Optical and Mechanical Properties Determined of Polymer Film Samples Exposed on the Materials International Space Station Experiment (MISSE) 1 and 2

Polymer films used on spacecraft multilayer insulation, sunshields, and electrical wiring insulation and those proposed for use on advanced inflatable and deployable spacecraft structures are particularly vulnerable to the degrading effects of the space environment. The NASA Glenn Research Center developed the Polymer Film Thermal Control (PFTC) Experiment and the Gossamer Materials Experiment, which collectively included 31 samples flown as part of the Materials International Space Station Experiment (MISSE)on two passive experiment carriers (PECs) referred to as MISSE 1 and MISSE 2. The MISSE 1 and MISSE 2 PECs were deployed on the exterior of the International Space Station (ISS) on August 16, 2001, and were retrieved on July 30, 2005. Each of the suitcase-sized PECs contained two exposure faces, or “trays.” When the PECs were deployed on the ISS, each PEC had one tray that was nominally exposed in the ram-facing direction and received atomicoxygen (AO) exposure and one tray that was nominally facing the wake direction and was intended to receive no AO.

MISSE 1 (upper left) and MISSE 2 (right) on the exterior of the ISS Quest Airlock.

The photograph shows the MISSE 1 and MISSE 2 PECs installed on the exterior of the ISS. Development of the PFTC and Gossamer Materials Experiments is described in detail in reference 1. Samples consisted of polymer films with or without front-side and/or back-side coatings. Polymers included polyimides Kapton HN (DuPont), Kapton H (DuPont), Kapton XC (DuPont), and Upilex-S (Ube Industries, Ltd.); fluorinated polyimide LaRC-CP1 (NASA); Teflon fluorinated ethylene propylene (FEP, DuPont); poly-p-phenylene polybensoxazole (PBO); and polyarylene ether benzimidazole TOR-LM (Triton Systems, Inc.).Coatings are described in the following table.

Following retrieval of MISSE 1 and MISSE 2, after approximately 4 years of space exposure, samples from the PFTC and Gossamer Materials Experiments were analyzed for changes in optical properties, mechanical properties, atomic oxygen erosion, and contamination. The samples flown on the PFTC and Gossamer Materials Experiments were analyzed during fiscal year 2006 both in-house at Glenn and through a contract with the University of Dayton Research Institute. Full details on the PFTC and Gossamer Materials Experiments exposure conditions, observations, and results are provided in reference 2, and results are briefly summarized here.

According to Kapton H erosion measurements, the AO-facing MISSE 2 PFTC Experiment tray experienced an atomic oxygen fluence of approximately 8.5×10²¹ atoms/cm². The non-AO trays actually experienced some exposure to atomic oxygen because of maneuversof the ISS during its mission. Erosion measurements of Kapton HN on the MISSE 2 non-AO-facing tray indicated an atomic oxygen fluence of approximately 2×10²⁰ atoms/cm². Contamination analysis of aluminum oxide witness coupons indicated approximately 1-nm-thick silica contamination on the AO-facing MISSE 2 tray and greater than 10-nm-thick silica contamination(total contaminant thickness of 25 nm) on the non-AO-facing MISSE 2 tray.

Mechanical properties data and optical properties data for these experiments are provided in the following tables. Sample descriptions in the tables indicate coating and polymer layers separated by a slash (/) in order from closest to farthest from the front, or space-facing, surface. Thickness of the polymer (as-manufactured) is indicated in the sample description.

The most significant degradation observed was for PBO film samples, which were completely degraded following the 4-year mission. This material was observed to have significant surface stress in its pristine condition, which may have played a role in its degradation. Mechanical properties data indicate that all exposed materials, except LaRC-CP1, experienced significantly reduced strength and elongation. The most significantly darkened polymer film was TOR-LM. Most other materials experienced low to moderate solar absorptance changes. Decreased emittance observed for the non-AO-facing polymer samples is evidence of the unplanned AO erosion. The results of the PFTC and Gossamer Materials Experiments are directly applicable to low-Earth-orbit spacecraft applications.

References

1. Dever, J.A., et al.: Exposure of Polymer Film Thermal Control Materials on the Materials International Space Station Experiment (MISSE). AIAA-2001-4924(NASA/TM--2002-211363), 2001. http://gltrs.grc.nasa.gov/Citations.aspx?id=1548
2. Dever, Joyce A., et al.: Preliminary Analysis of Polymer Film Thermal Control and Gossamer Materials Experiments on MISSE 1 and MISSE 2. Presented at the 2006 MISSE Post-Retrieval Conference sponsored by the Air Force Research Laboratory, Orlando, FL, June 26-30, 2006. Abstract online: http://www.grc.nasa.gov/WWW/epbranch/other/SpaceDurabilitytitles.html#1

Find out more about the research of Glenn’s Electro-Physics Branch: http://www.grc.nasa.gov/WWW/epbranch/

Glenn contacts:
Joyce A. Dever, 216-433-6294, Joyce.A.Dever@nasa.gov
Sharon K. Miller, 216-433-2219, Sharon.K.Miller@nasa.gov
Authors: Joyce A. Dever, Sharon K. Miller, Edward A. Sechkar, and Thomas N. Wittberg
Headquarters program office: Exploration Systems
Programs/projects: Crew Exploration Vehicle, International Space Station, Space Shuttle, Hubble Space Telescope

Next article

Previous article

Last updated: December 17, 2007

Responsible NASA Official: Gynelle.C.Steele@nasa.gov
216-433-8258

Point of contact for NASA Glenn's Research & Technology reports: Cynthia.L.Dreibelbis@nasa.gov
216-433-2912
SGT, Inc.

Web page curator: Nancy.L.Obryan@nasa.gov
216-433-5793
Wyle Information Systems, LLC

NASA Web Privacy Policy and Important Notices