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Formation of the lunar helium corona and atmosphereHelium is one of the dominant gases of the lunar atmosphere. Its presence is easily identified in data from the mass spectrometer at the Apollo 17 landing site. The major part of these data was obtained in lunar nighttime, where helium concentration reaches the maximum of its diurnal cyclic variation. The large night to day concentration ratio agrees with the basic theory of exospheric lateral transport reported by Hodges and Johnson (1968). A reasonable fraction of atmospheric helium atoms has a velocity in excess of the gravitational escape velocity. The result is a short average lifetime and a tenuous helium atmosphere. A description is presented of an investigation which shows that the atmosphere of the moon has two distinct components including low energy atoms, which are gravitationally bound in trajectories that intersect the lunar surface, and higher energy atoms, which are trapped in satellite orbits. The total helium abundance in the lunar corona is shown to be about 1.3 times 10 to the 30th power atoms.
Document ID
19780057675
Document Type
Conference Proceedings
Authors
Hodges, R. R., Jr. (Texas, University Richardson, Tex., United States)
Date Acquired
August 9, 2013
Publication Date
January 1, 1977
Subject Category
LUNAR AND PLANETARY EXPLORATION
Meeting Information
Lunar Science Conference(Houston, TX)
Funding Number(s)
CONTRACT_GRANT: NSG-7034
Distribution Limits
Public
Copyright
Other