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Megaregolith thickness, heat flow, and the bulk composition of the MoonModels developed to assess the effects of megaregolith on lunar thermal evolution are discussed. It is confirmed that the two sites where lunar heat flow was measured are probably unrepresentative, with heat flows about 25% higher than regional averages, due to focussing of heat flow towards regions with thin megaregolith. Numerous lines of evidence indicate that the megaregolith is generally 2 to 3 km thick under highlands (which cover about 83% of the total lunar surface), and 1 km thick under maria. In most models, megaregolith thickness is assumed to be roughly 6x greater over highlands than over maria. Based on sparse data for porosity among lunar rock types, and the correlation between thermal conductivity and porosity, it is assumed that megaregolith conductivity is roughly 20 kiloerg s(-1)cm(-1)K(-1), and bedrock conductivity is roughly 7x greater. It is also found that insulation by megaregolith exacerbates the problem of reconciling modest temperatures inferred for the (present) matle with a high rate of heat production; an upper limit of 30 ng/g for the bulk-Moon U content can be derived from this constraint alone.
Document ID
19850005414
Document Type
Conference Paper
Authors
Warren, P. H. (California Univ. Los Angeles, CA, United States)
Rasmussen, K. L. (Copenhagen Univ.)
Date Acquired
August 12, 2013
Publication Date
January 1, 1984
Publication Information
Publication: Lunar Planetary Inst. Conf. on the Origin of the Moon
Subject Category
LUNAR AND PLANETARY EXPLORATION
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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IDRelationTitle19850005400Analytic PrimaryConference on the Origin of the Moon