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Proceedings Paper

Potentials of combined in-orbit calibration methods demonstrated by the MOS-IRS mission
Author(s): Horst H. Schwarzer; Karl-Heinz Suemnich; Andreas Neumann; Thomas Walzel; Gerhard Zimmermann; Dirk Hagelschuer
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Paper Abstract

In-orbit calibration is an absolutely necessary and accepted tool to update the pre-flight calibration sets of remote sensing instruments on satellites. Only such a periodical recalibration guarantees the long term quality and accuracy of the data and the reliability of the thematic interpretation. Especially for watching global changes of the ocean coastal zones (phytoplancton, sediments, pollution etc.) using spectroradiometric measurements in the VIS/NIR spectral range we need high radiometric accuracy because of small and often only slightly different signals. The Modular Optoelectronic Scanner (MOS) on the Indian Remote Sensing Satellite IRS-P3 has been showing its capacity in this field for more than 4 years. One reason for this success is the sophisticated in-flight calibration using different methods, first an internal parameter check with lamps and second the absolute recalibration with the sun via spectralon diffusers. These two methods together allow the radiometric recalibration with an uncertainty of ± 0.5% with respect to the initial state and enables us in many cases to recognize which opto-electronical component is responsible for which kind of change in different spectral channels and spatial pixels. Radiation stress, satellite and orbit environment, degradation and surface cleaning effects in vacuum are some items which affect the opto-electronical components in different ways. Comparative investigations of some MOS optical components by experimental simulation of the radiation environment in the 820 km IRS sun synchronous orbit for 1, 2, 3 and 10 years radiation load confirm the in-orbit calibration results. The BRDF of the spectralon sun diffuser, the reflectance of anodized aluminum surfaces and the transmission of the front end quartz window did not change by the radiation stress but the transmittance of the front end optics decreases in the blue spectral region up to 10%. These results will be presented together with the in-orbit calibration results of MOS.

Paper Details

Date Published: 15 November 2000
PDF: 7 pages
Proc. SPIE 4135, Earth Observing Systems V, (15 November 2000); doi: 10.1117/12.494257
Show Author Affiliations
Horst H. Schwarzer, DLR (Germany)
Karl-Heinz Suemnich, DLR (Germany)
Andreas Neumann, DLR (Germany)
Thomas Walzel, DLR (Germany)
Gerhard Zimmermann, DLR (Germany)
Dirk Hagelschuer, DLR (Germany)

Published in SPIE Proceedings Vol. 4135:
Earth Observing Systems V
William L. Barnes, Editor(s)

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