Estimation of stray light contamination for current and next generation geostationary ocean color instruments in orbital measurement
- Paper number
IAC-09.B1.I.8
- Author
Ms. Yukyeong Jeong, Global Space Optics Laboratory, Korea, Republic of
- Coauthor
Prof. Sug-Whan Kim, Global Space Optics Laboratory, Korea, Republic of
- Coauthor
Ms. Soomin Jeong, Global Space Optics Laboratory, Korea, Republic of
- Coauthor
Mr. Dongok Ryu, Global Space Optics Laboratory, Korea, Republic of
- Coauthor
Ms. Sun Jeong Ham, Global Space Optics Laboratory, Korea, Republic of
- Coauthor
Mr. Jinsuk Hong, I&A Technology, Korea, Republic of
- Coauthor
Mr. Seonghui Kim, Korea Aerospace Research Institute, Korea, Republic of
- Coauthor
Mr. Seongick CHO, Korea Ocean Research and Development Institute(KORDI), Korea, Republic of
- Coauthor
Dr. Heong Sik Youn, Korea Aerospace Research Institute, Korea, Republic of
- Coauthor
Dr. Sun-Hee Woo, Korea Aerospace Research Institute, Korea, Republic of
- Year
2009
- Abstract
We report extensive modeling and analysis for the current and next generation ocean color instruments. The study is aimed at accurate estimation of stray light contamination caused by the Sun and the extended target area as viewed from the geostationary orbit. The instruments used in the study are GOCI of 140mm in aperture diameter and a next generation ocean color instrument (GOCI-2) of about 300mm in aperture diameter. Both instruments are designed to monitor key ocean environmental parameters around the Korean peninsular, providing 500 m and 200 m in spatial resolution from the geostationary orbit and high S/N of around 1000. During in-orbit measurement operation, these instruments are exposed to very strong sun light illuminating the Earth surface facing the instrument. The instrument aperture is then filled with not only the incident radiance from the target area, but also the stray incident light originated from the vicinity to the measurement target area. In particular, during the calibration measurement in the night time, the satellite tends to look at the Earth night section blocking the direct incident radiance from the Sun. When the sun, earth and satellite configuration is changed during the night or the transition from night to dawn, the strong sun light can contaminate the focal plane with the incident sun light skimming through the earth limb profile. These cause unique stray light problems for the science measurement and calibration operation. In attempt to find the best stray light suppression measure, we built complete 3D optical models of GOCI and GOCI-2. The models are benefitted with realistic optical property data incorporated to each and every optical component surface. A full 3D optical Earth model was also built using high resolution world coastal line data and the Sun was modeled in real scale for both geometric size and radiative power. These components were integrated to form a Monte Carlo ray tracing model for detailed computation of source-to-detector radiative transfer. The stray light levels were then estimated for possible Sun-Earth-payload configurations for science measurement and in-orbit calibration operation. The ray tracing simulation results imply that the stray light level can be increased so as to threaten the achievability of the target S/N ratio in particular sets of orbital configuration parameters. The study presents analysis model building, details of stray light computation and the strategy for strategy for stray light suppression.
- Abstract document
- Manuscript document
IAC-09.B1.I.8.pdf (🔒 authorized access only).
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