A Thermal Method for the Determination of Solar Absorptance and Thermal Emittance of Spacecraft Coatings

Document Number: 932122

Date Published: July 1993

Author(s):
F. Lura - German Aerospace Research Establishment
B. Biering - Institute for Space Sensor Technology
D. Hagelschuer - Research Center Berlin Adlershof

Abstract:
For the determination of the solar absortance \ga\ds and the thermal emittance \ge preferably optical methods are utilized. To these methods belong spectral reflectance \ga\ds and \ge measurements and/or emission measurements (only \ge), whereby for \ga\ds must be measured in the common range 0.3 \gmm to 35 \gmm with an essentially better resolution than 10 nm. Besides so-called integrated reflectance measurements are known, for which special detectors are used, in the above indicated special ranges. These optical measuring procedures are relatively exact. They deliver also information about a perhaps spectral selective behavior of surfaces, however, special measuring equipment is required.

The known thermal (or calorimetrical) methods [1] require, that the test surfaces are in the thermal balance with their environment and at least for the \ga\ds determination a suited solar simulator is required with high constance of the irradiation intensity during the entire measuring phase. Since these measuring phases up to the reaching of the thermal equilibrium are very long, this is a fundamental disadvantage of the thermal method. The work presented in this paper demonstrates possibilities, to neglect for the determination of \ge completely and to shorten the irradiation times for the \ga\ds determination drastically whereby the requirement of long time constance of the solar irradiation intensity does no longer play a dominant role.

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See other papers presented at International Conference On Environmental Systems, July 1993, Colorado Springs, CO, USA, Session: International Conference On Environmental Systems

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