Thermal distortion analysis of LEO earth observation satellite
- Paper number
IAC-08.C2.7.11
- Author
Mr. Sun-Won Kim, Korea Aerospace Research Institute, Korea, Republic of
- Coauthor
Mr. Jang-Joon Lee, Korea Aerospace Research Institute, Korea, Republic of
- Coauthor
Dr. Jin-Hee Kim, Korea Aerospace Research Institute, Korea, Republic of
- Coauthor
Dr. Jae Hyuk Lim, Korea Aerospace Research Institute, Korea, Republic of
- Coauthor
Dr. Juhun Rhee, Korea Aerospace Research Institute, Korea, Republic of
- Coauthor
Dr. Do-Soon Hwang, Korea Aerospace Research Institute, Korea, Republic of
- Coauthor
Dr. Ik-Min Jin, Korea Aerospace Research Institute, Korea, Republic of
- Coauthor
Dr. Hak Jung Kim, Korea Aerospace Research Institute, Korea, Republic of
- Year
2008
- Abstract
This paper shows the results of the bus thermal pointing error and safety for strength of structures due to thermal distortion and methodology of thermal distortion analysis for LEO earth observation satellite. The purpose of thermal control subsystem is to maintain all components within the allowable temperature limits for all operating modes using thermal hardware. But the temperature change within the limits leads undesired thermal distortion of satellite structures. Pointing error of payload and AOCS sensors due to thermal distortion makes image quality be degraded. Thermal pointing error is divided into two parts. One is payload thermal pointing error that is pointing accuracy of payload itself with respect to ideal payload reference frame. The other is bus thermal pointing error that is pointing accuracy of payload and AOCS sensors interface with respect to bus reference frame. Each thermal pointing error is allocated considering satellite pointing performance. Also, thermal distortion may cause structure failure. Thermal distortion analysis is performed in following three steps. At first step, thermal analysis is carried out to predict the worst-case thermal distortion expected during on orbit. These distortions occur as a result of the conditions which produce the largest temperature variation during operation. In both cases of hot and cold, temperatures from thermal analysis are extracted in accordance with a constant time step during an orbit. As parameters which affect thermal analysis, operating modes, seasonal variation, orbit and operation time are considered. The analysis model is tuned by thermal vacuum test results for STM (Structural and Thermal Model) to obtain accurate temperatures. At second step, temperatures that are output of thermal analysis are transformed to thermal loads that are input of structural analysis. Thermal analysis model is different from structural analysis model due to different physical aspects. Thus, temperatures from thermal analysis are mapped onto nodes in the FEA model for structural analysis by means of interpolation. After mapping, temperatures at structural nodes are transformed to temperatures at center of elements to apply NASTRAN physical card reflecting temperature gradient to thickness. Finally, structural analyses for worst thermal cases are carried out at each time step. Thermal pointing errors about each satellite axis are calculated by root sum square during an orbit and maximum thermal stresses are checked. In conclusion, we have found that the bus thermal pointing error and strength for designed satellite meet the requirements.
- Abstract document
- Manuscript document
IAC-08.C2.7.11.pdf (🔒 authorized access only).
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