A Comprehensive 3D Thermophysical Model for the Moon
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Feb 28, 2023
Surface and subsurface temperatures of the Moon are dictated by a complex interplay of several dependent parameters and therefore exhibit a significant variation both at local and regional scales. Knowledge of these temperature variations and thermophysical characteristics of the Moon is an important aspect for its scientific understanding (geophysical characterisation and thermal evolution). Such an information is also essential for planning future in-situ experiments, resource utilisation and even human exploration of the Moon.
Scientists at Physical Research Laboratory (PRL), Ahmedabad built a comprehensive three-dimensional thermophysical model for the Moon to derive its surface and sub-surface temperatures. A unique feature of this model is its ability to account for lateral heat transport in three dimensions by utilising the actual topography of any location on the Moon to compute its realistic surface and subsurface temperatures at any scale (from few cms to several kms.) Such a model is not available till date. The model considers all plausible conditions and parameters to derive the temperatures and thermophysical parameters of the lunar surface and subsurface to represent the most realistic scenario. The model results compare well with laboratory experiments and validated using Apollo in situ measurements.
Figure 1. Image showing the model derived surface temperatures for a small 100 sqm. area of Apollo 17 landing site, during lunar dusk time (21.5 Earth days). A contrast temperature variation (△T = ~300K) within the given area as predicted by the model shows its unique capability which was not available till date.
The capability of the model is demonstrated by deriving the thermophysical behaviour of a small area of Apollo 17 landing site at both regional and local scales (Figure 1). This work has several applications both for lunar science and exploration aspects. To list a few, it can be used to constrain the nature of the outermost porous/dust layer. Knowledge of the nature of this surficial layer on a global scale combined with model calculations of the subsurface heat propagation can help in estimating the subsurface boundary showing the influence of solar insolation. This is an important input for planning the depth of deployment of heat flow probes of future geophysical experiments on the Moon. This information can also effectively be used apriori in determining the lunar heat flow values based on remote observations and theoretical modeling. The unique ability of the model to import any complex topography facilitates the derivation of thermos-physical behaviour for any site of interest on the Moon to understand its local thermos-physics that has significant implications on polar water-ice prospecting studies and in situ resource utilisation. Further, in combination with laboratory measurements, the model will help to interpret data returned from future in-situ experiments, such as ChaSTE experiment on Chandrayaan-3 Lander. This model will also help understanding the local thermal environment of any location on the Moon which is an essential aspect for future human exploration and lunar habitat. Importantly, this work gains significance in view of the recent renewed interest in lunar exploration and planned attempts to send humans back to the Moon.
Durga Prasad, K., Rai, V. K., & Murty, S.V.S. (2022). A comprehensive 3D thermophysical model of the lunar surface, Earth and Space Science, 9, e2021EA001968. https://doi.org/10.1029/2021EA001968