AbstractThe Sun mission of the German-US-sunprobe HELIOS-A, the first man-made satellite which approaches the Sun as close as 0.3 AU, covers now more than half a sun-cycle.Therefore the long term behaviour of surface materials which usually are applied on spacecraft as aluminized Teflon, Second-Surface-Mirrors (SSM) made from fused silica and Solar Cells (SC), under extreme stresses and combined loads, shall be evaluated.Based upon the temperature readings of the house-keeping data from HELIOS, a semi-quantitative relationship between the different loads (e.g. radiation, solar wind) and the spacecraft response was established using the results of the first four orbits.From these temperatures, α(t, T)-values were calculated. The related changes of the absorptance values are interpreted in terms of degradation and contamination of the surface materials concerned. Here, not only physico-chemical considerations and models but also the results from thorough ground tests are used to describe the experienced effects by a semi-theoretical function.Taking the derived α(t, T)-values, temperatures are calculated and a long term prediction for 20 orbits is made. The predicted temperature values are compared with the housekeeping data of 15 orbits, i.e. until 1982; the deviations are explained and the validity of the chosen model discussed.


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    Titel :

    Material performance under combined stresses in the hard space environment of the sunprobe helios-a


    Beteiligte:
    Winkler, W. (Autor:in)

    Erschienen in:

    Acta Astronautica ; 10 , 4 ; 189-205


    Erscheinungsdatum :

    1982-12-21


    Format / Umfang :

    17 pages




    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Elektronische Ressource


    Sprache :

    Englisch