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Measurements of Lunar Dust Charging Properties by Electron ImpactDust grains in the lunar environment are believed to be electrostatically charged predominantly by photoelectric emissions resulting from solar UV radiation on the dayside, and on the nightside by interaction with electrons in the solar wind plasma. In the high vacuum environment on the lunar surface with virtually no atmosphere, the positive and negative charge states of micron/submicron dust grains lead to some unusual physical and dynamical dust phenomena. Knowledge of the electrostatic charging properties of dust grains in the lunar environment is required for addressing their hazardous effect on the humans and mechanical systems. It is well recognized that the charging properties of individual small micron size dust grains are substantially different from the measurements on bulk materials. In this paper we present the results of measurements on charging of individual Apollo 11 and Apollo 17 dust grains by exposing them to mono-energetic electron beams in the 10-100 eV energy range. The charging/discharging rates of positively and negatively charged particles of approx. 0.1 to 5 micron radii are discussed in terms of the sticking efficiencies and secondary electron yields. The secondary electron emission process is found to be a complex and effective charging/discharging mechanism for incident electron energies as low as 10-25 eV, with a strong dependence on particle size. Implications of the laboratory measurements on the nature of dust grain charging in the lunar environment are discussed.
Document ID
20090033069
Document Type
Conference Paper
Authors
Abbas, Mian M. (NASA Marshall Space Flight Center Huntsville, AL, United States)
Tankosic, Dragana (Universities Space Research Association Huntsville, AL, United States)
Craven, Paul D. (NASA Marshall Space Flight Center Huntsville, AL, United States)
Schneider, Todd A. (NASA Marshall Space Flight Center Huntsville, AL, United States)
Vaughn, Jason A. (NASA Marshall Space Flight Center Huntsville, AL, United States)
LeClair, Andre (NASA Marshall Space Flight Center Huntsville, AL, United States)
Spann, James F. (NASA Marshall Space Flight Center Huntsville, AL, United States)
Norwood, Joseph K. (NASA Marshall Space Flight Center Huntsville, AL, United States)
Date Acquired
August 24, 2013
Publication Date
July 21, 2009
Subject Category
Lunar and Planetary Science and Exploration
Report/Patent Number
M09-0543
Meeting Information
2nd Annual NLSI Science Forum(Moffett Field, CA)
Distribution Limits
Public
Copyright
Other