This apparatus distributes dust (typical of the Martian surface) in a uniform fashion on the surface of multiple samples simultaneously. The primary innovation is that the amount of dust deposited on the multiple surfaces can be controlled by the time that the apparatus operates, and each sample will be subject to the same amount of dust deposition. The exact weight of dust that is added per unit of sample area is determined by the use of slides that can be removed sequentially after each dusting.

Schematic depiction of the Dusting Apparatus. Dust is placed in central reservoir (orange container). The impeller on the bottom (blue) creates an air/dust suspension, which rises slowly (red arrows) in the tube surrounding the reservoir. The suspension settles on the coupons (yellow) below.
The objective was to produce the same weight of dust per unit sample area on each of eight samples that were part of an apparatus that measured the effective radiative emittance of dust-coated surfaces. The uniformity of dust deposition across all the samples was to be maintained as additional layers of dust were added. The unique nature of this problem is that the dust deposition was required to be spatially uniform on each sample, and deposited equally on all samples subjected to the dusting process. The dusting device also had to be movable so that after a dust layer is applied, the device could be removed and the samples could remain stationary in the experimental apparatus. In this way, the dust layer was not disturbed throughout the course of the experiments.

The dusting device comprises three parts: an aluminum sample table on which the samples are placed, a Plexiglas aerator tube that contains a fan and the dust aerator, and a chamber top for containment. The table supports the chamber top and the aerator tube as dusting is performed. The tube and the chamber top are removed after each dust layer is applied.

Test samples are arrayed uniformly around the table and the hole in the center admits the aerator tube and assures repeatable vertical alignment. A groove around the periphery of the table allows repeatable alignment of the chamber top with the table. Microscope slides are placed between samples on the table so that once dusting has been performed, they can be removed and weighed to determine the weight of dust per unit area added to the samples. As additional dusting is done, additional slides are removed and weighed so that the amount of dust that accumulates with multiple dustings can be determined.

This work was done by Kathryn Miller Hurlbert of Johnson Space Center, and Larry C. Witte and D. Keith Hollingsworth of the University of Houston. MSC-23944-1

NASA Tech Briefs Magazine

This article first appeared in the January, 2012 issue of NASA Tech Briefs Magazine.

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