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Significance of Landsat-7 Spacecraft Level Thermal Balance and Thermal Vacuum Test for ETM+ Instrument
Technical Paper
1999-01-2676
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
The thermal design and the instrument thermal vacuum (T/V) test of the Landsat-7 Enhanced Thematic Mapper Plus (ETM+) instrument were based on the Landsat-4, 5 and 6 heritage. The ETM+ scanner thermal model was also inherited from Landsat-4, 5 and 6. The temperature predictions of many scanner components in the original thermal model had poor agreement with the spacecraft and instrument integrated sun-pointing safehold (SPSH) thermal balance (T/B) test results. The spacecraft and instrument integrated T/B test led to a change of the Full Aperture Calibrator (FAC) motor stack “solar shield” coating from MIL-C-5541 to multi-layer insulation (MLI) thermal blanket. The temperature predictions of the Auxiliary Electronics Module (AEM) in the thermal model also had poor agreement with the T/B test results. Modifications to the scanner and AEM thermal models were performed to give good agreement between the temperature predictions and the test results. The correlated ETM+ thermal model was used to obtain flight temperature predictions. The flight temperature predictions in the nominal 15-orbit mission profile, plus margins, were used as the yellow limits for most of the ETM+ components. The spacecraft and instrument integrated T/B and T/V test also revealed that the standby heater capacity on the Scan Mirror Assembly (SMA) was insufficient when the Earth Background Simulator (EBS) was 15°C or colder, and the baffle heater possibly caused the coherent noise in the narrow band data when it was on. Also, the cooler cool-down was significantly faster than that in the instrument T/V test, and the coldest Cold Focal Plane Array (CFPA) temperature achieved was colder.
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Choi, M., "Significance of Landsat-7 Spacecraft Level Thermal Balance and Thermal Vacuum Test for ETM+ Instrument," SAE Technical Paper 1999-01-2676, 1999, https://doi.org/10.4271/1999-01-2676.Also In
References
- Kane, J. FAC Motor Stack Faxed to B. Markham of Landsat-7 Project Science Office Feb. 2 1999
- Landsat-7 Spacecraft to ETM+ ICD, Document 430-11-06-004, NASA Goddard Space Flight Center Geenbelt, MD Mar. 1999
- Markham, B. Landsat-7 Project Science Office, Personal Communication, NASA Goddard Space Flight Center Geenbelt, MD Jan. 1999
- Landsat-7 Mission Operations Center Temperature Data of ETM+ April 15 May 31 1999 NASA Goddard Space Flight Center Greenbelt, MD
- Choi, M. K. Thermal Assessment of Landsat-7 ETM+ Radiative Cooler in Thermal Vacuum Tests and in Flight Paper to be presented at 34th IECEC Vancouver, B. C., Canada Aug. 1-5, 1999 Paper No. 1999-01-2676