Discovery of Mass Anomalies on Ganymede

Anderson, J. D.; Schubert, G.; Jacobson, R. A.; Lau, E. L.; Moore, W. B.; Palguta, J.

doi:10.1126/science.1099050

Cited by 29 publications

(24 citation statements)

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“…Originally, these residuals were numerically differentiated by a cubic-spline technique developed for lunar mass concentrations (Muller and Sjogren, 1968; Paper I) yielding the spline fit acceleration data along the line of sight (Fig. 3) which Anderson et al (2004) used to produce their two and three mass point models. The large amount of noise, particularly in the wings, in the spline fit acceleration data complicated the inference of acceptable mass anomaly models.…”

Section: Sin φ) mentioning

confidence: 99%

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Mass anomalies on Ganymede

Palguta

Anderson

Schubert

et al. 2006

Icarus

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Section: Sin φ) mentioning

confidence: 99%

“…Solutions circled in red indicate broad positive anomaly regions. The locations of the two and three mass-point solutions published byAnderson et al (2004) are also included. The arrow shows the direction of the Galileo spacecraft along the trajectory track.…”

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confidence: 99%

Mass anomalies on Ganymede

Palguta

Anderson

Schubert

et al. 2006

Icarus

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“…In satellite geodesy there is a long history of local representations that have been applied successfully to different data types from satellites orbiting various planetary bodies. Examples include analysis for Venus [ Barriot and Balmino , ], Mars [ Beuthe et al , ], and Jupiter's moon Ganymede [ Anderson et al , ; Palguta et al , ], without even mentioning the many applications to Earth‐orbiting satellites. Prior to the SELENE and GRAIL missions the tracking data distribution for the Moon was extremely asymmetrical with no farside data available, and thus, the Moon was especially suitable for the application of local methods, mostly using Lunar Prospector data: Sugano and Heki [] and Goossens et al [] estimated anomalies while Han [] and Han et al [] used localized spherical harmonic functions to model the nearside gravity field.…”

Section: Introductionmentioning

confidence: 99%

High‐resolution local gravity model of the south pole of the Moon from GRAIL extended mission data

Goossens

Sabaka

Nicholas

et al. 2014

Geophysical Research Letters

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We estimated a high-resolution local gravity field model over the south pole of the Moon using data from the Gravity Recovery and Interior Laboratory's extended mission. Our solution consists of adjustments with respect to a global model expressed in spherical harmonics. The adjustments are expressed as gridded gravity anomalies with a resolution of 1/6° by 1/6° (equivalent to that of a degree and order 1080 model in spherical harmonics), covering a cap over the south pole with a radius of 40°. The gravity anomalies have been estimated from a short-arc analysis using only Ka-band range-rate (KBRR) data over the area of interest. We apply a neighbor-smoothing constraint to our solution. Our local model removes striping present in the global model; it reduces the misfit to the KBRR data and improves correlations with topography to higher degrees than current global models.Key Points We present a high-resolution gravity model of the south pole of the Moon Improved correlations with topography to higher degrees than global models Improved fits to the data and reduced striping that is present in global models

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“…It is possible that similar topographic anomalies will be detected in Cassini high‐resolution images of Rhea. Also, recent analysis of Galileo gravity science measurements at Ganymede by Anderson et al [2004] clearly indicates the presence of mascons, localized at the core‐ice shell interface (see Palguta et al [2004] for details about the characteristics of these mascons).…”

Section: Improvement In Model Parametersmentioning

confidence: 96%

Internal structure of Rhea

Castillo‐Rogez¹

2006

J. Geophys. Res.

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[1] We model the interior of Rhea on the basis of observational constraints and the results from geodynamical models available in the literature. Ten main types of models are defined, depending on the presence or absence of a high-pressure ice layer (ice II), and the extent of separation of the rock component from the volatiles. The degree-two gravity coefficients are computed for each of these models in order to assess which properties of the interior are likely to be inferred from Cassini radio science measurements scheduled on 26 November 2005. C 22 greater than 2.5 Â 10 À4 indicates that the satellite is undifferentiated, except for a slight increase in density with depth resulting from material self-compression. C 22 between 1.67 Â 10 À4 (lower bound) and 1.90 Â 10 À4 indicates the presence of a rocky core, whose radius can be determined from the satellite's mass and ices densities, for a given temperature profile. For other values, most of the ten models cannot be distinguished from each other. However, assumptions on the density of the rock phase, presence or absence of ice II, and the degree of differentiation could allow a unique model to be determined in many cases. While the calculation presented in this work assumes that Rhea is in hydrostatic equilibrium, it is likely that Rhea' gravity field is partly affected by nonhydrostatic anomalies.

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Discovery of Mass Anomalies on Ganymede

Cited by 29 publications

References 1 publication

Mass anomalies on Ganymede

Mass anomalies on Ganymede

High‐resolution local gravity model of the south pole of the Moon from GRAIL extended mission data

Internal structure of Rhea

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