Abstract All currently considered solar sail designs require the deployment of a thin reflective membrane. This membrane is stowed using some folding technique and sometimes coiled onto a spool. The temperature of the deployed sail membrane is a critical aspect for solar sail design. Depending on the geometry of the imprinted folding lines, sunlight may be reflected inside folding lines which would locally increase the temperature of the membrane. The analysis presented here aims for a quantification of that temperature increase. Microscope images of a 7.5 μ m thick polyimide membrane reveal the geometry of folding lines for different tensioning states. In addition, the opening of folding lines are analysed with a finite-element beam model. After the determination of the geometry as a function of the tensioning state, it is analysed how many reflections may appear in a folding line depending on its opening angle for a sail that is oriented perpendicular to the Sun. Two cases are investigated, deep space and low-Earth orbit. It is shown that, even for small tensioning states, the membrane geometry does not allow more than only two reflections. Depending on the material, this can cause a slight temperature increase that also depends on the investigated case (deep space or low-Earth orbit).

中文翻译：

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折叠太阳帆膜的温度升高

摘要目前所有考虑的太阳帆设计都需要部署薄反射膜。这种薄膜使用一些折叠技术存放，有时盘绕在卷轴上。展开帆膜的温度是太阳帆设计的一个关键方面。根据压印折叠线的几何形状，阳光可能会在折叠线内反射，这会局部增加膜的温度。此处介绍的分析旨在量化该温度升高。7.5 μm 厚聚酰亚胺膜的显微镜图像揭示了不同张力状态下折叠线的几何形状。此外，使用有限元梁模型分析折叠线的开口。在确定几何形状作为张紧状态的函数后，根据垂直于太阳方向的帆的张开角度，分析了折叠线中可能出现的反射次数。调查了两种情况，深空和近地轨道。结果表明，即使对于小的张紧状态，膜的几何形状也不允许超过两次反射。根据材料的不同，这可能会导致轻微的温度升高，这也取决于所研究的情况（深空或低地球轨道）。