate scheduling results: the sum of weights, average image quality, balance usage of satellites and selected task numbers. A multi-objective evolutionary algorithm is designed to solve the problem. Experimental results suggest that multi-objective mission planning produce good quality of planning result and our algorithm works well for the multi-objective mission planning problem of agile satellites.

Mission planning problem for remote sensing satellite imaging is studied. Firstly, the time constraint satisfaction problem model is presented after analyzing the characteristic of time constraint. Then, An optimal path searching algorithm based on the discrete time window is proposed according to the non-uniqueness for satellite to mission in the visible time window. Simulation results verify the efficiency of the model and algorithm.

No abstract

Doppler Centroid Analysis (DCA) technique is one of the major techniques that do permit a direct retrieval of ocean surface velocity from synthetic aperture radar (SAR) data. However, azimuth ambiguities in the SAR images severely restrict the capability of DCA technique to obtain accurate ocean surface Doppler velocities. Therefore, it is necessary to investigate how the azimuth ambiguities impact the Doppler velocity estimation performance and to evaluate how significant the impact is. In this paper, a model for ocean surface Doppler velocity estimation affected by azimuth ambiguities is developed resorting to jointly circular Gaussian processes, and its statistic is derived. The impact of azimuth ambiguities on Doppler velocity estimation performance in terms of Doppler centroid estimation bias and the standard deviation of Doppler centroid estimates is analyzed. The theoretical results are validated through simulation and Doppler velocities retrieved from Chinese Gaofen-3 (GF-3) SAR Doppler centroid estimates affected by azimuth ambiguities. This study will help researchers better understand the impact of azimuth ambiguities on Doppler velocity estimation, and will provide a theoretical reference for subsequent research on how to reduce the impact of azimuth ambiguities more effectively.