Metering structures of remote sensing instruments often have large openings or access holes. Shear panels that are X-shaped, such as those proposed for the Neutron Star Interior Composition Explorer (NICER), generally consist of C-channels and L-brackets to minimize structural distortion. This type of metering structure has large openings on the sides. Structural panels that have large access holes, such as those studied for the Landsat Operational Land Imager (OLI), generally consist of aluminum honeycomb panels with composite facesheets. Both types of metering structure require multilayer insulation (MLI) blankets to shield the internal components such as optics from sunlight and Earth albedo, and to minimize heat loss to 3K space by radiation. The issues of conventional MLI blankets for these metering structures include MLI sagging, stray light, and risk of micrometeoroid damage to optics.

An innovative design concept has been developed using black polyimide/Kevlar as the inner cover of MLI blankets for telescope or metering structures in space. It stiffens the MLI blankets so that they do not sag over large openings or access holes in flight. It forms a black enclosure to minimize stray light for the optics, and provides micrometeoroid protection for components inside the metering structure.

This innovation uses a thin (0.2 mm) layer of black polyimide/Kevlar as the inner cover of MLI blankets. This material is a 3-ply laminate that includes black polyimide, 200-gauge polyimide, Kevlar fabric, and adhesive. The black polyimide side of the MLI blankets faces the access holes or openings of the metering structure. Black polyimide has a high solar absorptance (approximately 0.93) and a high hemispherical emittance (approximately 0.82). Its tensile strength is high (about 2,148 kg/cm2), and it stiffens the MLI blankets so they won’t sag over large openings or access holes in flight. Kevlar fabric has been widely used as a bulletproof vest material, and provides protection for components such as optics and detectors inside the metering structure from micrometeoroid damage.

The areal density of black polyimide/Kevlar in this innovation is 222 g/m2. It has no significant impact on the mass of MLI blankets.

This work was done by Michael Choi of Goddard Space Flight Center. GSC-16796-1

NASA Tech Briefs Magazine

This article first appeared in the November, 2015 issue of NASA Tech Briefs Magazine.

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