A new topographic image atlas of Phobos

Wählisch, Marita; Willner, Konrad; Oberst, J.; Matz, Klaus-Dieter; Scholten, F.; Hoffmann, H.; Semm, S.; Neukum, G.

doi:10.1016/j.epsl.2009.11.003

Cited by 34 publications

(12 citation statements)

References 13 publications

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“…Because the least squares fit of multiple blackbodies can result in values Figure 1. Coverage map of high-quality TES spectra from orbit 551 on a Mars Express HRSC global photomosaic (Wälisch et al, 2010). greater than unity at some wavelengths, the resulting spectra are not strictly emissivity, and we report the values as emission or thermal emission. However, conversion of these data to standard emissivity following the methods of Christensen et al (2001) is also possible, though it requires the assumption of an emissivity maximum less than unity (in this case we choose 0.9 near 1,200 cm À1 ).…”

Section: Tes Data Processingmentioning

confidence: 99%

MGS‐TES Spectra Suggest a Basaltic Component in the Regolith of Phobos

et al. 2018

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The origins of the Martian moons Phobos and Deimos have been the subjects of considerable debate. Visible and near‐infrared spectra of these bodies are dark and nearly featureless, with red slopes of varying degrees. These spectra are generally consistent with those of carbonaceous asteroids, leading to the hypothesis that Phobos and Deimos are captured carbonaceous asteroids. The shapes and inclinations of the orbits of Phobos and Deimos present problems for the asteroid capture hypothesis. This had led researchers to suggest that Phobos and Deimos coaccreted with Mars or that they are the result of an impact with Mars or in the Mars vicinity. In this work, we reexamine Mars Global Surveyor Thermal Emission Spectrometer (MGS‐TES) data of Phobos and compare spectra of the Phobos surface to mid‐IR spectra of the ungrouped C2 meteorite Tagish Lake (a suggested analog for D‐class asteroids) and particulate basalt and phyllosilicate samples (mixed with carbon black to reduce their visible albedos) acquired in a simulated airless body environment. We find that Tagish Lake is a poor mid‐IR spectral analog to Phobos and that major spectral features in the Phobos spectrum are best matched by a silicate transparency feature similar to that found for finely particulate basalt. Other features in the spectrum are likely best explained by a phyllosilicate component. We suggest that these results indicate that at a portion of the Phobos surface regolith is derived from the Martian crust.

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Section: Tes Data Processingmentioning

confidence: 99%

MGS‐TES Spectra Suggest a Basaltic Component in the Regolith of Phobos

et al. 2018

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“…While gravitational and topographic datasets can each be used independently to make inferences about the interior structure of a planet, such results are often based upon hypotheses that are not easily testable or models that are highly underconstrained. Thus, although regional topographic models have been constructed for some moons and asteroids (such as Phobos (Wählisch et al, 2010), 433 Eros (Gaskell et al, 2008;Zuber et al, 2000a), Itokawa (Abe et al, 2006;Gaskell et al, 2008), Vesta ( Jaumann et al, 2012), Ganymede (Giese et al, 1998), Europa (Nimmo et al, 2003a,b;Nimmo et al, 2007), Iapetus (Giese et al, 2008), Mimas (Dermott and Thomas, 1988), Enceladus , Tethys , Dione , Rhea , and many of the irregularly shaped satellites of Saturn (Thomas, 2010)) and the longest wavelength gravitational fields and topography have been constrained for others (such as Io (Anderson et al, 2001a;Thomas et al, 1998), Europa (Anderson et al, 1998), Ganymede (Anderson et al, 1996b;Palguta et al, 2006), Callisto (Anderson et al, 2001b), Rhea (Anderson and Schubert, 2010), Titan (Iess et al, 2010;Lorenz et al, 2013), and Vesta (Konopliv et al, 2013a)), this chapter will focus on those planetary bodies for which the gravity and topography are both characterized to high resolution, namely, Earth, Venus, Mars, Mercury, and the Moon.…”

Section: Introductionmentioning

confidence: 99%

Gravity and Topography of the Terrestrial Planets

Wieczorek¹

2015

Treatise on Geophysics

134

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“…The DTM is used as a reference to compute ortho-rectified images. Such image maps are often applied in detailed analyses and are needed for accurately mapping surface features (Wählisch et al, 2010). On the other hand, a new spherical harmonic function model of degree and order 45 is provided that is used to compute volume estimates, bulk density, and rotation parameters (Willner et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Phobos' shape and topography models

Willner

Shi

Oberst

2014

Planetary and Space Science

Self Cite

104

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The global shape and the dynamic environment are fundamental properties of a body. Other properties such as volume, bulk density, and models for the dynamic environment can subsequently be computed based on such models. Stereo-photogrammetric methods were applied to derive a global digital terrain model (DTM) with 100 m/pixel resolution using High Resolution Stereo Camera images of the Mars Express mission and Viking Orbiter images. In a subsequent least-squares fit, coefficients of the spherical harmonic function to degree and order 45 are computed. The dynamic models for Phobos were derived from a polyhedron representation of the DTM. The DTM, spherical harmonic function model, and dynamic models, have been refined and represent Phobos' dynamic and geometric topography with much more detail when compared to Shi et al. (2012) and Willner et al. (2010) models, respectively. The volume of Phobos has been re-determined to be in the order of 5741 km 3 with an uncertainty of only 0.6% of the total volume. This reduces the bulk density to 1.867 0.013 g/cm 3 in comparison to previous results. Assuming a homogeneous mass distribution a forced libration amplitude for Phobos of 1.141 is computed that is in better agreement with observations by Willner et al. (2010) than previous estimates.

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A new topographic image atlas of Phobos

Cited by 34 publications

References 13 publications

MGS‐TES Spectra Suggest a Basaltic Component in the Regolith of Phobos

MGS‐TES Spectra Suggest a Basaltic Component in the Regolith of Phobos

Gravity and Topography of the Terrestrial Planets

Phobos' shape and topography models

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