National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
Crustal Density and Global Gravitational Field Estimation of the Moon from GRAIL and LOLA Satellite Data
Šprlák, Michal ; Han, Shin-Chan ; Featherstone, Will ; Novák, Pavel ; Pitoňák, Martin
We employ Newton’s integral in the spectral domain to solve two geodetic/geophysical tasks for the Moon, see [1]. Firstly, we determine density distribution within the lunar crust (inverse problem). For this purpose, we exploit GL1500E GRAIL gravitational field model and LOLA topography to estimate: 1) constant, 2) laterally variable, and 3) 3D spatially variable crustal density. Secondly, we calculate lunar gravitational field models inferred by these three crustal compositions (forward problem) up to spherical harmonic degree 2519 (corresponding to a spatial resolution of 2.2 km at the lunar equator). We test the performance of our new models, and of recent and independent forward models, against the official Level 1B and Level 2 GRAIL products. Our high resolution global gravitational field models will be an asset to future lunar lander navigation and geophysical exploration of the Moon.
Estimation of Litospheric Elastic Thicknes from In-orbitGOCE-based Vertical Gradients and CRUST1.0
Pitoňák, Martin ; Eshagh, Mehdi ; Šprlák, Michal ; Novák, Pavel
The lithospheric strength with respect to the loading is represented by a parameter called elastic thickness (Te) and places with larger value of Te flex less. In this contribution, we use the in-orbit vertical gravitational gradients measured by Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite for determining the elastic thickness over Africa. A forward computational method is developed based on the Vening Meinesz-Moritz (VMM) and flexural theories of isostasy to find a mathematical relation between the second-order vertical derivative of the gravitational potential and mechanical properties of the lithosphere. This method is developed in terms of spherical harmonics. Loading effects of topography and bathymetry, sediments and crystalline masses are calculated from CRUST1.0, in addition to estimates of laterally-variable density of the upper mantle, Young’s modulus and Poisson’s ratio. The second-order vertical derivatives of the gravitational potential are synthesised from the crustal model and different a priori values of elastic thickness to find which one matches the GOCE in-orbit vertical gradient. Our map of Te over Africa shows that the high values of Te are mainly associated with the cratonic areas of Congo, Chad and the Western African basin while the intra-continental hotspots and volcanoes, such as Ahaggar, Tibesti, Darfur, Cameroon volcanic line and Libya are connected by corridors of low Te.

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