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Adhesion in a Vacuum Environment and its Implications for Dust Mitigation Techniques on Airless BodiesDuring the Apollo missions, the adhesion of dust to critical spacecraft systems was a greater problem than anticipated and resulted in functional degradation of thermal control surfaces, spacesuit seals, and other spacecraft components. Notably, Earth-based simulation efforts did not predict the magnitude and effects of dust adhesion in the lunar environment. Forty years later, we understand that the ultrahigh vacuum (UHV) environment, coupled with micrometeorite impacts and constant ion and photon bombardment from the sun result in atomically clean and high surface energy dust particles and spacecraft surfaces. However, both the dominant mechanism of adhesion in airless environments and the conditions for high fidelity simulation tests have still to be determined. The experiments presented in here aim to aid in the development of dust mitigation techniques for airless bodies (e.g., lunar surface, asteroids, moons of outer planets). The approach taken consists of (a) quantifying the adhesion between common polymer and metallic spacecraft materials and a synthetic noritic volcanic glass, as a function of surface cleanliness and of triboelectric charge transfer in a UHV environment, and (b) determining parameters for high fidelity tests through investigation of adhesion dependence on vacuum environment and sample treatment. Adhesion force has been measured between pins of spacecraft materials and a plate of synthetic volcanic glass by determining the pull-off force with a torsion balance. Although no significant adhesion is generally observed directly as a result of high surface energies, the adhesion due to induced electrostatic charge is observed to increase with spacecraft material cleanliness, in some cases by over a factor of 10. Furthermore, electrostatically-induced adhesion is found to decrease rapidly above pressures of 10-6 torr. It is concluded that high-fidelity tests should be conducted in high to ultrahigh vacuum and include an ionized surface cleaning process.
Document ID
20120014578
Document Type
Technical Memorandum (TM)
Authors
Berkebile, Stephen (NASA Glenn Research Center Cleveland, OH, United States)
Gaier, James R. (NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
August 26, 2013
Publication Date
September 1, 2012
Subject Category
Lunar and Planetary Science and Exploration
Report/Patent Number
NASA/TM-2012-217723
AIAA Paper 2012-3465
E-18434
Meeting Information
42nd International Conference on Environmental Systems(San Diego, CA)
Funding Number(s)
WBS: WBS 780896.04.06.02.03
Distribution Limits
Public
Copyright
Public Use Permitted.

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