Interpretation of the lunar microwave brightness temperature spectrum: Feasibility of orbital heat flow mapping

Keihm, S.

doi:10.1016/0019-1035(84)90165-9

Cited by 138 publications

(135 citation statements)

References 35 publications

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“…Hence, at least qualitatively, a thermal inertia increasing with depth over the first cm into the surface would account for the observed behavior. Such a behavior is actually observed on the regolith of the Moon (Keihm 1984) and Mercury (Mitchell & de Pater 1994), and has also been shown to occur on asteroid 21 Lutetia (Gulkis et al 2012), with an increase of Γ from about 5 MKS to 30 MKS over a 5 cm depth. Another example of this situation is the fact that the thermal inertia of Galilean satellites as determined from eclipse measurements, i.e.…”

Section: Comparison With Other Distant Icy Bodiessupporting

confidence: 57%

“TNOs are Cool”: A survey of the trans-Neptunian region

Lellouch

Santos-Sanz

Lacerda

et al. 2013

A&A

135

143

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Aims. The goal of this work is to characterize the ensemble thermal properties of the Centaurs / trans-Neptunian population. Methods. Thermal flux measurements obtained with Herschel/PACS and Spitzer/MIPS provide size, albedo, and beaming factors for 85 objects (13 of which are presented here for the first time) by means of standard radiometric techniques. The measured beaming factors are influenced by the combination of surface roughness and thermal inertia effects. They are interpreted within a thermophysical model to constrain, in a statistical sense, the thermal inertia in the population and to study its dependence on several parameters. We use in particular a Monte-Carlo modeling approach to the data whereby synthetic datasets of beaming factors are created using random distributions of spin orientation and surface roughness. Results. Beaming factors η range from values <1 to ∼2.5, but high η values (>2) are lacking at low heliocentric distances (r h < 30 AU). Beaming factors lower than 1 occur frequently (39% of the objects), indicating that surface roughness effects are important. We determine a mean thermal inertia for Centaurs/ TNO of Γ = (2.5 ± 0.5) J m −2 s −1/2 K −1 , with evidence of a trend toward decreasing Γ with increasing heliocentric (by a factor ∼2.5 from 8-25 AU to 41-53 AU). These thermal inertias are 2-3 orders of magnitude lower than expected for compact ices, and generally lower than on Saturn's satellites or in the Pluto/Charon system. Most high-albedo objects are found to have unusually low thermal inertias. Our results suggest highly porous surfaces, in which the heat transfer is affected by radiative conductivity within pores and increases with depth in the subsurface.

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Section: Comparison With Other Distant Icy Bodiessupporting

confidence: 57%

“TNOs are Cool”: A survey of the trans-Neptunian region

Lellouch

Santos-Sanz

Lacerda

et al. 2013

A&A

135

143

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“…Two numerical simulations were performed, one with the force-restore method and one with the multilayer-force-restore method. In both simulations, we used a local emissivity of 0.98 ε = and a local solar albedo expressed by Keihm's [80] empirical formula (slightly rearranged) ( )…”

Section: Generalization Of the Resultsmentioning

confidence: 99%

Using Earth’s Moon as a Testbed for Quantifying the Effect of the Terrestrial Atmosphere

Kramm¹,

Dlugi²,

Mölders³

2017

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In the past, the planetary radiation balance served to quantify the atmospheric greenhouse effect by the difference between the globally averaged near-surface temperature of ns T ≅ 288 K and the respective effective radiation temperature of the Earth without atmosphere of e T ≅ 255 K resulting in ns e T T − ≅ 33 K . Since such a "thought experiment" prohibits any rigorous assessment of its results, this study considered the Moon as a testbed for the Earth in the absence of its atmosphere. Since the angular velocity of Moon's rotation is 27.4 times slower than that of the Earth, the forcing method, the force-restore method, and a multilayer-force-restore method, used in climate modeling during the past four decades, were alternatively applied to address the influence of the angular velocity in determining the Moon's globally averaged skin (or slab) temperature, α . Thus, the effective radiation temperature yields flawed results when used for quantifying the atmospheric greenhouse effect.

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“…The thermal conductivity in the regolith of an airless body is temperature dependent (Keihm 1984), as is the thermal inertia. This temperature dependence of Γ must be taken into account in order to compare our results with those obtained for NEAs (e.g.…”

Section: Discussionmentioning

confidence: 99%

Spitzer observations of the asteroid-comet transition object and potential spacecraft target 107P (4015) Wilson-Harrington

Licandro

Campins

Kelley

et al. 2009

A&A

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Context. Near-Earth asteroid-comet transition object 107P/ (4015) Wilson-Harrington is a possible target of the joint European Space Agency (ESA) and Japanese Aerospace Exploration Agency (JAXA) Marco Polo sample return mission. Physical studies of this object are relevant to this mission, and also to understanding its asteroidal or cometary nature. Aims. Our aim is to obtain significant new constraints on the surface thermal properties of this object. Methods. We present mid-infrared photometry in two filters (16 and 22 μm) obtained with NASA's Spitzer Space Telescope on February 12, 2007, and results from the application of the Near Earth Asteroid Thermal Model (NEATM). We obtained high S/N in two mid-IR bands allowing accurate measurements of its thermal emission. Results. We obtain a well constrained beaming parameter (η = 1.39 ± 0.26) and obtain a diameter and geometric albedo of D = 3.46 ± 0.32 km, and p V = 0.059 ± 0.011. We also obtain similar results when we apply this best-fitting thermal model to single-band mid-IR photometry reported by Campins et al. (1995, P&SS, 43, 733), Kraemer et al. (2005, AJ, 130, 2363 and Reach et al. (2007, Icarus, 191, 298). Conclusions. The albedo of 4015 Wilson-Harrington is low, consistent with those of comet nuclei and primitive C-, P-, D-type asteorids. We establish a rough lower limit for the thermal inertia of W-H of 60 Jm −2 s −0.5 K −1 when it is at r = 1 AU, which is slightly over the limit of 30 Jm −2 s −0.5 K −1 derived by Groussin et al. (2009, Icarus, 199, 568) for the thermal inertia of the nucleus of comet 22P/Kopff.

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Interpretation of the lunar microwave brightness temperature spectrum: Feasibility of orbital heat flow mapping

Cited by 138 publications

References 35 publications

“TNOs are Cool”: A survey of the trans-Neptunian region

“TNOs are Cool”: A survey of the trans-Neptunian region

Using Earth’s Moon as a Testbed for Quantifying the Effect of the Terrestrial Atmosphere

Spitzer observations of the asteroid-comet transition object and potential spacecraft target 107P (4015) Wilson-Harrington

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