Early Dynamics of the Lunar Core

A new technique has been developed for the measurement of the thermal conductivity of lunar core samples. According to this technique, the core sample is heated radiatively from the outside at a known rate, the temperature is measured at the surface of the coretube, and the thermal conductivity of the sample is determined by comparing the measured temperature with the theory. The technique conforms with the aims of lunar sample preservation in that the sample remains intact after the measurements. The solution, as obtained in this paper, of a thermal conduction equation for a composite circular cylinder, with zero initial temperature and a constant heat-flux at its outer boundary, provides a theoretical basis for the present technique. Because of their mathematical similarity, the corresponding problems for a composite slab or sphere were also solved and the solutions are presented for possible future application to the thermal conductivity measurements. Testing demonstrated the feasibility of the new technique. The thermal conductivity of a simulant lunar soil sample, as determined by the present technique under vacuum conditions at about 300 K for sample densities of 1.47-1.67 g cm -3 , is 2.05-2.65 x 10 -3 W m -1 K -1 , which compares favourably with that of the same sample, 1.61-2.89 x 10 -3 W m -1 K -1 at sample densities of 1.50-1.75 g cm -3 , as measured under similar conditions by the standard line heat source technique. We describe in detail the experimental apparatus construction and procedure; in particular, the number of precautions taken to preserve the samples from disturbances and to improve the measurement results. This technique was successfully applied to the thermal conductivity measurement of two Apollo 17 drill-core samples. The results, 1.9-4.9 x 10 -3 W m -1 K -1 , which is intermediate between the values of thermal conductivity of the lunar regolith determined in situ (0.9-1.3 x 10 -2 W m -1 K -1 and those of lunar soil samples measured in the laboratory under simulated lunar surface conditions (0.8-2.5 x 10 -3 W m -1 K -1 ) presents an important clue to the understanding of heat transportation mechanisms in the lunar regolith.

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Seismic Detection of the Lunar Core

Science ◽

10.1126/science.1199375 ◽

2011 ◽

Vol 331 (6015) ◽

pp. 309-312 ◽

Cited By ~ 282

Author(s):

R. C. Weber ◽

P.-Y. Lin ◽

E. J. Garnero ◽

Q. Williams ◽

P. Lognonne

Keyword(s):

Seismic Detection ◽

Lunar Core

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A lunar core of Fe-Ni-S

Geochimica et Cosmochimica Acta ◽

10.1016/0016-7037(73)90255-x ◽

1973 ◽

Vol 37 (1) ◽

pp. 165-170 ◽

Cited By ~ 24

Author(s):

Robin Brett

Keyword(s):

Lunar Core

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Lunar core: occam's razor?

Eos ◽

10.1029/eo065i014p00129-03 ◽

1984 ◽

Vol 65 (14) ◽

pp. 129

Author(s):

Peter M. Bell

Keyword(s):

Occam’S Razor ◽

Lunar Core ◽

Occam's Razor

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Phase equilibria of a low S and C lunar core: Implications for an early lunar dynamo and physical state of the current core

Earth and Planetary Science Letters ◽

10.1016/j.epsl.2017.02.003 ◽

2017 ◽

Vol 463 ◽

pp. 323-332 ◽

Cited By ~ 12

Author(s):

K. Righter ◽

B.M. Go ◽

K.A. Pando ◽

L. Danielson ◽

D.K. Ross ◽

...

Keyword(s):

Phase Equilibria ◽

Physical State ◽

Lunar Core

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Inverting travel times with a triplication

Bulletin of the Seismological Society of America ◽

10.1785/bssa07206a2147 ◽

1982 ◽

Vol 72 (6A) ◽

pp. 2147-2170

Author(s):

Hans S. Jarosch

Keyword(s):

Body Wave ◽

P Wave ◽

Inversion Method ◽

Linear Inversion ◽

Time Curve ◽

Wave Travel ◽

Data Points ◽

A New Technique ◽

The Right ◽

Lunar Core

abstract A new technique has been developed to overcome difficulties which arise when body-wave data in the form of T-delta is reduced to the tau-p form in the presence of cusps. The technique uses sophisticated constrained spline fits to allow for constraints on the derivatives and thus eliminates the possibility of points of inflexion occurring as well as making sure that the curvature is in the right direction. Having arrived at a good fit to the T-delta data with a single spline, the tau-p curve can be derived which has taken the cusp properly into consideration. The tau-p curve is then inverted with a new linear inversion method, which again takes into consideration whether a particular point lies on a prograde or retrograde branch. The technique is applied to the lunar seismic data, where at least one triplication is presumed to occur for the P-wave travel-time curve. It is shown that the present analysis is not accurate enough to address itself to the problem of a possible lunar core, since there are insufficient data points for events close to the antipode of the center of the lunar network.

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