The Oxford 3D thermophysical model with application to PROSPECT/Luna 27 study landing sites

King, O. G.; Warren, T.; Bowles, Neil E.; Sefton‐Nash, E.; Fisackerly, R.; Trautner, R.

doi:10.1016/j.pss.2019.104790

Cited by 21 publications

(7 citation statements)

References 17 publications

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“…The external thermal radiation on the lunar surface at these sites was calculated with the Oxford 3D thermophysical model (King et al., 2020) for a time period of one Earth year starting in November 2014. This model takes into account direct solar, albedo, and infrared radiation, as well as three‐dimensional shadowing and scattering effects on the lunar surface and was validated with LRO Diviner temperature measurements.…”

Section: Investigated Sitesmentioning

confidence: 99%

Dynamics of Subsurface Migration of Water on the Moon

2021

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The existence of lunar water has been confirmed through a variety of remote sensing data, but to date, ground truth remains to be provided. Extended in-situ measurements will allow determining the form and abundance of lunar water and thereby gaining knowledge about its origin, formation, stability, and mobility. Forms of water may vary from loosely adsorbed and highly volatile hydroxyl groups, to water molecules, to thick subsurface deposits of crystalline ice (e.g., Li et al., 2018, and references therein). Possible sources of lunar water are asteroid or comet impacts, surface interactions with the solar wind, and outgassing from the lunar interior (e.g., Anand, 2010;Lucey, 2009;Lucey et al., 2020). It is unclear however, how larger ice deposits can develop from such surface-related processes (Cannon & Britt, 2020). Vertical transport of lunar water down to several meters can occur by impact mixing of the surface regolith. But because this is a highly energetic process, it is likely that released volatile material will be lost by sublimation and can only accumulate via trapping on a colder regolith surface. Subsurface migration therefore mainly happens by diffusion of molecules along particle surfaces or in voids between particles. Molecules trapped at the surface may diffuse to deeper layers of regolith by a mechanism called ice pumping, caused by thermal gradients and

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Section: Investigated Sitesmentioning

confidence: 99%

Dynamics of Subsurface Migration of Water on the Moon

2021

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“…so that the integral equations given by ( 6) and ( 7) are simply related to (9). In terms of the reflected short-wavelength flux Q vis = Q refl + Q direct , and using (2) to substitute for temperature, we get…”

Section: Physical Description and Governing Equationsmentioning

confidence: 99%

“…Instead, they directly evaluate the scattered irradiance between each pair of facets, e.g. [3,4,5,6,7,8,9,10,11]. Heretofore, the most powerful model published to date for surface temperatures in lunar craters is due to Paige et al [12].…”

Section: Introductionmentioning

confidence: 99%

Fast hierarchical low-rank view factor matrices for thermal irradiance on planetary surfaces

Potter¹,

Bertone²,

Schörghofer³

et al. 2022

Preprint

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We present an algorithm for compressing the radiosity view factor model commonly used in radiation heat transfer and computer graphics. We use a format inspired by the hierarchical off-diagonal low rank format, where elements are recursively partitioned using a quadtree or octree and blocks are compressed using a sparse singular value decomposition-the hierarchical matrix is assembled using dynamic programming. The motivating application is time-dependent thermal modeling on vast planetary surfaces, with a focus on permanently shadowed craters which receive energy through indirect irradiance. In this setting, shape models are comprised of a large number of triangular facets which conform to a rough surface. At each time step, a quadratic number of triangle-to-triangle scattered fluxes must be summed; that is, as the sun moves through the sky, we must solve the same view factor system of equations for a potentially unlimited number of time-varying righthand sides. We first conduct numerical experiments with a synthetic spherical cap-shaped crater, where the equilibrium temperature is analytically available. We also test our implementation with triangle meshes of planetary surfaces derived from digital elevation models recovered by orbiting spacecrafts. Our results indicate that the compressed view factor matrix can be assembled in quadratic time, which is comparable to the time it takes to assemble the full view matrix itself. Memory requirements during assembly are reduced by a large factor. Finally, for a range of compression tolerances, the size of the compressed view factor matrix and the speed of the resulting matrix vector product both scale linearly (as opposed to quadratically for the full matrix), resulting in orders of magnitude savings in processing time and memory space.

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“…Experiments with mixtures of lunar soil simulants and water ice at cryogenic temperatures (Nurge 2012) show a significant increase of ε r in the frequency range below 100 Hz. Lunar subsurface ice is stable over geologic timescales at temperatures around 110 K and can be found at shallow depths accessible by PROSPECT (Paige et al 2010, Schorghofer and Aharonson 2014, Hayne et al 2015, King et al 2020, Reiss et al 2021. An in-situ measurement of the dielectric constant versus frequency and temperature therefore allows to detect the presence of water ice in lunar regolith.…”

Section: Electrical and Physical Properties Of Lunar Regolithmentioning

confidence: 99%

A drill-integrated miniaturized device for detecting ice in lunar regolith: the PROSPECT permittivity sensor

Trautner

Kargl

2021

Meas. Sci. Technol.

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The detection and characterization of lunar resources, including water ice, is a key area of interest for a new generation of lunar missions. The electrical properties of water ice in the extremely low frequency range support its detection by means of in-situ permittivity measurements. A new type of miniaturized subsurface permittivity sensor is presented, which is under development for the PROSPECT package on the Luna-27 lander mission. Here, the sensor concept is described, key design features are presented and possible operations modes are introduced. The expected accuracy for measurements of the relative permittivity along the borehole is ∼10-15% and depends mainly on the accuracy of borehole geometry models. Laboratory test results from a prototype sensor on a water ice/simulant mixture at cryogenic temperatures are presented, demonstrating the capability to detect water ice at 125 K. The improved capabilities of the flight design are discussed, operational modes are explained and alternative electrode configurations for lunar landers and rovers are proposed.

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The Oxford 3D thermophysical model with application to PROSPECT/Luna 27 study landing sites

Cited by 21 publications

References 17 publications

Dynamics of Subsurface Migration of Water on the Moon

Dynamics of Subsurface Migration of Water on the Moon

Fast hierarchical low-rank view factor matrices for thermal irradiance on planetary surfaces

A drill-integrated miniaturized device for detecting ice in lunar regolith: the PROSPECT permittivity sensor

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