The S1003 Experiment

This is the description from the "Yellow Book", NASA SP-473

Ion-Beam-Textured and Coated Surfaces Experiment (S1003)

Michael J. Mirtich, Jr. NASA Lewis Research Center Cleveland, Ohio

Background

Future spacecraft relying on thermal control surfaces or solar thermal power generation will be subjected to the near-Earth Shuttle enviroment prior to insertion into a geosynchronous orbit. The combined effects of the near-Earth Shuttle enviroment may be synergistic and may cause appreciable degradation prior to geosyncronous-orbit operations. In situ exposure of various candidate surfaces is required to evaluate material, optical, and/or electrical property durability so that a choice of surface materials can be made with respect to optical and or electrical performance, durability, and contamination protection requirements.

Objective

The objective of this experiment is to measure the effects of exposure to the Shuttle launch and near-Earth space enviroments on the optical properties of ion-beam-textured high-absorptance solar thermal control surfaces, the optical and electrical properties of ion-beam-sputtered conductive solar thermal control surfaces, and the weight loss of ion-beam-deposited oxide-polymer films.

The various types of surfaces to be tested include six major categories: (1) ion-beam textured high absorptance solar thermal control surfaces suitable for space solar-thermal (solar concentrator) application (e.g., materials such as copper, aluminum, Inconel, stainless steel, and silver); (2) painted and/or state-of-the-art solar thermal surfaces (e.g., black chrome); (3) ion-beam-sputtered conductive coatings for thermal and space charge control (e.g., indium-oxide-coated metalized FEP Teflon); (4) ion-beam-sputtered conductive coated solar sail materials for space charge control and cooling through emittance (e.g., sputtered coatings on Kapton such as indium-oxide, aluminum, and chromium); (5) micrometeroid-sensitive samples whose optical properties change only as a result of micrometeroid impact; and (6) Kapton coated with oxide-polymer films to minimize oxygen degradation at near-Earth orbit altitudes.

The objective for the first two categories of samples is to verify that the optical properties of the microscopic cone or ridge-type ion-beam-textured surfaces are more resistant to degradation than conventional solar thermal surfaces. The objective for the third and fourth categories of samples is to evaluate the electrical the electrical and optical durability of conductive coatings for thermal control and solar-sail radiative cooling applications. The objective for the fifth-category sample is to identify changes in the optical properties which can be attributed to micrometeroid impact. The objective for the sixth category is to measure any changes in optical or material properties of oxide-polymer-coated Kapton after exposure to the oxygen atom enviroment in near-Earth (Shuttle) orbit.

Approach

The experiment approach is to passively expose the samples to all enviroments of the entire mission. The optical properties (absorptance and emittance) of each surface will be measured in ground tests both before and after exposure to the enviroment. This will be done by experimentally measuring the spectral reflectivity between 0.33 and 2.16 mm using Gier-Dunkle integrating sphere to obtain the solar absorptance. The emittance will be obtained by measuring the spectral reflectance in the infrared between 1.5 and 15.5 mm using a Holraum reflectometer.

Electrical conductive coatings will be resistance documented before and after the LDEF flight. Comparisons will be made between the durability of the painted surfaces and the ion-beam-textured or sputtered surfaces. Additional tests, including weight loss. Auger and SEM measurements and/or chemical analyses may also be performed as the data warrants.

The experiment requires one-sixth of a 3-in.-deep peripheral tray. Figure 29 illustrates the experiment configuration and table 9 lists the samples that will be tested.
Figure 29.-Ion-beam-textured and coated surfaces experiment.

Klaus G. Paul, 6-20-1994