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Tuesday, August 11, 2020 | History

3 edition of Bounds on lithospheric thickness on Venus from Magellan gravity and topography data found in the catalog.

Bounds on lithospheric thickness on Venus from Magellan gravity and topography data

Bounds on lithospheric thickness on Venus from Magellan gravity and topography data

NASA grant NAGW-4784 : final report

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  • 16 Currently reading

Published by National Aeronautics and Space Administration, National Technical Information Service, distributor in [Washington, DC, Springfield, Va .
Written in English

    Subjects:
  • Lithosphere.,
  • Thickness.,
  • Venus (Planet),
  • Tectonics.,
  • Data processing.,
  • Planetary evolution.

  • Edition Notes

    Statement[principal investigator], Catherine L. Johnson; [co-investigator], David Sandwell.
    Series[NASA contractor report] -- NASA-113058., NASA contractor report -- NASA CR-113058.
    ContributionsSandwell, David., United States. National Aeronautics and Space Administration.
    The Physical Object
    FormatMicroform
    Pagination1 v.
    ID Numbers
    Open LibraryOL15548326M

    Magellan's fourth eight-month cycle of Venus mapping, which began in September , was dedicated to collecting gravity data. The computer-generated perspective shown here compares gravity and topography over a reg kilometers by 8, kilometers and extends from longitudes degrees east to degrees east and latitudes 40 degrees. Mapping crustal thickness using marine gravity data: Methods and uncertainties Yongliang Bai1, Simon E. Williams 2, R. Dietmar Müller, Zhan Liu3, and Maral Hosseinpour2 ABSTRACT Crustal thickness is a critical parameter for understanding the.

    Magellan to determine the l = m = topography data set [Rappaport et al., ]. 2. Flexure Measured From Residual Topography Introduction and Method [7] The surface topography of Venus was mapped by the Magellan spaceprobe by picking the first return from a radar signal transmitted downward to the surface at each altimetry point. of negative crustal thickness provides a lower bound. For a reasonable choice of geologic parameters, we can give a plausible upper bound of 24 km for the mean crustal thickness and a lower bound of 11 km. Data: The Magellan mission to Venus provides the best available gravity and topography data. Real spherical harmonic coefficients € h.

    The global surface of Venus was first mapped by the Magellan orbiter during with 50 km spatial and m vertical resolution. During three orbit regimes, the surface images were transmitted back to the Earth. These three orbiting motions of the spacecraft are called mapping cycle 1, 2 and 3.   Here we investigate the lithospheric structure of Venus by calculating its crustal and effective elastic thicknesses (Tc and Te, respectively) from an analysis of gravity and topography, in order to improve our knowledge of the large scale and long-term mechanical behaviour of its lithosphere.


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Bounds on lithospheric thickness on Venus from Magellan gravity and topography data Download PDF EPUB FB2

Bounds on Lithospheric Thickness on Venus from Magellan Gravity and Topography Data Johnson, Catherine L.; Sandwell, David; Abstract. The primary objective of the work executed under NAGW is to provide constraints on the thermal and tectonic evolution of Venus. Author: Catherine L. Johnson, David Sandwell.

Get this from a library. Bounds on lithospheric thickness on Venus from Magellan gravity and topography data: NASA grant NAGW final report.

[Catherine L Johnson; David Sandwell; United States. National Aeronautics and Space Administration.]. Bounds on Lithospheric Thickness on Venus from Magellan Gravity and Topography Data PI: Dr.

Catherine L. Johnson, Carnegie Institution of Washington Co-I: Professor David Sandwell, Scripps Institution of Oceanography 1. SUMMARY The primary objective of the work executed under NAGW is to provide constraints on.

Bounds on Lithospheric Thickness on Venus from Magellan Gravity and Topography Data. By Catherine L. Johnson and David Sandwell. Abstract. The primary objective of the work executed under NAGW is to provide constraints on the thermal and tectonic evolution of Venus.

Establishing thermal and tectonic evolution models requires not only. The primary objective of the work executed under NAGW is to provide constraints on the thermal and tectonic evolution of Venus. Establishing thermal and tectonic evolution models requires not only geological, but geophysical constraints, in particular the nature of temporal and spatial variations in crustal and lithospheric thickness.

The major topics of study completed under NAGW Lithospheric thickness may be determined solely from modeling topographic flexure or by combining gravity and topography data. On Venus even the highest resolution gravity is insufficient for. Gravity and topography data acquired by the Magellan spacecraft between and remain the most complete set for constraining the structure of the venusian lithosphere.

