Integrated analysis of FORMOSAT-5 remote sensing instrument in space

FORMOSAT-5 is the first space program fully developed by National Space Organization (NSPO). The Remote Sensing Instrument (RSI) will provide spatial resolution of 2 meters in panchromatic band and 4 meters in multi-spectral bands. The optical system is composed of two reflective aspheric mirrors and spherical corrector lens set. CFRP structure is used for the optomechanical system to reduce mass. Although the telescope system can be well aligned on ground, the space thermal environment can result in thermal distortion of telescope system and impact the final image quality. Flight predictions of FORMOSAT-5 RSI were done to get the quantitative thermal distortion of mirrors and structural system. The system optical performance, i.e. MTF, was also derived by the optical model with the input from thermal distortion results, i.e. Zernike polynomials. RSI performance in space is location-dependent. Detailed analysis results and discussions are revealed in this paper.