Temperature increase on folded solar sail membranes

Advances in Space Research, vol. 67, pp. 2688–2695

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 7.5μm 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).

Authors 2

1. Patric Seefeldt corresponding

   Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

   Affiliation as printed

   Institute of Space Systems, German Aerospace Center (DLR), 28359 Bremen, Germany

2. Bernd Dachwald Aachen Faculty of Aerospace Engineering

   FH Aachen

   Affiliation as printed

   Faculty of Aerospace Engineering, FH Aachen University of Applied Sciences, 52064 Aachen, Germany