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| Titel |
Investigating thermal properties of gas-filled planetary regoliths using a thermal probe |
| VerfasserIn |
M. D. Paton, A.-M. Harri, T. Mäkinen, S. F. Green |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
2193-0856
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Instrumentation, Methods and Data Systems ; 1, no. 1 ; Nr. 1, no. 1 (2012-03-29), S.7-21 |
| Datensatznummer |
250000130
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| Publikation (Nr.) |
 copernicus.org/gi-1-7-2012.pdf |
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| Zusammenfassung |
We introduce a general purpose penetrator, fitted with a heater, for
measuring temperature and thermal diffusivity. Due to its simplicity of
deployment and operation the penetrator is well suited for remote deployment
by spacecraft into a planetary regolith. Thermal measurements in planetary
regoliths are required to determine the surface energy balance and to
measure their thermal properties. If the regolith is on a planet with an
atmosphere a good understanding of the role of convection is required to
properly interpret the measurements. This could also help to identify the
significant heat and mass exchange mechanisms between the regolith and the
atmosphere. To understand the role of convection in our regolith analogues
we use a network of temperature sensors placed in the target. In practical
applications a penetrator will push material out of the way as it enters a
target possible changing its thermal properties. To investigate this effect
a custom built test rig, that precisely controls and monitors the motion of
the penetrator, is used. The thermal diffusivity of limestone powder and
sand is derived by fitting a numerical thermal model to the temperature
measurements.
Convection seems to play an important role in the transfer of heat in this
case. Firstly a diffusion-convection model fits the laboratory data better
than a diffusivity-only model. Also the diffusivity derived from a
diffusivity-convection model was found to be in good agreement with
diffusivity derived using other methods published in the literature. Thermal
diffusivity measurements, inspection of the horizontal temperature profiles
and visual observations suggests that limestone powder is compacted more
readily than sand during entry of the penetrator into the target. For both
regolith analogues the disturbance of material around the penetrator was
determined to have an insignificant effect on the diffusivity measurements
in this case. |
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