Analysis of Key Observational Geometric Parameters for a Moon-Based Earth Observation Multispectral Imager

Utilizing the Moon, the natural satellite, as an Earth observation platform and deploying a multispectral imager facilitates comprehensive observations of the Earth's large-scale phenomenon. In contrast to traditional space-borne platforms, a Moon-based multispectral imager observes the Earth from a long distance, and is directed towards the Earth using a turntable. In addition, the complex Sun-Earth-Moon geometry can also lead to issues with solar intrusion. All these factors pose challenges in the design of observational parameters. In this study, key observational geometric parameters are analyzed. The results indicated that the design of the Field of View (FOV) needs to take into account the maximum apparent radius of the Earth, the modification time interval, and pointing error. To ensure full observation of the Earth under any circumstances, the FOV diameter should be set to no less than 2.4°. During each synodic month, if the smallest angle between the sensor's line of sight and the solar direction falls below 5°, the Moon-based multispectral imager should pause its observations to evade the risk of solar intrusion. The temporal sampling interval is no longer greater than 4 h, and the spatial resolution is recommended not to exceed 20 km at the nadir point. All these findings obtained provide important basis for the design of parameters for the Moon-based multispectral imager.