# Modeling and Simulation of Sky Survey
## 4 Design of the Model Solving Algorithm
### Overall Arrangement Algorithm
Figure 10: _Cont._

## 6 Discussion

In this paper, we systematically analyze various conditions of the sky survey observation planning task and then establish a multi-objective optimization model with several constraints. An efficient planning strategy is an important part of the sky survey planning mission. If satellites in fixed orbits are left free to observe without observation sequence optimization, this will lead to an extremely low observation efficiency and even fail to meet the observation requirements during the lifetime of the satellite. Thus, the optimization of the sky survey observation sequence is especially important. For small-scale and short-time surveys, there are more mature heuristic algorithms that can solve the problem well. However, for wide and deep sky surveys, the heuristic algorithm seems incompetent and powerless. The core idea of the proposed algorithm is to obtain the prearranged sequence from two perspectives: the inefficient time period and the difficult observation sky area. In order to verify the correctness of the model and the reliability of the algorithm in this paper, a wide and deep sky survey mission with more than a 15,000 deg\({}^{2}\) area over a 10-year period is selected for the experiment, which has an essential improvement over the results of existing algorithms using homemade or small-scale datasets. According to the experimental results, it can be seen that the 10-year observation period Staged Design Algorithm proposed in this paper can complete the effective observation of sky areas and achieve the target of 15,000 deg\({}^{2}\) of sky survey three years ahead of schedule. The important parameters involved in the algorithm, such as the analysis of the inefficiency threshold, are also analyzed. ## 7 Conclusions

To solve the problems of incompleteness and deviation from the actual engineering tasks of existing studies on telescope survey optimization, this paper establishes a multi-objective model with complex constraints based on existing survey planning studies, which are split into observation constraints and orbit constraints, and designs a multi-stage greedy algorithm to solve it. The model is solved by combining the actual design orbit parameters

Figure 10: Presentation of observation results from the first year to the eighth year with parameter \(\tau_{1}=0.7\). of the China Space Station Telescope and the survey objectives. The results show that the 15,000 deg\({}^{2}\) survey target can be completed three years earlier using the Staged Design Algorithm proposed in this paper, indicating that the algorithm can actually improve the survey efficiency. The Staged Design Algorithm proposed in this paper can accomplish the task of wide and deep sky surveys very well, but there are still some improvements for enhancement. In this paper, only a single class of sky survey observations is performed for a single time, and depth observations and extremely deep observations can be considered for future work. In addition, the greedy algorithm is used in the process of prearranging inefficient time intervals and difficult observation sky areas. Although the algorithm reduces the complexity, it does not achieve the optimal observation of short time intervals, and should be further improved in the future by combining it with the algorithm related to Earth observation. Conceptualization, K.H., H.W., W.Z., and Y.X. ; Methodology, K.H., S.H. and W.Z. ; Software, K.H. and W.Z. ; Supervision, H.W., Y.X. and S.H. ; Validation, K.H. and S.H. ; Visualization, K.H., H.W. and W.Z. ; Writing--original draft, K.H. ; Writing--review and editing, K.H. and Y.X. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable. Informed Consent Statement: Informed consent was obtained from all subjects involved in the study. Not applicable. The authors declare no conflict of interest. ## References

* (1) [PERSON]; [PERSON]; [PERSON] SUMSS: A wide-field radio imaging survey of the southern sky. I.