We apply potential theory to model the crustal thickness of Venus from the relationship between gravity and topography data (Section 3). This analysis has been developed Cited by: 9.

Establishing temporal and spatial variations in lithospheric thickness on Venus is crucial to our understanding of the thermal and tectonic history of the planet. Magellan gravity and topography data, combined with a flexural model of compensation, in theory allow us to estimate lithospheric thickness globally, constraining the present day thermal boundary layer thickness: however, we are.

Global gravity and topography of Venus Gravity and topography data acquired by the Magellan spacecraft between and remain the most complete set for constraining the structure of the Venusian lithosphere.

We apply potential theory to model the crustal thickness of Venus from the relationship between gravity and topography data. [1] The topography of a terrestrial planet can be supported by several mechanisms: (1) crustal thickness variations, (2) density variations in the crust and mantle, (3) dynamic support, and (4) lithospheric stresses.

Each of these mechanisms could play a role in compensating topography on Venus, and we distinguish between these mechanisms in part by calculating geoid‐to‐topography.

The gravity and topography of Venus obtained from observations of the Magellan mission, as well as the gravity and topography from our numerical mantle convection model, are discussed in this paper. Gravity observations can be used to identify regions of hot, upwelling mantle. The Magellan spacecraft went into orbit around Venus in Augustand performed surface mapping of 98 percent of the planet with imaging radar for two years.

In its fourth day orbiting cycle, it began gravity. The gravity and topography of Venus obtained from observations of the Magellan mission, as well as the gravity and topography from our numerical mantle convection model, are discussed in this paper.

We used the hypothesis that the geoid of degrees 2–40 is produced by sublithospheric mantle density anomalies that are associated with dynamical process within the mantle. [6] To test the NGA approach for Venus, we calculated “observed” admittance (the spectral transfer function between gravity and topography), o F l, as a function of spherical harmonic degree, l, using a spatio‐spectral localization technique [Simons et al., ] and employing a scalable window.

The Magellan data are referenced to the cartographic system given by and are transformed into the system used by VIRTIS data, taking January as an approximate time of the Magellan observations.

However, the best correlation of the topography implied by temperature derived from VIRTIS infrared images and Magellan altimetry is found when. Venus’s crust is basaltic, dry, and probably about 30 km thick.

The mantle convects, giving rise to plumes, and has a similar composition and mean temperature (∼ C), but a higher viscosity (∼ Pa s), than that of the Earth. Inferred melt generation rates constrain the lithospheric thickness to between 80 and km.

From scalings of geoid/topography ratio and lithospheric basal slope as a function of internal Rayleigh number and viscosity contrast, we estimate lower bounds to these parameters of 10 7 and 10 5, respectively.

Several lines of evidence point to values near these lower limits, which puts Venus in the sluggish-lid regime of convection. ESTIMATES OF LITHOSPHERIC THICKNESS ON VENUS" C.L. Johnson and D. Sandwell, Scripps Institution of Oceanography, La Jolla, CA - Summary Magellan altimetry data have revealed many examples of topographic flexure on Venus.

Modeling of flexural features is of interest as it provides information on spatial (and for the earth. It places an upper bound at 90 +/- 10 km for the modal thermal lithospheric thickness of Venus, similar to the Earth’s oceanic lithosphere.

The low-excentricity, near-polar and relatively low altitude ( km) orbit of EnVision offers the opportunity to obtain a high-resolved gravity field at each longitude and latitude of the Venusian globe. Catherine L. Johnson has written: 'Bounds on lithospheric thickness on Venus from Magellan gravity and topography data' -- subject(s): Planetary evolution, Data processing, Tectonics, Lithosphere.

The spatial variation of the geoid/topography ratio over the large Venusian volcanic highland Beta Regio is suggestive of thermal compensation, i.e., support of the highland's topography by lithospheric thinning. Both the thickness of the lithosphere and the density contrast at its base can be inferred from a quadratic regression of suitably filtered ( km.Magellan gravity and topography data, combined with a flexural model of compensation, in theory allow us to estimate lithospheric thickness globally, constrain-ing the present day thermal boundary layer thickness: however, we are hindered by the varying spatial reso-lution of the gravity data, which places a lower bound.for lithospheric cooling on the Earth, the swell-push force G isthe gravitational constant,g is theaverage acceleration of gravity ( m/s2), k 5 (1/l is equal to geoid height times 2g2/2fG.

Fleitout and Frio-x,1/l y) is the two-dimen-devaux (, ) and Crough () extended this idea sional wavenumber vector where lis wavelength, and z.