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The Gaofen-3 (GF-3) satellite is China's first civilian quad-polarized C-band imaging microwave satellite that can provide high-resolution marine and land observations. Also, it is China's first low Earth orbit remote sensing satellite with a design life of eight years. During the design and development of this satellite, many major challenges have been overcome, such as the design of complex radio frequency channels, difficult system integration, high quantitative requirements, and strict component life requirements. In this article, a series of independent technological innovations in the development of GF-3 is presented. Meanwhile, the on-orbit operation of the satellite in the past five years is introduced, as well as the application of satellite data in marine observation, emergency relief, disaster reduction, surveying and mapping, water conservancy, etc. The further advancement and improvements of the GF-3 satellite are described at the end of this article.

The spotlight SAR usually can realize a high resolution image, which needs the beam having the capability of beam scanning. The satellite attitude swing is a way to realize the beam scanning, but this way will cause the attitude jitter, then the image quality of spotlight SAR will be affected. So the effect of satellite attitude error on spotlight SAR is analyzed in this paper. First the paired echo is analyzed, which is caused by the error of satellite attitude, then the effect of attitude jitter on space-borne SAR image qualities is summarized based on the theoretical analysis and computer simulation. The analytical mathematical expression is deduced, which is useful in analysis of attitude stability and SAR image qualities. Moreover, the swing of the satellite antenna phase center is analyzed, and the effect on peak side-lobe ratio and integrated side-lobe ratio is shown. The computer simulations verify the effect of attitude errors on image quality.