Remote Emissivity Measurement System for Spacecraft Materials Testing

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Space Technology The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws. OBJECTIVE: Develop a spectral emissivity measurement system for evaluating thermal control material responses to a simulated space environment. DESCRIPTION: The space environment can induce optical property changes in spacecraft thermal control materials. These changes must be characterized in order to evaluate system performance. A spectral emissometer is desired for integration into a cryogenic vacuum space simulation chamber. This emissometer must be capable of measuring emissivity with the samples installed inside the vacuum chamber. Current methods require attaching temperature instrumentation, which is challenging for some materials and test parameters, or require close proximity to the measurement sample. An emissometer is required that can acquire data at a distance from the samples, up to 3 meters. The system can be vacuum compatible and installed inside the chamber or installed outside the chamber with a provided window as the optical interface. The system should be able to measure spectral data from approximately 2 to 14 micrometers ( m) for samples with emissivity ranging from 0.2 to 0.95. Several systems exist in the chamber to help facilitate emissivity measurements. The chamber walls are designed for low infrared reflection and emission. An in-chamber blackbody source can be utilized as a reference. Non-contact heating of the samples is achieved with existing chamber systems. The ability to measure or estimate sample temperature can be challenging dependent on the type of material. The system should be designed to measure emissivity without knowledge of the sample temperature. Interference from other radiation sources and diagnostic systems is not expected. PHASE I: Demonstrate a proof-of-concept system that can measure emissivity at one infrared wavelength (between 2-14 m) on a 5 cm^2 sample at a distance of 1 meter. Feasibility of extending the measurement range to 3 meters should be considered. The demonstration should include measurements at temperatures ranging from 25 to 500 degrees Celsius). Methods to integrate the system to a vacuum chamber should be considered. PHASE II: Demonstrate a proof-of-concept system that can measure emissivity between 2-14 m on a 1 cm^2 samples at range of 2-3 meters. The system should have the ability to measure emissivity at a variety of elevated sample temperatures ranging from 25 to 200 degrees Celsius. The system should be integrated to a vacuum chamber for the demonstration. PHASE III DUAL USE APPLICATIONS: Phase III may involve follow-on non-SBIR/STTR funded R&D or production contracts for products, processes or services intended for use by the U.S. Government. Military applications could include population of space situational awareness materials databases and signature models and measurement of aircraft paints and coatings. Commercial applications could include building and construction material design and solar power material performance. REFERENCES: 1. Arnold Engineering Development Complex Test Capabilities Guide, Space Test Branch , pg. 8-10, https://media.defense.gov/2021/Jun/23/2002747597/-1/-1/1/2021%20TEST%20CAPABILITIES%20GUIDE.PDF; 2. J. R. Markham, K. Kinsella, R. M. Carangelo, C. R. Brouillette, M. D. Carangelo, P. E. Best, and P. R. Solomon Bench top Fourier transform infrared based instrument for simultaneously measuring surface spectral emittance and temperature, Rev. Sci. Instrum. 64, 2515 (1993).; 3. A. R. Ellis, H. M. Graham, Michael B. Sinclair, J. C. Verley, "Variable-angle directional emissometer for moderate-temperature emissivity measurements," Proc. SPIE 7065, Reflection, Scattering, and Diffraction from Surfaces, 706508 (29 August 2008); https://doi.org/10.1117/12.796507; 4. Adibekyan, et al., "Emissivity Measurements Under Vacuum in the Wavelength Range from 4 Microns to 100 Microns and Temperature Range from -40oC to 500oC at PTB , AMA Conferences 2013; 5. Markham, et al., FT-IR Measurements of Emissivity and Temperature During High Flux Solar Processing , Journal of Solar Energy Engineering, Vol. 118, pp. 20 29, February 1996 KEYWORDS: Emissivity; Thermal Control; Spacecraft; Space Environment; Space Simulation