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Aperture Valve for the Mars Organic Molecule Analyzer (MOMA)NASA's participation in the multi-nation ExoMars 2018 Rover mission includes a critical astrobiology Mass Spectrometer Instrument on the Rover called the Mars Organic Molecule Analyzer (MOMA). The Aperture Valve is a critical electromechanical valve used by the Mass Spectrometer to facilitate the transfer of ions from Martian soil to the Mass Spectrometer for analysis. The MOMA Aperture Valve development program will be discussed in terms of the initial valve design and subsequent improvements that resulted from prototype testing. The initial Aperture Valve concept seemed promising, based on calculations and perceived merits. However, performance results of this design were disappointing, due to delamination of TiN and DLC coatings applied to the titanium base metals, causing debris from the coatings to seize the valve. While peer reviews and design trade studies are important forums to vet a concept design, results from testing should not be underestimated. Despite the lack of development progress to meet requirements, valuable information from weakness discovered in the initial Valve design was used to develop a second, more robust Aperture Valve. Based on a check-ball design, the ETU / flight valve design resulted in significantly less surface area to create the seal. Moreover, PVD coatings were eliminated in favor of hardened, non-magnetic corrosion resistant alloys. Test results were impressive, with the valve achieving five orders of magnitude better sealing leak rate over end of life requirements. Cycle life was equally impressive, achieving 280,000 cycles without failure.
Document ID
20150004062
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Engler, Charles
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Canham, John
(ATK Space Systems, Inc. Beltsville, MD, United States)
Date Acquired
April 2, 2015
Publication Date
May 1, 2014
Publication Information
Publication: The 42nd Aerospace Mechanism Symposium
Subject Category
Lunar And Planetary Science And Exploration
Mechanical Engineering
Distribution Limits
Public
Copyright
Public Use Permitted.
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