Impact Research of Drift of the Local Time of Descending Node on the Imagery of CCD Camera

The orbit plane’s orientation of the satellite in sun synchronous orbit relative to the sun is settled, i.e., the local time of descending node (hereinafter named as LTDN) of the satellite is almost steady. The LTDN of earth observing remote sensing satellites such as IKONOS, SPOT, Worldview, ZY-3, VRSS-1 and GF-1 selected 10:30 am. However, the LTDN will shift on account of the influence of many aspects, such as satellite’s orbit injection error. The LTDN shift of domestic remote sensing cameras (CBERS, ZY, GF-1, etc.) is controlled in ±30 min. The deviation of local time will have an impact on imaging quality. Based on the fact, a research and analysis approach of impact on the imaging radiometric quality of CCD camera resulted from the LTDN’s drift is presented. By comparing the calculation results, the impact on remote sensing CCD camera’s imaging can be obtained. The contrasts result shows that the imaging performance in observation period of a year and latitude observation scope restricted by solar altitude angle, and imaging SNR has been improved with the LTDN’s shift towards positive values and has a reduction with the LTDN’s shift towards negative values. The maximum variation in these performance parameters under the condition of the LTDN’s drift in ±30 min can reach about 15 days, 2.2°, and 0.93 dB. Study and analysis result in this paper can give a quantitative reference to the CCD camera’s imaging quality analysis. Meanwhile, it can also provide a data support to the optimal design orbit and the shift control strategy of LTDN in future remote sensing satellite system.